INTEGRATED SOIL MANAGEMENT FOR SUSTAINABLE … · different production constraints (soil acidity, vertic properties, low fertility, shallow soils, saline and poorly drained soils)

AGL/MISC/23/99

INTEGRATED SOIL MANAGEMENT FORSUSTAINABLE AGRICULTURE AND

FOOD SECURITY IN SOUTHERNAND EAST AFRICA

AGL/MISC/23/99

INTEGRATED SOIL MANAGEMENT FOR SUSTAINABLEAGRICULTURE AND FOOD SECURITY IN SOUTHERN

AND EAST AFRICA

PROCEEDINGS OF THE EXPERT CONSULTATION

Harare, Zimbabwe8-12 December 1997

H. Nabhan A. M. Mashali

A. R. Mermut

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONSRome, 1999

Preface

Land degradation, either natural or induced by humans, is a continuing process. It has become,however, an important issue through its adverse effects on national natural resources, foodsecurity, and the livelihood of the world population. Much has been said and documented aboutland degradation but there are still gaps of knowledge, due to the fact that only a few countrieshave really developed cost-effective technologies for mitigation. Inappropriate land use is amajor cause of declining soil quality. In many countries, especially in sub Saharan Africa, thereis continuous stress on the limited land resources due to population pressure. Food security isdirectly related to the ability of land to support the population.

Causes for land degradation are numerous and include decline of soil fertility, development ofacidity, salinization, alkalization, deterioration of soil structure, accelerated wind and watererosion, loss of organic matter and biodiversity. Efforts to restore productivity of a degradedland must be coupled with efforts to recognize productive capacity of soil resources. Restoringthe soil quality for crop production through the appropriate soil management and conservationtechniques is important for all nations, primarily those at risk with respect to food security.Although cost effective options are available to restore the soil quality and productivity, there isa need to increase awareness at high policy-making level with sound scientific evidence. It is,therefore, important to develop spatial or other databases about the extent of soil degradation, itsbiophysical, economic and social impacts, as well as successful examples of soil productivityimprovement programmes.

The FAO Land and Water Development Division (AGL), in collaboration with the SubregionalOffice for Southern and East Africa (SAFR) and the Agricultural Technical and ExtensionServices (AGRITEX) of Zimbabwe, organized this expert Consultation on "Integrated SoilManagement for Sustainable Agriculture and Food Security" with the following mainobjectives:

• examine the status of land degradation under contrasting agro-ecological conditions;

• exchange experiences on constraints for controlling land degradation and examinepossible solutions to overcome these constraints;

• discuss proposals for national and subregional programmes in support of landdevelopment schemes to enhance soil productivity, in support of food security in sub-Saharan Africa.

During the Consultation, held in Harare from 8 to 12 December 1997, overview and countrypapers were presented by senior specialists from Eritrea, Ethiopia, Kenya, Malawi, Namibia,South Africa, Tanzania, Uganda, Zambia, and Zimbabwe, FAO Headquarters and from manynational and international institutions. Besides the representatives from the ten countries, anadditional ten soil scientists, agricultural land development planners, extensionists and farmers’union officials from various Ministry of Agriculture departments of Zimbabwe, as well as eightscientists from the Tropical Soil Biology and Fertility Programme (TSBF), and FAO consultantsand resource persons from the UK, Sweden and the International Soil Research and InformationCentre (ISRIC) participated in the Consultation. The wide range of participants in the

iv

consultation reflects the international interest in land degradation in sub Saharan Africa. Theseproceedings provide very useful information about land degradation in general and the situationin the ten countries of the region.

In the light of discussions, recommendations are made to increase exchange of experience andactivities in the area of research and technology development, especially the assessmentmethodologies, extension and training, policies and legislation, strategies, publications andnetworking.

Integrated soil management for sustainable agriculture and food security in Southern and East Africa v

Contents

page

SUMMARY REPORT 1

OVERVIEW PAPERS 15

Land degradation with focus on salinization and its management in Africa,by A.M. Mashali 17

Land degradation in relation to food security with focus on soil fertility management,by H. Nabhan 49

Erosion-induced loss in soil productivity and its impacts on agricultural productionand food security, by M. Stocking and A. Tengberg 91

Soil degradation assessment and soil conservation inventory on a SOTER basis:Asian experience, by G.W.J. Van Lynden 121

Socio-economic impacts of soil management for sustainable agriculture andfood security in Africa; with particular reference to Zimbabwe, by D. Tawoneziand P.N. Sithole 127

Soil and water conservation, soil moisture management and conservation tillagein Zimbabwe, by G. Nehanda 153

COUNTRY REPORTS 177

Eritrea 179

Ethiopia 197

Kenya 211

Malawi 231

Namibia 247

South Africa 263

Tanzania 295

Uganda 319

Zambia 337

Zimbabwe 355

vi

Annex 1 Opening and closing addresses 383

Annex 2 Programme 389

Annex 3 List of participants 393

Annex 4 Maps 397

Integrated soil management for sustainable agriculture and food security in Southern and East Africa vii

Acknowledgements

The contribution through country and overview papers by the country specialists and resourcepersons is greatly acknowledged.

The efforts of AGRITEX staff, Messrs H.Nabhan, A.Mashali, C.F Mushambi, A.Savva and MsK. Franken in the organization of the Expert Consultation are highly appreciated .

Special thanks are due to Messrs H.Nabhan, A.Mashali, M.Gosi ,and A.R. Mermut for thecompilation, review and editing of these proceedings .

Integrated soil management for sustainable agriculture and food security in Southern and East Africa 1

Summary report

Nearly one thousand million ha of vegetated land in developing countries are subjected to variousforms of degradation, resulting in moderate or severe decline in productivity. About 490 millionha in Africa are affected by different types of degradation from the approximately 2 976 millionha total land area in Africa. Of this total land, 72% (2 146 million ha) are problem soils withdifferent production constraints (soil acidity, vertic properties, low fertility, shallow soils, salineand poorly drained soils). Poor and inappropriate soil management is the main cause of physicaland chemical degradation of cultivated land. Soil degradation is the most serious environmentalproblem affecting sub-Saharan Africa (SSA). In many parts of SSA fallow periods are beingreduced considerably and farmers are increasingly cultivating marginal lands susceptible tovarious forms of degradation. Increasing population pressure, particularly in vulnerable regionshas caused serious soil productivity decline especially under extensive farming practices. This ismanifested by declining yields, decreasing vegetation cover, salinization, fertility decline andincreasing erosion.

With recent emphasis on the priority programme of FAO on Food Production in Support ofFood Security (SPFS), issues related to land degradation and its negative impact on foodproduction as well as land improvement for enhanced productivity are receiving special attention.Rectifying soil degradation and sustaining crop production through appropriate management andconservation are, therefore, important components in the effort towards security. Successfulexperience and initiatives for soil improvement in specific countries or socio-economic and agro-ecological environments have taken place but their wider dissemination for the benefit of othercountries, even in the same region, is rather limited. There is an urgent need to develop andimplement sub-regional and national programmes, as well as projects at community level tocontrol land degradation and to improve land productivity.

Therefore, the FAO Land and Water Development Division (AGL), in collaboration with theSubregional Office for Southern and East Africa (SAFR) and the Agricultural TechnicalExtension Services (AGRITEX) of Zimbabwe, has organized this Expert Consultation

The FAO Subregional Office for Southern and East Africa represents 21 countries. Of these,four are in the Indian Ocean and 17 are within the continent of Africa (Figure 1).

Out of the 21 countries, ten were given the opportunity to participate in this importantExpert Consultative Workshop on Integrated Soil Management for Sustainable Agriculture andFood Security. The main objectives of the workshop were:

• Discuss the status of land degradation under contrasting agro-ecological and socio-economicconditions.

• Exchange experiences on constraints for controlling land degradation and examine possiblesolutions to overcome these constraints.

• Develop national and sub-regional programmes in support of land development schemes toenhance productivity in support of food security in the region.

Summary report2

Reversing the process of soil degradation and sustaining crop productivity through soilmanagement and biodiversity conservation are important aspects of food security. Although costeffective options are available, there is a need to increase the awareness campaign at high policy-making level as well as maintain the determination of agriculturists to achieve their goals. It is,therefore, important to document the information on the extent of soil degradation, itsbiophysical, economic and social impacts as well as successful examples of soil improvementprogrammes within the region.

ATTENDANCE

The Expert Consultation was attended by senior specialists from ten African countries of theSubregion for Southern and East Africa: Eritrea, Ethiopia, Kenya, Malawi, Namibia, SouthAfrica, Tanzania, Uganda, Zambia and Zimbabwe. Besides representatives from the mentionedcountries, some ten soil scientists, agricultural land development planners, extension and farmers'

FIGURE 1Countries served by the FAO Subregional Office for Southern and East Africa


unions from relevant departments of Zimbabwe, as well as eight scientists from the Tropical SoilBiology and Fertility Programme (TSBF) - Kenya, Malawi, Tanzania Zambia, Zimbabwe andUganda - and officials from FAO Headquarters (2), FAO Subregional Office for Southern andEast Africa (2), Regional Office for Africa (1) and FAO consultants and resource persons fromEngland, Sweden and the International Soil Research and Information Centre (ISRIC)participated in the Consultation, with a total of 35 participants.

OPENING OF THE EXPERT CONSULTATION

On Monday, 8 December, after registration of the participants, the Opening Session took place atSt. Lucia Park Training and Development Center, where H.E. the Minister of Lands andAgriculture, Cde Kumbirai Kangai and the Chief of the Soil Resources, Management andConservation Service of FAO Headquarters, Dr P. Koohafkan (on behalf of the Land and WaterDevelopment Division of FAO, and the Southern and East Africa Subregional FAORepresentative, Ms V. Sekitoleko), addressed the Expert Consultation. The opening session wasfollowed by three overview papers on (i) Land degradation and its impact with focus on salinityand fertility decline and their management; (ii) Erosion induced loss productivity, its implicationon land use and food security; and (iii) Methodologies of soil degradation assessment with focuson GLASSOD /SOTER using the Asian experience (ASSOD).

COUNTRY PAPERS

Three technical sessions were devoted to discussion of country papers on:

• Evaluation of country production and projected demands• Evaluation of per caput arable land, crop yields and causes of yield stagnation• Assessment of soil degradation: its causes and its bio-physical and socio-economic impact• Available technological options for controlling soil degradation and for productivity• Successful cases on improved soil management scheme and reasons for success• Institutional, socio-economic and policy issues related to land resources and degradation.

Three papers were also presented from Zimbabwe on:

• Socio-economic aspects of soil management for sustainable agriculture and food security inAfrica

• Soil and water conservation, soil moisture management and conservation tillage inZimbabwe

• Water harvesting and small-scale irrigation.

OTHER BUSINESS

A video show of the 14th meeting of the Soil Science Society of East Africa (SSSEA) on"Enhancing farmers efforts to combat soil degradation has been demonstrated to the Consultationparticipants. The video indicated that scientists, administrators, policy makers and farmers wereconcerned with the issue of soil degradation in the sub-region (Uganda and Tanzania participatedin that meeting). Commitment of Uganda Government and other sub-regional governments to theissue of soil degradation was outlined. The SSSEA members were happy to note that FAO would

Summary report4

respond to the deterioration of soil productivity through the establishment of a new Southern andEast Africa Subregional Network on Management of Degraded Soils.

One day (10 December) was devoted to field visits and on-site discussions. The participantswere driven to Mangwende Communal Area in Murehua and shown three programmes on soilfertility:

• The effect-of low and high quality manure on the improvement of soil fertility on crop.• The effect of storage practices on the quality of communal area manure.• The use of legume inoculant on a crop of soybeans and the effect of residual N (Nitrogen) on

crop rotation.

After discussions on each programme, the participants were shown active and reclaimedgullies in the same area. Lastly, the group visited a stream bank conservation programme, wherefarmers are encouraged to cultivate pieces of land situated away from the river bank. On thispiece of land, these farmers were provided with fencing materials by the Department of NaturalResources and a well for drawing water was dug using funds from a donor agent. The water isused for irrigating the gardens.

PARTICIPATORY WORKING GROUP DISCUSSIONS

One and-a-half days have been devoted to group discussions. The participants were divided intothree groups to discuss the following issues:

• present and outlook for food production and security in the participating countries,

• identification of land degradation and degraded soils - quantification of magnitude anddistribution,

• assessment of human-induced soil degradation, proposals, methodologies for assessment.Soil vulnerability to different degradation processes (as early warning system). Ifmethodologies are available, how they can be used for the sub-region (data availability tocarry out such assessment),

• dominant types of land degradation, (chemical, physical, biological), causes and processes,

• research, measuring, interpretation and prediction methods including new technologies(modelling, GIS, expert system, decision support system, remote sensing, etc.),

• bio-physical-environmental and socio-economic impacts of soil degradation: (i) evidence andindicators of impacts of degradation on productivity, and (ii) assessment of economicimpacts of degradation,

• technologies available for improving the productivity of degraded soils: constraints andsolutions. Sustainable integrated management of degraded soils (techniques): (i) availabletechnologies for addressing or controlling various types of degradation: and physicaldegradation - fertility decline – salinization and (ii) analysis of factors which are limitingwider adoption of improved technologies to above major types of degradation,

• policy and land tenure issues: institution set-up and coordination at local subnational andnational level, farmers' participation in land improvement schemes, role of associations,cooperatives, extension services: (i) government responsibility: monitoring of soildegradation, control at country and regional level (regulation, legislation, etc.) and (ii)


influencing, decision makers/increasing awareness about land degradation and solutions forland productivity improvement,

• research and monitoring requirements: (i) applied research, decision support system,integrated approach, monitoring system, requiring more research, mechanism, programmesand government support and interest, (ii) the role of private (multinational) companies, largefarms, and (iii) the role of farmer associations, organizations,

• national and regional plans for improvement and control of soil degradation,

• proposal for a network on management of degraded and problem soils in the subregion -objectives, activities, mechanisms, membership and expected outputs includingnewsletters/publications, pilot field activities (demonstration of trials on improvedmanagement techniques), training, workshop, etc.

At the end of these group discussions, three summary reports were produced.

RECOMMENDATIONS

In the light of the discussions, the Expert Consultation agreed on the following recommendationsas the basis of future activities.

Technologies and Research

• Further investigation and understanding of existing indigenous technologies,

• Compiling available technologies,

• Pursue integrated and sustainable soil management issues such as biophysical, economic andsocial viability,

• Develop problem oriented and farmer participatory research approach to tackle landdegradation problems in the sub-region.

Extension and Training

• Both demonstrations and training of people (research, extension, farmer) should be part ofthe introduction of new technologies,

• Technologies should be made available to farmers through extension programmes in thecountry wherever applicable,

• Support for farmer conservation groups.

Policies, Institutions and Laws

• Formulate effective land tenure and land use policies to create conducive environment forimproved integrated management technology for land degradation control,

• Creation of enabling policies to encourage management, conservation and sustainability ofland resources should include land tenure, environmental protection and a set of frameworkfor conservation,

• Countries should commit themselves to review natural resources and implementation of thepolicies,

Summary report6

• People should be trained to implement these policies,

• Create strong institutions to backstop management and conservation initiatives at local level,

• Strengthen institutional capacity to adopt and utilize new and improved technologies.

Strategies

• Causes of food insecurity should be identified as well as strategies to address these causesand the possible constraints to these strategies.

Models

• Prediction models should be used as possible scenarios to monitor land degradation.

Standard Analytical Methods

• Quality control and standardized analytical methods are required to make comparison ofresults between countries within the sub-region.

Assessment of methodologies

• Available methodologies for the assessment of land degradation include WOCAT,GLASOD, ASSOD, etc. It is recommended that in using similar methods for the sub-region,the following should be considered:

• The scale on which the information is presented should be revised on a regional basis,utilizing the polygon concept as is done in Asia studies (ASSOD),

• Countries should concentrate on the quantification of land degradation processes,

• Countries should consider the utilization of the ASSOD impact evaluation methodology andmodify it when deemed necessary for the sub-region conditions,

• Existing impact assessment technologies may be reviewed and utilized wherever applicable(reference Jan de Graaff, Stocking, etc.),

• The state-of-the-art of existing technologies should be compiled through modified and moreeffective mechanisms suitable for the sub-region, i.e. modification of WOCATmethodologies.

Projects

• First priority: projects to keep good land conserved. Dissemination and implementation ofgood practices,

• Rehabilitation of degraded land - target "hot spots" and "potential hot spots”. Use of besttechnologies (irrigation, improved fallow, etc., adapted to local social and economiccircumstances),

• Use of food security scenarios as tools to design and target implementation projects andappropriate interventions.

Publications

• Prepare a state-of-the-art/overview document on management of degraded soils in Africawith particular reference to the Southern and East Africa sub-region conditions.


Networking

• The group agreed to create a new network on the management of degraded soils. The firstactivity of this network should include the evaluation of ongoing networks in the region asTSBF (Tropical Soil Biology and Fertility), ALASA, CIMMYT (soil fertility), etc. Based onthis evaluation, activities of the proposed network will be identified including supplementaryfield work to control other land degradation processes not included ongoing networks,newsletters, internet, workshops, farmer-to-farmer visits and prediction models.

GROUP DISCUSSION REPORTS

Group discussion report for Group One (Tanzania, Kenya, Ethiopia, Eritrea)

Outlook of food situation

Eritrea and Ethiopia experience food deficit. Tanzania and Kenya are self-sufficient at countrylevel but not at household level. All countries require improved technology for future foodproduction.

Types and extent of soil degradationType Eritrea Ethiopia Kenya TanzaniaErosion +++ +++ +++ +++Fertility decline ++ ++ ++ ++Acidification + + + +Sodicity/salinity ++ ++ ++ ++Compaction and crusting + + ++ +Water logging ++ +

+ : Low, ++ : Moderate, +++ : High

Technologies applied to control degradationTechnology Eritrea Ethiopia Kenya TanzaniaSoil & water conservation ++ ++ +++ +++Minimum tillage + +Inorganic fertilizer + + +++ +Liming +Manure & organic + fertilizer ++ ++BNF + + ++ +Agroforestry ++ +


Assessment of land degradation

• Kenya has identified indicators of land degradation but the assessment techniques need to bedeveloped in the four countries.

• Modelling and GIS facilities are in place but need to be utilized effectively.

• The socio-economic impact of degradation in the four countries is high. However, thequantitative assessment has not been adequately undertaken.

Soil degradation indicators identified

• Yield decline

• Reduced fallow periods

Summary report8

• Deforestation

• Encroachment on marginal land

• Erosion features (gullies, siltation of dams)

• Loss of biodiversity

• Shrinkage of agricultural land

Availability of technology

Technologies Eritrea Ethiopia Kenya TanzaniaSoil & water conservation ++ ++ +++ ++Minimum tillage + + +++ +Inorganic fertilizer ++ ++ +++ ++Liming + + + +Manure & organic + fertilizer ++ + + ++BNF + + ++ +Agroforestry + + + +Salinity reclamation + + + +


Adoption of technologies

Technologies Eritrea Ethiopia Kenya TanzaniaSoil & water conservation + + ++ ++Minimum tillage + + + +Inorganic fertilizer + + ++ +Liming + + + +Manure & organic + fertilizer + + ++ ++BNF + + ++ +Agroforestry + + + +Salinity reclamation + + + +


Constraints limiting adoption

• Soil and Water Conservation: Labour shortage, lack of training, lack of awareness, decreasein size of agricultural land, lack of credit, poor extension, poor infrastructure, poor linkage,land tenure systems

• Minimum Tillage: Lack of information, lack of extension services, lack of inputs (herbicidesand equipment)

• Inorganic Fertilizers: High costs, limited availability, lack of knowledge, adverse effects onsoils

• Liming and Liming Materials: Not adequately researched, lack of information, high costs,lack of awareness on acidity problems

• Manure and Organic Fertilizers: Unavailability, alternative uses (fuel), lack of transport,poor storage, preservation, ow nutrient content

• Biological Nitrogen Fixation: Lack of adequate research, lack of seed inoculants, poorfixation (low P), lack of information


• Agroforestry: Competition with crops (light, moisture nutrients), incomplete package, lack ofawareness, land shortage, lack of seedlings, lack of convincing results

• Salinity reclamation: Lack of awareness, technology not well developed, high input costs

Policy issues

• Land use policies and tenure systems exist in the four countries but they vary

• Existing instruments to enforce land use policies are not effective

• Farmer participation in all countries exists, but needs to be further promoted

• Cooperatives and farmer associations exist but they are poorly managed

• The ratio of extension/farmers is very wide and at the same time facilities for effectiveextension are very limited

Research and monitoring requirements

• Private sector supports research on cash crops in Kenya and Tanzania

• All research in Ethiopia and Eritrea is supported by Government

• NGOs are actively involved in research in all countries

• Applied research, decision support and monitoring systems are in place in the four countries,but they need to be strengthened

National and regional plans

• Regional Programmes in Soil and Water Conservation include IGAD, ICRAF, CAHI (AHI,AFRENA), SWNM (soil, water, nutrient management and others)

Group discussion report for Group Two (Zambia, Zimbabwe and Uganda)

Status of food security

• Issues and problems

• National: seasonal fluctuations in food security - imports of food, post-harvest storage anddistribution

• Subnational: accessibility and availability, post-harvest storage and distribution

• Type of food, preference: Matoke (Uganda), Maize - monocrop (Zimbabwe and Zambia)

• Household: affordability and availability e.g. draught power h/h structure,entrepreneurship/resources/land, labour, capital, seasonal deficits, access to technology

Does land degradation cause food insecurity?

• How?

• Fertility decline

• Population migration

Summary report10

• Shift from cropping to livestock which promotes overgrazing

• Higher albedo and higher soil surface temperatures

• Greater vulnerability to drought

Positive effects of land degradation (trigger)

• Adaptation

• Diversification

• Technology uptake and intensification

Examples from the region: smallholder irrigation (Zimbabwe - Mvuma), banana mulching(Uganda - Kabale), agroforestry (Zambia, Chipata), smalholder irrigation (Uganda - Mbuka).

Conditions for positive outcome

• Enabling policy environment

• Institutional and legal framework

• Political (in)stability

• Marketing and economic incentives

Degradation Case Studies

‘Hot Spots’Zambia: Southern province, smallholder rainfed monocropping of maize (fertility decline and soilerosion) (4 to 5 years of cropping before critical level is reached).Farm size: 2.5-5 haSoil type: AcrisolCrop: maizeErosion rates: 20 tonnes/ha/yearFarm family: 2 adults + 4 childrenProduction potential: 3,600 kg/ha

Zimbabwe: North eastern part (Mutoko), natural region 4, soil erosionSoil type: AcrisolsFarm size: 1-2 haErosion rates: 50-60 tonnes/haCrop: MaizeFarm family: 2 adults + 4 childrenProduction potential: 3 tonnes/ha

Uganda: Kabale, soil erosion because of steep slopes (water erosion)Crop: Sorghum (less susceptible to bad conditions than maize)Soil type: FerralsolErosion rate: 10-30 tonnes/haYield potential: 2 tonnes/haFarm size: 1 ha


Successful SpotsUganda: Nangabo (near Kampala)Local institutions and strong farmer-to-farmer interactionAccess to technologyGood marketing infrastructureCrop: sweet potatoesManagement: crop rotation, mulching, livestock interaction

Zimbabwe: smallholder irrigation in Mushandike near Maswingo, 1 ha per farmer, abandoneddryland farming in surrounding areasCrops: maize and riceSoil type: CambisolErosion rate: 10-20 tonnes/haYield potential under irrigation: 6-7 tonnes/ha

Zambia: Eastern Zambia, Saeli, Chipata South, maize - previously serious soil erosionSoil type: Cambisols, 5% slope (pockets of Acrisols)Agroforestry technology approachFarm Size: 0.25 haErosion rate: 45 tonnes/ha before, now 5-10 tonnes/halots of biological measuresYields now: 4.5 tonnes/ha (formerly 1.5 tonnes/ha)crop rotation

‘Potential’ Hot Spots:Zambia: northern province (acidification)Soil type: Ferralsol/AcrisolSub-humid, shifting cultivation zone

Uganda: Mount Elgon/ Mbale area (water erosion on steep slopes)

Zimbabwe: Zambezi Valley, shallow and erodible soils, tsetse clearance encourages immigration

General Degradation Issues

• Fertility depletion - presently N, P, and S deficits (cropping, erosion, leaching, humification),potentially K by the same processes

• Organic matter depletion - affects plant available water, soil structure, erodibility, nutrientsupply, biodiversity, soil moisture and soil humidity (erosion, burning, conventionalploughing)

• Acidification - Al toxicity, nutrient imbalance, P-fixation (leaching, acid parent material,cropping and organic matter depletion, fertilizers)

• Devegetation - wind and water erosion, siltation, desertification, reduced base flow of rivers,reduced biodiversity and ozone depletion, organic matter and nutrient supply (shiftingcultivation and shortened fallow cycle, wood fuel, overgrazing, construction, fire, landclearing)

Summary report12

Recommendations

Technologies, research and monitoring

• Further investigation and understanding of existing indigenous technologies

• Compiling (inventorying) available technologies

• Integrated sustainable soil management - biophysical, economic and social viability

Policies, Laws, Institutions, and Extension

• Formulation/ Creation of enabling policies to encourage conservation and sustainable landuse should include: land tenure, support for farmer conservation groups - need to set a legalframework for conservation rather than setting it against degradation

• Creation of strong institutions to backstop conservation initiatives at local level

Networking

• Sharing information, experiences, good practice and expectations

• Formalize and strengthen existing networks between and among all stakeholders (not onlybetween scientists), e.g. newsletters, internet, forums, workshops, farmer-to-farmer visits

• Networking the networks at local level

Projects

• First priority: projects to keep good land conserved through dissemination andimplementation of good practice

• Rehabilitation of degraded land to target ‘hot spots’ and potential ‘hot spots’ through use ofbest technologies (irrigation, improved fallows etc. adapted to social and economiccircumstances - see Table 1)

• Construction of food security scenarios to design and target implementation projects andappropriate interventions

Group discussion report for Group Three (Malawi, Namibia, Zimbabwe, South Africa)

Identification, quantification, extent, distribution and assessment of land degradation

• For Malawi, Namibia, Zimbabwe and South Africa the major forms of degradation areerosion and fertility decline and depending on the country soil acidity (South Africa), sodicityand salinity (Namibia).

• There is doubt on the validity of the assessments since it was done for some countriesqualitatively and also only for cereal production.

• With certain reservations the countries agreed that the information on the above topics isacceptable when the heading of Table 3 (given in Summary analysis of country papers byC.F. Mushambi; page 175) is changed to include “for cereal production” and the footnotesmay be changed as follows: (i) sodicitv/salinity to sodication/salinization; (ii) causes ofdegradation be changed to include impacts; (iii) nutrient loss due to erosion be added as anindicator of soil fertility decline and (iv) that improper irrigation management be added as acause of sodification and salinization.


TABLE 1Examples of best practice technologies

Technology (examples) ConditionsConservation tillage (minimum tillage, includingripping, subsoiling and residue management andridging)

- Weed control - herbicidal or mechanical- Grazing control- Appropriate equipment

Improved fallow (green manure, cover crops - Stylo) - Research station only to date/ more on-farmresearch is needed

- Sufficient land- Not becoming invasive/ a weed- Integration with livestock

Soil amelioration (liming, manuring, composting,inorganic fertilizers, termite earth)

- Availability and cost of materials- Expert knowledge- Analytical services

Grazing management (zero grazing, short duration,paddocking, improved pastures - legumes, perennialgrasses)

- Skills, technical knowledge- Materials- Sufficient land- Water- Community participation- Veterinary service

Irrigation (surface - canals, borders, basins;sprinkler; trinkler/drip (micro))

- Water availability- Capital- Knowledge and technology- Suitable land and soil- Community participation- Institutional support

Contour bunds; grass strips and terraces - Labour- Equipment- Land

Crop rotation (grass fallow, sweet potatoes) - Enough land- Labour for mounding

Bio-physical and economic impactsQuantitative data on impacts are not available for many degradation processes.

Outlook for food production and security

• The production and requirement data (see below) presented are open to criticism. A certaintime frame might not be representative of the true picture.

• We should not get involved in detailed food production scenarios since other institutions arealready doing this.

• It is not to say that national food security figures are relevant to household food securityfigures.

Technologies available for improving the productivity of degraded soils

• Networks are absent for inventories of existing technologies.

• Factors limiting application of technology are: (i) lack of information; (ii) cost and (iii) lackof knowledge with respect to cost-benefits (illiteracy).

Research and monitoring requirements

• There is in general a lack of expertise/skills to utilize new technologies and also anunavailability of these technologies exists.

Summary report14

Policy and land tenure issues, national and regional plans

• There is a need for countries to make evaluations of existing policies on land use planning,incorporating sustainable utilization of natural resources.

Networks and project proposals/programmes

• RSA Sustainable Utilization of Natural Resources; Biodiversity

• Namibia Ecosystems Conservation and Protection Programme; Agro-ecological ZoneProgramme

• Regional ELIMS


Overview papers

16


Land degradation with focus on salinizationand its management in Africa

Recent estimates indicate that the global demand for food, fibre and bio-energy products isgrowing at an annual rate of 2.5% and that of developing countries at 3.7% (FAO 1993). Worldpopulation has doubled in the past 40 years and may double again in the next century to approach11 thousand million by the year 2100 (World Resources Institute 1992). The population in Africais expected to increase to 2 193 million in 2100. Historical evidence suggests that an annualgrowth in output of only 1% can be expected from area increase at global level. Henceoptimization of the productive potential of land including degraded land must form a majorcontribution to meeting the increased demand. However, the greatest challenge for the comingdecades lies in the fact that many production environments are unstable and degrading. At riskfrom starvation, farmers are forced to strive for maximum production from the limited landresources available; this is leading to neglect of the long-term husbandry needs of the soil andwater resources. Exhaustion of these resources is the result: decrease of inherent soil fertility,erosion by wind or water and salinization. Africa's lands are suffering from poor andinappropriate land management resulting in rapid land degradation, massive soil loss, fallingyields, deforestation, the disruption of water resources and the destruction of natural pastures.About 490 million hectares in Africa are affected by different types of degradation.

In rainfed areas, fallow periods are declining below safe limits and marginal land andproblem soil with severe production constraints are being put under cultivation in an attempt tomeet demands without adoption of proper and efficient water and soil management practices. Ofthe approximately 2 976 million hectares total land in Africa, 2 146 million hectares are problemsoils (72%) with different production constraints (soil acidity, vertic properties, low fertility,shallow soils, saline and poorly drained soils). On irrigated lands, improper water use and systemmanagement not only detract from attainment of potentials, but also cause productive land to bewithdrawn from cultivation through waterlogging and increasing salinity and sodicity.Salinization in Africa is one of the degradation processes and affects widespread areas mainly inarid and semi-arid regions. Drought combined with the different forms of land degradation isseriously contributing to considerable yield decline and loss in food production, and hence thefood security at household and country level, particularly in countries which cannot easily financeincreased need of food imports. Land degradation is proceeding so fast that few African countriescan hope to achieve sustainable agriculture in the foreseeable future.

A.M. MashaliTechnical Officer, Soil Reclamation, Soil Resources, Management and Conservation Service,

Land and Water Development Division, FAO, Rome, Italy

Land degradation with focus on salinization and its management in Africa18

Neither traditional systems of using the land, nor the responses of traditional societies toincreasingly severe pressures on the land, have been able to cope with the rapid growth ofpopulation and degradation processes in Africa for most of this century. The problem is usuallyidentified only after the situation has become serious. Large quantities of soil have already beenlost and the productivity of land seriously impaired. Governments have to recognize that theirproductive land is a limited and irreplaceable resource which should be carefully managed andprotected against all forms of degradation and thus desertification. Only when the seriousness ofdegradation is recognized and its causes properly identified is it possible to develop agriculturalpractices and management measures that will ensure safe use of the land. Unfortunately widerdissemination of results from successful experiments and initiatives for soil improvement ofdegraded land in one country for the benefit of other countries (even in the same region) is ratherlimited. In order to alert policy makers, there is a need to provide evidence and justification forcorrective methods which are based on in-depth assessment of the extent, severity of landdegradation and their economic and social impacts.

Issues related to land degradation and its negative impacts on food production and foodsecurity as well as development of appropriate technologies to enhance productivity of degradedsoils are receiving special attention and are an important part of the priority programmes of FAO.

DEFINITION OF SOIL DEGRADATION, DESERTIFICATION AND SALINITY PROBLEMS

Soil degradation and desertification

Soil degradation is defined as a "process which lowers the current or the potential capability ofsoil to produce (quantitatively or qualitatively) goods or services". Soil degradation implies aregression from a higher to lower state - a deterioration in productive capability. The process isnot necessarily continuous and may take place between periods of ecological stability orequilibrium. It is usually a complex process in which several features can be recognized ascontributing to a loss of productive capacity. It can result from land uses or from processesarising from human activities such as: erosion, deterioration of physical, chemical and biologicalproperties of the soil or long-term loss of natural vegetation. Recently degraded land is defined asland which due to natural process or human activity is no longer able to properly sustain aneconomic function or the original natural ecological function. Vast areas of Africa continue to beeroded and the degradation of the arid and semi-arid and dry sub-humid regions becomes soserious (resulting from adverse human activities and climate variations) that a new word,desertification, was coined to describe the gravity of the situation. Soil degradation processeswhether chemical, biological or physical may occur simultaneously or sequentially and they areinterrelated. A definition of desertification is "the intensification or extension of desertconditions". It is a process leading to reduced biological productivity with consequent reduction inplant biomass and destruction of the equilibrium of soil, vegetation, air and water in the areassubject to edaphic or climatic aridity (FAO 1984). Desertification hazards refer to the naturalsusceptibility of the land to desertification and manmade factors (ISRIC/UNEP 1990). It isconsidered as a comprehensive expression of economic and social processes as well as those ofnatural or man-induced processes.

An important difference between soil degradation and desertification is that soil degradationis not necessarily continuous; it takes place over relatively short periods and can be reversed.Also desertification or the danger of it, is confined to the arid, semi-arid and sub-humid areas,whereas soil degradation can occur in all climates. Furthermore, certain processes important tothe concept of soil degradation are not considered desertification, i.e. waterlogging, depletion ofplant nutrients and acidification.


Soil salinization

Soil salinization as a process of land degradation is defined as the accumulation of excess salts inthe root zone resulting in partial or complete loss of soil productivity and eventual disappearanceof the vegetation. Salt-affected soil is simply defined as a soil that has been adversely modifiedfor the growth of most crop plants by the presence of soluble salts, exchangeable sodium or both.Any quantitative definition, however, must be arbitrary because of the broad range of crop salttolerance. Salt-affected soils are normally divided into three broad categories: saline, sodic andsaline sodic. Other categories of salt-affected soils though less extensive are commonly met indifferent parts of the world and include acid sulphate soils, acid soils, degraded sodic soils andmagnesium solonetz. The problems of soil salinity occur in all continents and under all climateconditions. They are most widespread in the arid and semi-arid regions, but salt-affected soilsalso exist extensively in sub-humid climates, particularly in coastal regions where intrusion ofseawater through estuaries and rivers, and through groundwater, causes large-scale salinization.Soil salinity is a problem in irrigated lands particularly where saline water is used for irrigation.Salinity problems occur as well where crops are grown under rainfed conditions. There salinityhas several local names, but is most commonly known as dryland salinity or saline seeps.Although weathering of rocks and primary minerals is the main source of all salt, salt-affectedsoil rarely forms through accumulation of salts in situ.

EXTENT OF LAND DEGRADATION, DESERTIFICATION AND SALINIZATION

Land degradation and desertification

Though soil degradation is largely manmade, its pace being governed primarily by the speed atwhich population pressure mounts, irregular natural events, such as droughts, exacerbate thesituation. Such a sequence of events is not just a thing of the past. In many countries of thetropics and sub-tropics it is happening right now, and at an alarming scale. The 1982/1985drought, for example, had a dramatic effect on the speed of land degradation in most Africancountries. Human activities usually aggravate the effect of the physical processes leading todesertification through an inadequate system and policy of land tenure, bad communications, andlack of awareness of acute problems and economic and social conditions.

Much of Africa's land base is environmentally delicate and easily damaged. Large areas ofcropland, grassland, woodland and forest are already seriously degraded. FAO reported in 1981that in Africa north of the Equator more than 35% of the land was affected by either erosion orsalinization. While it is now generally recognized that land degradation in general, and soilerosion and salinization in particular, are widespread and serious, very few reliable data areavailable on its extent or degree. Part of the problem is that much of the available data arereported in different ways and not in readily comparable forms (Sanders 1991). An indication ofthe extent to which the African continent (Figure 1) is subject to soil constraints is given inTable 1. It should be noted that the extents shown in this table are not cumulative since certainconstraints overlap one another (FAO 1986). The table indicates that major constraints arecaused by steep slopes and erosion. In semi-arid areas where exploitation of the land hascontinued for thousands of years, accumulation of soluble salts created a serious constraint toproduction, particularly in Egypt, Libya, Morocco, Tunisia, Somalia, Algeria, Sudan, Ethiopia,Eritrea, Botswana, Chad, Kenya, Tanzania and South Africa. Table 2 gives a summary of mostdegradation problems in the six climatic regions of Africa.


More recently ISRIC (International Soil Reference and Information Centre), under the aegisof UNEP and in collaboration with FAO, has produced a World Map of the Status of Human-Induced Soil Degradation at a scale of 1:10 m (ISRIC/UNEP 1990) known as GLASOD. Itidentifies 4 degrees of degradation (light, moderate, strong and extreme). Five types of humanintervention were identified as resulting in soil degradation: deforestation and removal of naturalvegetation (579 million hectares), overgrazing of vegetation by livestock (679 million hectares),improper management of agricultural land (552 million hectares), over exploitation of vegetativecover for domestic use (133 million hectares), and industrial activities leading to chemicalpollution (32 million hectares). According to GLASOD, 1964 million hectares of agriculturalland worldwide are degraded (Table 3), of which 494 million hectares (25%) in Africa. Table 4gives an indication of the extent and severity of land degradation problems in Africa.

FIGURE 1Main agro-ecological zones of sub-Saharan Africa



TABLE 2Summary of most serious degradation problems by region Region Arable land Grazing land Forest landMediterraneanand North Africa

Declining soil fertilityWind and water erosionSalinization on irrigatedlands

General degradation ofvegetation both in qualityand in quantityWind and water erosion

Degradation of vegetationas the deficit in fuelwoodand timber increasesWater erosion on degradedforest land

Sudano-SahelianAfrica

Decline in nutrient levels ofthe soilsDecline in soil physicalpropertiesWind and water erosion

General degradation ofvegetation both in qualityand in quantityWind erosion in sub-humid areas

Degradation of vegetation

Humid and Sub-humid Africa

Decline in nutrient levels ofthe soilsDecline in soil physicalpropertiesWater erosion

Degradation ofvegetationWind erosion in sub-humid areas

Degradation of vegetation

Humid CentralAfrica

Degraded soil physicalpropertiesDegraded soil chemicalproperties

Sub-humid andmountain EastAfrica

Water erosionDegradation of soil physicalpropertiesDegradation of soilchemical properties

Degradation in qualityand in quantity ofvegetationWater erosion

Degradation of vegetationWater erosion

Sub-humid andsemi-aridSouthern Africa

Water erosionDegradation of soil physicalpropertiesDegradation of soilchemical properties

Degradation in qualityand in quantity ofvegetationWind erosionWater erosion

Degradation of vegetationErosion

TABLE 3Human-induced soil degradation for the world (GLASOD)

Type Light Moderate Strong Extreme Total Total(Mha) (Mha) (Mha) (Mha) (Mha) (%)

Loss of topsoil 301.2 454.5 161.2 3.8 920.3Terrain deformation 42.0 72.2 56.0 2.8 173.3WATER 343.2 526.7 217.2 6.6 1093.7 55.7Loss of topsoil 230.5 213.5 9.4 0.9 452.2Terrain deformation 38.1 30.0 14.4 - 82.5Overblowing - 10.1 0.5 1.0 11.6WIND 268.6 253.6 24.3 1.9 548.3 27.9Loss of nutrients 52.4 63.1 19.8 - 135.3Salinization 34.8 20.4 20.3 0.8 76.3Pollution 4.1 17.1 0.5 - 21.8Acidification 1.7 2.7 1.3 - 5.7CHEMICAL 93.0 103.3 41.9 0.8 239.1 12.2Compaction 34.8 22.1 11.3 - 68.2Waterlogging 6.0 3.7 0.8 - 10.5Subsidence of organicsoils

3.4 1.0 0.2 - 4.6

PHYSICAL 44.2 26.8 12.3 - 83.3 4.2TOTAL (Mha)

(percent)749.038.1

910.546.1

295.715.1

9.30.5

1964.4 100


TABLE 4Human-induced soil degradation in Africa, GLASOD (in million hectares)

Type/Degree Light Moderate Strong Extreme ~Total

Water erosion 57.5 67.4 98.3 4.3 227.4 (46%)Wind erosion 88.3 89.3 7.9 1.0 186.5 (38%)Chemical deg. 26.0 27.0 8.6 - 61.5 (12%)Loss of nutrients 20.4 18.8 6.2 - 45.1Salinization 4.7 7.7 2.4 - 14.8Pollution - 0.2 - - 0.2Acidification 1.1 0.3 - - 1.5Physical degr. 1.8 8.1 8.8 - 18.7 (4%)Compaction 1.4 8.0 8.8 - 18.2Waterlogging 0.4 0.1 - - 0.5Total* 174 (35%) 192 (39%) 124 (25%) 5 (1%) 494 (100%)

TABLE 5Regional distribution of salt-affected soils in 1 000 hectares

Regions Solonchaks/saline phase

Solonetz/sodic phase

Total % of the totalarea affected

North America 6,191 9,564 15,755 1.65Mexico and Central America 1,965 - 1,965 0.21South America 69,410 59,753 129,163 13.55Africa 53,492 26,946 80,438 8.44South and West Asia 83,310 1,798 85,108 8.92South East Asia 19,983 - 19,983 2.09North and Central Asia 91,621 120,065 211,686 22.20Australasia 17,359 339,971 357,330 37.48Europe* 9,121 21,105 52,082 5.46Total 352,452 579,202 953,510 100.00

* The difference between the total salt-affected soils and existing saline and sodic soils in Europerepresents the potential salt-affected soils (20 856 million hectares).

Salinization

Land salinization has been identified as a major process of degradation. Information on the exactextent, distribution and degree of degradation is not available for all soils of countries affected bysalinity. In some countries, even the existence of these soils was discovered only through a surveyor the pressing demand for agricultural utilization of a region. As a general figure about 7% ofthe total soil surface of the world is covered by salt-affected soils: Australia 45%, Asia 21%,South America 7.6%, Africa 8.5%, North America 0.9%, Central America 0.7%, and Europe4.6%.

Based on the FAO/UNESCO Soil Map of the World, Table 5 shows regional distributionand percentage of salt-affected soils. It should be borne in mind that areas given in Table 5 arenot necessarily arable but cover all the salt-affected lands. In Africa the problem is particularlyserious in the countries north of the Sahara, in the Sahel, in East Africa, Botswana, South Africaand Namibia. Salt-affected soils are known also in Ethiopia, Kenya, Tanzania and Zimbabwe(Table 6). Table 7 shows that globally more than 76 million hectares of land is human inducedsalt-affected soil, out of which 52.7 million hectares (69%) is in Asia, 14.8 million hectares(19%) in Africa and 3.8 million hectares (5%) in Europe (Oldeman et al 1991). The four degreesof light, moderate, strong and extreme salt-affected land cover 34.6 million hectares, 20.8 millionhectares, 20.4 million hectares and 0.8 million hectares, respectively.


TABLE 6Distribution of salt-affected areas in the countries of the FAO Subregion for Southern and EastAfrica

Country Area (000 hectares) TotalSaline/Solonchaks Sodic/Solonetz

Angola 581 81 662Botswana 6 765 906 7 671Comoros 0 0 0Ethiopia 8 084 2 714 10 798Kenya 5 838 2 838 8 676Lesotho 0 153 153Madagascar 512 520 1 032Malawi 69 0 69Mauritius 0 0 0Mozambique 1 203 113 1 316Namibia 3 478 1 657 5 135Rwanda 0 0 0South Africa 1 158 5 714 6 872Swaziland 0 39 39Tanzania 1 963 325 2 288Uganda 26 87 113Zimbabwe 349 957 1 306

TABLE 7Global extent of human-induced salinization

Continent Light(Mha)

Moderate(Mha)

Strong(Mha)

Extreme(Mha)

Total(Mha)

Africa 4.7 7.7 2.4 - 14.8Asia 26.8 8.5 17.0 0.4 52.7South America 1.8 0.3 - - 2.1North and Central America 0.3 1.5 0.5 - 2.3Europe 1.0 2.3 0.5 - 3.8Australasia - 0.5 - 0.4 0.9Total 34.6 20.8 20.4 0.8 76.6

ASSESSMENT OF LAND RESOURCES IN AFRICA RELATED TO LAND DEGRADATION ANDDESERTIFICATION

The need for a systematic global assessment of land degradation and desertification has beenhighlighted on many occasions and the following are some of FAO's activities in this regard.

• A provisional methodology was developed for the assessment and mapping of landdegradation. Two types of assessment were made, i.e. present degradation and degradationrisk. Six groups of soil degradation were recognized - water erosion, wind erosion, excessof salt, chemical degradation, physical degradation and biological degradation (FAO 1979).

• A provisional methodology for assessment and mapping of desertification was developed(FAO 1984). Seven desertification processes were identified (degradation of the vegetationcover, water erosion, wind erosion, salinization, reduction in soil organic matter, soilcrusting and compaction and accumulation of substances toxic to plants or animals. Threedifferent aspects were considered, i.e. status, rate and inherent risk of desertification.


• A more comprehensive and detailed set of information has been assembled and analysed forthe African continent. The information shows that only 5% of total area in Africa has none toslight soil constraints while 55% has severe or very severe constraints (Table 8). Six mapson desertification hazards in Africa, scale 1:5-25 m, resulted from these analyses (soilconstraints, water action, wind action, salinization, animal pressure, population pressure (seesix maps by UNEP, 1984) and desertification hazards (window) (UNDP/FAO 1984). Table9 shows the degree of desertification hazards by country in the FAO Subregion of Southernand East Africa.

• A recent study undertaken by the Winand Staring Centre of the Netherlands (Stoorvogeland Smaling 1990) for FAO covering 38 Sub-Saharan African countries, was based on thenet removal of the micro-nutrients, N, P and K from the rootable soil layer. The results ofthis study show that nutrient depletion is quite severe in Sub-Saharan Africa. In almost all


of the 38 countries more than 10 kg of N, 4 kg of P205 and 10 kg of K20 per ha per year arebeing lost from the soil. The highest nutrient depletion rates were found in East Africa ascompared to West Africa (moderate), Central Africa and the Sahelian Region (moderate tolow). Countries with the highest depletion rates were found in most cases associated withhigh degrees of erosion as in Kenya and Ethiopia.

• ISRIC (International Soil Reference and Information Centre) has produced a World Map ofthe Status of Human-induced Soil Degradation (GLASOD) at a scale of 1:10 m(ISRIC/UNEP 1990) for UNEP and in collaboration with the Winand Staring Centre,ISSS, FAO, ITC, UNEP (1992) has published an atlas on desertification with mapsindicating soil degradation severity in general and specifically water erosion, chemicaldeterioration, and overgrazing and deforestation (see Maps Annex 4). The results of theabove studies show that the constant feature of land resources in Africa is the high degreeof variation observed amongst countries. If land itself is taken as the base resource itappears that some countries are better endowed in terms of availability of productive landthan others.


TABLE 8Average data for Africa by process

Componentanalyses

Rating class

None to slight Moderate Severe Very severe(000 km2) % (000 km2) % (000 km2) % (000 km2) %

Soil constraints 1,258 5 11,261 40 11,962 43 3,446 12Water action 23,573 84 3,514 13 550 2 290 1Wind action 19,043 68 6,361 23 1,057 4 1,466 5Salinization 20,932 75 2,167 8 1,802 6 3,026 11Animalpressure

10,952 39 11,865 43 2,871 10 2,239 8

Populationpressure

15,335 55 8,924 32 2,952 10 716 3

Source: UNEP/FAO 1984


• To categorize the agroclimatic and soil resources initially by country, and subsequently forthe region, with a view to identifying constraints to agricultural production and by inferenceto the horizontal expansion of cultivated area, a common classification and system ofinterpretation could be employed. Fortunately, a common base exists in the forms of theFAO/UNESCO Soil Map of the World which characterizes and delineates the soils in auniform manner. Therefore FAO could carry out assessment of land resources in Africa.The method used is based on soil data from the FAO GIS (Geographic Information System)using the FAO/UNESCO Soil Map of the World, the Fertility Capability Classification(FCC) developed by the North Carolina State University, and agroclimatic data from FAO'sGlobal Agro-ecological Zones Study (World Soil Resources Reports 48/1-4, 1978-81, Landand Water Development Division, FAO).

However, the process of grouping land areas according to constraints to agriculturalproduction is particularly complex because in many cases individual tracts of land will


exhibit a combination of soil and agroclimatic constraints. At the same time theenvironmental requirements of individual crops vary considerably so that what is a severeconstraint for one crop may be less severe or no constraint to another. Where a combinationof constraints occurs, grouping may be enhanced by identifying the most limiting of theseconstraints. However, this becomes difficult when, as is the present case, the base data andmapping scale (1:5 million) are of rather a general nature. Despite these drawbacks anattempt has been made to identify the major natural constraints to agricultural productionand their extent by country, in the continent. Extents listed include all soils whetheroccurring as dominant soils or associated soils, or as inclusions. Areas of non-soils such asCalciers, bare rock or moving dunes are excluded. Sixteen categories of natural constraintsto agricultural production have been identified (Table 10). This study shows that the mainagricultural production constraints in Africa are in the following order: low K reserves(20.4%) > acid soil (15.9%) > Al toxicity (15.0%) > low nutrient retention (13.2%) >shallow soil (11.7%) > free CaCO3 (11.1%) gravel (10.2%) > steep slopes (8.7% > poor


drainage (6.7%) > P fixation (6.8%) > salt-affected soil (3.9%) (this figure for salt-affectedsoil is lower comparing it with 8.5% given in Table 6 because it does not includewaterlogged areas due to poor drainage conditions) > Vertisol (3.7%) > amorphousmaterials (0.2%) > acid sulphate soils (0.1%).

• A two-year project on Mapping of Soil and Terrain Vulnerability in Central and EasternEurope (SOVEUR) was signed between FAO and the Government of the Netherlandswithin the framework of the FAO/Netherland Government Cooperative Programme. Theobjectives of the project are the establishment of a geographic database and production ofassociated maps at a scale of 1:2.5 million on human induced soil degradation and soilvulnerability for Central and Eastern Europe as a tool for targeting appropriate correctiveactions. Like the previous assessment of soil degradation at a global level, GLASOD 1:10million and Asia Regional (ASSOD 1:5 million scale), the assessment of soil degradation inCentral and Eastern Europe will serve as a means to increase awareness of soil degradation.


In view of the scale and the anticipated available data, the inventory is like GLASOD basedon experts' estimates. Together with the Soil and Terrain Data (SOTER) to be collectedand the soil vulnerability assessment, the status of soil degradation will be produced. Theassessment will be based on the SOTER map (Soils and Terrain Digital Database) at scaleof 1:2.5 million. Same methodologies and the produced guidelines can be applied forassessment of the status of soil degradation in Africa.

TABLE 9Degree of desertification hazards by country in the FAO Subregion for Southern and East Africa

Country Desertification hazards rating

None to Slight* Moderate Severe Very severe% area % area % area % area

Angola 85.8 11.4 2.6 .2Botswana 39.3 60.7 0 0Burundi 100.0 0 0 0Comoros Islands 100.0 0 0 0Ethiopia 44.4 36.2 15.0 4.4Kenya 13.0 64.3 21.0 1.7Lesotho 26.9 57.2 0 15.9Madagascar 91.4 6.1 2.4 <.1Malawi 94.5 5.5 0 0Mauritius 100.0 0 0 0Mozambique 79.9 20.1 .1 0Namibia 25.5 50.2 24.3 .1Rwanda 100.0 0 0 0South Africa 11.4 17.5 33.3 37.8Swaziland 69.6 30.4 0 0Tanzania 65.4 33.4 1.2 0Uganda 80.2 19.2 .6 0Zambia 97.1 2.9 0 0Zimbabwe 39.2 55.0 5.8 0

Note: *Includes areas not rated for desertification hazards. Land degradation hazards may occur.

CAUSES OF DEGRADATION, DESERTIFICATION AND SALINIZATION

It is necessary to identify the causes and origin of degradation so that the real causes and not thesymptoms are controlled. In the past the problems were usually treated from an engineeringperspective, the planners seldom paid much attention to incorrect land management and use, ofwhich surface runoff and soil loss were only the symptoms. They attacked the symptoms of theproblems, not the causes. A sound understanding of the causes of land degradation anddesertification can prevent governments embarking on costly but unsuccessful programmes. Forexample, an analysis of badly eroded areas may lead to the conclusion that the problem isexcessive population pressure on the land and that little can be done unless this pressure isreduced.

Degradation and desertification

Degradation and desertification have taken place in various regions of the globe, and due tovarious causes. However, most if not all of these causes are closely interrelated, the occurrenceof one usually leading to the occurrence of one of the others. Major processes causing soildegradation can be defined as follows:



a. Plant cover degradation and deforestation. From time to time unusual events may occur,such as fires, drought or floods, but usually the natural ecological system is able to quicklyrecover without any, or very little, permanent damage being done, Problems arise whenman tries to alter a stable environment to meet one or more of his needs. In rainfedagriculture many areas, particularly those in the lower rainfall areas in the tropics, are veryfragile and the removal of the natural vegetation, growing different types of plants at alower density than would be found under natural conditions, and introducing more animals,create conditions which are likely to lead to land degradation and desertification.Overstocking and overgrazing are serious problems on their own in many countries inAfrica and are one of the principal causes of desertification, but they also aggravate theeffects of drought. The main effect of the degradation of the vegetation cover is then theexposure of the soil to other processes which, in turn, may destroy the soil structure,leaving the land less productive and with its productive potential seriously impaired andbecoming subject to desertification. The increasing use of trees and brushwood for fuel,leading progressively to deforestation, has accelerated desertification over much of semi-arid Africa. At present deforestation is proceeding 30 times faster than reforestation. In theearly 1980s it was estimated that 3.7 million hectares were being lost each year. Thedestruction of the forests is mainly a result of clearance for agriculture. In brief, incorrectland use and bad land management (from the land being used in a manner incompatiblewith its capacity) are main factors causing deterioration of land cover and thus landdegradation.

b. Wind erosion. Wind erosion in Africa occurs most frequently in the arid and semi-aridregions of the tropics, but wind erosion is also a problem in lands even up to rainfalls of750 or 800 mm. Especially areas where dryland agriculture is being practised with little orno vegetation, light-textured soils easily become subject to wind erosion. Wind erosionfrequently leaves the land subject to other forms of degradation such as water erosion. In(semi-) arid climates natural wind erosion is often difficult to distinguish from humaninduced wind erosion, but natural erosion is often aggravated by human activities.

c. Water erosion. Water erosion is another spectacular form of land degradation which canalso play an important part in the formation of deserts. Large areas of once productive riverflats may become covered with a layer of fresh deposit, rivers and irrigation canals maybecome blocked, while dams and lakes may fill with silt. Once the process of water erosionhas started, runoff increases with an accompanying damage to soil property and evenpossible loss of life. Water erosion is most likely to occur when the land is used for arableagriculture as the soil is then exposed without vegetative cover at certain times of the year.Loss of topsoil itself is often preceded by compaction or crusting causing a decrease ininfiltration capacity of the soil and leading to accelerated runoff and soil erosion. A jointFAO/UNDP study on land degradation found that 11.6% of Africa's land north of theequator was affected by water erosion.

d. Soil crusting, sealing and compaction (physical deterioration). Compaction, sealing andcrusting occur in all continents, under nearly all climates and soil physical conditions. Soilcrusting and compaction has been identified as one of the processes of desertification, themain reason being that if land is not cultivated correctly, the structure of the surface soilcan be broken down and destroyed. In addition, the heavy action of some implements tendsto pulverize and break down the structure of soils, leaving them subjected to both surfacecrusting and compaction. Closely related to crusting is soil compaction. Cultivated soils


can become compacted in a number of ways. For example, the wheels of heavy machinescan quickly compact soils. Soil crusting and compaction tend to increase runoff, decreasethe infiltration of water into the soil, prevent or inhibit plant growth and leave the surfacebare and subject to other forms of degradation.

e. Reduction of soil organic matter and biological degradation. In the tropics in Africa, i.e.in warm or hot climates, oxidation of the organic matter is rapid and most of the soils arerelatively low in organic matter (FAO 1983). About 1.7 billion hectares of tropical soils arelow in organic matter and nutrient reserves. In the tropics organic matter decomposes aboutfive times faster than in temperate climates. Unfortunately, in many of the areas which aresubject to desertification there is a general shortage of vegetation, crop residues are notreturned to the soil but are used as animal feed or fuel; animal manure is not spread on thefields but is used as fuel, and the pressure on the land to produce grain crops is intense.Under such conditions the organic matter level and the volume of vegetation cover drop, thefertility of the land declines and the soil becomes subject to other processes such as surfacecrusting, wind and water erosion.

f. Excessive toxic substances, other than salinization (chemical degradation). Soil toxicitycan be brought about in a number of ways, but typical examples are from municipal orindustrial wastes, oil spills, the excessive use of fertilizer, herbicides and insecticides, or therelease of radioactive materials and acidification by airborne pollutants. While soil toxicitymay be a relatively minor problem at present, it is likely to become of increasingimportance in future years.

g. Cultivation practices and improper management. Cultivation practices introduced in manydeveloping countries have often been unsuccessful because practices have been copied fromsystems that are appropriate elsewhere in very different conditions and circumstances. Thiscausative factor is defined as improper management of agricultural land. In Africa, thereare many examples of unsuccessful mechanization projects which have failed as a result ofill-adapted land clearing and cultivation systems, inappropriate equipment and poor supportservices, policies and strategies.

h. Shifting cultivation. Shifting cultivation is popularly blamed as unproductive and a seriouscause of desertification. However, many shifting cultivation systems were appropriate andsustainable at low population pressures. Various kinds of shifting cultivation are practisedby the vast majority of farmers in the least developed countries and most vulnerablecountries of different regions. Generally they are no longer adequate to meet currentdemand because of increases in population. However, until practical feasible alternativesare proved and the conditions for their adoption facilitated, serious problems will persist.

i. Land users' involvement. In Africa, farmers, pastoralists and those who relied on woodlandand forests or agricultural land for their livelihoods were often regarded as part of theproblem, rather than as the potential solution. Few attempts have been made to analyse thereal causes of land misuse, such as land tenure systems, labour shortages and lack ofeconomic incentives, information and advice (FAO 1990). Population pressures may behigh, agricultural pricing and policies inappropriate, inputs unavailable, or land tenuresystems may be forcing farmers to over-exploit or neglect the long-term husbandry needs ofthe soil to prevent degradation. Other causes may be identified as growing the wrong cropon the wrong land, subsidies systems, taxes or outmoded laws or social customs.


Causes of salinization and sodication

It is necessary to identify the causes and origin of salinity and sodicity so that the causes and notthe symptoms are controlled.

Salinization

In semi-arid and arid areas of the world, the scarcity, variability and unreliability of rainfall andhigh potential evapotranspiration affect water and salt balance of the soil. Low atmospherichumidity, high temperature and wind velocity promote the upward movement of the soil solutionand the precipitation and concentration of the salts in the surface horizons. In arid regions,various types of Na, Mg and Ca salts are concentrated, mainly chloride and sulphate. In morehumid climates, salts are less concentrated and Na dominates in carbonate and bicarbonateforms which enhance the formation of sodic soils. In the geography and geochemistry of theformation of saline soils, the following salt accumulation cycles can be distinguished. They arenot necessarily exclusive (Mashali 1989).

Natural cycles

• Marine cycles connected with the accumulation of marine salts in areas lying near the sea orsaline lake and lagoon ecosystems: The sea water influences, directly or indirectly, soils andgroundwater of these areas, giving rise to saline soils and groundwater with saltconcentration ranging between 25 and 100 g/l. In coastal aquifers including lagoonecosystems freshwater usually overlies a transition zone which in turn overlies the salineseawater. The rising water tables of saline aquifers due to increased recharge or the upwardleakage from deeper aquifers not only causes land salinization but will also increase theseepage of saline groundwater into rivers and watercourses and enhance their salinization.

• Continental cycles in which salinization results from the migration and redistribution of saltaccumulated earlier in sedimentary salt bearing rocks, or from the deposition of salts duringthe process of weathering and soil formation in surface and groundwater: The result is theaccumulation of carbonates, sulphates and chlorides in regions without natural drainage.This is more commonly in depressions and low-lying areas than in higher parts of thelandscape. The discharge of saline effluents from drainage schemes, or from evaporationbasin (ponds), lagoon ecosystems or runoff from land affected by salinization can alsocontribute to increased salinity of the watercourses.

• In rainfed agriculture, development of saline seeps involves recharge and discharge areas. Indischarge areas, groundwater rises to soil surface creating a seep. As water evaporates fromseepage area, salt accumulates and forms saline soils. The most important contributoryfactors which may aggravate the saline seep problem are fallowing practices, denudation ofvegetation by overgrazing, drought or fire, when replacing native vegetation includinggrasses with agricultural fields and cropping systems with lower potentialevapotranspiration requirements, or other practices which result in the accumulation ofwater in the recharge areas.

• Artesian cycles: If salts migrate with artesian waters through aquifers in, e.g. tectonic faultareas or in vast, deep continental depressions, salinity may develop as a result ofevaporation under arid desert conditions.


Soil and water mismanagement cycles

Anthropogenic cycles in which man, through poor soil and water management and agronomicpractices, aggravates soil salinization and sodication. These practices include the following:

• Irrigation cycles are characterized by a complex combination of salt movements. Inirrigation areas with insufficient drainage, water table rises leading to waterlogging andsecondary salinization. In irrigated areas the following can cause soil salinization:∗ Insufficient water applications, to the extent that crop water requirements and salt

leaching requirements are not met.∗ Irrigation at low efficiency: the efficiency of water use is generally low, less than 30-

40%, due to seepage losses from canals during conveyance and distribution of irrigationwater, and water losses on the farm due to poor irrigation practices. Most of the waterlost finds its way to groundwater, thus gradually raising the water table leading towaterlogging and its effects on soil aeration, root penetration and nutrient availability,and to soil salinization under arid and semi-arid environments. Over-irrigationcontributes to the high water table, increase in the drainage requirement and is a majorcause of salinity build-up in many irrigation projects of the world. Therefore, a properrelationship between irrigation, leaching, and drainage must be maintained in order toprevent irrigated lands from becoming excessively waterlogged and salt-affected(Rhoades, Kandiah and Mashali 1992).

∗ Irrigation with saline water or marginal quality water: Since good quality water is notalways available, there has been a trend in some countries to use water of marginalquality for irrigation. Overpumping in the freshwater zone which overlies the salineseawater in coastal aquifers and lagoon ecosystems changes the equilibrium between thefresh and saline water, and causes the intrusion of seawater in aquifers degrading thequality of the fresh groundwater zone. Continued irrigation with such low qualitygroundwater has contributed to the expansion of land salinization. Drainage water ismixed with fresh water and used for irrigation in different countries. Treated municipalwastewater has been used on small scale for irrigation. Using saline water or marginalquality water for irrigation without proper soil and water management and agronomicpractices, encourages soil degradation by salinization and sodication. The effect dependson salt concentration and composition, quantity and method of irrigation waterapplication and soil properties.

• Poor levelling: Variations of macro and micro relief also contribute to soil degradation indifferent ways. Small differences in elevation may result in salinization of the lower parts asthe water table is closer to the surface and becomes more subjected to evaporation. On theother hand, changes in the micro relief in the order of 30 cm result in increasing salt contenton raised spots and better leaching in dips which may explain the spotty nature of salinityobserved in poorly levelled but otherwise normal fields.

• Dry-season fallow practices in the presence of shallow water table.

• Misuse of heavy machinery leading to soil compaction and poor drainage conditions.

• Excessive leaching during reclamation techniques with insufficient drainage.

• Use of improper cropping patterns and rotations.


Sodication

The sodication process involves the presence of soluble sodium salts in the soil solution andtheir adsorption on the exchange complex. The following processes responsible for the formationof sodic soils in the Near East Region have been given by El-Gabaly (FAO 1971):

• desalinization in the absence of enough divalent cations and with insufficient drainage;

• evaporation of groundwater rich in NaHC03 and Na2C03 formed under particular geologicstructure in areas having regional faults;

• decomposition of sodium alumino silicates which may lead to the formation of NaHC03 andNa2C03 and silica;

• denitrification and sulphate reduction under anaerobic conditions;

• migration and accumulation of sodic salts in arid climates;

• use of water with low salinity, in the order of 100-300 ppm, but with dominantly HC03-ions, especially in heavy textured, slowly permeable soils.

BIO PHYSICAL AND SOCIO-ECONOMIC IMPACTS OF DEGRADATION

The impact of land degradation affects both production and people.

Effects on production

• Various forms of degradation can cause serious and severe decline in soil productivity andcrop yields.

• To overcome reduction in yield farmers will increase inputs including seeds, fertilizers, etc.

• Degradation can reduce response to any inputs, for example in salt-affected soil crop yieldresponse to fertilizer application will be less as salinity is a limiting factor.

• Degradation processes may reduce possibility for alternative land use. For example in salt-affected soils farmers are forced to cultivate only salt tolerant crops which might not alwaysbe high-income cash crops.

• Irrigation schemes may fail because of the development of one or more of the degradationprocesses. For example salinity will reduce efficient use of water (i.e. crop yield per unitwater) causing reduction in return from capital investment and labour inputs.

• Degraded soil is more fragile with greater risk and always subjected to other forms ofdegradation. For example biological or physical degradation (soil crusting, compaction,etc.) will reduce organic matter level and level of vegetative cover and with decline infertility (chemical degradation) and soil becoming subject to other processes such as windand water erosion.

• Siltation of reservoirs due to water erosion, for example, will reduce the available water forirrigation. An off-site effect of deforestation and erosion of watershed areas is thedestabilization of river flow, causing flooding after rain and reduced flow in subsequentperiods. Downstream irrigation and drainage system can also be damaged as a result ofsedimentation caused by erosion. In salt-affected soil, saline water table through seepageinto river and watercourses can enhance salinity of fresh river water.

• When degradation is identified the required rehabilitation programme will need highinvestment cost such as in reclamation projects of salt-affected soils. In economic terms the


cost of degradation by erosion or soil fertility decline may reach a 5-10% production lossfor a light degree of degradation or 20% for moderate, and 75% for severe degradation.Degradation by salinity may reach 65% in moderate conditions or even 100% in severeconditions.

Effect on the people

• Abandonment of the land where severe degradation occurred which increased the number oflandless farmers.

• Reduction in food production, food supply, low food security leading to famine in somecases. The famines in Ethiopia in the 1970s and 1980s were at least partially due to theeffect of land degradation brought about by years of soil erosion (Sanders 1987).

• Increased labour requirement: for example, deforestation and erosion forces farmers to gofor long distances to collect their fuel or water which means more labour required to do thesame job. More labour is required for rehabilitation of degraded land. Reduced crop yieldsand more required inputs in degraded soils will reduce labour use efficiency.

• Lowered income of the poor small scale farmers from agriculture: as a consequence farmerswill be forced to work on land of others or migrate to cities searching for other sources ofliving or ultimately depend on famine relief. During the Sahel drought of the early 1970s,nearly one million "environmental refugees", a sixth of the population, were forced to leaveBurkina Faso. Half a million more left Mali because of desertification processes (FAO1990).

LAND RECLAMATION AND MANAGEMENT TECHNIQUES

Land degradation

The restoration of soil degradation and the protection from the causes of desertification call forthe application of certain management and conservation measures and the undertaking ofnecessary precautions. Measures such as contour cultivation, tied ridging, terracing, stripcropping, dense vegetation and planting cover crops, mulches, fast growing trees, selection ofproper crop rotation, quick growing species and integrated cropping system, provision ofalternative fuel sources, check structures, protected watersheds, proper land preparation andploughing, application of fertilizer, amendments and organic manures, and drainage systems arequite often mentioned as the techniques which help to protect and improve the land. However,the following are among the priorities:

• In dryland agriculture, improving soil productivity and water conservation by promotingdryland farming and water harvesting techniques: communities can build devices such assmall dams to conserve water and can plant trees to protect the upper slopes of their land.Farmers can be persuaded to use dryland farming techniques such as early ploughing, stripfarming with the minimum of soil disturbance (minimum tillage), Conservation tillage, ascompared to clean tillage, could promote the maintenance of soil structure and aggregates atthe surface and thus reduce wind and water erosion. However, under specific conditionsconventional tillage could promote water infiltration, control weeds and reduce mechanicalimpedance to root growth. Also short-season drought-tolerant cultivars can be used. Severalare available, though not yet adopted, that have appropriate agro-ecological adaptation andmeet people's consumption preferences.


• Controlling wind erosion with fast growing trees and shrubs as windbreaks and shelterbelts, live fencing and roadside planting: studies have shown that spacing of the shelterbeltscan be 20 times the height of the tallest growing trees, this being the zone of protection.Narrow belts, 1-3 rows wide, already have a considerable effect. Shelterbelts improve themicroclimate, prevent soil erosion, reduce the quantity of irrigation water used and protectthe crop from desiccation. On the other hand, shelterbelts occupy a portion of the land, useplant nutrients, and shade the plants grown adjacent to the windbreak rows.

• Integrating trees and livestock with arable farming, maintaining a good cover, protects thesoil. On flat farmland, a good method of soil protection is to leave stubble and leaves on thesurface after harvest and at planting. In this regard, maximum recycling of organic productshould be encouraged both from within and from outside the farm (crop residues, animalmanure, composts, urban wastes). Improve land use systems including appropriate croprotation, intercropping, agroforestry and related tree based farming systems; species that fixnitrogen should be considered.

• Applying dune stabilization measures: it is common practice to start with planting grassesfollowed by bushes and then by trees. However, in several areas afforestation starts aftermechanical fixation, i.e. the surface of the dune might be fenced with dry grasses and thelike in a checkerboard system. Plant species used for afforestation must be able towithstand drought, salinity, low soil fertility and fluctuations in surface temperature andhave deep root systems capable of reaching the moisture in deep layers, or horizontal spreadthat allows for efficient use of surface rain and any dew. Chemical fixation using chemicalssuch as crude oil, asphalt and synthetic rubber latex is recommended when cost of labour isvery high and the areas need to be stabilized in a short period.

• Water erosion can be checked by many agronomic methods such as terraces to stop watererosion on steep slopes, level terraces to interrupt the rain flow and filter the water into thesoil, and waterways lined with concrete, stone or even grass to direct the water down andploughing along the contour of gentle slopes to check erosion. Studies shown that ifcontouring and strip cropping are combined, soil loss is reduced by 75% compared to up-and-downhill cultivation. Mulches reduce the impact of raindrops and hold moisture andallow it to infiltrate into the soil.

• Grazing strategies should give attention to localized concentration of stock as around saltlicks, watering points and settlements, and measures should be taken to avoid intensive localgrazing and trampling and to propose a system to limit numbers of stock - which onlyappears feasible with the grazers' cooperation.

• Techniques that directly increase range productivity are disease control and animal healthimprovement, pasture regeneration through grass seedling and forage plantation.

• Management plan must be site specific. Participative approach in which both the selectionof solutions and their implementation are decided in cooperation with the beneficiary groupsincluding farmers, all land users and farmer associations. Identification, selection andfarmer's adoption through participatory approach of improved and alternative packages oflow-cost, low-risk soil management and conservation practices are required therefore toaddress and control land degradation. In this regard, integrated approach should beencouraged whenever feasible. Issues like changing in pricing policy, subsidy of inputs,market liberalization, land tenure reforms, infrastructures, policy and socio-economicaspects, environmental aspects should be considered in any management plan.


• Promotion of quantitative assessment of the impacts of degradation on productivity atregional, sub-regional and national level: this includes survey of the present state ofdegradation, potential risks of degradation, and monitoring of soil changes.

• Promoting research and encouraging national coordination between governmentdepartments, local non-government organizations, parastatal bodies, universities andresearch institutions.

• Rehabilitating irrigation schemes suffering from salinization or sodication. Summaries ofthe hydraulic, physical, chemical and biological technologies to control salinity and sodicityare described below.

Management practices for salt-affected soils

Salt-affected soils exist under a wide range of hydrological, physiographical conditions, soiltypes, rainfall regimes and socio-economic settings. Therefore, there is no single technique oragricultural system that will be applicable to all areas. Management of salt-affected soil foragricultural purposes requires a combination of agronomic and management practices dependingon a careful definition of the main production constraints and requirements based on a detailed,comprehensive investigation of soil characteristics, water monitoring (rainfall, surface water andgroundwater), and a survey of local conditions including climate, crops, economic, social,political and cultural environment and existing farming systems. Management of salt-affectedsoils for agricultural use is largely dependent on water availability, climatic conditions, cropstanding and the availability of resources. Several practices should be combined into anintegrated system according to requirement. Summaries of the hydraulic, physical, chemical,biological and human aspects to improve productivity of salt-affected soils and other alternativeforms of land use rather than crop production are discussed in Table 11.

Hydraulic practices

Leaching

To prevent the excessive accumulation of salt in the root zone, extra water (or rainfall) must,over the long term be applied in excess of that needed for ET and must pass through the rootzone in a minimum net amount. This amount, in fractional terms is referred to as "the leachingrequirement". The recent trend is to minimize these leaching requirements in order to preventraising the groundwater and minimize the total load to the drainage system. Methods to calculatethe leaching requirement and predict crop yield losses due to salinity were described byRhoades, Kandiah and Mashali (1992). The quantity of salts removed per unit water can beincreased by intermittent flooding or even more by sprinkler and frequent irrigation. Leachingshould preferably be done when the soil moisture is low and water table is deep. Leachingshould be timed to precede the critical growing stages. Leaching at times of lowevapotranspiration demand is recommended, as at night, during high humidity, in cooler weatheror outside the cropping season.

Irrigation practices

Management of water should ideally maintain a relatively high soil moisture content (as in dripirrigation) during the cropping season and at the same time allow for periodic leaching. Goodirrigation management has two objectives, the achievement of high crop yields with high wateruse efficiency, and the protection of land from waterlogging and salinization. The methods andfrequency of irrigation and amount of water applied are of prime importance in controlling


salinity. They are determined by such factors as potential evapotranspiration, root proliferationand depth of root penetration, capacity of soil to store and transmit water and nature of plantresponses to soil moisture stress. Sprinkler irrigation allows a close control of the amount anddistribution of salts and water. Drip irrigation results in salt accumulation at the outside edge ofthe zone moistened by the emitters. Improvement in salinity control generally comes hand inhand with improvements in irrigation efficiency. The key is to provide the proper amount ofwater to the plant at the proper time. The distribution system of irrigation water should bedesigned and operated so as to provide water on demand and in metered amounts as needed,particularly when saline water is used for irrigation. Seepage losses from irrigation canalsshould be reduced by lining the canals with impermeable materials or by compacting the soil toachieve a very low permeability.

TABLE 11Management practices and human aspects of management related to uses of salt-affected lands

HYDRAULIC:- Leaching (requirement, frequency)- Irrigation (system, frequency, cyclic "dual rotation" strategy in irrigation with saline water,

operating delivery system efficiently and lining irrigation canals- Drainage (system, depth, spacings, purpose, intercepting drainage, reuse drainage water for

irrigation)

PHYSICAL:- Land levelling- Tillage, land preparation, deep ploughing, subsoiling- Seedbed shaping (planting procedures)- Sand or mineral soil material cover- Salt scraping

CHEMICAL:- Amendment- Soil conditioning- Mineral fertilization

BIOLOGICAL:- Organic, green manure and legumes- Crop rotation and pattern- Growing suitably tolerant crops "varieties"- Mulching- Crop residue

HUMAN ASPECTS OF MANAGEMENT:

- Socio-economic aspects including farmers involvement, needs and preferences- Policy- Environment- Institution, organization, operation and maintenance

POSSIBLE ALTERNATIVE LAND USES IN COASTAL AND LAGOON ECOSYSTEMS:

- Fish farms, rice-shrimp systems- Halophytes, mangroves, timber and fuelwood- Chemicals, industrial raw material production and salt making- Recreation parks- Preservation zone (swamp forest)


The "dual rotation cycle" management strategy (Rhoades 1984) can be used to enhance thefeasibility of re-using drainage waters for irrigation: in this system: sensitive crops in therotation are irrigated with low salinity water (fresh water) and salt tolerant crops are irrigatedwith saline drainage water. For the salt-tolerant crops, the switch to saline water is usually madeafter seedling establishment; pre-plant irrigation and initial irrigation being made with lowsalinity irrigation water. The secondary drainage resulting from such re-use should also beisolated and used successively for crops (including halophytes and tolerant trees) of increasinglygreater salt tolerance. The ultimate unusable drainage water, which in this strategy will bereduced to the minimum, should be disposed of to some appropriate outlet or treatment facility.

Drainage practices

Leaching and drainage are the basic requirements for successful amelioration of saline or sodicsoils. When underlying layers are permeable and relief is adequate, natural drainage mayfunction well. Since such conditions are rare in areas where saline and sodic soils occur, adrainage system will usually be required. Methods adopted to remove excess salt from the rootzone include scraping, which removes the salt accumulated on the soil surface by mechanicalmeans; washing away the surface salt crusts through flushing water over the surface in the rarecases with soils of low permeability and adequate slope; and, most commonly, leaching. Varioustypes of drainage are used all over the world: surface drainage in which ditches are provided sothat excess water will run off before it enters the soil; subsurface drainage for the control of thegroundwater table at a specified safe depth, consisting of open ditches or tile drains orperforated plastic pipes; mole drainage where shallow channels left by a bullet shaped devicepulled through the soil can act as a supplementary drainage system connected to the maindrainage system (open or closed); and vertical drainage by pumping out excess water fromtubewells when the deep horizons have an adequate hydraulic conductivity. Reducing deeppercolation of excess water by drainage will generally reduce the salt load returned to river aswell as reduce water loss. Saline drainage water should be intercepted as mentioned throughdrainage systems. Such drainage water can be disposed of by pond evaporation or by injectioninto some isolated deep aquifer, or it can be used as water supply where use of saline water forirrigation is appropriate.

Physical management

Several mechanical methods have been used to improve infiltration and permeability in thesurface and root zone and thus to control saline and sodic conditions (Mashali 1995)

Land levelling

Careful levelling of land makes possible a more uniform application of water for better leachingand salinity control. For coarse levelling, simple scrapers or levellers may be used, while for finelevelling, use of laser guidance has recently been adopted which is more effective (precision 1 to3 cm) but more expensive and time consuming. Land levelling causes a significant amount ofsoil compaction by the weight of heavy equipment and it is advisable to follow this operationwith subsoiling, chiselling or ploughing to break up the compacted layer and restore or improvewater infiltration.

Deep ploughing and tillage

Tillage is usually carried out for seedbed preparation and soil permeability improvement, but ifimproperly executed might form a plough layer or turn a saline layer and bring it closer to the


surface. Deep ploughing is most beneficial on stratified soils having an impermeable layer. Itloosens the soil aggregates, improves the physical condition of this layer and increases air spaceand hydraulic conductivity. Deep ploughing in sodic soils should only be carried out aftereliminating the sodicity, otherwise the mechanical disturbance may cause collapse of the soilstructure. The selection of the right plough type, tillage sequence, ploughing depth and moisturecontent at the time of ploughing and subsoiling should provide good soil tilth and improve soilstructure.

Subsoiling

Subsoiling opens channels to improve soil permeability. The shape of the subsoiler's shank andthe space between shanks depends to a large extent on the depth, thickness, hardness andcontinuity of the impervious layer.

Sanding

Sanding is used in rare cases to make a fine textured surface soil more permeable by mixingsand into it, thus a relatively permanent change in surface soil texture is obtained. Adding sandto the soil surface (10-20 cm on the surface) as a better media for plant establishment is used asa physical management practice in some saline conditions.

Planting procedures

Special planting procedures that minimize salt accumulation around the seed are helpful ingetting better stands under saline conditions. Certain modification of the furrow irrigationmethod are recommended including planting in single or double rows or in sloping beds.

Chemical practices

Chemical amendments

Chemical amendments are used to neutralize soil reaction to react with sodium carbonate andreplace exchangeable sodium by calcium, followed by leaching for removal of salts derived fromthe reaction of the amendments with sodic soil. Gypsum is by far the most common amendmentfor sodic soil reclamation. Calcium chloride is highly soluble and would be a satisfactory soilamendment, especially when added to irrigation water, but is difficult to handle and generallyexpensive. Lime is not an effective amendment for reclamation of sodic soils when used alone,but has a beneficial effect when combined with a large amount of organic manure. Sulphur, too,is effective. It is inert until it is oxidized to sulphuric acid by soil micro-organisms. All othersulphur containing amendments (sulphuric acid, iron sulphate, aluminium sulphate) are effectivebecause of the sulphuric acid originally present or formed upon microbial oxidation orhydrolysis. The choice of an amendment at any place will depend upon its relative effectivenessas judged from improvement of soil properties and crop growth, availability of the amendments,relative costs involved, handling and application difficulties and time allowed and required foran amendment to react in soil and effectively replace adsorbed sodium. The dosage ofamendments must be equivalent to the quantity of exchangeable sodium to be removedconsidering the purity and type of the different amendments. The effectiveness of the amendmentdepends on the application method, i.e. broadcasting, incorporation in the soil by disking orploughing, mixing to greater depth, metering into irrigation water or spraying on the soil surfacein case of sulphuric acid.


Soil conditioning

Attempts have been made to coagulate soil particles and provide aeration and betterpermeability and water infiltration by using soil conditioners. Factors limiting the use of soilconditioners are high costs, the difficulty of achieving intensive mixing during incorporation inthe soil and limitation of beneficial effects to a shallow surface layer.

Mineral fertilization

Salt accumulation in soil may affect nutrient contents and availability for plants in one or moreof the following ways: by changing form in which nutrient is present in soil; by enhancing lossof nutrients from soil; through cation and anion interaction effects; through effects on non-nutrient (complementary) ion on nutrient uptake - all, adverse interactions between salt presentand fertilizers, decreasing fertilizer use efficiency. The benefits expected from reclamation ofsalt-affected soils will not be obtained unless adequate plant nutrients (but not in excess) aresupplied as fertilizer or by other means. The type of fertilizer used in salt-affected soils shouldpreferably be of acid reaction and contain calcium rather than Na. It may also be necessary totake into account the complementary anions present.

Biological practices

• Incorporating organic matter in soil has two principal beneficial effects on saline and sodicsoils, improvement of soil permeability and release of carbon dioxide and certain organicacids during decomposition. This will help in lowering pH, release of cations bysolubilization of CaCO3 and other soil minerals, thereby increasing the EC, andreplacement of exchangeable Na by Ca and Mg which lowers the ESP.

• Farm manure acts both as a source of nutrients and to improve soil structure andconditions. Green manure has a similar effect on soil properties and as a source of nutrientsas organic matter.

• Fallowing encourages upward movement of salts. Therefore, it is advisable to crop landcontinuously, particularly when a wetland crop is one of the components of the croppingsequence. Growing legumes will improve soil structure.

• Mulching to reduce evaporation losses will also decrease or prevent soil salinization.

• Crop residue application is one of the easiest methods to improve water infiltration,especially for small farmers who do not have the resources to implement more costlycorrective measures. Unfortunately in many instances, the small farmers use crop residuesfor other purposes and little, if any, is returned to the soil. Both crop residue left on the soilsurface as well as the root system of the crop improve soil structure.

• Judicious selection of crops that can produce satisfactorily under moderately saline or sodicconditions has merit in some cases. In areas where it is not practical to reclaim salt-affectedsoils completely, or even to maintain conditions of low salinity and adsorbed sodium, sothat farmers have to live with the existing conditions for some time, an alternative crop canbe selected that is more tolerant of the expected soil salinity or sodicity and can produceeconomic yields.


The factors that affect plant response to salt-affected soils include stage of crop growth, rootstock in the case of fruit trees, crop varieties and climatic conditions.

Human aspects

Farmers should become active participants in the development of appropriate managementsystems and should become the main originators of technical solutions to their environmentalproblems. The technological package available should be field tested under farmers' conditionsand acceptance of newly developed technologies ascertained. Extension officers, project staffand farmers should be trained in all aspects of crop tolerance and management practices. Otherfactors such as pricing and marketing policies, labour, infrastructure development, intensivetraining and extension programmes should be considered. It is now recognized that social andeconomic factors have a decisive influence on farmers' decisions to accept any new technologyand therefore have to be fully taken into account. An environmental impact assessment shouldbe undertaken to identify the possible impacts of the proposed activities on the environment. Itis, in essence, a tool in the decision making process. A sufficient budget of local funds foroperation and maintenance should be reserved. Various aspects of a large management anddevelopment scheme should be controlled by a special development authority under the politicalresponsibility of one minister.

Alternative forms of land use

In some cases, instead of reclaiming salt-affected soils to suit the existing crops, some plantspecies could be selected to suit the environment. Such plants can be introduced on barren salinewasteland and lagoon ecosystems. The green matter (biomass), or seed produced on these landscould be used in numerous ways such as forage, manure and for making pulp for paper, andcould also be converted into other value added products such as chemicals, medical products,methane gas or alcohol for fuel and solvent purposes. Of these plants the jojoba (Simmondsiachinensis) is an example. Halophytes can be grown under very saline conditions, the culmsprovide fibre for high quality paper production, and the seeds can have medical value (Juncusvigidus). Mangroves provide fuel in parts of the world that are chronically short of firewood.

In very saline soils, fish farms and salt making are practised particularly in coastal andlagoon ecosystems.

NETWORK ON INTEGRATED SOIL MANAGEMENT FOR SUSTAINABLE USE OF SALT-AFFECTED SOILS

Although many countries are using salt-affected soils because of their proximity to waterresources and the absence of other environmental constraints, there is a clear need for a soundscientific basis to optimize their use, determine their potential, productivity and suitability forgrowing different crops, and identify appropriate integrated management practices. Because ofthis and the increasing awareness of continuing soil salinization and sodication, FAO's RegularProgramme is supporting national institutes in countries having problems of salt-affected soils tostrengthen their experimental programmes on adapted soil management practices. Since 1990,collaborative projects have been identified to develop management practices for sustainable useof salt-affected soils: experiments and demonstrations on pilot farms are ongoing in twenty-onecountries in different regions - Near East Region (Egypt, Iran, Syria and Tunisia); Asia andPacific Region (China, Indonesia, Pakistan, Philippines, Thailand and Vietnam); Latin America


Region (Argentina, Brazil and Mexico); Europe Region (Hungary, Italy, Spain and Turkey);North America (Canada) and Africa Region (Kenya, Nigeria and Tanzania).

To avoid the fragmentation of technical research and development efforts in soilmanagement of salt-affected soils in developing countries and to stimulate coordination of workbetween different international and national organizations in the field of salt-affected soils, aNetwork was established by FAO in association with the Subcommission of Salt-affected Soilsof ISSS, on Integrated Soil Management for Sustainable Use of Salt-affected Soils. Twenty-onecountries are now participating in the Network - those involved in the ongoing collaborativeprojects. The objectives of the Network are the dissemination of information, improvedcoordination among scientists and extension staff, strengthening field experimental programmes,and extension of appropriate management practices to increase productivity of salt-affected soilsor land irrigated with saline water in participating countries. Activities of the Network includethe above mentioned collaborative projects through experiments and demonstration pilot farms,publishing of a six-monthly Newsletter (SPUSH), and every two years holding an InternationalWorkshop.

CONCLUSIONS

Africa is a vast continent with 55 countries covering a large range of environmental conditions,cultures, political systems and economies. It is therefore impossible to produce a conservationblueprint that can be applied without modification to all parts of the continent. If the problemsof land degradation are to be overcome, each country must develop its own conservationstrategy, policies and programmes, and tailor them to its own unique circumstances. Nationalaction is needed to identify for each country the seriousness and causes of degradation and toaccordingly suggest solutions based on techniques designed both to raise yields and to preventdegradation. It is important that reasons for the problems be understood. Failure to do so canwaste a great deal of time, effort and money.

Physical conservation measures will still be needed such as terracing, proper drainagesystems, provision of alternative feed sources, check structures, protected watersheds, waterharvesting techniques, live fencing and roadside planting, applying dune stabilization methods,etc. However, much greater emphasis should be placed on increasing and maintaining the land'svegetation cover through appropriate agronomic and forestry techniques and introducing soundmanagement practices through proper land preparation and ploughing, amendment using cropresidues, mulching, quick growing species and integrated cropping systems, conservation of soilmoisture, preventing foundation of bad soil structure, tolerance of crop and livestock, etc. Thisapproach protects the land surface from wind and water erosion and improves soil conditions byincreasing fertility and organic matter content. Schemes that encourage better use of land shouldbe implemented such as relocating land users, proper land tenure system, encouraging the use offarm inputs, working with farmers, providing technical advice and training, encouragingparticipation of land users, development of national institutions, coordinating internationalaction and catalyzing regional programmes.

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FAO. 1979. A provisional methodology for soil degradation assessment. FAO, Rome. ISBN 92-5-100869-8.

FAO. 1983. Keeping the land live - soil erosion: its causes and cures. Herbert W. Kelley. Soils Bulletin50, FAO, Rome.

FAO. 1984. A provisional methodology for assessment and mapping of desertification. FAO, Rome.ISBN 92-5-101442-6.

FAO. 1986. African agriculture: The next 25 years. The land resource base. Annex II: pp. 116.

FAO. 1990. The conservation and rehabilitation of African lands - An international scheme.ARC/90/4. FAO, Rome.

FAO. 1993. Agriculture: Toward 2010. FAO Conference, Twenty-seventh Session, November 1993.FAO, Rome.

ISRIC/UNDP. 1990. World map of the status of human-induced soil degradation. An explanatory note.

Mashali, A.M. 1989. La salinizzazione e la desertificazzione del suolo. Genio Rurale N. 11:50-62. Italy

Mashali, A.M. 1995. Integrated soil management for sustainable use of salt-affected soil and networkactivities. Paper presented in the International Workshop on Integrated Soil Management forSustainable Use of Salt-affected Soils, held in Manila, the Philippines, 8-10 November 1995.Proceedings of the Workshop, pp. 55-75.

Oldeman, L.R., Hakkeling, R.T.A. and Sombroek, W.G. 1991. Second revised edition. World map ofthe status of human-induced soil degradation. An explanatory note. Wageningen. InternationalSoil Reference and Information Centre (ISRIC). 35 pp.

Rhoades, J.D. 1984. New strategy for using saline water for irrigation. Proc. ASCE Irrigation andDrainage Speciality Cong., Water Today and Tomorrow, 24-26 July 1984, Flagstaff, Arizona. pp.231-236.

Rhoades, J.D., Kandiah, A. and Mashali, A.M. 1992. The use of saline water for crop production.Irrigation and Drainage Paper 48. FAO, Rome. 133 pp.

Sanders, D.W. 1987. Food and Agriculture Organization activities in soil conservation. In:Conservation Farming on Steep Lands. Ed. Moldenhauer and Hudson. Soil and WaterConservation Society and the World Association of Soil and Water Conservation, Ankeny, Iowa,USA. ISBN 0-935734-19-8.

Sanders, D.W. 1991. International activities in assessing and monitoring soil degradation. Paperpresented to the International Workshop on Assessment and Monitoring of Soil Quality, RodaleResearch Center, Emmaus, Pennsylvania, USA, 11-13 July 1991.

Stoorvogel, J.J. and Smaling, E.M.A. 1990. Assessment of soil nutrient depletion in Sub-SaharanAfrica: 1983-2000, Vol. 1: Main Report, Report 28. The Winand Staring Centre, Wageningen,The Netherlands.

UNEP. 1984. Assessment of desertification. Environmental Conservation Special Issue 11, 1.

UNEP/FAO. 1984. Map of desertification hazards. Explanatory note. UNEP. May 1984.

UNEP/FAO. 1992. World Atlas of Desertification. Edward Arnold. A Division of Hodder andStoughton, London.

World Soil Resources Institute 1992. World resources 1992-93. A report by the World Soil ResourcesInstitute in collaboration with the United Nations Environmental Programme and the UnitedNations Development Programme, New York. Oxford University Press. 385 pp.



Land degradation in relation to food securitywith focus on soil fertility management

The majority of developing countries are faced with difficulties of securing enough food for theirrapidly growing population. Countries with limited land and water resources, particularly thosewhich cannot easily finance increased food imports, will be faced with serious problems. Landdegradation, in different forms, is seriously affecting the soil resources and contributing toconsiderable yield decline, loss in food production, and hence the food security at household andcountry levels. Food security cannot be achieved without effective planning and improvedmanagement strategies of soil, water and nutrient resources. Appropriate soil management andconservation practices are now available, for correcting or minimizing the degradation that alsoenhances land and labour productivity.

Nearly 1.4 thousand million ha of vegetated land in developing countries are subjected toland degradation, resulting in moderate or severe decline in productivity known as soilimpoverishment. Some 9 million ha lands in the world have had their original biotic function fullydestroyed and reached the point that rehabilitation is likely uneconomic. About 490 million ha, inAfrica alone, are affected by various forms of degradation.

Poor and inappropriate soil management systems are the main causes of physical andchemical degradation of cultivated lands. Increasing population pressure, particularly invulnerable regions, has resulted in serious soil fertility decline, especially under extensive farmingpractices. Decreasing yields and vegetation cover and increasing erosion are the typicalmanifestations of mismanagement practices. As a result, farm labour productivity and revenuesfrom agriculture are falling, migration to urban areas is increasing. There is a need to increaseefforts to encourage countries utilizing already known methods and continue to develop new onesto conserve resources, to secure food for mankind.

With recent emphasis and priority programme of FAO on food production in support of foodsecurity, issues related to land degradation and its negative impacts on food production, as wellas land improvement for enhanced productivity, are now receiving a special attention. Rectifyingsoil degradation and sustaining crop production through appropriate soil management andconservation technologies are, therefore, important components of food security. FAO (AGL)with its lead technical, catalytic and coordinating role, has been and will continue to assistmember countries in that direction, e.g. strengthening country efforts to combat land degradationand to improve land productivity.

H. NabhanSenior Officer, Soil Management, Land and Water Development Division, FAO, Rome, Italy

The author of this paper did not participate in the Expert Consultation due to unavoidablecircumstances. The paper, however, was presented by Dr A. Mashali of the same Division

Land degradation in relation to food security with focus on soil fertility management50

So far, assessment of the extent of soil degradation has been attempted at global and/orsmall-scale level (1:10 or 1:5 million mapping). While such global assessment is useful, it has itslimitation, if effective programmes or policy measures have to be implemented in a given countryto address soil degradation and to promote soil improvement schemes. Successful experiences andinitiatives for soil improvement in a specific country or socio-economic and agro-ecologicalenvironment have taken place, but their wider dissemination for the benefit of other countries,even in the same region, is rather limited.

Despite the availability of cost-effective technical options for soil management andconservation, little would be achieved without a policy at high level and promotion of this policyfor the implementation of effective programmes, which are designed to address the direct andunderlying causes of soil degradation. In order to alert policy and decision makers, there is a needto provide evidence of degradation and justification for corrective measures, based on in-depthassessment of the extent, severity of land degradation and their economic and social impacts.Well-documented information on successful examples of soil improvement technologies andinitiatives are also required.

Half of the low income food deficit countries (LIFDCs), where the Special Programme forFood Security (SPFS) is or will be implemented, are in sub-Saharan Africa (SSA). In the shortand medium-terms, the technological packages for enhancing productivity in these SPFS mayheavily rely on low-cost, low-risk options. As such, appropriate and integrated soil and nutrientmanagement for conservation and improvement of the soil resource, in addition to proper waterharvesting and irrigation management, are among the essential elements for enhancing cropproduction and ensuring food security.

Land degradation, is recognized as the most critical problem affecting the agriculturalgrowth and causing increased rural poverty in SSA. In many parts of SSA, fallow periods arebeing reduced considerably and farmers are increasingly cultivating marginal lands susceptible tovarious forms of degradation. The high potential agricultural lands play a vital role in food,fodder and forest products, and are increasingly under threat due to loss of soil fertility. Withoutrestoration of soil fertility, and controlling further degradation on land currently under cultivation,SSA countries will face the chronic food insecurity and hunger.

Soils in most SSA countries have inherent low fertility and are characterized by: (i)deficiencies in major nutrients, particularly N and P; (ii) low soil organic matter; and (iii) poorstructure and low water holding capacity. In addition, these soils do not receive adequate externalnutrient replenishment since SSA countries have the lowest fertilizer consumption in the world,estimated at 10 kg nutrients/ha (as compared to 90 kg/ha of world average, 1990/93; 60 kg/ha inthe Near East and 130 kg/ha in the Far East). The deficiencies in plant nutrients and organicmatter are manifested in: (i) low plant and livestock productivity; (ii) low efficiency in usingwater from rain and irrigation; (iii) low efficiency in using inorganic and organic fertilizer; and(iv) high incidence of erosion.

Agricultural growth in many SSA countries has been stagnant over the past three decades,averaging below 2% annually. Cereal production, for example, has decreased from 150 to 130kg/person over the same period. Food production per capita has been declining in SSA since the1970s, in contrast with the increase in Asia and South America (Figure 1). Under the current rateof population growth (estimated over 3% annually), it is essential to attain an agricultural growthrate of at least 4% per year to counter this food imbalance and reduce poverty. This can beattained mainly through increased productivity in areas presently under cultivation.


There is a convincing reason to believe that this poor performance in agriculturalproductivity in SSA countries is related to declining soil productivity. This paper focuses on thedegradation of soil resources in sub-Saharan Africa.

TYPES AND CAUSES OF LAND DEGRADATION

Definitions

Land is defined as the terrestrial bio-productive system that comprises soil, vegetation, and waterresources, other biota and the ecological and hydrological processes that operate within thesystem. It refers to all natural resources that contribute to agricultural production, includinglivestock and forestry (FAO, 1976; UNEP, 1992).

Land degradation is the temporary or permanent lowering of the productive capacity of land(UNEP, 1992). It refers to reduction in productivity of croplands, range and pastures, forest andwoodlands, resulting from land uses or from processes arising from human activities such as:erosion; deterioration of physical, chemical and biological properties of soils; long-term loss ofnatural vegetation. A new definition was recently given to land degradation as "Land which dueto natural processes or human activity is no longer able to properly sustain an economic functionand/or the original natural ecological function".

Desertification: because of the considerable controversy about the term, the definition given inthe Convention to Combat Desertification may be retained: it is land degradation in arid, semi-arid and dry sub-humid areas resulting from adverse human activities and climatic variation(UNEP, 1992).

Recognition of land degradation at different levels

Traditionally land degradation is identified at three levels:

FIGURE 1World food production per caput


• at field level, land degradation results in reduced productivity;

• at national level, land degradation results in a range of problems such as damage todownstream infrastructure through flooding and sedimentation, reduction in water qualityand changes in the timing and quality of water flows.

• at global level land degradation can contribute to:

- climate change (through increased emissions of greenhouse gases - carbon dioxide"CO2", methane "CH4" and nitrous oxide "N2O" - and changes in the ability of terrestrialecosystems to serve as carbon sinks),

- damage the bio-diversity (both directly in degraded areas and indirectly by inducingexpansion of cultivated land), and

- pollute international waters (through sediment loads and changes in hydrological cycles).

Forms and causes of soil degradation

Major forms of soil degradation are water and wind erosion, other physical degradation, andchemical degradation.

Major causes: deforestation, overgrazing, agricultural mismanagement/over exploitation ofcultivated lands.

The forms of physical degradation would include crusting, compaction, waterlogging,reduced infiltration, removal or decline in organic matter due to de-vegetation. The forms ofchemical degradation would include acidification, salinization/sodication, nutrient depletion orexcessive leaching, pollution from industrial wastes, mining, and application of agro-chemicals.

FIGURE 2Relationship between population pressure and soil productivity


It must be underlined that soil degradationprocesses, whether chemical, physical, orbiological may occur simultaneously orsequentially, and they are interrelated. As such, aclear distinction cannot often be made among thevarious forms of degradation: examples arewaterlogging and salinization, erosion anddecline in organic matter content, erosion andnutrient loss, etc. Figures 2 and 3 show theinterrelationship and causes of soil degradation.

In order to understand the dynamics,relationship of these processes, and formsof degradation, a brief description of theprominent ones is given below:

Soil erosion is defined as the detachment andlateral transport of soil particles on the soilsurface by water and by wind. Determinants oferosion are rainfall, vegetation/ground cover,topography, and properties (erodibility) andslope inclination. Soil erosion causes loss oforganic matter, nutrients and utility water andstructural deterioration, which result in lower yield and soil fertility. The amount of productivitydeclines depends on the crop planted (example maize as high input crop is more sensitive thanlow input crop such as cassava). Decline in productivity due to erosion will also depend on thesoil properties that curtail yield. Soils in the humid tropics (Oxisols, Ultisols) usually suffer fargreater yield loss than less intensively weathered soils (Alfisols, Inceptisols). Compacted surfaceor iron crusts or deterioration of soil structure would promote water runoff and increase erosion,resulting in reduction of groundwater recharge and lowering the water table. Erosion has alsoserious off-site damage through sedimentation on cropland and downstream infrastructure.

Compaction is an increase in bulk density due to external load leading to deterioration of soilphysical properties such as root penetration, hydraulic conductivity and aeration. The maincauses are mechanized farming systems, forest clearance machinery, grazing. In agriculturalengineering there are many methods to reduce compaction, for example, to loosen the soilmechanically or biologically, to reduce the load on the surface of the soil (combined tillage, widetyres, etc.).

Crusting is due to destruction of aggregates in the topsoil by rain and it is closely linked to soilerosion. Crusting reduces infiltration and promotes surface runoff. It inhibits germination andemergence. Lower infiltration rates reduce water retention and aggravate drought stress. Surfacecrusting increases with lack of organic matter application to the soil or insufficient recycling ofharvested crop residue (Stainer,1996).

Waterlogging/Salinization: Waterlogging is the lowering in land productivity through the rise ingroundwater close to the soil surface. Waterlogging is linked to salinization, both are oftenbrought about by incorrect irrigation management. Salinization refers to all types of soildegradation brought about by the increase of salt content in the soil. It thus, covers the build-up

FIGURE 3The downward spiral to the poverty trap


of free salts and sodication due to the development of dominance exchange complex by sodium.Salinization can also be caused by the incursion of sea -water into coastal areas. Human-inducedsalinization is the result of improper irrigation, soil and water management. Due to the highosmotic potential of the water, salinization reduces the amount of water available to plants,results in phytotoxicity, damages soil structure due to high sodicity, impairs infiltration capacityand consequently causes serious decline in yields. If the salinity/sodicity level is high, the soilcould be completely lost from agricultural production. There are some 77 million ha, worldwide,affected by various degrees of salinization, including about 19 million ha in SSA.

Acidification and Al Toxicity: Soil acidification takes place during the agricultural/cropping useof land. The direct causes are heavy leaching and nutrient export, decomposition of organicmatter, and the considerable application of acid reacting fertilizers (NH4SO4, urea). About aquarter of tropical soils are acidic soils with pH values below 5.5 in the upper horizon, but withno Al phytoxicity (Sanchaez and Logan, 1992) About 1.5 billion ha of tropical land areassociated with highly acidic soils, which contain phytoxical Al in solution. Al saturation in thesesoils exceeds 60% of the upper 50 cm. The Al ions directly damage the roots and thus reducenutrient and water uptake and consequently reduce yields significantly.

Decomposition of Organic Matters and its Impact on Nutrient Retention: Soil organic matterplays a key role in soil fertility. The linkages between soil degradation and carbon storage in soilsare complex (Figure 4). Organic matter ensures favourable physical conditions, including waterretention capacity. It provides a balanced and slow-flowing source of nutrients and a base forcation exchange.

In cropping systems involving tillage, organic matter diminishes rapidly. Some forms oftillage, particularly in arid and semi-arid environment, encourage oxidation of organic matterthroughout the profile, resulting in carbon being released to the atmosphere rather than its buildup in the soil. Lower production of crops or pastures (due to degradation or soil erosion or

FIGURE 4Soil carbon cycle and some effects of degradation


nutrient depletion) will result in lower carbon inputs in subsequent period (e.g. less root material,less leaf litter, less crop residues, etc.). In the tropics organic matter, on average, decomposesabout five times faster than in the temperate climate.

About 1.7 thousand million ha of tropical soils are low in organic matter and nutrientreserves, they contain <10% weatherable minerals in the sand and silt fractions. These soils cansupply only a limited amount of N, P, K, Ca, Mg and S. They are particularly common in thehumid tropics (66% of the surface) and the savannahs (55% of the surface).

Because of leaching, particularly in the humid areas, soluble nutrients from the root zone canbe transported into deeper soil layers. The consequent acidification produces Al and Fe-oxyhydroxides leading to P fixation. This P fixation which is more frequent in humid tropics, butalso takes place to significant degree in savannahs and steep highlands. If the exported nutrientsfrom the soil are not compensated by mineral and organic sources of plant nutrients or bysubsequent delivery through weathering of soil minerals, the nutrient content of the soil willdecline rapidly.

Soil Fertility Decline: In general, this is defined as short term deterioration in soil chemical,physical and biological properties. Sometime it could be referred to as soil fertility or soilproductivity decline. Though erosion adversely affects soil fertility, because of loss of nutrients,the main processes other than erosion, which contribute to soil fertility decline are:

• lowering of soil organic matter, with associated decline in soil biological activity;

• degradation of soil physical properties (structure, aeration, water holding capacity) as aresult of reduced organic matter;

• adverse changes in soil nutrient resources, including reduction in availability of majornutrients (N, P, K), existence of micro-nutrient deficiencies and development of nutrientimbalances;

• build up of toxicity due to acidification and/or pollution.

SOIL NUTRIENT DEPLETION IN SSA

Winand Staring Centre in the Netherlands undertook an assessment of the state of soil nutrientdepletion in Sub-Saharan Africa, and the results were published in 1990 (Stoorvogel andSmaling, 1990). Nutrient balances were calculated, through a Model, for the arable lands of 38countries in SSA. The assessments were made for 1983 and the year 2000 and provided, on acountry to country basis, data on the net removal of the macro-nutrients, from the rootable soillayer. Assumptions were made to quantify the various mechanisms that contribute to the flow ofN, P and K into and out of the soil. A simple model was established for the purpose of simulatingthe processes of nutrient inputs and nutrient outputs from the soil.

The inputs used in the above-mentioned assessment were mineral fertilizers, manure,deposition by rain and dust, biological nitrogen fixation. The outputs were harvested products,crop residues, leaching, gaseous losses and erosion (Figure 5). The results of the study showedthat nutrient depletion is quite severe in SSA. An annual average nutrient loss in SSA wasestimated at 24 kg nutrients per hectare (10 kg N, 4 kg P205 and 10 kg K20). The average loss inthe year 2000 was estimated at 48 kg nutrients per hectare per year (i.e. a loss equivalent to 100kg fertilizer product per ha per year).


Classes of nutrient loss rates (in kg/ha) were established for 38 countries (low, moderate,high, and very high; Table.1). The highest nutrient depletion rates were found in East Africa ascompared to West Africa (moderate), Central Africa and the Sahelian Region (moderate to low).Countries with the highest depletion rates were found to be in most cases associated with highdegrees of erosion (e.g. Kenya and Ethiopia). Classes of nutrient loss and distribution of countriesin 1983 are given in Table 2.

FIGURE 5Nutrient flows in the soil

Input and output factors governing nutrient flows in the soil


TABLE. 1Classes of nutrient loss rates (in kg/ha/year)

Class N P205 K20

Low <10 <4 <10Moderate 10-20 4-7 10-20High 21-40 8-15 21-40Very high >40 >15 >40

TABLE 2Countries classified by nutrient depletion rate in 1983

Low Moderate High Very HighAngolaBotswanaCentral African RepublicChadCongoGuineaMaliMauritaniaMauritiusZambia

BeninBurkina FasoCameroonGabonGambiaLiberiaNigerSenegalSierra LeoneSudanTogoZaire

Côte d'IvoireGhanaMadagascarMozambiqueNigeriaSomaliaSwazilandTanzaniaUgandaZimbabwe

BurundiEthiopiaKenyaLesothoMalawiRwanda

As an example, Figure 6, shows the nutrient inputs/outputs and the net removal inZimbabwe and Swaziland (62 and 55 kg of nutrients net removal/ha/year, respectively).

It may be noted that this "study" (Stoorvogel and Smaling, 1990) was the first globalassessment of nutrient depletion. It draws attention to issue and the need of corrective measures,and its results are quoted by various scientists and policy makers since the publication of thereport.

Some scientists, however, raised concern about the methodology and approach usedin the study, as it implies a lot of approximation and aggregation at country level,which could be misleading and mask the "bright" spots and the "hot" spots whereurgent nutrient replenishments are required. It would be more appropriate, however,to carry out the assessment of nutrient balances (using the same concept of the model)at watershed or community level, in view of the complicated dynamics of nutrientflows and transfer of fertility, in small geographical areas and/or specific farmingsystems.

Considering the scale-inherent simplification of nutrient balance assessment at country level,a study was undertaken in Kisii District in South-West Kenya, 1992 (Smaling et. al, 1992). Landuse types and land/water classes (combinations of rainfall zones and soil units) were combinedinto geographically well-defined land use systems, with NPK inputs by mineral fertilizers,manure, wet and dry deposition, biological N fixation, outputs by above-ground crop parts,leaching, denitrification, and erosion. The aggregated nutrient balance (net removal) for the KisiiDistrict was - 185 kg nutrients/ha/year. For all nutrients, removal of harvested product was thestrongest negative contributor, followed by erosion. Sensitivity analysis revealed that changingmineralization rate and soil N content had an important impact on the N balance. (The netnutrient removal for the whole of Kenya was earlier estimated by Stoorvogel and Smaling at 85kg nutrients/ha/year).


The study also revealed that practices such as zero tillage, mulching, strip cropping, alleycropping, and considerably reduce erosion and consequently the nutrient's loss. Integrated nutrientmanagement approach was also emphasized, as a combination of mineral fertilizers, manure andcrop residues gave the highest maize yields (long-term trial, 5-10 years) as compared todifferent/individual treatments of each. The results of such a study at "district level" could betranslated into packages to provide advice on land use planning and management issues. Themethodology used in the study could be applied in other districts (or countries) and proved to bevaluable for researchers, policy makers and farmers in understanding the systems of integratedsoil and nutrient management.

FIGURE 6Nutrient balance for Zimbabwe and Swaziland in 1983 in kg/ha/year


Other studies estimated that 4 million tonnes of nutrients are harvested annually in Sub-Saharan Africa, while only ¼ of it is returned to the soil in the form of fertilizers. For example,on the 6.6 million ha of land cultivated in Burkina Faso, an estimated 95 000 tonnes of N, 28 000tonnes of P205 and 79 000 tonnes of K20 are lost annually as a result of nutrient mining. In theGambia, for example, the estimated nutrient removal by the major crops amounted to 26 000tonnes of nutrients - N, P205, K20 - per annum, against nutrient inputs of only 2 850 tonnes frominorganic fertilizers and 5 640 tonnes from organic manure.

Besides declining yields due to nutrient mining, this type of degradation would alsocontribute to deterioration of soil structure due to reduction in biomass and organic matter,reduced water infiltration and increased erosion. With population pressure and low level offertilizer or nutrients use, farmers may be forced to cultivate marginal/low productive lands andhence the continuation of the vicious circle of land degradation.

The attempt to maintain crop yields through application of commercial fertilizers,without due consideration to corrective soil management practices, such as themaintenance of soil organic matter and improving both physical and chemical soilconditions with low-cost packages and local resources is inappropriate. Emphasizingfertilizer use alone to address the nutrient mining may not be applicable/relevant inmany countries in Sub-Saharan Africa, where fertilizer use is still very limited and isalmost stagnant for the last 15 years.

ASSESSMENT OF SOIL DEGRADATION

GLASOD

For the first time, an attempt was made to map the severity of soil degradation at Global level,under the project "Global assessment of human-induced soil degradation", known as GLASOD(Oldeman et al., 1990b). The project was undertaken by the International Soils Research andInformation Centre (ISRIC), under the aegis of UNEP and in collaboration with FAO. The mapwas at the scale of 1:15 million at the equator and 1:13 million at 30o latitude. A standardizedmethodology, including definitions, was developed through international consultations. Datafrom individual countries was provided by leading experts in the field. The authors of GLASODacknowledge, however, that there are certainly some deficiencies and that the assessment shouldbe regarded as first approximation (Oldeman et al., 1990a,b) (Table 3).

An estimated 2 thousand million ha of agricultural land worldwide are degraded(Table.3).

TABLE 3Major terrain division of the GLASOD map (in million ha)

Continents Non usedwasteland

Stableland

Other terrain (nondegraded)

Human induced,soil degradation

Total landsurface

Africa 732 441 1 299 494 (17%) 2 966Asia 485 1 426 1 597 748 (18%) 4 256South America 28 368 1 129 243 (14%) 1 768Central America 53 27 163 63 306North America 75 1 043 672 95 1 885Europe 1 116 614 219 950Australia 95 250 434 103 882World 1 469 3 671 5 909 1

964(15%) 13 013


GLASOD identifies four categories or "Degrees" of degradation (light, moderate, strong andextreme). About 749 million ha is identified as light degree of soil degradation, implying asomewhat reduced productivity, but manageable in local farming system (including some 25million ha in Asia and 174 million ha in Africa). About 910 million ha are classified asmoderately degraded, which require major improvements to restore productivity, often beyond themeans of small scale farmers in developing countries. Some 340 million ha of this moderatelydegraded land is found in Asia and over 190 million ha are located in Africa. Strongly degradedsoils cover an area of 296 million ha worldwide, of which 108 million ha in Asia and 124 millionha in Africa. These soils are not any more reclaimable at farm level and are virtually lost. Majorengineering work is required to restore their productivity. Extremely degraded soils areconsidered unreclaimable and beyond restoration. Their worldwide coverage is almost 9 millionha, of which 0.5 million ha in Asia and 5 million ha in Africa.

Direct causes of degradation. GLASOD estimates soil erosion to be the most important form ofsoil degradation, because about 56% of the degraded lands are affected by water erosion and 28%by wind erosion (Table 4).

The most important causes of water erosion are deforestation (43%), overgrazing (29%),and agricultural mismanagement (29%). For wind erosion the major causes are overgrazing(60%), agricultural mismanagement (16%), over exploitation of natural vegetation (16%) anddeforestation (8%).

The most important forms of chemical degradation are loss of nutrients and organic matter(mainly in South America and Africa) and salinization (in Asia). The main reasons for chemicaldegradation are agricultural mismanagement (56%) and deforestation (28%).

GLASOD maps also show physical degradation in temperate zones, mainly attributed tocompaction because of the use of agricultural machinery. Some of the basic data of GLASOD,particularly for Africa, are given in Tables 3, 4, 5, and 6. It may noted that individual countrytables showing the overall severity of degradation and main causes can be retrieved fromGLASOD database.

It may be concluded that while the assessment provided by GLASOD is useful at aglobal level, it has its limitations (because of the very small scale) to be used atcountry level for concrete planning of agricultural production and/or degradationcontrol measures. More detailed and in-depth assessments are required per country(example the recent assessment carried out in Togo at scale of 1:500 000) (Brabant etal., 1997).

TABLE 4Human-induced soil degradation for the world, GLASOD (in million ha)

Type/Degree Light Moderate Strong Extreme ~Total*Water erosion 343.2 526.7 217.2 6.6 1 094 (56%)Wind erosion 268.6 253.6 24.3 1.9 548 (28%)Chemical degradation 93.0 103.3 41.9 0.8 239 (12%)•Loss of nutrientsnutrients

52.4 63.1 19.8 - 135

•Salinization 34.8 20.4 20.3 0.8 76•Pollution 4.1 17.1 0.5 - 22•Acidification 1.7 2.7 1.3 - 6Physical degradation 44.2 26.8 12.3 - 83 (4%)•Compaction 34.8 22.1 11.3 - 68•Waterlogging 6.0 3.7 0.8 - 11Total* 749 (38%) 910 (46%) 296 (15%) 9 (1%) 1 964 (100%)

*rounded figures for the totals


TABLE 5Human-induced soil degradation in Africa, GLASOD (in million ha)

Type/Degree Light Moderate Strong Extreme ~TotalWater erosion 57.5 67.4 98.3 4.3 227.4 (46%)Wind erosion 88.3 89.3 7.9 1.0 186.5 (38%)Chemical degradation 26.0 27.0 8.6 - 61.5 (12%)•Loss of nutrients 20.4 18.8 6.2 - 45.1•Salinization 4.7 7.7 2.4 - 14.8•Pollution - 0.2 - - 0.2•Acidification 1.1 0.3 - - 1.5Physical degradation 1.8 8.1 8.8 - 18.7 (4%)•Compaction 1.4 8.0 8.8 - 18.2•Waterlogging 0.4 0.1 - - 0.5Total* 174

(35%)192

(39%)124

(25%)5 (1%) 494 (100%)

TABLE 6Human-induced soil degradation in Asia, GLASOD (in million ha)

Type/Degree Light Moderate Strong Extreme ~TotalWater erosion 124.5 241.7 73.4 - 440.6 (59%)Wind erosion 132.0 74.6 14.4 0.2 221.2 (30%)Chemical degradation 31.8 21.5 19.5 0.4 73.2 ( 1%)•Loss of nutrients 4.6 9.0 1.0 - 14.6•Salinization 26.8 8.5 17.0 0.4 52.7•Pollution - 1.5 0.3 - 1.8•Acidification 0.4 2.5 1.2 - 4.1Physical degradation 5.7 6.0 0.4 - 12.1 ( 2%)•Compaction 4.6 5.0 0.2 - 9.8•Waterlogging 0.4 - - - 0.4Total* 294

(39%)344

(46%)108

(14%)0.5

(1%)747 (100%)

ASSOD

Based on the recommendations of the Expert Consultation of the FAO Asian Network of ProblemSoils (1993), UNEP formulated a project under the title: Assessment of the Status of Human-induced Soil Degradation in South and Southeast Asia (ASSOD). The project was financed byUNEP and the responsibility for coordination and implementation was entrusted to theInternational Soil Reference and Information Centre (ISRIC), in close collaboration with FAOand national natural resource institutions in 17 countries of the sub-region. FAO providedfacilities, technical and financial support during the implementation of the project.

The assessment of degradation was undertaken at a scale of 1:5 million, using refinedGLASOD methodology, computerized database linked to GIS, physiographic maps and databasesconstructed along the lines of the internationally endorsed SOTER (Soils and Terrain DigitalDatabase) approach (FAO, WSRR no 78, 1994).

Besides detailed geo-referenced maps and information on dominant degradation types, whichcan be derived from the ASSOD database, the extent and impacts of degradation can be moreprecisely assessed. ASSOD maps and database provide credible and valuable contribution to theworldwide concern about soil degradation and its negative impact on agricultural productivity.An obvious next step would be to prepare these kinds of maps and evaluations at higherresolution for specific regions of countries of concern.

An initiative/project similar to ASSOD for Southern and East Africa is recommended.


HIGHLIGHTS OF STUDY ON LAND DEGRADATION IN SOUTH ASIA

Through the inter-country project RAS/93/560, and collaboration between FAO, UNEP andUNDP, a supplementary study (to GLASOD) was undertaken. The results were published in1994, in the FAO World Soil Resources Report ("Land degradation in South Asia, its severity,causes and effect upon the people; FAO, WSRR No 78, 1994). Besides the GLASOD data,additional information derived from surveys or estimates by government institutions andspecialists was used for the study. It is also the first time that an attempt was made (by thisstudy) to quantify (even with a lot of approximation) the economic loss caused by the variousforms of degradation at a regional level. Comparison and cross checking were made with thestandard GLASOD data and methodology and adjustments/corrections were made, asappropriate. The main countries covered by the study were: Afghanistan, Bangladesh, Bhutan,India, Iran, Nepal, Pakistan and Sri Lanka.

In addition to the elaborated estimates on soil erosion and its impacts, the report providedmore information (though not very conclusive) on "evidence of soil fertility decline". On the basisof this study, however, the GLASOD estimates for soil fertility decline (degradation) were revisedin India and Pakistan.

For promoting exchange of experiences among the Regions, items related to landdegradation, fertility decline, their causes and impacts are highlighted below.

Causes

The following direct and underlying causes of soil degradation have been identified:

Direct Causes are the unsuitable land use and the inappropriate soil management practices (theyvary with the type of degradation):

• deforestation of fragile land, unsuitable for sustained agricultural use• overcutting of vegetation• shifting cultivation without adequate fallow period• overgrazing• non-adoption of soil and water conservation practices• extension of cultivation into lands of low potential or high natural hazards (marginal lands)• improper crop rotations• deficient plant nutrients and negative nutrient balance• unbalanced fertilizer use• problems arising from planning and management of irrigation schemes• over pumping of groundwater, in excess of capacity for recharge.

Underlying Causes

• population increase• land shortage• land tenure, short-term or insecure tenancy• poverty and economic pressure.

The underlying causes are linked (Figure 7). The two external, or driving, forces are "limitedland resources" and "increase in rural population". These combine to produce "land shortage",resulting in small farms, low production per farm and increasing landlessness. The consequenceof land shortage is "poverty". Land shortage and poverty, taken together, lead to "unsustainableland management practices", which are the direct cause of degradation


Soil fertility aspect, Asian experience

The problem of soil fertility decline has not previously received enough attention. On a nationalscale, increases in crop yields are falling behind rates of increase in fertilizer use. Surveys haveshown that application of soil organic material is declining. Micronutrient deficiencies are widelyreported, where farmers have attempted to sustain yield by application of major nutrients only. Inlong-term experiments, yield responses are declining except where fertilizers are applied inconjunction with organic manure. This form of degradation is found in both the humid and dryzones. Whilst its widespread occurrence is not in doubt, more precise and quantitative estimatesof its extent and severity will require further surveys and monitoring of soil changes.

Evidence and factors that are contributing to soil fertility decline are summarized below:

• Organic matter depletion: Crop residues are widely used for fuel and fodder and not returnedto soil. Use of farmyard manure is limited. In Bangladesh, for example, the average OMcontent declined by 50%, from 2% to 1% over the past 20 years.

• Continuing negative plant nutrient balance (nutrient mining): Removal of nutrients from thesoil by the harvested crops appears substantially to exceed inputs as fertilizers or naturalreplenishment.

• Imbalanced fertilizer application: Fertilizer use in the region is concentrated on N, forexample, the N:P:K ratio for India was (in 1992) 1.00:0.33:0.17, compared with1.00:0.52:0.40 for the world. Imbalanced fertilizer use is considered to be among theprincipal causes of low fertilizer use efficiency and yield stagnation.

• Secondary and micronutrient deficiencies: An increasing incidence of S and Zn deficienciesis occurring in the region, thus limiting yields and crop response to fertilizers.

• Lower response to fertilizers: Increases in fertilizer use is not matched by increases in cropyield: a levelling off, or plateau, in crop yield increases which took place in the 1960s and

FIGURE 7Causal nexus between land, population, poverty and degradation


1970s is continuing in the region. The Grain Nutrient Ratios are falling. A striking examplefrom a 33-year fertilizer experiment (at Bihar, India) showed that despite changes inimproved varieties, wheat yields have declined substantially over the period with N, NP, andNPK fertilization, whereas they have risen with farmyard manure (Goswami and Rattan,1992).

Despite the above indicators, it is difficult to establish any significant trends in soil fertility.That is mainly because of the lack of long-term monitoring.

Drawing from the experience in Asia, which certainly has some similarities in someAfrican countries, there is a need to study the soil fertility decline trends.

Two methods are appropriate:

• long-term experiments with standardized methodology through well established network;

• monitoring of changes in soil properties and relevant land quality indicators, over long periodon a statistically-based selection of on-farm sites (Young, 1991).

Bio-physical and socio-economic impacts of degradation

The effects of land degradation may be grouped as effects on (i) production and (ii) consequenceson the people:

Effects on production

• Reduced crop yields.

• Increased inputs and greater costs where farmers, out of necessity, attempt to combatreduction in yields with increased inputs, particularly fertilizers.

• Reduced response to inputs, for example lowering of organic matter content as a result ofdegradation will lower the response to fertilizers.

• Reduced productivity of irrigation systems because of salinization for example, therebyleading to less efficient use of capital investment and labour inputs into the development ofirrigation schemes.

• Lower flexibility of land use, for example reduced crop yields may force farmers to growonly cereals, and this can lead to further decline in soil fertility.

• Greater risk, degraded soil is less resilient and less able to recover from production riskssuch as drought, erosion will reduce OM content and water holding capacity of the soil.

• Loss of water for irrigation, an off-site effect of deforestation and erosion of watershedareas, is the destabilization of river flow, causing flooding after rain and reduced flow insubsequent periods. Downstream irrigation and drainage infrastructure can also be damagedas a result of sedimentation caused by erosion.

Effects upon the people

• Increased landlessness, abandonment of land, where degradation has reached severe degree.

• Reduced and less reliable food supplies, lowering of crop yields means reduced production offood crops, increased risks, lower supplies and lowered food security.


• Increased labour requirements. erosion, deforestation, drying up of rivers caused bydestabilized flow, forces farmers to collect fuel-wood and water from long distances (e.g.more labour); labour used in reclamation and rehabilitation of land is labour lost fromproduction; reduced crop yields and increased inputs both have the effect of reducingfarmers' return from labour.

• Lower incomes and welfare, out of all consequences of land degradation is lowering ofincomes of the resource poor/small scale farmers as a result of: "increased inputs or reducedoutputs". With land degradation occurring, it becomes a declining resource and as aconsequence, labour and capital are less efficiently applied and productivity is lowered.

Land degradation means that farmers must either accept a lowered productivity of food orelse put in greater effort and resources to maintain production. It is the poor who suffer mostfrom land degradation. Poor farmers, particularly those with small landholding, have neither theresources to combat land degradation and enhance productivity, nor the options to meet short-term disasters such as flood, drought, pest attack, etc. Because of land shortage and decliningproductivity, accentuated by degradation, the poor farmers may have only limited options:clearance (or deforestation) of fragile lands for agricultural production which cannot be sustainedbecause they have not the required resources; work on the land of others; migrate to cities orultimately depend on famine relief.

Economic cost of degradation

The estimates of cost could be based primarily on the measurement of two variables: productionloss or replacement cost.

i. Production loss is the reduced productivity of the soil as a consequence of degradation,which could be expressed as a percentage of production from the undegraded soil. Forerosion and soil fertility decline, the assumptionsare: a 5-10% production loss for a "light" degree ofdegradation, 20% for "moderate" and 75% for"strong" degradation. In the case of salinity, therespective assumed losses based on experimentaldata, are 15%, 65% and 100%, respectively.

ii. Replacement cost is the cost of additional inputs(basically fertilizers) used by farmers in order tomaintain production levels on the degraded soils.

Based on the method of production loss, the cost ofland degradation in South Asia region was estimated atsome US$10 thousand million per year (FAO WSSRNo.78, 1994) (Table.7).

Addition of the off-site effects of erosion would substantially increase this figure. The on-sitecost is equivalent to 2% of the Gross Domestic Product of the region, or 7% of its AgriculturalGross Domestic Product.

For indicative purposes, other estimated costs due to land degradation are:

• Australia: Annual loss of production was estimated at US$300 million due tosalinity/waterlogging, US$200 million due to soil structure deterioration, and US$80 milliondue to erosion.

TABLE 7Estimated cost of land degradationin South Asia.

Type ofdegradation

Cost US$thousand million

per yearwater erosion 5.4wind erosion 1.8fertility decline 0.8waterlogging 0.5salinization 1.5


• Zimbabwe: Total financial cost, due to annual loss of nutrients by erosion, from arable lands(i.e. equivalent cost of fertilizers) was estimated at US$150 million (1986).

• Burkina Faso: The estimated annual loss of nutrients (mining) amounted to US$159 millionin terms of N, P, K fertilizers (1983).

• Desertification costs the world an estimated US$42 billion a year.

Despite the approximation in the estimations of costs of degradation, they arerequired to provide evidence in order to alert policy and decision makers (atregional, national and sub-national level) for promoting conducive policies and forimplementing appropriate programmes for addressing soil degradation andimproving productivity, and where possible, to reverse the effects of past degradation(i.e. reclamation and rehabilitation). In this respect, sub-regional and/or nationalstudies for estimation of economic costs of degradation, in Africa, are recommended.

LIMITATIONS OF DATA AND GAPS RELATED TO LAND DEGRADATION

Despite years of concern over the effects of land degradation on crop lands, critical gaps remainwith respect to the data and information.

• The data and information are highly fragmented, incomplete and often unreliable; theinformation on land degradation often stops short of addressing the productivity issues whichare of fundamental interest to policy makers, agricultural planners as well as the farmers.

• Much of the data is purely qualitative. Land is classified as "undegraded", "degraded" or"severely degraded" but the meaning of these labels and the magnitude of each category areseldom made precise.

Examination of available data on crop yields, at national level, does not often provide strongevidence that degradation is affecting productivity. In many countries, the yields appear to haveincreased over the last decades, even in SSA (though per capita production has fallen). Thesedata, however, do not mean that there is no land degradation. Some examples are:

• Data on average national yields may well conceal significant regional or sub-nationalvariations.

• National yield data are often suspect, both in terms of quality and in terms of representation.If data collection tends to favour the more prosperous farmers using improved techniques,for example, it may miss degradation problems experienced by the bulk of farmers.

• Agricultural technology has improved and input levels have been increasing and this mayhave offset some of the effects of degradation, e.g. in the absence of degradation, yieldincreases might have been faster.

• Expansion of agriculture into new, as yet undegraded areas, may mask the effects ofdegradation on existing agricultural land.

As such, it should be emphasized that assessment of degradation and its impacts onproductivity at a national/aggregated level could be misleading. For meaningfuladvisory services and planning purposes for enhancing agricultural production andfor implementation of measures to control degradation, attention should also be paid


to the site-specificity of the problem. It is not usually necessary to have completeinformation in the entire country. What is needed is information on the specific area"hot spot" where interventions have to be envisaged. There is also a need for morequantitative data on the effects of degradation on productivity. Long-term, on-farmtrials and more precise monitoring mechanisms are required in this respect.

Since the global assessment of human induced soil degradation (GLASOD) and the study onnutrient depletion in sub-Saharan Africa were disseminated in 1990, considerable debate hasarisen, however, over the magnitude of the problem. Recent reviews and detailed studies, forexample in Ethiopia, Kenya, El Salvador or Togo, (Pagiola, 1997; Brabant et al., 1997)challenge the "more catastrophic views" of the nature, extent and severity of land degradation,particularly the erosion. None of these studies, however, suggests that land degradation is not aproblem.

For example, the detailed assessment of land degradation in Togo (at a scale of 1:500 000)showed that 77% of the land has "minor" degradation caused mainly by farming activities andonly 1.6% of the country is severely degraded. The study also confirmed the hypothesis that themain cause of chemical degradation is the change in farming system due to population pressure.In this respect, however, no quantitative relationship was established, but indicators formonitoring were suggested: the ratio of crop fields to fallow land, as main indicator of populationpressure on the land. Population distribution and cropping density are, therefore, two factors tobe monitored attentively; the former through periodic census results, and the latter by interpretingsatellite images.

CONTROLLING LAND DEGRADATION, CHANGES IN APPROACHES/PROJECT DESIGN

Approaches for addressing land degradation

These may include:

• Changing production technology, for example, by introducing practices such as minimum orconservation tillage, application of manure, or agroforestry.

• Adding conservation techniques to production systems, for example, by introducing terracesin steeplands.

• Changing patterns of land use, for example, by relocating cropland and pastures to lowerslopes and reforesting steeper slopes or by changing stocking rates on grazing land. Suchefforts are often undertaken on a watershed scale.

If degradation is far advanced, such measures might have to be preceded by reclamationand/or rehabilitation of the affected areas (as in case of moderate or strong degree ofsalinization).

Any land degradation control effort must begin with the diagnosis of the problem, i.e. anassessment of the extent and severity of land degradation (in a more quantitative manner) and adiagnosis of the main causes of this degradation. Some countries that are seriously affected byland degradation have already started the diagnosis process through, for example, preparation oftheir National Environmental Action Plans (NEAPs) or National Action Programmes (NAPs).


These allow combating desertification within the framework of CCD, e.g., providing newopportunities to review land degradation problems and prioritize interventions.

Changes in approaches and project design

Historically, the approach taken by most land degradation control projects has been to encourageland users to adopt some specific conservation measures. The proposed measures were generallycentrally selected by specialists. Various forms of incentives were introduced ranging fromsubsidy, credit, free inputs or payment of even all the cost of implementation of heavy structures(for erosion control for example).

Many recommended conservation measures, while technically sound in terms of preservingland, were inappropriate to farmers' conditions. Insufficient attention was paid to the constraintsfaced by the land users and causes of their use of degrading practices. Moreover, insufficientattention was paid to the policy and socio-economic environment. In many cases such approachhas failed; adoption of the recommended practices was low, in other cases the practices wereabandoned once the project ceased, seldom did adoption spread to other land users who did notreceive subsidies, or financial incentives.

Therefore, emphasis of land degradation control projects has recently changed, to take intoaccount the following basic principles:

i. Land degradation control efforts or projects have been moving toward a more participatoryapproach, in which both the selection of solutions and their implementation are decided uponand executed in cooperation with beneficiary groups. An example is the approach of"Gestion des terroires" or the so called "Community-Based Natural ResourceManagement" (Pagiola, 1997). In this approach, communities design and implement aresource management plan with the help of a multidisciplinary team of technicians. The planincludes rules governing access to and exploitation of common resources such as pasture,forest and water, and specific land improvement work mainly on common lands but also onindividual holdings.

The new approach also includes:

• management plan must be site-specific, e.g. there are no "blue prints";

• management units must be based not only on social units (e.g. villages) but on naturalresources units (such as watersheds) that need to be treated together for managementpurposes;

• when a resource is shared by several communities, the management unit needs toinclude all users;

• a multidisciplinary production system approach is considered, even where one activitysuch as grazing is dominant;

• government departments and relevant farmers advisory services have to be adapted tothe approach and directed to support the schemes at community level or decentralizedstructure.

ii. Much greater attention is now paid to changing the incentive framework within which landresource management decisions are made; such as change in pricing policy, marketliberalization, land tenure reforms, etc.


The World Bank and other agencies, such as IFAD, have already devoted considerableresources to assist countries in implementation (with the new approach described above) ofprojects aiming at controlling land degradation and improving its productivity. Projectsusing this approach are already implemented in West Africa. Similar watershed landmanagement projects have also been carried out in Latin America with technical assistancefrom FAO.

PROPOSALS FOR MONITORING AND STRENGTHENING EFFORTS TO COMBAT LANDDEGRADATION

If comprehensive and integrated action is not taken to combat both direct and underlying causesof land degradation: land resources would be destroyed and there will be further economic lossesat national level, negative consequences on the environment at global level; and the poor farmerwill suffer. In order to enhance the knowledge and monitor the status of land degradation and tostrengthen the efforts for combating degradation, the following proposals may be considered:

i. Establishment of regional or sub-regional Collaborative Programme and guidelines for in-depth assessment of land degradation, which would include survey of the present state ofdegradation and monitoring of soil changes.

ii. Study of the economic and social effects of degradation upon the people, which will requirecollaboration between land resources and management specialists as well social scientists.

In this respect, initiating a sub-regional project on the assessment of soil degradationand its impacts in Southern and East Africa (in line with ASSOD "Soil degradation inSouth and South-East Asia") would be useful.

Moreover, there is a need for harmonization of methodologies and promotion ofquantitative assessment of the impacts of degradation on productivity at national/sub-regional level, using 1:1 million SOTER database (example: impact of erosion or fertilitydecline, Case Study/Project in Kenya, Argentina and Uruguay -UNEP/ISRIC). This ofcourse is subject to the concerned countries' interest, commitment and eventually thepossibility of donor's support.

iii. Design and implementation of programmes and measures to combat land degradation wouldinclude:

• Clarify institutional responsibilities, and perhaps the establishment of high-level advisorycommittees on policies related to land degradation and its combat.

• Identify focal institutions and coordination mechanisms for land degradation assessmentand monitoring.

• Identify priorities with respect to type of degradation, critical and "hot" spots.

• Plan and implement national, sub-national and/or community-based programmes forcontrolling degradation and for enhancing productivity, such as:

- watershed land management and conservation projects;

- community-based natural resources management projects "Gestion des terroires";


- elaboration and implementation of National Action Programmes for combattingdesertification and drylands development projects;

- promoting the adoption of ISCRAL (Soil conservation and rehabilitation schemes) atnational, sub-regional and regional level.

Allocation of national resources, increased funding and international support would berequired.

In this respect, there is a need of: more effective regional and/or sub-regional co-operation, networking for exchange of experience and technologies, increasingawareness and dissemination of information on land degradation and correctivemeasures for its control; mobilization of national financial resources and commitmentto the issue; promotion of donor support, technical assistance from bilateral andinternational relevant agencies (such as FAO) for the implementation of landdevelopment programmes.

Networks

Networks established through regional collaborative programmes, with the support of FAO andUN Agencies, continue to play an important role in exchange of ideas, experiences andtechnologies as well as assistance in policy and project formulation related to land degradationcontrol and land productivity improvement.

While several relevant networks are still operating in Asia, with the support of UN agenciesparticularly FAO, not much attention has been given to the Africa region with respect tonetworks, which specifically deal with land degradation and land improvement issues. Moreover,if a specific network is established in Africa, with technical support of FAO, the participatingcountries would benefit from global exchange of information, technologies and methodologiesetc., through interlinks with existing global and regional networks, in Asia and Latin America,which are supported by FAO.

The FAO Soil Resources, Management and Conservation Service (AGLS) has provided anddisseminated to FAO member countries and partner institutions: technical assistance,information, methodologies, concepts and frameworks, technologies and global assessmentrelated to land resources, management and conservation. In addition, AGLS has been at theforefront of creating international linkage and networks concerned with land management andconservation. Examples of relevant ongoing networks (supported by FAO/AGLS) are givenbelow:

• Asian Network on Problem Soils

• Asian Bio and Organic Fertilizer Network

• Asia Soil Conservation Network for the Humid Tropics (ASOCON)

• Network on conservation tillage in Latin America (RELACO)

• Association with WOCAT (World Overview of Conservation Approaches andTechnologies)

• Global Network on Integrated Soil Management for Sustainable Use of Salt Affected Soils

• The Network on the Management of Gypsiferous Soils (Near East and Mediterranean).


* It is, therefore, proposed, subject to debates and endorsement of this consultation, to createan "African Network on Degraded and Problem Soils". Such a network would deal withissues related to soil degradation, its assessment and promotion of soil management andproductivity improvement technologies. The Network could also promote, through TCDCmechanisms, transfer of knowledge and experience in areas related to sustainablemanagement of problem soils, such as: acid soils, saline soils, gypsiferous soils,calcareous soils and vertic soils. This African Network will be interlinked with the abovementioned ongoing networks (assisted by FAO) to ensure global and intra-regionalexchanges of experience and know-how. The proposed Network, however, could cover atinitial stage some countries in Southern and East Africa (i.e. countries under SAFR).

THE SPECIAL PROGRAMME FOR FOOD SECURITY (SPFS)

At present, there are 86 low-income food deficit countries (LIFDCs), including 43 countries inAfrica and 9 in Latin America and the Caribbean. These countries are home to the vast majorityof the world’s 800 million chronically undernourished people. Many LIFDCs, particularly inAfrica, do not grow enough food to meet their needs and lack sufficient foreign exchange to fillthe gap by purchasing food on the international market. After the approval of the Council in June1994, the SPFS was launched by FAO and at present it is operational in 20 countries. Initiallylaunched with modest FAO Regular Programme funds, the SPFS is now supported by severaldonor countries and international agencies, including the World Bank, African DevelopmentBank, IFAD, WFP and UNDP.

The SPFS helps farmers increase food production and productivity in LIFDCs. It respondsto the urgent need to boost food production in these countries in order to meet the growing marketdemands and help eradicate food insecurity. The SPFS implementation consists of two phases: a"pilot phase" of some 3 years’ duration, followed by an "expansion phase" that takes place afterresults of the 4 components of the pilot phase have been assessed and the policy and investmentplan have been prepared and approved at national level. The pilot phase, which usually startswith participatory on-farm demonstrations, consists of 4 interrelated components:

• Improved water control, including low-cost small-scale irrigation.

• Sustainable intensification of crop production systems, through improved technologies1 andagricultural inputs.

• Diversification of production, including aquaculture, small animal and horticulture.

• Removal of constraints to increased food production, through participatory approach

World Food Summit (WFS)

The successful expansion of the SFPS will play an important role in achieving food securityobjectives, set out by the World Food Summit (WFS), held in Rome, November 1996.Representatives of 186 countries approved the Rome Declaration and the WFS Plan of Actionthat included recognition of the need to pursue, through participatory means, sustainableintensified and diversified food production:

1 Including Integrated Soil, Water and Nutrient Management.


"Objective 3.2, Commitment Three of the Plan of Action is: to combat environmentalthreats to food security, in particular, drought and desertification, pests and erosionof biological diversity and degradation of land and aquatic-based natural resources,restore and rehabilitate the natural resource base, including water and watersheds,in depleted and over exploited areas to achieve greater production".

Complementarity and the place of ISWNM1 in the SPFS

Sustainable increase of food production is critical for achieving household food securityparticularly in resource poor areas. Improper land use and management, over cultivation,physical, chemical and biological soil degradation cause serious decline in productivity, especiallyin countries or areas subjected to increased population pressure on limited and/or fragile lands.Identification, selection and farmers’ adoption, through participatory approach, of improvedand alternative packages of low-cost, low-risk soil management and conservation practices are,therefore, required to address/control land degradation, to maintain and enhance soil fertilityand hence, soil productivity and food production.

The adoption of improved packages of technologies related to soil, water and nutrientmanagement at farm level is rather limited, particularly in LIFDCs, because the development ofthese technologies has often not taken into due consideration the socio-economic environment ofthe farmers nor the specific potentials and constraints of the natural resources base at farm and atcommunity level.

Despite the availability of segmented technologies on soil, water and plant nutritionmanagement; the holistic approach and integrated packages are still lacking. In addition,effective approaches and mechanisms for participatory technology development and transfer tofarmers are inadequate. Field level technicians and grass-root extension workers still lack trainingin such integrated approach to facilitate farmers’ adoption.

The sustainable intensification of production systems in agriculture is a key for foodsecurity and requires a coherent and integrated development of appropriate technologies, know-how and tools related to soil, water and plant nutrition management. Assisting farmers’ decision-making for increasing their income, optimizing the use of their natural resources and inputs andimproving and/or conserving the productivity of their resource base is a prerequisite for suchsustainable intensification and food security.

Intensification of production systems, usually requires an increased supply of plant nutrients.Monitoring of plant nutrient balance and supply to the crops, control of losses, arresting depletionand ensuring accumulation are essential for increased productivity, income and safe environment.

Poor water and irrigation management at farm level result in substantial losses inproductivity and scarce water resources. In irrigated areas, the misuse of water and poorirrigation practices are causing moisture deficit, induced waterlogging, soildegradation/salinization and declining productivity. Poor water control and harvesting in rainfedagriculture result in poor yields per unit area and do not allow any meaningful intensification. Assuch, water management at farm level is an essential element in crop production intensification.

1 ISWNM: Integrated Soil, Water and Nutrient Management.


Optimizing the physical, chemical and biological conditions of the soil will alsoprovide the synergy and base of successful crop identification. Improving the soilconditions will enhance the efficiency of agricultural inputs (seeds, fertilizers andother sources of plant nutrients), will promote water use efficiency (either rain orirrigation water through increase in infiltration, improvement in water-holdingcapacity and reduction in runoff), and will reduce pest attacks (through appropriatetillage practices, aeration and optimal soil organic matter and plant residuemanagement).

It is evident that there are interactions and complementarities among the various componentsof a pilot project (under the SPFS or land improvement schemes). Segmented interventions orseparate schemes (for water control or soil fertility/productivity improvement, etc.) would notnecessarily result in a significant or sustainable yield increase.

An integrated approach (and intervention/project implementation) of soil, water and nutrientmanagement, and wherever feasible to be linked with integrated pest management, should bepromoted in order to address soil degradation and declining productivity, and to enhanceagricultural production and food security.

FERTILIZERS USE DEVELOPMENT IN SSA, THE CONTRAST WITH ASIA AND RELATEDISSUES

The average world fertilizer consumption during the period 1990/1993 was 130 million metrictonnes of nutrients. It declined to 121 million metric tonnes (MMT) in 1993 and it reached 131MMT in 1995/96. Africa, comprising 58 countries, accounts to only 2.6% of world fertilizerconsumption, and the share of Sub-Saharan Africa(SSA) is 1.2%. Fertilizer consumption inAfrica continues to be restricted to some 12 major consumers1; about 63% of the regional totalfertilizer consumption occur in Egypt, Morocco and South Africa.

The average fertilizer consumption in SSA during 1990/93 was only 2.16 MMT, comparedto 51.2 MMT in Far East developing countries and 5.4 MMT in Near East. The contrastingevolution of fertilizer consumption in Asia and in SSA could be depicted from Figure 8. Whilefertilizer consumption has developed rapidly in Asia, there is an alarming stagnation of fertilizerconsumption in SSA (Table 8). There is also a great disparity in fertilizer consumption among thecountries of SSA (Figure 9). With the exception of 12 countries2 in SSA, the average fertilizeruse is below 10 kg nutrients/ha of arable land (compared to 130 kg/ha in the Far East and 60kg/ha in the Near East, and about 90 kg/ha as world average).

The stagnation of fertilizer use in SSA could be attributed to the following constraints:

• lack of coherent medium and long-term policy for fertilizer use development;• inefficient input procurement and distribution systems and inexperienced organizations;• shortage of foreign currency and balance of payment problems;• low price of agricultural produce;

1 Algeria, Egypt, Kenya, Libya, Malawi, Morocco, Nigeria, South Africa, Sudan, Tunisia, Zambia

and Zimbabwe.2 Zimbabwe, Kenya, Mauritius, Swaziland (>40 kg nutrient/ha); Malawi (20-40 kg/ha); Ivory Coast,

Lesotho, Mauritania, Nigeria, Tanzania, Togo, Zambia (10-20 kg/ha); Burkina Faso, Congo,Ethiopia, Gambia, Mali, Senegal (5-10 kg/ha); the remaining 26 countries of SSA (< 5 kg/ha).


• inconsistent agricultural input pricing and subsidy policies;• limited access of smallholders to agricultural credit and poor purchasing capacity;• inadequate advisory institutions and supporting data/information base;• poor infrastructure facilities.

Between 1980 and 1991, fertilizer consumption in India1, China2 and other Asian developingcountries almost doubled, in contrast with the alarming stagnation in SSA over the same period.The unbalanced fertilizer use in Asia (N:P205 ratio of 3.19 and P205:K20 of 2.65 in 1993 forexample), however contributes to the limited increase in yields and the low fertilizer useefficiency in some countries of the region.

TABLE. 8Fertilizer consumption, Asia and SSA (1000 M tonnes of nutrients)

1. India, China and South East Asian Countries1980 1982 1984 1986 1988 1990 1991 1992 1993

N 19 887 20 177 25 904 25 544 32 903 34 669 35 558 37 286 34 846P205 5 544 6 570 7 884 7 471 10 596 12 087 13 433 12 615 10 909K20 1 924 2 140 2 659 2 621 3 991 4 499 5 139 4 408 4 109Total 27 335 28 887 36 447 35 636 47 490 51 255 54 130 54 309 49 864

2. Sub-Saharan Africa1980 1982 1984 1986 1988 1990 1991 1992 1993

N 995 1 017 907 948 997 1 073 1 054 1 137 1 193P205 719 782 734 668 687 644 625 639 782K20 305 339 336 312 330 361 363 367 385Total 2019 2 138 1 977 1 928 2 014 2 078 2 042 2 143 2 360

1 In India from about 6.5 million tonnes in 1980/83 to 12 million tonnes in 1990/93.2 In China from some 16 million tonnes in 1980/83 to 29 million tonnes in 1990/93.

FIGURE 8Evolution of fertilizer consumption: Asia, South America and sub-Saharan Africa


The lack of important fertilizer industry in SSA has certainly contributed to the slow andlow fertilizer use development.

About 87% of the production of N fertilizers takes place in South Africa and Nigeria andvery small units are also operational in Zimbabwe, Senegal, Mauritius and Zambia. Some 85% ofthe production of P fertilizers takes place in South Africa and Nigeria, small units exist inZimbabwe and Senegal. There is no production of potash fertilizers in the continent. On thecontrary, with the development of the fertilizer sector in Asia and the Near East, the developmentof the fertilizer industry did not take place in SSA, though ample raw materials are available:rock phosphates, natural gas, naphtha.

For the development of the fertilizer sector in Africa, a combination of the following wouldbe required:

• the organization of sub-regional fertilizer markets, justifying plants of viable size;

• the connection of those markets with joint ventures (for fertilizer production facilities)providing the capital and the security of sales;

• revision of the actual taxation, banking rates, margins of distribution, etc.;

• a proactive national programme for fertilizer demonstration and technical advice onintensification to farmers;

• a re-organization of the marketing of agricultural produce and inputs, improvement ofinfrastructure, providing fair on farm prices and lower distribution costs.

Structural Adjustment Programmes (SAPs)

Since 1980, the major lending international institutions introduced Structural AdjustmentProgrammes (SAPs) in many countries in Africa. More than 80% of these programmes includeda condition related to agricultural pricing/subsidy and/or parastatal institution reforms.

The relevant impacts of these SAPs were:

• devaluation of local currencies;• decline or removal of subsidies on agricultural inputs;• suppression of government/parastatal monopolies in input import and distribution;• increased interest rate on agricultural credit;• decrease in output/input price ratio and decrease in the profitability of fertilizers;• no consistent trend in fertilizer consumption or availability.

Despite the deregulated systems in fertilizer procurement and distribution, in many Africancountries, there is still a need to address:

• high import costs due to complexity and lengthy procedures and limited economy of scale inimports (small quantities);

• higher costs due to inefficient fertilizer demand forecasts, implying in many casesconsiderable stocks;

• inadequate supply or severe shortage in remote areas (higher costs for the private sector);

• insufficiently trained personnel in the whole marketing channels (new involvement of theprivate sector).


FIGURE 9Fertilizer use level in Africa (average 1988-1990)


Pricing and subsidy

Among the important fertilizer policy instruments is the subsidy. Usually during the introductorystage, fertilizers are heavily subsidized to promote their adoption and use by farmers. However,with the development of their use and the increasing volume of fertilizer consumption in a givencountry, the volume of subsidy constitutes a heavy financial burden on the government. This callsfor more emphasis of both research and extension on enhancing fertilizer use efficiency in orderto achieve the production targets with lesser volume of fertilizer products. Improving fertilizersupply and distribution systems (including reduction in physical losses and costs) are among theareas of intervention (both from the public and the private sector) to reduce the fertilizer farm-gate prices in order to lessen the impact of subsidy removal.

Experience of many countries suggests that if it is socially desirable to phase out subsidies,they should be phased out gradually and with improvements in procurement, marketing anddistribution, as well as research and extension. Ad hoc and abrupt changes in pricing/subsidy arecounter-productive for steady fertilizer use level. Like the subsidy policy, the privatization of thefertilizer sector's operations should also be gradual and supported with adequate development ofskills, infrastructure and institutional development.

Fertilizer donations

The supply of fertilizer in many SSA countries has been partly secured through aid-in-kind. It isobserved, however, that most of the traditional donors are reducing or suppressing their fertilizergrants, mainly due to the difficulties encountered by many countries to utilize the fertilizer saleproceeds effectively for agricultural development programmes.

In order to sustain at least a modest fertilizer supply in many countries in Africa, tosupplement the local sources of plant nutrients, appropriate and effective linkages betweenagricultural commodities export and fertilizer imports should be envisaged (e.g. financingfertilizer imports from the proceeds of cash crops exports).

Conclusion:

The stagnation of fertilizer use in SSA would imply that, for the intensification of cropproduction and for soil fertility restoration, more emphasis should be placed onIntegrated Plant Nutrition Systems (IPNS), with focus on mobilization of localorganic sources of plant nutrients: composting, mixed cropping, green manuring,farmyard manure, agroforestry, etc. Depending on the country's condition, the localsources could be supplemented by external/mineral fertilizers. The use of localphosphate rock should be promoted whenever it is feasible and economically viable.

SOIL MANAGEMENT OPTIONS FOR ADDRESSING SOIL FERTILITY DECLINE

Soil fertility depletion in smallholder farms is the fundamental biophysical root cause fordeclining per capita food production in Africa, and soil fertility restoration/recapitalization shouldbe considered as an investment in natural resource capital. Besides improved soil managementpractices , accompanying technologies such as soil conservation, and enabling policies are neededto make recapitalization operational. The issue of who should pay for this recapitalization isbased on the principle that those who benefit from a course of action should incur the costs of itsimplementation. On-farm maintenance costs should be borne by farmers, whereas national and


global societies may share the costs of substantial phosphate and other soil amendmentapplications (Sanchez et al., 1997).

There is no single technology that would lead to soil fertility restoration and soil productivityimprovement due to the diversity of the bio-physical, ecological and socio-economic environmentof the farmers' community. A lot of technologies have been generated but, in most cases, thebottleneck lies in their adoption and implementation, particularly by the small scale farmers.

Nevertheless, the known technological options for restoration of soil fertility could begrouped as follows (Mokwunye et al., 1996):

• increased and more efficient use of mineral fertilizers;

• exploitation and use of locally available soil amendments such as phosphate rocks, lime anddolomites;

• maximum recycling of organic products, both from within and from outside the farm (cropresidues, animal manure, composts, urban waste/refuse, etc.);

• improved land use systems, based on both indigenous and improved methods such asappropriate crop rotation, intercropping, agroforestry and related tree-based farmingsystems, increased use of species that can fix N from the atmosphere, alternatives to slash-and-burn so that fallows can be improved;

• effective methods to control wind and water erosion, tailored to indigenous knowledge andemphasizing local biological resources and simple physical structures;

• promotion of the Integrated Plant Nutrition Systems (IPNS) which aims at maintenance oradjustment of soil fertility and of plant nutrient supply to an optimal level for sustaining thedesired crop productivity, through optimization of the benefits from all possible sources ofplant nutrients (organic and inorganic) in an integrated manner.

Constraints and potentials of these alternative technologies are given below:

• To restore soil fertility and achieve specific yield targets, technologies that save nutrientsfrom being lost from the agro-ecosystem may not be sufficient; they need to be supplementedby technologies that add nutrients to the agro-ecosystem. When used judiciously, i.e. propertype, amount and timing of application for the specific crop, soil and climatic conditions, useof mineral fertilizers can result in considerable production increases without harming theenvironment. The two major environmental risks of continuous fertilizer use in Africa aresoil acidification and the accelerated depletion of nutrients that are not included in thefertilizer. Farmers buy mineral fertilizers to achieve immediate product increases rather thanto increase soil fertility. In some African countries, the use of local phosphate rock is aviable alternative to the use of expensive soluble imported P fertilizers, particularly in areasclose to the phosphate deposits (to minimize transport and distribution costs). The use ofphosphate rock is particularly attractive in P-deficient areas with relatively high rainfall andon acid soils, for wetland rice and on leguminous species, and in areas where tree crops arecommon or where afforestation is envisaged.

• Organic material serves as an indispensable source of plant nutrients. In addition, organicmaterial improves the soil chemical, physical and biological conditions. Maximum use oforganic inputs includes maximum recycling of both on-farm and off-farm supplies.Reported major constraints are labour, transport, and low nutrient concentration.


Technologies that involve low-capital inputs such as crop rotations, green manures, fodderbanks, improved fallows, and agroforestry systems have a role to play in the restoration ofsoil fertility. The extent to which this can be successful is largely determined by soil,climate, farmers' willingness to invest scarce labour into improving their land and cropmanagement practices, and the degree to which the policy environment is "enabling".

• Erosion is a very important cause of nutrient depletion. Therefore, soil and waterconservation is of prime importance in restoring soil fertility through nutrient-saving ratherthan nutrient-adding mechanisms. Major constraints to soil and water conservation practicesare the labour requirements and the fact that farmers see no immediate economic gain fortheir efforts. This highlights the need to combine efforts on soil and water conservation andsoil fertility restoration.

• The philosophy behind IPNS shows that a combination of technologies is better able toredress nutrient imbalance and depletion in African agro-ecosystems. Under an IPNSphilosophy, the farmer can optimize the allocation of the different production factors todifferent parts of his/her land. This may involve both low- and high-external input practices.As mentioned earlier, the stagnation of fertilizer use development in many SSA countriesimplies that more emphasis should be placed on IPNS and maximum use of organic inputsand local phosphate resources, in order to address soil fertility decline.

Examples of soil and plant nutrition management practices for addressing fertilitydecline and enhancing soil productivity are discussed below:Maintenance and increase of soil organic matter

Options for improvement and maintenance of the soil organic matter in soils are: (a) intensifyingbiomass production per unit area, within the existing cropping system by improving the soilmoisture regime particularly in rainfed areas, balanced fertilization and improving soil conditionsthrough amendments and better husbandry; (b) increasing biomass production through changes inthe cropping/farming system such as intercropping, improved rotations and fallows that includegrasses and agroforestry systems; (c) reduction of the rate of loss of soil organic matter throughmaintenance of soil cover to keep soil temperatures down, slowing down of erosion,avoiding/controlling fires, stimulation of soil fauna growth and change to minimum tillagetechniques; and (d) application of organic materials (farmyard manure, compost, plant residues,etc.) which would favour accumulation and build up of humus substances in the soil.

Within the above range of options, the application of organic materials would involve acapital for simple and low-cost equipment, know-how for improving the quality of organicmaterials and an input of labour by the farmer. Each option would be decided upon by the farmerdepending on the value of the crop, the expectation for an attractive price, availability of residuesand cattle on the farm and availability of farm labour.

Use of soil amendments and fertilizers for addressing specific soil limiting factors

For highly acid soils, the application of limestone or dolomite would reduce aluminium toxicityand improve availability of calcium and magnesium. Since liming requirement could be up to 4-5Mt/ha, transport cost and labour required for application should be assessed.

Experience obtained in Madagascar, however, showed good results with a basal dolomitedose of 1-2.5 Mt/ha (depending on the soil type and pH) followed by a maintenance applicationof 350 kg/ha, from the third subsequent year. The best results, however, were obtained by


applying about 500 kg/ha of dolomite in combination with fertilizers, mainly phosphate, andorganic manures in the first year.

On the other hand, for sodic or saline/sodic soils in arid/semi-arid environment the use ofgypsum as soil amendment is essential for restoring the productivity and the reclamation of theseproblem soils.

Phosphate rock (PR) deposits of potential economic significance occur at more than 100locations in at least 31 countries in sub-Saharan Africa (e.g. in Togo, Mali, Senegal, Tanzania,Burkina Faso, Niger, Angola, etc.), and often in proximity to P-deficient arable lands. Thequantity of resources and the average P205 concentration varies from less than 100 000 tonnes togreater than 800 million tonnes and from 5% to 33% P205 (Appleton, 1995).

Some of these materials of sedimentary origin and reactive have been found to be suitablefor direct application, while others are only effective when partially acidulated, compacted ormixed with organic inputs. Igneous PR deposits (Burundi, South Africa, and Zimbabwe) areseldom suitable for direct application and are best used to manufacture superphosphates orpartially acidulated PR.

Despite the existence of such resources (Figure 10), few countries have mobilized theirresources and their use as direct application is still very limited. There is a need for additionalagro-economic evaluation and assessment of the reasons for restricted use (Togo, for example,produces some 2.5 million tonnes of phosphate but only some 300 tonnes are used as directapplication in the country). Farmers are still reluctant to use PR because of the dusty character ofthe finely ground materials, its slow reactivity and perhaps the less visible direct effect on thegrowing crop as compared to P fertilizers. The choice of P source depends on many factors suchas cost differentials between PR and superphosphates, soil acidity and the P-sorption capacity ofthe soil. Cost differences per kg P can be major; the more acid the soil, the more rapid thedissolution rate of PR. Given these variables as well as logistic, financial and infrastructureconsideration, the choice of P fertilizers source and the rate for replenishment is "site" and"situation specific".

The degree of solubility, accessibility and processing and transport costs vary widely. Thesolubility of phosphate rock can be increased through various processes, including grinding,heating or acidification. Low-cost grinding may be most practical for high rainfall areas withhighly acid soils.

The high residual effects of PR has an important bearing on its agro-economic evaluation.This is an area that has often been neglected since economic benefits are made on the basis of oneseason's agricultural production. Although PRs are most effective in wet soils/high rainfall, theyhave proved effective also in drier zones of West Africa (Mokwunye et al., 1996).

In this respect it should be noted that long-term benefit (or economic return to farmers)from investment in land improvement (for example, the application of lime, gypsum or rockphosphate) have often not been adequately demonstrated to farmers and, therefore, this should begiven due consideration in projects aiming at restoration of soil fertility and land productivityimprovement.

Additionally, there is a need for complementary studies to include:


• Inventory of resources, synthesis of applied research and experiences on the useof soil amendments such as: lime, dolomite, gypsum, etc. in land improvementschemes in selected countries of Sub-Saharan Africa.

• Inventory of resources, synthesis of agronomic and economic benefit from the useof local rock phosphates, as compared to phosphate fertilizers, in some targetedcountries of Sub-Saharan Africa. The reasons of the limited use and/or extendeduse in specific country (countries) could be highlighted by the study for morerational follow-up actions in Soil Fertility Initiative related projects.

FIGURE 10Location of phosphate depostis in sub-Saharan Africa excluding South Africa (Appleton, 1995)


Phosphorus-replenishment strategies are mainly fertilizer-based with biologicalsupplementation, while N replenishment strategies are mainly biological with chemicalsupplementation.

Techniques to replenish soil P, therefore, consist of P fertilization (either from commercialfertilizer or PR, as appropriate), the effective use of available organic sources and therefore themaintenance of activity and biodiversity of key soil organisms such as mycorrhiza. Decomposingorganic inputs produce organic acids that help solubilize phosphate rocks. The integration ofavailable organic resources with commercial fertilizers and/or PR - may be the key to increasingand sustaining levels of P capital in tropical soils.

For example, in Western Kenya, an interesting soil fertility recapitalization strategy focusedon:

• Improved fallow of Sesbania Sesban (6-14 months). The fallow will reduce the Strigainfestation and supply some 100 kg N/ha.

• Contour bunds, ditches for controlling soil erosion with Tithonia plants. Additional Tithoniaare also planted near hedges and along field boundaries.

• Application of organic resources such as compost and cattle manure produced on the farm.

• Application of PR, incorporated with the Tithonia and other leguminous fallow leafymaterials, before planting the maize crop.

The on-farm research in Western Kenya with (Minjingu) PR, at the rate of 250 kg P/ha, incombination with 1.8 t/ha of Tithonia diversifolia dry biomass showed substantial increase inmaize yields (from 1.8 to 4.2 t/ha). The benefit from Tithonia was also attributed to addition ofK, as this plant is also high in K concentration. Subsequent research confirmed higher maizeproduction with sole application of Tithonia biomass than with an equivalent rate of NPK mineralfertilizers ( Sanchez et al., 1997). P replenishment, however, must usually be accompanied by Nreplenishment (from organic and/or inorganic sources) in order to be effective, because most ofP-deficient soils are also deficient in N.

Emerging evidence suggests that N demands can be met biologically through BiologicalNitrogen Fixation (BNF) for maize crop yields in the order of 4 tonnes/ha. Two-year oldSesbania fallows (in Chipata, Zambia) doubled the maize yields over a 6-year period, incomparison with continuous unfertilized maize production. Agroforestry systems like Sesbaniafallows are thus able to substitute fertilizer N application, for profitable maize production.

Green manure fallows also provide sufficient N inputs through BNF to meet the needs of onesubsequent maize crop. The use of Mucuna, for example (to fix N and smother Imperata weeds)is expanding rapidly in some Western African countries such as Benin and Ghana (IITA, 1995).

Improving soil physical conditions and soil moisture

Soil structure is important for all aspects of soil use and management. A well structured soil,which does not crust under rainfall, will provide optimal water conditions if the water inputs aresufficient. Repeated cultivation without any effort to redress structural degradation will result in adecline in productivity. For most soils, maintenance and improvement of existing structure couldbe achieved through optimization of the organic matter content and of the activity and species'diversity of the soil fauna and other organisms. Conservation tillage, as compared to clean tillagefor example, could promote the maintenance of soil structure and aggregates at the surface and


thus reduce wind and water erosion.Under specific soil conditions,however, conventional tillage couldpromote water infiltration, controlweeds, reduce mechanical impedanceto root growth and promote the incor-poration of crop residues into the soil.

Tests and demonstrations onfarmers field in Ethiopia showed thatdouble ploughing, using an improvedand locally produced plough (mould-board) at a cost of $30 per unitincreased cereal yields by 28% andsaved considerably on labour inputsfor weeding. Application of therecommended dose of importedfertilizers increased yields by 31% onthe same soil type (Nitosols,Combisols). Adopting the combinedpractices increased yields by 48%.

The inter-linkage betweendifferent aspects of soil physics and the central role of soil structure are shown in Figure 11. Theadoption of simple measures such as water harvesting and more efficient in situ capture ofrainfall, improvements of water infiltration and increasing the water holding capacity of soilscould yield significant improvements in productivity, especially in drier climates.

Examples of measures which could be adopted by farmers to retain water on the surface andthereby increase the time available for infiltration include mulching, contour tillage, tied ridging,contour planting, strip cropping. These and similar measures would also reduce splash erosionand evaporation of water from the surface. Improved infiltration and percolation could bepromoted by tillage, sub-soiling to break compact surface and subsurface layers; and measures toincrease soil organic matter levels and liming to improve soil structure and promote biologicalactivity.

CONCLUSION

The diversified agro-ecological conditions and socio-economic environment of the farmers makeit unlikely that a single technology will lead to the goal of soil fertility restoration and cropproduction intensification. There should be a close linkage between the respective technologiessuggested, since land development combined with water control are known to contributepositively to crop production intensification. In this respect an "Integrated Soil, Water andNutrient Management Approach" for the restoration of soil fertility and productivity is required,since segmented intervention on soil, water or nutrients may not result in a significant orsustainable yield increases.

The majority of small-scale/ resource-poor farmers in Africa are faced with constraintswhich are limiting their ability to adopt improved technological innovations and appropriatemanagement practices. These constraints could include: limited access to credit, lack of timelyand availability of agricultural inputs such as fertilizers, seeds, farm implements, soilamendments; inadequate involvement of NGOs and private sector for facilitating input supply

FIGURE 11The central importance of soil structure (after Lal,1994)


and distribution; limited infrastructure, lack of effective linkage between research and extension,inefficient extension service; institutional weakness and lack of appropriate and enablingmechanisms for farmers' participation and direct involvement in the identification of productionconstraints, selection and testing of appropriate technological packages; and last but not least thelack of enabling and conducive policies to address the underlying causes of degradation and toenhance farmers adoption of improved technologies.

Realistically, farmers are expected to adopt improved technologies for soil fertilityrestoration where there is: a conducive macro-economic policy; a need for productionintensification caused by land scarcity without possibility for expansion; a secure access to landwhere farmers will benefit from their investment in land improvement; access to credit andmarkets of agricultural inputs and farm produce.

It is obvious that soil fertility restoration in Africa will require significant policychanges/reforms at local level by rural communities and decentralized administrative authorities,at national level by governments, and also at global level by donors and international agenciesconcerned with agricultural development. These policy reforms would address the prevailingfarmers' constraints and promote the implementation of effective measures to ensure, inparticular, appropriate land tenure systems, efficient agricultural credit, sound agriculturalpricing policies for farm produce and inputs and possibly short-term targeted agriculturalsubsidies for soil amendments. Moreover, there is a need for appropriate institutional set-up andcoordination, efficient farmers’ organizations, important adaptive research and extensioneducation.

Technological options for restoration of soil fertility and enhancing productivity areavailable, but the bottleneck is their wider adoption by the small scale farmers for whichenabling policies and conducive measures must be in place.

REFERENCES

Appleton, J.D. 1995. Indigenous rock phosphate mobilization, processing and use in Sub-SaharanAfrica, British Geological Survey, UK; AGL:FAO/PNP/95/16 E.

Brabant, P. et al. 1997. Human-induced land degradation in Togo, Explanatory notes on the landdegradation index map (1:500 000). C.N.E. No. 112. ORSTOM.

FAO 1976. A framework for land evaluation. FAO Soils Bulletin 32. FAO, Rome.

FAO 1990. International Scheme for conservation and rehabilitation of African Land (ISCRAL),ARC/90/4, Rome.

FAO, WSRR No. 78. 1994. Land degradation in South Asia, its severity, causes and effects upon thepeople. (Report compiled by A. Young 1992, UNDP/FAO/UNEP).

Goswami, N.N. and Rattan, R.K. 1992. Soil health - key to sustained agricultural productivity. FertilizerNews (India).

IITA. 1995. Annual Report of 1994. International Institute of Tropical Agriculture, Ibadan, Nigeria.

Lal, R. 1994. Sustainable land use systems and soil resilience. In: Soil Resilience and Sustainable LandUse. D. J. Greenland and I Szabolcs (eds.). CAB International, Wallingforth, UK, pp. 41-67.

Mokwunye, A.Z. de Jager, A. and Smaling, E.M.A. 1996. Restoring and maintaining the productivity ofWest African soils: Key to sustainable development. IFDC, Africa.

Oldeman, L.R., Hakkeling, R.T.A., and Sombroek, W.G. 1990. Human-induced soil degradation.Revised 2nd edition. International Soil Reference and Information Centre, Wageningen, TheNetherlands.


Oldeman, L.R., Engelen, V.W.P., Van Pulles, J.H.M. 1990. The extent of human induced soildegradation. Annex 5 "World map of the status of human-induced soil degradation, an explanatorynote". ISRIC, Wageningen.

Pagiola, S. 1997. Draft paper "The global environmental benefits of land degradation control onagricultural land"

Sanchez, P.A. and Logan, J.J. 1992. Myths and science about the chemistry and fertility of soils in thetropics. SSSA Special Publication No. 29.

Sanchez, P. et al. 1997. Soil fertility replenishment in Africa: an investment in natural resource capital.Paper presented at ICRAF Meeting on Approaches to Replenishing Soil Fertility in Africa - NGOPerspectives, Nairobi, Kenya.

Smaling, E.M.A., Stoorvogel, J.J. and Windmeijer 1992. Calculating soil nutrient balances in Africa atdifferent scales. II. District scale. DLO, The Winand Staring Centre, Wageningen.

Steiner, K.G. 1996. Causes of soil degradation and development approaches to sustainable soilmanagement. GTZ, Margraf Verlag, Germany.

Stoorvogel, J.J. and Smaling 1990. Assessment of soil nutrient depletion in Sub-Saharan Africa: 1983-2000. Report No. 28. Winand Staring Centre, Wageningen.

UNEP 1992b. Desertification, land degradation (definitions). Desertification Control Bulletin 21.

Young, A. 1991. Soil monitoring: a basic task for soil survey organizations. Soil Use and Management7.


Appendix 1

UN/FAO frameworks and initiatives related toland degradation and management

It is evident that land degradation and sustainable land resources management are importantissues as underlined in the relevant chapters of Agenda 21 of the Earth Summit, the InternationalScheme for Conservation and Rehabilitation of African Land (ISCRAL), the Convention toCombat Desertification (CCD), and the Soil Fertility Initiative (SFI).

Since such global initiatives have considerable implications on FAO or member countries'programmes, for addressing degradation and for improving land productivity, some arehighlighted in Annex 1 and 2.

AGENDA 21

The most prominent outputs of the UN Conference on Environment and Development (UNCED)were the Rio Declaration on Environment and Development and its Agenda 21 ActionProgramme. Agenda 21 presents a blue-print for action to achieve sustainable development intothe 21st century. Of the total 40 chapters of the Agenda, 3 chapters are relevant to landdegradation, sustainable land resources management and conservation:

Chapter 10: Integrated approach to the planning and management of land resources (forwhich FAO/AGL is the task manager).

Chapter 12: Managing fragile ecosystems: combatting desertification and drought.Chapter 14:

Chapter 10: its broad objective is to facilitate allocation of land to the uses that provide thegreatest sustainable benefit and to promote the transition to a sustainable and integratedmanagement of land resources. It emphasizes that “expanding human requirement are placingan increasing stress on these land resources and the resulting conflicts and competition arecreating inefficient and ineffective patterns of use. Integrated physical, economic and socialparameters with land use planning and management is suggested as a practical technique thatcan help resolve conflicts and move towards an optimal use of land and its natural resources”.

Chapter 12: assigns a high priority to combatting desertification (land degradation in arid, semi-arid and dry sub-humid), to the implementation of preventive measures to conserve lands that arenot yet degraded, or which are only slightly degraded. It draws the attention to the importance ofthe participation of local communities, rural organizations, governments, NGOs and regional,national and sub-national organizations, in the process of combatting both desertification anddrought. Among the programme areas under this chapter are: combatting land degradationthrough appropriate management and conservation and reforestation; strengthening the knowledgebase and developing information and monitoring systems.

Chapter 14: draws attention to policy and agrarian reform, people’s participation and humanresource development, income diversification, land conservation and rehabilitation, improved andintegrated management of inputs for sustainable food production and rural development.


ISCRAL

The purpose of the FAO International Scheme for the Conservation and Rehabilitation of AfricanLands (ISCRAL) (FAO, 1990) is to provide a framework by which African countries candevelop their own programmes to fight degradation and improve land productivity.

ISCRAL discusses the extent and implications of land degradation, examines lessons frompast projects addressing the issue and suggests a new sustainable approach based uponintegrating conservation and production to provide land users with immediate benefits. ISCRALFramework for Action at national level emphasizes the control of degradation by firstdetermining the reasons for misuse; encouraging participation to allow land users to organizetheir resources, plan and implement solutions, develop national institutions to provide land userswith needed support. At the regional level, the emphasis is upon information networks, advancedtraining and research. At the international level, long-term financial support, close cooperationof governments, NGOs, technical assistance agencies and financing institutions are emphasized.

(Similar schemes are being adopted by several countries in Asia “CLASP” and LatinAmerica “CORTALC”).

CCD

The objective of the UN Convention to Combat Desertification and mitigate the effects of droughtin countries experiencing serious drought and/or desertification, particularly in Africa, througheffective action at all levels, supported by international cooperation and partnershiparrangements. Action contributing to the sustainable development of affected areas, is to becarried out within the framework of an integrated approach consistent with Agenda 21.

The CCD specifies (i) a series of action programmes, (ii) a framework for scientific andtechnical cooperation and (iii) supporting measures:

• Action Programmes (Articles 10, 11, 12): concerned with elaboration of National ActionProgrammes (NAP), Sub-Regional Action Programmes and International Cooperation.

• Technical and scientific cooperation (Article 16): deals with information collection,analysis and exchange to ensure systematic observation of land degradation in the affectedarea and to understand better and assess the processes of drought and desertification - anarea of prime interest to FAO in general and AGLS in particular. (Article 18) which dealswith transfer, adaptation and development of technology.

• Supporting measures (Article 19) deals, among others, with capacity building of all types -an area where FAO has a particular strength.

Besides the global mechanism for mobilization of resources, the Permanent Secretariat (thelocation of which was decided by the recently held Conference of the Parties), the Committee onScience and Technology (on which FAO is represented), are already functioning. Throughcollaboration with other UN agencies (IFAD, UNDP, GEF funding resources), FAO is assistingmember countries in the formulation and implementation of National Action Programmes (underCCD) as well as the formulation of pilot projects in land resources use, management andconservation (example Mali, Cuba). FAO/AGLS is also promoting a comprehensive drylands anddesertification control programme.


Appendix 2

Soil Fertility Initiative (SFI)

It has been recognized that the key to restoration and enhancement of soil fertility is the collectiveresponsibility of many parties, including governments, inter- and non-governmental organizationsand all stakeholders in the food production process. Accordingly, the World Bank has taken theinitiative to provide the leadership to assemble and coordinate a global effort that will focus onreversing the detrimental effects that result from soil degradation and nutrient depletion in Sub-Saharan Africa. Other international organizations involved in the initiative are FAO, ICRAF,IFDC, IFA and IFPRI.

In support of the larger goals: poverty alleviation, food security and environmentalprotection; the major objective of the SFI is to improve the productivity of cultivated lands andthe revenue of farmers through a combination of technology adaptation and policy reform.

The thrust of the SFI will include:

• dissemination of appropriate technologies for the restoration and maintenance of soilfertility and intensification of agriculture through an integrated approach using organic andinorganic fertilizers, erosion control, land and water management to enhance food securityand farm income;

• promotion of enabling policies that would correct market and institutional constraints toimprove soil productivity; and

• development of programmes that would provide incentives and bring the full participation ofindividual farmers and communities for the restoration of soil fertility and improved landmanagement.

The SFI was officially launched during the World Food Summit, November 1996.

After the Summit, consultation took place between FAO and the World Bank (January1997) in order to design modalities of cooperation in support of the SFI and its linkage with theSpecial Programme for Food Security (SPFS), particularly in SSA. A workshop was organized inTogo (April 1997) with the participation of 120 delegates representing 22 countries in SSA, sub-regional institutions, NGOs and private sector, international development and researchorganizations, including FAO. The workshop re-emphasized the need for recapitalization,maintenance, and improvement of soil fertility, as a basis for long-term food security. A draftstrategic framework for soil fertility improvement was also outlined.

After a series of discussions and refinement, involving FAO, the "Framework of NationalAction Plan for Soil Fertility Improvement" was developed.

The salient features of the Framework are summarized below:

Rationale:

A National Action Plan has to promote actions, capital and labour investments for soil fertilityimprovement and for the supporting sectors (e.g. improved availability and accessibility of soil


amendments and inputs for agricultural intensification), and for alleviating socio-economic andtechnical constraints,

The soil recapitalization and improvement is a prerequisite to improved efficiency of inputsand higher productivity. Improved soil productivity are in the interest of not only the farmingcommunity but also the national society and the international community as a whole. It couldtrigger rural and national economic development, improve farmers' standard of living, whilecontrolling environmental degradation and help in reducing rural migration, etc.

Steps during the preparatory phase for the NAP:

• Implementation of a national workshop and working groups: The workshop will permitidentifying the needs for Soil Fertility Improvement, create general awareness and establishworking groups which include all stakeholders (NGOs, farmers groups' representatives,agricultural input/output producers and distributors, research and extension services, policymakers and multidisciplinary technicians). The groups will assist in:

- identification of actions/investments to be promoted;- definition of socio-economic constraints to be alleviated;- indication of ministries and public services to be involved;- institutional arrangements to be made (at public level) and to be promoted (at private

level);- preliminary studies to be executed;- strategies for implementation

• Identification of ministries, institutions and public services to be involved: The creation ofa conducive environment and input & output market development surpasses the competenceof the Ministry of Agriculture. As such it is expected that other ministries will have to play arole in the SFI such as: ministries of environment & forestry, finance, planning, science &technology and social affairs. Arrangements have also to be made to identify theresponsibilities and operational involvement of various institutions at national, sub-nationaland local level.

• Preliminary data and studies: The data required for the preparation of a National ActionPlan for SFI would include: geographical and agro-ecological characteristic data, socio-economic data, agricultural data as well as agricultural policies and strategic data andorientation. Studies and agricultural constraints analysis will also be required during thepreparatory phase.

The constraints and possible solutions related to soil fertility improvement will depend on thenational, sub-national or local socio-economic and agro-ecological conditions in a givencountry. The strategies to implement the NAP will vary from one country to another,depending on the extent and magnitude of soil degradation and nutrient depletion, localavailability of inputs, other soil management technologies, available means and donorcommitments. As such, the strategy may, for example, start with "Pilot Project" in selectedareas in the country, and gradually expand the scope and area coverage for an investmentoriented large-scale national programme.

• The implementation of the NAP will involve the participation of all stakeholders and thestrategy adopted by the government, donors or lending agencies support. The real executorsof the SFI (the farmers) and the private sector may wait until the conducive policyenvironment and the market development are in place.


Monitoring and evaluation of the NAP performance have also to be established, this wouldinclude a core of "Indicators". These indicators are likely to include:

• physical indicators such as nutrient balance, land use systems and intensity, land cover,increased use of amendments, organic and inorganic fertilizer, and measurements of soilfertility (pH, CEC, OM, nutrient status);

• economic indicators such as trends in crop yield, livestock productivity, output levels, pricesand rural income;

• social indicators such as rate of adoption of improved soil management practices by farmersand farming communities, increased stability of rural communities (e.g. reduced migration);

• environmental indicators such as rate of deforestation, state of rangelands and erosion.

WB/FAO collaboration in formulating and implementing pilot projects in landmanagement and soil fertility improvement

The Plan of Action adopted by the World Food Summit called for concerted efforts at alllevels to raise food production and increase access to food, with focus on the Low Income FoodDeficit Countries (LIFDCs), particularly in Africa, with the objective of reducing by half thepresent level of malnourished people in the world by the year 2015.

Subsequently a memorandum of understanding between FAO and the WB was signed, inorder to strengthen the collaboration of the two institutions within the framework of the SpecialProgramme for Food Security (SPFS), and in particular promote rural development and foodsecurity programmes in the Africa Region, through implementation of projects in the fields of: (i)low cost small-scale irrigation, water control; (ii) improved land management and soil fertilityenhancement; (iii) crop intensification and diversification; (iv) analysis of policy constraints,policy reform and capacity building.

Both institutions would seek, as appropriate, to mobilize supplementary resources to meetthe requirements of jointly agreed programmes. After a series of consultations between the twoinstitutions, it has been agreed to launch the preparation of "National Action Plan for SoilFertility Improvement" and relevant pilot projects in a number of Sub-Saharan African countries,in connection with the ongoing/foreseen SPFS. Initially, the following countries would beincluded: Guinea, Niger, Malawi, Madagascar, Rwanda, Burkina Faso, Eritrea, Ethiopia,Mali, Ghana, Senegal, Benin, Lesotho.

It may be noted that the pilot projects will be conceived to ensure participative landmanagement and fertility improvement schemes, draw upon the experiences of WB/FAO assistedprojects: ("Gestion de terroires" - community-based natural resources management), theimproved land husbandry methods, the Farmer Field Schools (as extension instrument forpromoting site-specific integrated soil, nutrient and pest management) as well as theconservation/minimum tillage; in representative agro-ecological conditions and contrasting socio-economic environment.


Erosion-induced loss in soil productivityand its impacts on agricultural production

and food security

Since 1984, the United Nations Food and Agriculture Organization (FAO) has been supportingan international initiative to investigate the impact of soil erosion. The FAO has taken the lead inpublicizing the threats to sustainability, developing research designs to quantify the impacts, andencouraging the research and development community of professionals to design ameliorativemeasures. It has been the lead agency to support the Network on Erosion-Induced Loss in SoilProductivity. This Network provides data for local, national and international agencies on soiland water conservation; establishes norms for economic planners on the costs and benefits oferosion control and soil conservation; identifies the agro-ecologies where concerted action isneeded now or in the near future to avert substantial agricultural production loss and theconsequent food security threats brought about by soil erosion. With the recent emphasis andpriority programme of FAO on food production in support of food security, issues related to landdegradation and its negative impacts on food production as well as land improvement forenhanced productivity are receiving special attention. Rectifying soil degradation and sustainingcrop production through appropriate soil management and conservation measures are, therefore,important components in the efforts towards food security.

It is timely, therefore, that this Expert Consultation on Integrated Soil Management forSustainable Agriculture and Food Security in Southern and East Africa should consider theimpact of soil erosion on food security. A primary link in the threat to food supplies is thediminution in soil quality and consequent decline in crop yields. A complex set of processes isinvolved which will be addressed by the Consultation. This contribution from the Soil Resources,Management and Conservation Service (AGLS), Land and Water Development Division of FAOin Rome was commissioned from Michael Stocking and Anna Tengberg of the OverseasDevelopment Group, University of East Anglia in Norwich who have been working with SouthAmerican members of the Network, and brought together a selection of data sources on erosion-induced loss in soil productivity which have particular applicability to Southern and East Africanconditions. It is hoped that the scenarios constructed for the region will assist participants of theConsultation in their deliberations on this important subject, and provide a unique data set fromwhich to assess the potential threats to sustainable agriculture and food security.

Michael Stocking, Overseas Development Group, University of East Anglia, Norwich, UK Anna Tengberg, Physical Geography Earth Sciences Centre, Goteborg, Sweden

Erosion-induced loss in soil productivity and its impacts of agricultural production and food security92

SOIL EROSION TO FOOD SECURITY

This paper is about soil degradation and its influence on productivity. Productivity, with itsemphasis on the long-term ecological sustainability of soil resources, is the key determinant offood security. We focus principally on soil degradation by water erosion1. According to globalassessments such as GLASOD (Oldeman et al, 1990), water erosion is the principal cause of thenearly 2 million hectares (22.5% of total land use) of degraded agricultural, pasture and forestland worldwide. Soil erosion by water affects the physical and chemical status of a soil, and in sodoing it reduces soil quality, long-term productivity and crop yields. Understanding the process ofsoil degradation is crucial to addressing the whole problem of erosion-induced loss in soilproductivity. It changes the erosion-productivity link from a `black-box’ model where we areunable to intervene because of not knowing why yields decline, to a `grey-box’ where some lightis shed and remedial measures can be designed to target the principal processes. So, for example,if soil erosion reduces yields because of nutrient losses, the resource manager will be alerted tomeasures which may replace nutrients. Some of these relationships between componentprocesses, type of degradation and means of improvement are explored in Table 1. This paperwill, therefore, dwell on the best available evidence for the process reasons for decline inproductivity.

TABLE 1Component processes and types of soil degradation

Component process Type of soil degradation Improvement measuresPhysical soilmanagement

CrustingCompactionSealingWind erosionWater erosionDevegetationOvertillage

Live barriersTerracingRevegetation of denuded landTree protectionSoil decompactionBreaking up pansCover cropsWindbreaksSoil depositionImproved tillage methods

Soil watermanagement

Impeded drainageWaterloggingReduced waterholding capacityReduced infiltrationSalinization

IrrigationWater harvestingField drainageDraining of waterlogged areasFilter strips

Soil nutrient andorganic mattermanagement

AlkalinizationAcidificationNutrient leachingRemoval of organic matterBurning of vegetative residuesNutrient depletion

FertilizationCompostingGreen manuringAnimal manuringFlushing of saline/alkaline soilsLiming acid soils

Soil biologymanagement

Overapplication of agrochemicalsIndustrial contamination

Introduction of biotic organismsNitrogen-fixing microorganisms

Vegetationmanagement

Decline in vegetative coverDecline in biodiversityDecline in species compositionDecline in valued species

Increased vegetative coverIncreased species diversityImproved species compositionImproved availability of valued species

Source: adapted from Scherr and Yadav, 1996

1 The following sections will also discuss linkages with the Consultation themes on physical and

chemical degradation of soils. To separate these degradation processes and treat themindependently of water erosion is an abstract distinction. Nevertheless, the differences will proveuseful in discussing the process of loss of soil productivity - or how soil degradation affects foodsecurity.


Implicit in decline in productivity is the threat to food security. Some authors see soil (orland) degradation as posing the main threat to global food supplies (Brown and Kane, 1994;Pimentel et al, 1995). Others argue that land degradation is overestimated (Crosson, 1994) andthat some African populations have been able to adapt, cope and even overcome apparentlysevere degradation (Tiffen et al., 1994). Concern over whether food security is threatenedperhaps disguises that degradation has a significant impact on rural livelihoods, making itinevitable that rural producers find it increasingly difficult to survive (IFAD, 1992).

These and related issues were discussed at a workshop on land degradation and itsimplications for food supply, organized by the International Food Policy Research Institute(IFPRI) in 1995 (Scherr and Yadav, 1996). The conclusion of that meeting was that landdegradation could be a potentially serious threat to both food production and rural livelihoods,particularly in densely-populated areas of current rural poverty. The threat, however, is notuniform. It depends upon a variety of environmental, social, economic, demographic and politicalcircumstances. These complex permutations of factors are beyond the scope of this paper, exceptto highlight the intricate sets of processes which lead to land degradation and to suggest a numberof critical “hot spots” where land degradation poses a significant threat to food security for largenumbers of poor people - see selected African examples given in Table 2. The IFPRI Workshopfelt that future policy interventions should focus on such “hot spots”. This Consultation would,no doubt, derive different areas where interventions are needed. However, the principle is thesame: to combat the potential threats to food security and rural livelihoods, targeting of effort iscrucially needed.

This paper seeks to lay the groundwork of environmental and soil physico-chemicalcircumstances that contribute to erosion-induced loss in soil productivity. It is impossible to makeprojections and determine planning priorities and conservation strategies without good qualitydata on both the rate of decline in productivity with erosion and the biophysical processesresponsible. So much of the debate has been marred by lack of data and uninformed speculation,often hugely exaggerated, that developing countries face massive food deficits because of soildegradation. We shall bring together the quantitative experimental evidence, and conduct anumber of scenario predictions of future production in a degrading environment, in order toinform the debate.

TABLE 2“Hot spots” for land degradation in Africa

Nutrient Depletion Water & Wind Erosion Vegetation Degradation Constraints to YieldIncrease

Semi-arid croplandsof Burkina Faso andSenegal (leading tooutmigration)Large areas undertransition to shortfallow or permanentcropping

Reduction of siltdeposits in Nile Deltafollowing constructionof Aswan High Dam

Subhumid SE Nigeria onsandy soils

Wind erosion in SahelMechanization in NorthAfrica causing water andwind erosion

Mechanization withinappropriate ploughingtechniques (e.g. transitionzone of West Africa)

Arid and semi-aridrangeland devegetation(e.g. Ciskei), particularlynear water sourcesDevegetation due tointensive collection ofwood fuel (around cities)Devegetation due tooverstocking (e.g.Morocco and Tunisia)

Reduced yields due toImperata andChromalaena infestationin degraded soils

Unsustainability ofannual crops in humidlowlands of WestAfricaDensely-populatedhighlands in Rwanda,Burundi and Kenya -no obvious source ofproduction increase

Lack of suitabletechnology for cropsgrown in areas lessthan 300 mm rainfallin North Africa

Source: adapted from Scherr & Yadav, 1996


DEFINITIONS

This paper is specifically about erosion-induced loss in soil productivity; that is, the decline insoil productive potential that can unambiguously be ascribed to soil erosion by water. There areother reasons for production to decline: almost any cropping can, for example, lead to an offtakeof nutrients which exceeds natural rates of renewal or resupply. These other reasons are functionsof the land use system, and may also be related to erosion. It is hard entirely to separate theportion of yield decline attributable to erosion. For practical purposes, if there are quantities ofnutrients and organic matter in the sediment and runoff water, then there is prima facie evidencethat erosion-induced loss in soil productivity is occurring because these are losses which wouldnot have happened without erosion. More difficult to identify is where erosion may be causingphysical and structural deterioration of the soil and where it induces certain chemical deficienciesand/or toxicities.

The word ‘productivity’ is much used and abused. In the literature it is often confused with‘production’ or even ‘yield’. From the original FAO review (Stocking, 1984) on erosion-productivity, the following definitions were offered:

• Productivity is a measure of the rate of accumulation of energy, or, in the context of soil (orland or agricultural) productivity, it is the productive potential of the soil system that allowsthe accumulation of energy in the form of vegetation. Soil productivity is, therefore, afunction of many factors including individual soil variables, climate, management and slope.It is close to the concept of ‘soil fertility’1, being a real and intrinsic property of the soil.However, it is conceptual and encompasses the whole range of factors that contribute to soilquality.

• Production is the total accumulation of energy, without necessary reference to how quicklyor over what area or with what assistance it accumulates; and agricultural production isnormally measured as crop yield, or the amount of production per unit area over a given time.

• Yield is a measure of production. It can also be used as an indicator of productivity. As anindicator it is imperfect because yield is an expression of historical production whereasproductivity is an expression of potential (i.e. future) production.

In modern farming systems, then, production includes artificial enhancements such asfertilizer, improved tillage practices and high yielding varieties. Production integrates not only theinherent soil properties but also the technologies applied to the soil system. Productivity, on theother hand, should strictly relate to the inherent soil quality and refer to the productive potentialof the soil. It follows that soil productivity can be masked by technology. A decline in soilproductive potential could (and usually is, in intensive agricultural systems) compensated byinputs such as irrigation or agro-chemicals. Intensive production systems can use soil merely as agrowing medium through which plant requirements are met artificially. In such systems,production can be extremely high, but the soil productivity can be extremely low. One way oflooking at erosion-induced loss in soil productivity is to see it as a real loss in the soil’s qualityand as a factor which makes agricultural production more costly, risky and tied to the continualprovision of inputs.

1 ‘Soil fertility’ is another term commonly misapplied, being often limited to the chemical status of

the soil only. In fact, fertility embraces all the soil’s functions that contribute to it supportingvegetative growth - including soil structure, permeability and depth.


If agricultural production becomes divorced from soil qualities, external factors will prevailin assuring continued output. The cycle of continued production while soil quality deterioratesalso means that the decline in soil productivity of land goes unnoticed. Hidden loss in soilproductivity is a major difficulty for researchers and policy-makers. Not only does it makeidentification of decline in soil quality problematic, but also it calls into question whether aproblem exists at all. Soil productivity1 is, therefore, a key criterion of food security. It relates tofuture production and describes how far the intrinsic quality of the soil resources may underpinthat production. While actual production may be adjusted by access to and application oftechnology, soil productivity may only be enhanced by careful conservation of soil restorativefunctions such as nutrient cycles, soil biota and plant-available soil water holding capacity.Additionally, food security holds the notion of empowerment of land users to provide productiveoutput for their areas without continual reliance on externally-sourced inputs. Similarly, theconcept of soil productivity embraces a security of future production which utilizes natural soilprocesses. This is why, we agree with other authors that erosion-induced loss in soil productivityis the major threat to food security.

GENERAL RELATIONSHIPS BETWEEN EROSION AND PRODUCTIVITY

There is strong evidence that yield decline with erosion follows a curvilinear, negativelyexponential form (Figure 1). In other words there is a sharp initial decline from a status of highproductivity, followed by successive stages of decreasing impact. The implication of this generaltrend is that it is vitally important to define the starting point when making observations onerosion-induced loss in soil productivity. An initially pristine soil will have a very severe decline,whereas an already badly-eroded soil may not suffer much further decrease in yield. A furtherimplication is that, other things being equal, efforts at conservation should be aimed at preventinggood soils from eroding rather than trying to save eroded soils from more erosion2. Althoughremarkably similar, there are some variations in the detail of the curvilinear relationship. Thedifferences are mainly related to initial yield levels, type of soil, cropping system and levels ofmanagement. Soil type differences will be the main focus in this paper. Comparisons will bemade, whenever possible, between how yields vary for a standard reference crop (rainfed maize)for the principal tropical and subtropical soil types, balancing the fact that some soils erode moreeasily while others display a much larger yield decline per tonne of soil loss. Nevertheless, inusing yield as the indicator of soil productivity, it can make a substantial difference in our view ofproductivity whether the crop itself is susceptible to the soil factors which may diminish witherosion, and whether our analysis commences on a soil that is already eroded. These last points ofdetail will not be dwelt upon here but they will be important in specific cases. However, this

1 Some authors differentiate between crop productivity and soil productivity. Crop productivity is

determined by the agronomic characteristics of the crop and soil productivity by the inherentproperties of the soil. Thus yield alone cannot be used to compare productivity of soils that havebeen planted with different crops and subject to different management practices.

2 Things are not, however, equal. This utilitarian approach to allocating priorities for conservationefforts on the best soils ignores other good reasons why already-degraded soils should be targeted.For example, the poorest people tend to live on the poorest soils; conversely, it might be seen associally irresponsible to concentrate conservation resources in areas which are already wellendowed and where richer sections of society predominate. Also, marginal and degraded areasusually give rise to huge off-site impacts such as sedimentation of water storages.


paper will make a strong conceptual distinction between (1) erosion rate differences and (2)impact differences per unit of erosion for the various reference soils.

In another paper (Tengberg et al., 1998), a conceptual framework for erosion-productivitymodelling is presented which may be helpful to this Consultation to show the different datasources and successive steps to construct loss in production scenarios (Figure 2). The first step isto collect site-specific data on soil, slope, rainfall and cover (Block A: Figure 2). Because of thedirect link with erosion impact, a farming system characterization is then needed (Block B) whichincludes crop, management and levels of inputs. Through erosion rate (Block C) and erosionimpact (Block D), the overall soil productivity for any land use scenario may be presented as thepredicted yield changes over time (Block E), and may be converted into monetary values (BlockF). Block A thus incorporates the physical attributes of the site which control erosion over time,while Block B takes in land use and management which both influence the impact of erosion andare in turn affected by erosion. The two blocks (A & B) control very different conceptualproperties of the whole erosion system - we term them ‘resilience’ and ‘sensitivity’.

Resilience is the property that enables a land system to absorb and utilize change; it isliterally the resistance to a shock such as a soil erosion event. Soil loss-time relationships (BlockC: Figure 2) express such an ability: the steeper the line, the less resilient is the soil. A soil whichlacks resilience is easy to degrade, and after misuse land management has great difficulty inrestoring its productive potential. Sodic soils are the most extreme example of poor resilience;they erode easily when wet through deflocculation of colloids which have more than 15%exchangeable sodium. Furthermore, the severe impact of erosion, including piping, cannot easilybe reversed. That is why many sodic soils make up typical ‘badlands’ landscapes: e.g. central

FIGURE 1General form of the relationship between soil loss and yields compiled from various sources

Cumulative soil loss (t/ha)


Mashonaland, Zimbabwe in the Ngezi/Mondoro area. Conversely, a resilient soil will not erodeeasily, but the effect of the erosion is variable. For example, a deep Vertisol is resilient in havinglow erosion rates, but the consequent degradation may have different impacts.

Sensitivity is the degree to which a land system undergoes change when subjected to anexternal force. It can also be seen as how readily change occurs with only small differences inexternal force. In the modelling framework, it is the degree of impact that a unit amount oferosion exacts (Block D). In the general erosion-productivity curve, good soils are far moresensitive than degraded soils. Similarly, many Ferralsols may be subject to high erosion (i.e. theylack resilience), but the effect of that erosion may only be small. A Phaeozem, in contrast, maydisplay a massive impact to a unit quantity of erosion, thereby demonstrating its extremesensitivity at least initially. For practical purposes, it would be good to identify the possiblepermutations of resilience and sensitivity of southern and East Africa soils. High sensitivity, lowresilience conditions (e.g. some fragile rangeland ecologies; or steep slope environments) should,if they are important contributors to production and supporters of rural livelihoods, be priorityareas for targeting intervention. High sensitivity, high resilience conditions (e.g. some clayeyhumid tropical rainforest soils on low angle slopes) suggest conservation approaches usingorganic matter as a buffer against their sensitivity. Low resilience, low sensitivity situations (e.g.many Acrisols and Andosols that erode easily but uncover subsoil that is not significantly inferiorto the eroded topsoil) will need low-cost agronomic conservation approaches. High resilience, lowsensitivity conditions (e.g. perhaps some of the humic Nitisols on low angle slopes) can probablylook after themselves.

FIGURE 2Conceptual framework for modelling erosion-yield-time relationships

A

Site-Specific

Datasoil, slope,

cover,

Time

CErosion Ratesoil loss-timerelationshipsRESILIENCE

EPotential YieldReduction or

Nutrient Losseswith TimeD

The Impact ofErosion

soil loss-yield/nutrient lossrelationshipsSENSITIVITY

BFarmingSystem

crop, inputs,management

FLoss in

Productionor

ResourceValue


CHEMICAL DEGRADATION: AN OVERVIEW

In the original FAO (1979) Provisional Methodology for Soil Degradation Assessment,chemical degradation was limited to two principal processes: acidification and toxicities.Acidification was defined as the decrease of base saturation (i.e. total exchangeable bases dividedby cation exchange capacity, expressed as a percentage change per year). Toxicity was theincrease in toxic elements (other than salinization or sodication) in ppm/year. Today, it is perhapsuseful to see chemical degradation more widely as the set of processes that lead to a diminution ofthe chemical status of the soil. This includes the loss of chemical components (nutrients) from thesoil by water erosion, and the effects such losses have on other soil functions. In a useful chapteron the ‘myths about the chemistry and fertility of tropical soils’, Sanchez and Logan (1992)challenge the received wisdom and prevailing perceptions that the soils of the tropics areuniversally acid, infertile and incapable of sustained agricultural production. Manifestly, theevidence of substantial increases in per capita food production in tropical Asia and Latin Americabelie this prejudiced view of chemical potential of tropical soils. Yet it is inescapable that soilchemical status in the tropics can be very changeable and susceptible to rapid decline. Ratherthan brand all tropical soils as chemically fragile, it is more reasonable to divide soil chemicalfertility into a number of specific soil constraints, each of which is examined for its relationshipto erosion - see Sanchez et al, 1987, for specific examples, and Sanchez and Logan (1992) forfurther details on the following categories taken from their work:

Low nutrient reserves: about 36% of the tropics (1.7 billion ha) have such soils, defined ashaving less than 10% weatherable minerals in the sand and silt fractions. These are the highlyweathered soils with limited capacity to supply P, K, Ca, Mg and S. They are particularlyprevalent in the humid tropics. Because the nutrient storage in the soil is so small, so transitoryand concentrated in the organic cycling, water erosion may be very effective in impacting thesesoils and causing substantial productivity decline. However, any usage is also a challenge tosustainable production on these soils and in humid environments where stripping the land of itsnatural vegetation inevitably deletes the major part of the nutrient cycle.

Aluminium toxicity: one third of tropical soils (about 1.5 billion ha) have sufficiently acidconditions for soluble Al to be toxic for most crop species. This constraint is defined as wheremore than 60% Al-saturation occurs in the top 50 cm of soil. Erosion can easily tip the balance ofacidity by removing the buffering of organic matter and by encouraging leaching and removal ofbases. Al-toxicity is one of the most serious chemical degradation processes, which has thepotential to cause very sudden and serious declines in yield with only moderate levels of erosion.The humid tropics and acid savannas are most at risk, with Ferralsols and Acrisols mostcommonly affected.

High phosphorus fixation: many tropical clay soils fix large quantities of added P. Fixation inthis context refers to rendering plant-available P (usually soluble) into insoluble forms that cannotbe used by most crops in the short term. This affects about 22% or 1 billion ha, being mostcommon in the humid tropics and acid savannas. P-fixation is directly related to clay content,organic matter and acidity - loamy Ferralsols and Acrisols are least affected. As with Al-toxicity,there is a close correspondence of the effects of water erosion with increase in P-fixation onsusceptible soils.

Low cation exchange: soils with a critically low level of effective cation exchange capacity(ECEC< 4 cmolc kg-1) occupy about 5% of the tropics. Such low values indicate limited ability to


retain nutrient cations against leaching. These would be poor soils anyway even without watererosion.

Salinity and alkalinity: locally, serious salinity (electrical conductivity >4 dS m-1) and alkalinity(> 15% Na saturation) problems occur, mainly in the humid tropics, semiarid tropics andwetlands. Water erosion may exacerbate the problems by transfer of salts and waterlogging.

Table 3 summarizes the extent of the various aspects of chemical degradation for Africa as awhole, and the potential links with water erosion.

TABLE 3Main chemical soil constraints in Africa and relationship to erosion

Soil constraint Extent(millions ha)

Extent(% Africa)

Relation to water erosion

Low nutrient reservesAluminium toxicityHigh P fixation by FeoxidesAcidity without Al-toxicityCalcareous reactionLow CEC

SalinityAlkalinity

615479

205

471332397

7518

2016

7

161113

3-

Made substantially worse by erosionInduced by erosion on susceptible soil

Induced by erosion on susceptible soil

Can be made worse by erosionNo direct linkSelective removal of colloids by erosionmakes this worseWashing in of additional saltsCause of some of the worst forms of erosion

Source: areal data based on Sanchez and Logan, 1992

PHYSICAL DEGRADATION: AN OVERVIEW

Physical degradation refers to adverse changes in soil physical properties, including porosity,permeability, bulk density and structural stability. The FAO (1979) methodology divided it intotwo primary aspects: increase in bulk density and decrease in permeability, both measured inpercentage change per year. As with chemical status, it is now useful to see physical degradationmore broadly as encompassing the range of soil physical properties that affect plant growth andcrop production. Again, the soils of the tropics are highly variable in their physical properties andtheir susceptibility to change. Following the categories in Cassell and Lal (1992), the followingtypes of soil physical degradation may be identified. Only a brief account can be given here:

Mechanical impedance: closely related to soil structure, this refers to the mechanical resistancethe soil offers to shoot emergence and root growth. Essentially, it is an increase in overall bulkdensity which reduces the volume of macropores and increases soil strength. The process ofmechanical impedance may be generated in a number of ways. First, soil compaction is anoutcome of intensive farming methods, usually involving mechanization, where soil structuralunits (aggregates) disintegrate into soil separates, thereby becoming prone to being packed intodenser masses. Fragments are pushed ever more tightly into pore spaces. At the same time,ultradesiccation may occur on tropical soils with low organic matter. Setting hard when subject toextreme drying in the subhumid and semiarid tropics, they develop a hard consistency andextreme compaction, even in their natural state. Soil erosion and runoff may assist the process byremoving colloids and water; and the rate of erosion itself may be greatly accelerated on suchsoils.


Crusting is perhaps the single most common physical degradation feature of tropical soils,occurring as a function of high intensity rainfall and poor vegetation cover. Crust strength mayimpede germination of crops and prevent water infiltration. It depends upon factors such as soiltexture, soil structure, aggregate stability and water content. Soils with a loamy sand texture aremost at risk of crusting. The process of formation of a crust is directly related to the degree ofsplash erosion on bare soil surfaces, and hence to water erosion.

Pans are layers of high bulk density at depth in the soil. They form a barrier to root penetration,limiting soil depth and productivity, especially if the pan is exhumed over time by surfaceerosion. Plough pans are common on Ferralsols and Acrisols in the tropics when subjected tomouldboard ploughing or discing. Duripans (also known as laterite and plinthite) are generallyhard sheets of Fe-Al cemented soil. It is estimated that about 130 million ha of savanna soils inwest Africa have such concretions; in Niger and Burkina Faso with mean annual rainfall of 200-500 mm, iron-rich duripans probably affect half the land surface. Duripans form over longperiods of time, possibly in response to devegetation and changed water balances - it is difficult todraw a direct link with water erosion, although the two processes may occur simultaneously. Afinal mechanical impedance is the occurrence of lag-gravels at depth. These represent old erosionsurfaces, now buried, and are often severely compacted and rigid. As with duripans, they becomean important threat to productivity as they are exhumed by surface erosion.

Changing soil-water relations: as noted by Cassell and Lal (1992), the fate of precipitation, onceit has arrived at the soil surface, is intimately linked to soil structure. A changing structurebecause of physical degradation easily affects the water balance, infiltration, plant-available soilwater and soil productivity. There is a good case for suggesting that reduced plant-availablewater is the single most common cause for reductions in yield consequent upon erosion in theseasonal, semiarid and sub-humid tropics. Even though total annual rainfall may be adequate,plants may undergo severe moisture deficiencies because of excessive runoff. That runoff may beinduced by a deteriorating soil structure. The various aspects of soil-water relations identified byCassell and Lal (1992) are:

• Infiltration is a function of soil structure, pore-size distribution, pore-connectivity andantecedent moisture conditions. The infiltration capacity of most tropical soils under naturalvegetation exceeds all but the most extreme rainfall intensities. However, once subject tocultivation, surface crusting and reduction in micropores substantially reduce infiltration. It isonly if tillage can leave a rough surface with a high surface water storage capacity that totalmoisture penetration can be maintained. Eroded soils have notoriously low infiltration rates.Once water has infiltrated, its retention in the soil can vary greatly depending on porosity,pore-size distribution, organic matter content, biological activity and soil management.Generally, it can be said that water erosion processes combine to produce far lower waterretention characteristics than in non-eroded soils.

• Puddling is the surface deterioration of soil structure when wet. Puddling occurs when soilstrength is low. There is no direct link to water erosion, except that runoff from areas ofpuddled soil is greater.

Increased soil erodibility is also an aspect of soil physical degradation, especially in the tropics.Normally, erodibility is considered to be an intrinsic function of static soil properties. However,soil erodibility is intimately bound with water-stable aggregates and organic matter content. Boththese properties are affected by water erosion. At the Institute of Agricultural Engineering,Harare, on a high-clay soil, once organic carbon content had decreased below 2%, soil erodibilitysuddenly increased fivefold (H.A. Elwell, personal communication).


EVIDENCE OF SOIL PRODUCTIVITY CHANGES WITH EROSION

Data sources

In this section we will mainly draw upon findings from the FAO-sponsored Erosion-ProductivityNetwork, which is using a standardized design to generate comparative data from different soilsand agro-ecologies - see list of references relating to the historical development of the Network.This programme was initiated following an inventory of erosion-productivity research indeveloping countries (Stocking, 1984). It was found that there was a need to quantify the impactof erosion and also to identify soil processes affected by erosion as well as limiting factors forcrop growth.

It is not the purpose here to detail the experiment1. The experimental procedure has alreadybeen widely disseminated (Stocking, 1986a; da Veiga and Wildner, 1993) and 23 research groupsworldwide now constitute the Erosion-Productivity Network. Each group is autonomous, workingbroadly on the suggested experimental design but with local adaptations according to typicalpractices and research resources. Briefly, the experiment involves soil loss and runoff plots ofabout 50 m2. The plots are cleared of vegetation and then allowed to erode naturally by rainfall.Twelve plots are organized in three replicate blocks. Two to three levels of erosion are achievedby covering the plots with varying degrees of artificial mesh, and a fourth treatment is kept asbare soil. The experiment is designed to take four to seven years, depending on the level of priorerosion achieved by natural rainfall. Once sufficiently differentiated levels of erosion are obtainedbetween the treatments, differences in productivity may be assessed in relation to the cumulativeerosion since the start of the trials.

Because an important objective of the experiment is to explain yield declines in terms of thespecific effects of erosion on soil quality, seven groups of variables are recommended forcontinuous monitoring: runoff and soil loss; physical and chemical characteristics of in situ soil;chemistry of the eroded sediments, including their enrichment ratios; chemistry of runoff water;biological activity of the soil; climatic factors; and plant parameters to indicate growth stress.This full menu of variables does represent a significant burden on our developing countrypartners, and hence individual groups have autonomy to choose those variables which are ofprincipal interest and that are within their capacity to Provide reliable data. Due to the long timeperiod needed to finish the two phases of the experiment and thus to get tangible results, not allparticipating groups have yet reported the final findings. We therefore have to draw, not only onthe results reported from Africa, but also from South America, which in many parts has similaragro-ecologies to Africa. An example from Indonesia of the erosion of an Acrisol is also included,as information on the impact of erosion on this soil type is scarce. We also present some findingsfrom associated studies of erosion phase (i.e. topsoil depth) and its relation to soil productivity inorder to complement the information base. The progress made so far in quantifying the impact oferosion in terms of changes in yield and soil chemical and physical properties is organizedaccording to country and site where the research was carried out. The impact of erosion on majorsoil types is subsequently discussed and across site comparisons are made.

Nitosols are very vulnerable to soil productivity decline caused by erosion. But unlike manyother soil types, virgin untruncated Nitosols have very deep topsoil so that even though soil loss is

1 See also Olson et a.l (1994) who discuss a variety of other methods.


relatively high, long periods of erosion are needed before soil productivity changes becomepronounced (Boxes 1 & 2).

The situation is quite different for red sub-tropical soils. Evidence from soil erosion-productivity experiments, using the FAO standard design, in southern Brazil indicates that soilerosion has a considerable impact on the productivity of Ferralsols and Cambisols. Decreasingyields, reduction of organic C, increasing soil acidity and free aluminium, and P-fixation arecommon problems, especially for Ferralsols (Boxes 3 to 5).

The reason that we only include one example of erosion-productivity research from a trulysemi-arid area is twofold. First, very few experiments have been carried out in this type ofenvironment and second, it takes a longer time to get good results because of low and highlyvariable rainfall (Box 6).

BOX 1 - EUTRIC NITOSOL, ETHIOPIA

Slope: 10-20%Rainfall: 1,335 mmCropping System: haricot beansThis experiment was carried out in the Ethiopian Highlands at the Gununo Soil Conservation ResearchStation, using the FAO standard design. Average annual soil loss for bare soil amounted to 144 t/ha.Seed yield (haricot beans) was closely correlated with erosion. Erosion also induced considerablechanges in soil chemical properties. Organic matter and total N content declined with erosion. Among thebasic cations on the exchange complex, erosion had its greatest impact on Mg and the Ca/Mg ratio - Mgincreased with erosion and consequently the Ca/Mg ratio dropped (after Tegene, 1992).

BOX 2 - HUMIC NITOSOL, KENYA

Slope: 27-34%Rainfall: 1,006 mmCropping System: maize with fertilizersThis experiment took place in the Kenyan Highlands at Kabete Campus Erosion Research Farm outsideNairobi. The FAO standard design was used. Average annual soil loss from bare soil amounted to 124t/ha. Erosion resulted in a decline in maize yields. Generally, erosion had a more negative effect on soilchemical properties than on physical properties. P was the nutrient most vulnerable to losses througherosion. Changes in in situ soil pH, organic C and N content were significantly correlated with cumulativesoil loss (after Gachene, 1995).

BOX 3 - RHODIC FERRALSOL, BRAZIL (SAÕ PAULO STATE)

Slope: 10%Rainfall: 1410 mmCropping System: maize without fertilizersThis experiment was conducted at the Experimental Station, belonging to Instituto Agronômico doCampinas. Annual soil losses for bare soil amounted to 51 t/ha. After seven years of induced erosionthere was a 50% decline in yield, amounting to a loss of 4kg/ha of maize per tonne of cumulative soilloss. Losses of nutrients (organic C, P, K, Ca and Mg) in the runoff and eroded sediment were alsosignificant with far higher levels of losses associated with the eroded sediment. Changes in the in situ soilwere less clear, but the decrease in organic C and increase in acidity could unambiguously be attributedto soil erosion. Erosion also affected the nutrient content of the crop - mainly N, Ca and B (afterTengberg et al., 1997a).


BOX 4 - RHODIC FERRALSOL, BRAZIL (SANTA CATARINA STATE)

Slope: 16%Rainfall: 1,850 mmCropping System: maize without fertilizersThis study was conducted at EPAGRI’s (Empresa de Pesquisa Agropecuária e de Extensaõ Rural deSanta Catarina) Research Station at Chapecó. Annual soil losses for bare soil amounted to 290 t/ha.After three years of erosion, 60% of the crop yield was lost from treatments with high erosion comparedto a treatment with very little erosion. However, due to the extraordinarily high soil losses measured atthis site, yield decline per tonne of soil loss was only 0.12 kg. There were also significant changes in thein situ soil content of organic C, P, K and Ca+Mg. Moreover, soil acidity and Al increased (after Tengberget al., 1997b).

BOX 5 - EUTRIC CAMBISOL, BRAZIL (SANTA CATARINA STATE )

Slope: 24%Rainfall: 1,750 mmCropping System: maize without fertilizersThis study was conducted by EPAGRI at an Agricultural College at Itapiranga. Annual soil losses frombare soil amounted to 23 t/ha. After three years of erosion 25% of the yield was lost, but due to relativelymodest soil losses yield decline per tonne of soil loss was higher than for the Ferralsols at Campinas andChapecó and amounted to nearly 19 kg. Erosion did not give rise to any significant effect on in situ soilproperties for this soil (after Tengberg et al., 1997b).

BOX 6 - EUTRIC CAMBISOL, BOTSWANASlope: 0.5-1%Rainfall: 525 mmCropping System: sorghumThis trial was located at Content Farm, Sebele. The FAO standard design was used. Average annual soilloss from bare soil amounted to 9 t/ha. No erosion-induced losses in productivity are directly discernible.However, a negative logarithmic relationship best fits the soil loss-yield data, but this relationship is notstatistically significant. Significantly higher amounts of N, P and K are lost from bare soil plots than fromplots under good cover. Absolute nutrient losses are greatest from the runoff losses than soil losses. Sorunoff loss seems more important at this site than soil loss. Moreover, infiltration was not affected by soilerosion (after Pain, 1992).

Two parallel erosion-productivity experiments are conducted in Tanzania - one based onerosion phase/soil depth, which looks at a number of different soil types and another one on aFerralsol that uses the FAO experimental design (Boxes 7 & 8).

BOX 7 - EROSION PHASE, TANZANIA

Three locations with different soils and agro-ecological conditions were studied: (1) Nitosols in the humideco-zone; (2) Ferralsol and Lixisol in the sub-humid zone; and (3) Cambisol, Alisol and Luvisol in thesub-humid/semi-arid zone. For the soils in the sub-humid/semi-arid zone, maize production wasinfluenced by soil depth, soil pH and the sand fraction in the soil. The productivity of the Luvisol was alsoinfluenced by available water capacity. For the Alisol, sand and clay fraction as well as available watercapacity influenced yields. For the Ferralsol, maize yield was affected by sand and silt fraction and bulkdensity of the soil. For the Lixisols, organic C and total N had a significant influence on yield (afterKaihura, 1996).

Information on the impact of erosion on the productivity on Luvisols (Box 9) is scarce andnow somewhat dated. For associated soils such as Acrisols (Box 10), we have had to refer toIndonesian data, again without yield impact information.


BOX 8 - FERRALSOL, TANZANIA

Slope: 4%Rainfall: 830 mmCropping System: maizeThis experiment was instigated in 1994 and conducted at Sokoine University of Agriculture, Morogoro. Bythe time of writing no yield has yet been reported. Average annual soil losses for bare soil amounted to 5t/ha. The impact of erosion on soil properties has been described by Mtakwa & Shayo-Ngowi (1997), whoconclude that available P is the nutrient most vulnerable to losses through the eroded sediment, whileexchangeable Mg suffers least losses.

BOX 9 - LUVISOL, NIGERIA

Slope: 5-10%Rainfall: 1,100-1,500 mmCropping System: maize and cowpeasThis study was carried out at the International Institute of Tropical Agriculture in western Nigeria during1976 and 1977. It was found that a negative exponential relationship best described the fall in yield withcumulative soil loss. The pattern in yield loss for both the grain crop and the legume was similar. Thedrastic declines in yield were attributed to a decrease in clay and organic matter content with erosion anda reduction in rooting depth with its associated water-holding capacity and poorer water infiltration (afterLal, 1981; Stocking & Peake, 1986).

BOX 10 - ORTHIC ACRISOL, INDONESIA

Slope: 13%Rainfall: 3000 mmCropping System: variety of food cropsThis study was carried out by the Centre for Soil and Agroclimatic Research, Lebak District, 65 km NWof Bogor. Annual soil losses for bare soil were extraordinarily high and amounted to between 260 t/ha to425 t/ha. While no information exists on the impact of erosion on productivity, its impact on soilproperties was documented. All the macronutrients decreased, except Al. The largest reduction was inorganic carbon followed by N. The micronutrients (Fe, Cu and Zn) showed the opposite trend, possiblyincreasing to near-toxic levels for some crops (after FAO, 1991).

BOX 11 - HAPLIC PHAEOZEM, MOZAMBIQUE

Slope: 3-5%Rainfall: 500-800 mmThis study is carried out at the Agrometeorological Experimental Centre for the South of Save River atBoane. The installation of the experiment was completed in 1995, so as yet not much data is available.However, there seems to be significantly higher losses of N from the more eroded plots (after Pereira etal., 1996).

BOX 12 - LUVIC PHAEOZEM, ARGENTINA

Slope: 1-2%Rainfall: 880 mmCropping System: maize without fertilizers, and crop rotation of wheat and soybeansThis experiment is carried out at the Argentine Agricultural Research Institute’s Experimental Station atMarcos Juarez, in the middle of the Pampas Region. At this site, different depths of soil have beenartificially removed (i.e. desurfaced). The different treatments were subsequently planted with wheat andsoybeans. Natural erosion rates from different cropping systems have been measured in parallel in largerunoff plots. Annual soil losses from bare soil amounted to 13 t/ha. Yields declined significantly withincreasing soil removal. However, due to the very low erosion rates at the site, according to themonitoring of soil loss and runoff, it can take up to 50 years before yield reductions become discernible.Desurfacing resulted in a reduction of organic matter, C, N and P. No major changes occurred in texture,moisture equivalent, conductivity, pH or bulk density (after Stocking & Tengberg, 1998; Weir, 1997).


Phaeozems are not common in Africa, but are included here as there is an ongoingexperiment in Mozambique on a Phaeozem, and also because they are considered to be one of thevery best agricultural soils (Boxes 11 & 12).

EROSION RATES

As noted earlier, erosion rates are related to the resilience of the soil to erosion: that is, its abilityto withstand erosional processes. We combined this aspect of resilience into a conceptual model(Figure 1) where resilience is the quality that determines the nature of erosion-time relationships.Since food security necessarily must consider to what extent erosion progresses over time, it isimportant to examine typical soil loss rates for the soils discussed in the previous sections. At thesame time, sensitivity helps us to conceptualize the impact of unit amounts of erosion. Table 4summarizes our best estimates at differential erosion rates based on the evidence of the studiesreported in the section “Data sources”. It uses the management levels which will be taken up inthe section “Scenarios of Yield Decline Over Time for Southern and East Africa” of this paper inorder to construct food security scenarios.

We could have used a soil loss model such as SLEMSA (Soil Loss Estimation Model forSouthern Africa), which has been locally validated for the Zimbabwe Highveld. However, sincethe FAO Erosion-Productivity Network results give us comparative data for actual soils on theslopes for which these soils are typically found, we felt it preferable to use actual measurementsfor the scenario constructions. Most of the soils in Table 4 are on moderately steep slopes, exceptthe Phaeozem and one of the Cambisols, which occur in nearly flat terrain. The Acrisol and oneof the Ferralsols have by far the highest erosion rates, followed by the Nitosols. The Phaeozemhas the lowest erosion rate, partly due to the gentle slope of the site, but also the Cambisols seemto be resilient, even on moderately steep slopes. Increasing the degree of soil cover has the leastimpact on the Acrisol and the largest impact on the Nitosols in reducing erosion and improvingsoil resilience.

TABLE 4Estimates of annual soil losses (tonnes/ha) for different soils and treatments.

Goodcover

Moderatelygood cover

Poorcover

Bare soil Typical croppingsystem withoutconservation

Eutric Nitosol (10-20% slope) 1 38 90 144 17Humic Nitosol (27-34% slope) 0.4 20 86 124 29Rhodic Ferralsol (10% slope) 16 -- 38 51 --Rhodic Ferralsol (16% slope) 76 94 187 290 --Orthic Acrisol (13% slope) 117 157 200 297 113Eutric Cambisol (24% slope) 1 5 9 23 --Eutric Cambisol (0.5-1% slope) 2 2 6 9 6Luvic Phaeozem (1-2% slope) 0.2* 0.6* 5* 13 0.6

Note: *estimates

DISTRIBUTION OF REFERENCE SOIL TYPES IN AFRICA

The following discussion is limited to what we call our Reference soil types: i.e. those soils forwhich we can reasonably confidently either construct erosion-yield-time relationships based onexperimental data from Africa and South America or make inferences based on soilcharacteristics and an understanding of resilience and sensitivity. It serves to give an overview of


the likely relevance of our constructed scenarios to be presented in Section “Scenarios of YieldDecline Over Time for Southern and East Africa”. The main information source is FAO/Unesco(1977).

Acrisols occur most often in the Sudano-Zambezian savanna zone where eco-climaticconditions tend to be unfavourable to agricultural development. Acrisols are found mainly onpoor materials (Luvisols of higher base saturation normally develop on richer materials). Thesoils concerned are therefore mainly poor and are subject to difficult ecological conditions. InEastern Africa most Ferric Acrisols occur in Tanzania. These soils are covered with Miombowoodland and degraded formations such as Zambezian-type tree savannas. Subsistenceagriculture based on cassava, sorghum, eleusine (finger millet), beans and some groundnuts andmaize is combined with livestock raising.

Cambisols are found in all the ecological zones of Africa from the equator to the edge of thedesert. They are characteristic of a recent stage of soil formation and therefore possess a fairlyhigh potential fertility. Their use depends essentially on ecological and topographical conditionsas well as management.

Ferralsols, which represent the final stage of ferralitic weathering, are widely distributedthroughout central Africa. These soils, which have a low adsorbing complex and are often highlydesaturated and possess no mineral reserves, have a limited potential fertility. The fertilizingelements of Ferralsols are mostly immobilized in the organic matter of the soil and in the plantcover. The content of clay is also of importance for their fertility.

Phaeozems are not widely distributed in Africa. In Morocco they occur in relatively flatterrain under a Mediterranean climate and are generally planted with wheat. In Nigeria they arefound in a hot tropical climate and are used for extensive grazing and cereal agriculture. Thereare also patches of Phaeozems on the Mozambique Plain, which is characterized by aeolian andfluvial deposits. Phaeozems are excellent soils for both traditional and modern agriculture. Theyhave no soil limitations and are very suitable for all crops and for pastures. Seasonal drought isthe only limiting factor.

Fluvisols are very important in many African valleys. They occupy the best drained parts ofthese valleys and usually occur in association with Gleysols, Vertisols and Regosols. In the humidtropics they are more fertile than neighbouring soils.

A wide variety of Luvisols occur in Africa. Most Luvisols are found under unfavourableeco-climatic conditions, and the irrigation water needed for intensification of agriculture is oftenlacking. These soils are therefore best suited for extensive livestock raising combined with thecultivation of essential food crops.

Nitosols occur under forest or savanna in dissected terrain with a humid tropical climate.They are typical of the intermediate stage of ferralitic weathering of materials of fine or mediumtexture. They are more fertile than Ferralsols, and in general they still have some mineralreserves.

Andosols occur in the volcanic regions of Cameroon, Zaire, Rwanda, Uganda, Kenya,Tanzania and Ethiopia. Highland Andosols show considerable potential fertility, but the degree ofsaturation depends on rainfall. In Uganda, Tanzania and Kenya, Andosols occur under highlandforest. The main crops are bananas, beans, peas, potatoes and vegetables. Livestock raising andcultivation of arabica coffee and tea are also important activities.


FIGURE 3General erosion-productivity relationships for the major soil types with initial maize grainyield on virgin land set to about 4000 kg/ha

FIGURE 4Scenario for maize yield decline over time for a Ferralsol with high erosion rate


In many African valleys there are large areas of Vertisols, especially in regions with a longdry season. In eastern and southern Africa they are particularly well represented in Tanzania andSouth Africa. Vertisols are sometimes inundated by river floods or submerged by rain water thataccumulates in poorly drained depressions. The natural vegetation is generally grass savanna.Vertisols are very heavy and difficult to work and are rarely used for traditional agriculture. Theyare preferably used for extensive grazing.

THE IMPACT OF EROSION

As is clear from the inventory of data sources and soils, information on the impact of erosion isstill lacking for some important agricultural soils in the tropics, notably for Acrisols, Fluvisols,Andosols and Vertisols. However, as some of these soils occur in association with soils for whichthe impact of erosion has been quantified, some extrapolations and comparisons are justified.This is, for example, the case for Acrisols with Luvisols, and for Ferralsols, Nitosols andCambisols to be considered in relation to each other. For the soils where both soil loss and itsimpact on production have been measured, there generally seems to be a curvilinear decline incrop yields with cumulative soil loss, as also noted earlier. This relationship most often takes anegative exponential or logarithmic form (Figure 3), with different exponents for different soils.These relationships, which are related to the sensitivity of the soil to erosion, together with typicalerosion rates (the resilience) for different soils under different levels of management, can nowform the basis for modelling of yield changes with erosion over time.

From Figure 3, Luvisols and Nitosols have the lowest sensitivity to erosion, followed by theFerallsols and Cambisols, while Phaeozems have the highest sensitivity. However, if we relatethese results also to the resilience of the soils to erosion and typical erosion rates for differentsoils and settings (Table 4), the Phaeozem and the Cambisol appear as the least problematic soils.

Some general conclusions can be drawn as to the impact of erosion on soils in the tropics:

• in humid to sub-humid tropical areas, productivity correlates highly with soil loss, generallyon negative exponential or logarithmic form, which makes it feasible to use simple soil loss-productivity models. In semi-arid areas the situation is different as water availability becomesa major constraint to crop growth and temporal variability in rainfall is high,

• all soils are sensitive to losses in organic C,

• soil chemical properties are more influenced by erosion than soil physical properties,particularly for the ferralitic soils, for which high soil acidity, Al toxicity and P-fixation canfollow erosion,

• in general, legumes are more tolerant to soil erosion than cereals,

• a good soil cover is very effective in reducing productivity decline.

SCENARIOS OF YIELD DECLINE OVER TIME FOR SOUTHERN AND EAST AFRICA

By using the relationships for yield decline with cumulative soil loss (soil sensitivity) for differentsoils (Figure 3) and combining these relationships with typical soil losses for different levels ofmanagement (soil resilience; Table 4), we can predict yield changes over time. These yieldchanges are the basic data needed for food security scenarios. For our reference soil types, theyenable predictions to be made as to how long soils can continue to produce under any specified


management condition including level of soil conservation. Such predictions are initiated inSection “Erosion-Productivity Issues Important to Food Security”. As in all modelling we have tobase our scenarios on a number of assumptions, such as stable climatic conditions, stable erosionrates and general applicability of broad management categories. A further assumption in order tosimplify the analysis is that there is only one cropping season per year. For the bimodal growingseasons of East Africa, compensatory adjustments may be needed. However, the most importantassumption is that there exists a universally good correlation between soil loss and productivity.Accurate, reliable and rational relationships between cumulative soil loss and yield, and forerosion rates under specified conditions are at the heart of making estimates of food security.Hence, in this section we elaborate scenarios for yield decline over time for the major soil typesand discuss the relative importance of soil sensitivity versus soil resilience. The underlyingprocesses, as reflected in changes in soil chemical and physical properties, are also discussed andsummarized based on the evidence presented in previous sections.

Overall, the Ferralsols have the second highest erosion rates (Table 4). Ferralsols are deeplyweathered, leached, stoneless and clayey. Virtually no weatherable minerals remain in the uppertwo metres, rendering the soil extremely limited in potential fertility. Its sensitivity to yield declineis, therefore, moderate, but its resilience to erosion is very poor. Ferralsols as a broad group aretherefore judged to have low resilience and moderate sensitivity, resulting in high erosion ratesbut relatively low impact per unit quantity of soil loss. However, due to the very high annual soillosses in our example, maize yield declines dramatically with erosion and is virtually down to nilafter ten years with erosion even with a good soil cover (Figure 4). This indicates that physicalconservation structures, such as terraces are necessary in hilly areas to sustain the productivity ofFerralsols.

From two earlier studies (Young and Wright, 1979; Stocking, 1986b), the significantcharacteristics of Ferralsols in relation to degradation processes are:

• low supply of available plant nutrients - erosion has little additional impact,

• strong acidity, high in free aluminium - erosion may set in train a large impact from Al-toxicity, if it is not already evident,

• low levels of available phosphorus - erosion may also cause a critical threshold of P-fixation,

• no reserves of weatherable minerals - erosion has little additional impact,

• topsoil organic matter easily lost - erosion will assist natural rates of humification..

Conclusion: Ferralsols: low resilience, moderate sensitivity. Addressing erosion rate bycombinations of structures and biological measures is indicated.

By the same analysis, Nitosols are considered to be one of the safest and most fertile soils inAfrica, but at low input levels a distinction needs to be drawn between Dystric and EutricNitosols. The rainforest Eutric Nitosols suffer:

• acidity problems and P-fixation - both exacerbated by erosion,

• substantial increases in erodibility with losses of organic carbon - strongly related to erosion.


Nitosols have therefore a moderate resilience and moderate to low sensitivity, which result instable yield with erosion with a good soil cover or high levels of management, without physicalconservation structures, but steadily declining yields for lower levels of management (Figure 5).Good cover and maintenance of organic matter as a buffer against acidity and its associatedproblems and as a measure to reduce soil erodibility are essential ingredients of a managementand conservation strategy for Nitosols. Conclusion: Nitosols: moderate resilience, moderate tolow sensitivity. Biological conservation measures effective for both erosion rate and erosionimpact.

Luvisols have been described as the ‘mid-point in the spectrum from poor to good tropicalsoils’. However, they do suffer substantial physical and chemical degradation which is closelyrelated to water erosion:

• moderate nutrient levels, concentrated in topsoil - erosion has a substantial initial impact,

• low to moderate organic matter content - erosion has some impact,

• weak topsoil structure, prone to crusting - erosion has a significant impact on crusting andknock-on effects such as reduced plant-available water.

Luvisols do not, therefore, have the highest erosion rates (moderately resilient), and theirsensitivity to erosion is moderate to low, which results in yield scenarios similar to those for theNitosol (Figure 6). However, many African Luvisols are currently used for smallholdercultivation at low levels of productivity and will not suffer much further decline. Conclusion:Luvisols: moderate resilience, moderate to low sensitivity. Productivity of Luvisols can bemaintained only by addressing erosion rate and by conserving nutrients and water-holdingcapacity on-site. This is most obviously accomplished by tillage practices which maximizesurface water infiltration (e.g. contour ridging; tied ridging) and biological measures whichmaintain cover.

Our database contains little specific information on one of the poorest of tropical soils:Acrisols. It has most of the degradation hazards of Ferralsols but with some additional physicaland chemical problems when cultivated:

• low supply of plant nutrients and trace elements - both affected by erosion,

• strong acidity, low calcium, high free Al - all made worse by erosion,

• topsoil organic matter easily lost - assisted by erosion,

• weak structure - subject to wind erosion, crusting and compaction,

• argillic B-horizon - if compacted and exhumed, an extremely serious impediment toproduction.

Acrisols have, therefore, a very low resilience and a moderate sensitivity. Erosion impact islikely to be similar to that for Luvisols. However, erosion rates are higher and initial productivitylower (Figure 7). As the poorest of the major soil groups, erosion is unlikely to have muchadditional impact to what has already occurred within historical times. Conclusion: Acrisols: verylow resilience, moderate sensitivity. Having the worst combination of resilience and sensitivity,agricultural production cannot be sustained beyond 1-2 years and only continuous cover (grass orforest) is indicated.


FIGURE 5Scenario for maize yield decline over time for a Nitosol

FIGURE 6Scenario for maize yield decline over time for a Luvisol


FIGURE 7Maize yield decline over time for an Acrisol

FIGURE 8Scenario for maize yield decline over time for a Cambisol


Cambisols are the tropical ‘brown earths’ with somewhat higher base status than Luvisols,but otherwise fairly similar limitations. Erosion rates are low in our case examples from SouthAmerica and Botswana (Table 4) and they are judged to have high resilience. They do haveincreasing clay with depth, and therefore have moderate sensitivity to erosion. The good resilienceand the moderate sensitivity of the Cambisols therefore result in less dramatic yield losses witherosion than for the previously discussed soils (Figure 8). It is noteworthy that even with a verylow level of management, there will still be something to harvest after 20 years of erosion.Conclusion: Cambisol: high resilience; moderate sensitivity. The most robust of our referencesoils; low-cost, mainly agronomic, measures of conservation such as intercropping or surfaceresidue management may be worthwhile.

Phaeozems have a good structure and are generally resistant to erosion (good resilience).The Phaeozem in our example in Table 4 is subject to the lowest soil losses, partly as a result ofgood structure and partly because of the very gentle slope at the site. However, according toFigure 3, Phaeozems have a very high sensitivity to erosion - i.e. large yield losses per unit of soilloss. But as Phaeozems are often found in flat terrain on aeolian and fluvial plains, which is thecase with Phaeozems in both Argentina and Mozambique, we combine very low erosion rateswith high sensitivity in the modelling of yield changes with erosion. It appears from Figure 9 thatHigh resilience in combination with high sensitivity result in high and relatively stable yields forgood to moderately good management (cover), whereas yields for lower levels of managementdrop drastically after only a few years. Conclusion: Phaeozems: high resilience, high sensitivity.The key to the sustainable use of Phaeozems is good vegetation cover.

EROSION-PRODUCTIVITY ISSUES IMPORTANT TO FOOD SECURITY

Erosion-productivity research issues

Having established scenarios for yield decline with erosion over time with different levels ofmanagement for some major soils in East and southern Africa, we are now in a position to

FIGURE 9Scenario for maize yield decline over time for a Phaeozem


consider the differential impact of erosion on food security. However, the foundation for goodpredictions is good research. Our ability to construct erosion-yield-time relationships has beenhampered by missing data and uncertainties caused often by dubious results. Data on specificagro-ecologies are drawn from in-country research groups who have limited resources andcompeting demands on their time. Therefore, before constructing the final scenario projections onfood security, it is relevant to the issues of this Expert Consultation to report on the findings ofthe March 1996 Erosion-Productivity Workshop held in Chapecó, Brazil (Stocking and Benites,1996) - see Box 13. This was a gathering of 28 researchers from 14 countries, representing thecombined experience of many of those actively engaged in erosion-productivity research.

BOX 13 – CONCLUSIONS AT THE FAO WORKSHOP, BRAZIL, 1996

Methodological issues: problems remain with the collection and analysis of information.Data base: there is a need for a general data base on erosion-productivity and a standard protocol; information is currentlytoo scattered and difficult to compare.Soil management and rehabilitation: a focus on soil management is indicated, with particular emphasis on organic andinorganic fertilizers and green manures.Evidence of productivity decline: the strong evidence of productivity decline should be related to economic costs of erosionand benefits of conservation.Continuity of research: the experiments should continue, but the reward system for in-country researchers is inadequate.Communication: there has been a lack of communication between researchers; a coordinated effort will require better liaisonand learning form others.Farmer participation: farmers are key partners in these research outputs and must be more involved.Economics of soil erosion: the results are not yet in a form suitable for economists and policy makers to appreciate thesignificance.Contact with planners: the research is isolated from strategic national programmes and policies and should be re-prioritizedthrough planning departments.

Source: adapted from Stocking and Benites, 1996

The Chapecó Workshop was concerned mainly with the erosion-productivity experiments,and naturally emphasized the research and the role of the researcher. Several of the highlightedissues (Box 13) are worth elaborating for this Expert Consultation in the context of soil fertility,soil degradation and food security:

• methodologies for deriving erosion-productivity relationships necessarily have to simplifycomplex reality in order to obtain results that are comparable. The report on the Workshop(Stocking and Benites, 1996) listed some of the problems and desirable changes which haveyet to be enacted. Recommendation: for southern and East Africa, address the critical needfor provision of good quality comparable data through a standard research protocol, clearadvice on recommended methodologies and adequate local support,

• emphasis to date has been on erosion, rather than conservation and production. For the manydegraded conditions in southern and East Africa, it would be more appropriate to examineconservation-induced gain in productivity through practices such as green manuring, livebarriers, minimum tillage and crop sequences and rotations. However, the same questionsarise: what are the relationships? How can we predict the gain in future production with suchimproved practices? Standard experimental designs are again indicated in order to provide anadequate data base. Recommendation: a new emphasis on soil rehabilitation should bepromoted, using measures that can be employed by farmers to improve eroded soils, but stillobtaining the data to construct accurate scenarios,

• farmer involvement has been missing from erosion-productivity research to date. Issues ofsoil fertility and food security intimately involve rural households, their labour, capital andresources, as well as farmers’ own technologies and adaptations. Recommendation: any new


phase of erosion-productivity or conservation-productivity research must be carried out on-farm and with the immediate involvement of land users.

FOOD SECURITY ISSUES

What are the implications of unchecked (or partially checked) soil erosion for food security? Foodsecurity is itself a balance between supply and demand: the supply is provided by the soilresources, crop management and the farming system; the demand comes from the needs of thepopulations who depend on the production of the farming system. For simplicity, this analysistakes the rural household’s needs as paramount; that is, demand is derived from the immediatefood needs of farmers and their families. Therefore, a farm-level perspective is taken of foodsecurity. With the household as the unit for analysis, we assume that each adult householdmember consumes approximately 200 kg of grain per year, and that children’s consumption is 50per cent less. A household is taken to comprise two adults and six children. A unimodal rainfallpattern is assumed with one harvest per year. These assumptions lead to a critical yield level of1000 kg/ha/year to meet household food security. The number of years it takes to reach criticalproduction levels differs greatly between soils and management levels (Table5). For the Ferralsoland the Acrisols, it takes only between one to four years to reach the critical level. The other soilsrespond more favourably to an increase in the degree of soil cover and thus good managementsustains a tolerable production level for longer than a generation. For the moderate cover, whichmost closely resembles the cover given by conventional cropping of maize, the Phaeozem givesthe longest period with tolerable yields. For the lower levels of management, the Cambisol bestmeets food consumption requirements.

TABLE 5Years taken for the different soils in the scenarios to reach a critical yield level of 1000 kg/ha/yrwith continued erosion

Management level Ferralsol Acrisols Luvisol Phaeozem Cambisol NitosolGood cover 3 4 93 200 210 950Moderate cover 2 3 23 65 42 19Poor cover 1 2 9 7 23 4Bare soil 1 1 5 3 9 3

These estimates of “food-secure productive life” could also be used to ascertainsustainability of production for the different soils. If effective sustainability is taken to be aproductive life of at least one generation, say 50 years, then only a few of the conditions in Table6 are allowable without special precautions.

Ferralsols and Acrisols: any continuous use is unsustainable. If cropping is to be contemplated atleast two or more of the following measures must be considered:

• mechanical conservation measures such as bench terraces to bring erosion well below thegood management” levels of 76 t/ha,

• provision of long rest-periods; Young and Wright (1979), based on expert opinion, specify atleast 3 years in 4 as the rest-period requirement,

• high inputs of nutrients and calcareous amendments to maintain both soil chemical fertilityand pH,

• cropping systems with high biomass production which can be used for mulch and greenmanure, irrigation.


Luvisols and Cambisols: continuous sustainable production is possible under good managementwith high levels of maintained cover. Productivity problems arise from a mixture of limitednutrient availability to the topsoil, low levels of organic matter and relatively poor water-holdingproperties:

• annual cropping needs to be rotated so that poor cover crops such as cotton alternate withbetter cover crops such as maize and beans,

• intercropping and agroforestry systems are ideal in maintaining cover and retaining nutrientson-site,

• tillage practices which retain water and minimize impedance (e.g. crusting) should beencouraged.

Nitosols: with good management, production can be maintained indefinitely without specialmeasures. The rehabilitation of eroded Nitsols (e.g. the Ethiopian Highlands; Lesotho andSwaziland Highvelds) would seem to be a high-priority task with possible substantial gains inproduction in the short term. Rehabilitation would involve the re-creation of a topsoil whichmight only take a decade or so of careful cropping and build-up of organic matter. So, forcontinuous and sustainable production:

• attention to possible acidity problems through liming and/or organic buffers,

• attention to P-fixation, again by liming and by resupply of soluble P,

• maintenance of organic matter levels (organic C > 2%) to keep soil unerodible and resistantto rainsplash and detachment.

Phaeozems: these are the most robust amongst our Reference Soils with highest resilience.However, they are sensitive to yield decline. Although not abundant in Africa, areas ofPhaeozems should be carefully protected for food security purposes:

• although suitable for most continuous cropping under smallholder agriculture, a minimumlevel of management standard must be maintained,

• good to moderate crop cover needs to be maintained, in which case erosion rates will remainlow and productivity unchallenged,

• no particular special management practices are indicated, other than a balanced resupply ofchemical components and maintenance of water-holding properties.

From the above analysis, it can be deduced that farm management level and type ofmanagement are crucial in determining food security. All soils, other than Acrisols and Ferralsols(which would demand special precautions), are capable of meeting the food needs of growingpopulations provided that overall crop management is good and particular soil-related constraintsare addressed. Studies in East and Central Africa have shown that farm management depends onfarmers’ access to resources. Richer farmers are likely to have a higher level of management thanpoorer farmers (cf. Scoones, 1996). Interventions designed to address household food securitytherefore need to take account of both soil type and the wide range of socio-economic conditionsfarmers are facing that determine their overall resource level. Our preliminary analysis of foodsecurity indicates that, without soil and water conservation structures, all groups of farmers onFerralsols and Acrisols are likely to reach critical yield levels only after a few years, whereas forthe other soil types, poorer farmers are more at risk. Even Ferralsols and Acrisols could continue


to provide a sustainable production under long-cycle shifting cultivation, but that is becoming animpossibility as populations increase and available land per person diminishes. At this stage, it isimportant to differentiate between ‘food production security’ and ‘food consumption security’ (cf.Reardon et al., 1988). It is well-known that so-called farmers in southern and east Africa havedeveloped highly diversified income-generating opportunities. For richer households (often thosewith the most highly diversified income base, encompassing, for example, off-farm income),‘consumption security’ may not be a problem although ‘production security’ may be at risk, asthese households generally generate enough cash income for purchasing additional food. Forpoorer households and households with a low degree of income diversification, ‘productionsecurity’ and ‘consumption security’ tend to go hand in hand. Poorer and marginal householdstend to live on the poorer soils - Luvisols, for example, which are fairly easy to cultivate butwhich lose their fertility quickly. So, for effective food security at the household level, policy willneed to target these marginal groups subsisting on some of the most difficult soils. Our analysissuggests this may be a daunting task. Without prejudice to the discussions at the ExpertConsultation in Harare, the following policy issues and recommendations (to add to those alreadygiven at Section “ Erosion-Productivity Research Issues” are relevant from the scenariopredictions and associated soil-related constraints:

• food security is a useful way of viewing the conceptual term ‘sustainability’: if productioncan be assured for a reasonable length of time (we have assumed 50 years), then foodsecurity is effectively achieved. Recommendation: food security is an indicator of both soilproductivity and sustainability - policy makers should establish food security targets at avariety of levels (household, community, national and regional) and researchers couldrespond by providing recommendations for targeting particular soils, environments andsocioeconomic groups.

• Secure access to soil resources and the means to achieving “good management” are vital tothe protection of the environment and of future production. While a soils-led analysis such aswe present provides a baseline for making scenario predictions, the reality is that farmersrespond according to their social and economic needs, not to the wishes of society.Recommendation: soil fertility, productivity and sustainability are not politically neutral; theyneed to be incorporated into policy issues concerning equitable and fair access to resources,advice and subsidies in order to promote the wider benefit to society of the good managementthat is expected of farmers.

Finally, the analysis of soil erosion and food security indicates that we are dealing withcomplex situations, where full knowledge of every permutation of soil sensitivity and resilience aswell as farmer resource level is an impossibility. An adaptive management and policy approach isneeded, where it is essential to allow solutions to emerge from the local level. It is thus time totake the erosion-productivity experiments on-farm and together with farmers identify problemsand remedies for different soils and settings. Remedies could, for example, encompass thedevelopment of existing indigenous soil and water conservation techniques (Reij et al., 1996).Furthermore, the links between management levels and farmer resource levels also indicates thatit is important to support the diversification of the rural income base. However, we leave it to theparticipants in this Workshop to discuss and identify appropriate policies for coping with erosioninduced loss in soil productivity in their respective countries. Our hope is that we have, throughthe work of our colleagues in the FAO-sponsored Erosion-Productivity Network, set a baselinewhereby appropriate policy recommendations can be developed in the knowledge of how the soilproductive resources would respond and whether people might gain the food needs that theyrequire.


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Pereira, L.M.R., Famba, S.I. and van den Berg, M. 1996. Erosion-Induced Loss in Soil Productivity inMozambique - Causes and Solutions. Report for the Second Workshop on Erosion-Induced Loss inSoil Productivity: Causes and Solutions, Chapecó, Santa Catarina, Brazil. 4-8 March 1996, 12 pp.

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Reij C., Scoones, I. and Toulmin, C. 1996. Sustaining the Soil: Indigenous Soil and Water Conservationin Africa. Earthscan, London, 260 pp.

Sanchez, P.A. and Logan, T.J. 1992. Myths and science about the chemistry and fertility of soils in thetropics. In: Lal, R and Sanchez, P.A. (eds.) Myths and Science of Soils in the Tropics. SSSASpecial Publication No.29, Soil Science Society of America and the American Society ofAgronomy, Madison, Wisconsin, pp.35-46.

Sanchez, P.A., Pushparajah, E. and Stoner, E.R. (eds.) 1987. Management of Acid Tropical Soils forSustainable Production. IBSRAM Proceedings No.2, International Board for Soil Research andManagement, Bangkok.

Scherr, S.J. and Yadav, S. 1996. Land degradation in the developing world: implications for food,agriculture, and the environment to 2020. Food, Agriculture and the Environment DiscussionPaper 14, International Food Policy Research Institute, Washington DC.

Scoones, I. 1996. Hazards and Opportunities. Farming Livelihoods in Dryland Africa: Lessons fromZimbabwe. Zed Books, London, 267 pp.

Stocking, M. 1984. Erosion and Soil Productivity: A Review. Soil Conservation Programme, Land andWater Development Division, UN Food and Agriculture Organization, Rome, 102pp.

Stocking, M.A. 1986a. The Impact of Soil Erosion in Southern Africa: A Research Design for AssessingPhysical and Economic Losses in Soil Productivity. SADCC Soil and Water Conservation andLand Utilization Programme, Report No. 2.

Stocking, M. 1986b. Tropical red soils: fertility management and degradation. In: Nyamapfene, K.,Hussein, J. and Asamadu, K. (eds.) The Red Soils of East and Southern Africa. Proceedings of anInternational Symposium, Harare, February. Manuscript Report IDRC-MR170e. InternationalDevelopment Research Centre, Ottawa.

Stocking, M. and Benites, J.R. 1996. Erosion-Induced Loss in Soil Productivity: Second Workshop -Preparatory Papers and Country Report Analyses. Report of the Workshop, Chapecó, SantaCatarina, Brazil. UN Food and Agriculture Organization, Land and Water Development Division,Rome, 53pp.

Stocking, M. and Peake, L. 1986. Crop yield losses from the erosion of Alfisols. Tropical Agriculture(Trinidad), 63: 41-45.

Stocking, M. and Tengberg, A. 1998. Soil conservation as incentive enough - experiences from southernBrazil and Argentina on identifying sustainable practices. In: D.W. Sanders, P.C. Huszar, S.Sombatpanit, & T. Enters (eds.), Using Incentives in Soil Conservation. Oxford & IBH PublishingCo, Dehli for The World Association of Soil and Water Conservation. (in press)

Sanders, D. and Stocking, M.A. 1992. Erosion-induced loss in soil productivity. Paper to ISCOConference, People Protecting Their Land, Sydney Australia.


Stocking, M. and Benites, J.R. 1996. Erosion-Induced Loss in Soil Productivity: Second Workshop -Preparatory Papers and Country Report Analyses. Report of the Workshop, Chapecó, SantaCatarina, Brazil. UN Food and Agriculture Organization, Land and Water Development Division,Rome, 53pp.

Stocking, M.A. and Peake, L. 1985. Erosion-Induced loss in soil Productivity: trends in research andinternational cooperation. Paper to IV International Conference on Soil Conservation, Maracay,Venezuela (published in the Conference Proceedings and as a report - FAO/Overseas DevelopmentGroup, Norwich)

Stocking, M.A. 1986. The impact of soil erosion in southern Africa. A research design for assessingphysical and economic losses in soil productivity. Report No 2, SAADCC Soil and WaterConservation and Land Utilization Programme, Maseru, Lesotho.

Stocking, M.A. 1988. Networking the impact of erosion. Soil Technology 1: 289-292.

Stocking, M.A. 1995. Erosion-productivity research in South America. A mission report to reviewprogress. Land and Water Development Division, UN Food and Agriculture Organization,Rome.Tegene, B. 1992. Effects of erosion on properties and productivity of eutric nitisols inGununo area, southern Ethiopia. In: Hurni, H. and Tato, K. (eds.): Erosion, Conservation andSmall-scale Farming. Geographica Bernensia, Berne, Switzerland, (582 pp.): 229-242.

Tengberg, A., Stocking M. and Dechen, S.C.F. 1997a. The impact of erosion on soil productivity - anexperimental design applied in São Paulo State, Brazil. Geografiska Annaler, 79 A: 95-107.

Tengberg, A., Stocking, M. and da Veiga, M. 1997b. The impact of erosion on the productivity of aFerralsol and a Cambisol in Santa Catarina, southern Brazil. Soil Use and Management, 13: 90-96.

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Soil degradation assessment and soilconservation inventory on a SOTER

basis: Asian experience

This paper will present the methodology and some results of a recent soil degradation assessmentfor South and Southeast Asia (ASSOD), and of an inventory of soil and water conservationactivities in Thailand and SE. China (WOCAT) using the same base map units derived from a1:5 M physiographic map that was compiled following the SOTER methodology. This approachoffers a strong framework using standardized and internationally accepted methodologies(SOTER, ASSOD or GLASOD, WOCAT) that can be applied at different scales. Parts of thisapproach have also been - or will soon be - implemented in Africa (GLASOD: whole continent at1:7 M; SOTER: Kenya 1:1 M, Benin; WOCAT: Eastern, Southern and Western Africa 1:5 M).

GLOBAL AND NATIONAL SOILS AND TERRAIN DIGITAL DATABASE (SOTER)

Background

Policy-makers, resource managers and the scientific community at large have repeatedlyexpressed the need for ready access to soil and terrain resources through geo-referenceddatabases in order to make assessments of the productive capacity of soils, to have a betterunderstanding about the risks and rates of soil degradation and to better quantify processes ofglobal change. The SOTER programme is a system which can store detailed information onnatural resources in such a way that these data can be readily accessed, combined and analysedfrom the point of view of potential use, in relation to food requirements, environmental impactand conservation.

SOTER characteristics and development

SOTER provides an orderly arrangement of natural resource information through the creation ofa computerized database containing all available attributes on topography, soils, climate,vegetation and land use, linked to a Geographic Information System, through which each type ofinformation or combination of attributes can be displayed as a separate layer or overlay, or intabular form. SOTER is an initiative of the ISSS and was adopted at the 13th World Congress ofSoil Science in 1986.

Under a UNEP project, ISRIC developed a methodology for a World Soils and TerrainDigital Database (SOTER) for use at a scale of 1:1 M, in close cooperation with the LandResources Research Centre of Canada, FAO, and ISSS.

G.W.J. van LyndenInternational Soil Reference and Information Centre, Wageningen, The Netherlands

Soil degradation assessment and soil conservation inventory on a SOTER basis: Asian experience122

SOTER was tested in three areas,involving five countries (Argentina, Brazil,Uruguay, the USA and Canada), using localdata. Results were reported at the 14th WorldCongress of Soil Science in 1990. Based onthe experience obtained in the pilot areas theSOTER methodology was further refined anda training programme and course materialwere developed by ISRIC. In 1993 theProcedures Manual for Global and NationalSoils and Terrain Digital Databases wasjointly published by UNEP, ISSS, FAO, andISRIC (in English and Spanish), accompaniedby attribute input software. A SOTER basedmethodology for an assessment of watererosion risk and for Automated LandEvaluation (ALES) was developed. In 1993the SOTER programme was implemented atnational level in four countries (Argentina,Uruguay, Kenya, and Hungary). In Argentina and Uruguay, SOTER windows at scales up to1:100,000 are also scheduled. These national SOTER programmes were formulated and financedby UNEP with technical support and coordination provided by ISRIC. More recently a 1:500 000SOTER project started for Hainan Province in China with UNDP funding. The programmes arecarried out by the national soil research organizations.

In 1992, an international panel convened by UNEP to evaluate the SOTER programme,recommended not only implementation of SOTER activities at a national level, but also thedevelopment of small-scale continental SOTER databases. In 1993, an action plan for thecompilation of a Latin American SOTER at a scale of 1:5 M was jointly formulated and financedby UNEP, FAO, and ISRIC, which was finalized this year. Within the framework of the ASSODproject (see below), the SOTER methodology was used to prepare a physiographic map for Asiaat a 1:5 M scale in 1995. It is hoped that this map will be complemented with a full SOTER (soil)database in due course. Currently a 1:2.5 M SOTER map is under preparation for Central andEastern Europe in the context of the project Soil Vulnerability Assessment in Central and EasternEurope (SOVEUR).

ASSESSMENT OF THE STATUS OF HUMAN-INDUCED SOIL DEGRADATION IN SOUTH ANDSOUTHEAST ASIA (ASSOD)

Recently a project called Assessment of the Status of Human-Induced Soil Degradation in Southand Southeast Asia (ASSOD) was completed by ISRIC in collaboration with FAO and nationalinstitutions. The project is a sequel to the UNEP/ISRIC survey of Global Assessment of theStatus of Human-Induced Soil Degradation (GLASOD; Oldeman et al. 1991). In 1993 an ExpertConsultation in Bangkok of the (FAO) Network on Problem Soils in Asia made arecommendation (RAPA, 1993) for the preparation of a soil degradation assessment covering 17countries in South and Southeast Asia based on a modified GLASOD methodology. A newphysiographic map for Asia at a scale of 1:5 million that was compiled by ISRIC (van Lynden,1993) following the SOTER methodology was used as the mapping basis for this assessment.


ISRIC was the coordinating institution for ASSOD, while national soils- or agriculture researchinstitutions were providing the data. The project was jointly funded by UNEP, FAO and ISRIC.

Methodology

Guidelines for the assessment of human-induced soil degradation in South and Southeast wereprepared by ISRIC, based on the GLASOD methodology. Natural resource institutions in theparticipating countries were requested to provide degradation data following these guidelines. Themost important differences with the GLASOD methodology, besides the geographical focus (17countries in S. and SE Asia) and the larger scale (1:5M), are the assessment of impacts onproductivity as a function of management level (rather than the degree of degradation). Like theGLASOD map, ASSOD provides information and increase awareness on soil degradationproblems among policy- and decision-makers and the general public in the region. It describes thecurrent status of (human-induced) soil degradation, but with more emphasis on the impacts ofdegradation on productivity and on trends of degradation (recent past rate). The impact of soildegradation was evaluated on the basis of the expected productivity increase (or decrease) forthree levels of management (high, medium, low). More emphasis was also placed on the rate ofdegradation, the latter being considered an important item in degradation dynamics and inprioritization of conservation areas. Finally, a greater flexibility in data handling and analysiswas achieved by storing the information in a digital database linked to a GIS. Unlike GLASOD,the number of identified degradation types and related characteristics is now potentiallyunlimited. The link with a GIS facilitates the preparation of various outputs and thematic mapson specific items.

This showed a general trend towards a slow or moderate increase in degradation for allmajor degradation types, although for water erosion in particular some smaller areas show animproving trend. Although the project has recently been terminated, improvement and updating inthe future will remain possible. A report is available with two accompanying maps (one showingthe dominant degradation types for the entire region, the other showing specific degradation typesfor four “windows”) and various graphs. Individual maps on specific themes or for specificregions can be produced on request. Information from ASSOD was extensively used in thesecond (revised) edition of the World Atlas of Desertification, which has been recently publishedby UNEP.

Results

The ASSOD results show a wider variability of degradation types in comparison with theGLASOD map for the same region, with especially more frequent occurrence of fertility declineand salinization. Compared to the GLASOD map, water erosion is much less dominant(Figure 1). This is probably more the result of differences in scale and approach than of realchanges in degradation. Water erosion (on and off site) nevertheless still is the most widespreaddegradation type (398 M.ha or some 22% of the entire land area, see Figure 2) with agricultureand deforestation being reported as the main causative factors. Second in importance is chemicaldeterioration (mostly fertility decline), covering some 210M.ha or 11 % of the total land area.The main causative factor for this degradation type is agriculture. This type of degradation islargely concentrated in the more humid tropical parts of the region. Wind erosion (on- and offsite) is understandably concentrated in the Western and Northern arid and semi-arid parts of theregion, covering some 175 M.ha (9% of total land area). Its main causes are overgrazing and to alesser extent deforestation and over-exploitation of natural vegetation. Physical deterioration was


generally considered less important although locally waterlogging, aridification orurbanization/industrialization are significant.

WORLD OVERVIEW OF CONSERVATION APPROACHES AND TECHNOLOGIES (WOCAT)

In 1992 the World Association of Soil and Water Conservation (WASWC) together with theCentre for Development and Environment in Bern initiated a “counterpart” project of GLASOD:

FIGURE 1ASOD GLASOD comparison

FIGURE 2Relative distribution of degradation types and non-degraded land (as percentage of total landarea)


the World Overview of Conservation Approaches and Technologies (WOCAT), to assess whatmeasures are being taken against degradation (in particular soil erosion). Data on extent andimpact of soil and water conservation (SWC) are not available at a global level, but are evenrather scanty or incomplete at national levels. The project developed a standard methodology toevaluate existing SWC technologies and the approaches to implement these technologies in thefield. Rather than considering only technical aspects (as in many SWC handbooks), the “enablingenvironment” is also evaluated which facilitates the identification of reasons for success orfailure. Comprehensive questionnaires have been developed that are filled in during regionalworkshops. Three such workshops have been organized to date for eastern Africa, southernAfrica and western Africa respectively. The results of the questionnaires are stored in a digitaldatabase and can be extracted in summarized or full form.

Moreover, specific geo-referenced data are collected for map compilation. For Africa themap units of the GLASOD map (1:15 M) served as a basis for the WOCAT map, enablinglinkage to the degradation data. In spite of the global scale of the assessment, the methodologycan be used at national and even sub-national level as well: a first national WOCAT workshopwas held in Thailand in September 1997 and very recently a sub-national workshop was held inChina, initially covering Fujian province in the Southeast. The mapping basis for both of theseinventories was the SOTER based physiographic map that was also used for the 1:5 Mdegradation assessment (ASSOD), thus offering a geographical linkage between physiographicinformation (SOTER), type, extent, impact and rate of degradation (ASSOD) and land use data,SWC type, effectiveness, extent, etc. (WOCAT). When - at least part of - the Asian SOTERdatabase will be completed with soil data in the near to medium term future, this will result in acomprehensive geo-referenced database on soils, terrain, degradation and conservation, whichwill be a useful tool for planners and decision makers. More detailed studies and applicationscould be implemented for certain “hot spots” using the same methodologies.



Socio-economic aspects of soil managementfor sustainable agriculture and food security in

Africa with particular reference to Zimbabwe

As in the past decades, the satisfaction of the ever-growing demand for food remains the majorchallenge to world agriculture. This is particularly true in Africa where tremendous socio-economic transformation renders traditional small scale farming systems incapable of meetingthis challenging demand. In fact it is the only continent in the world where per caput foodproduction has constantly been declining over the past decades (Hailuetal 1992). Rapid increasesin the African population demand increased production of food from land. To meet this need, vasttracks of land are being brought into production. The total area of cultivable land available toAfrica is however limited as is its productive potential. Land must be carefully managed if itsproductivity is to be maintained or increased. If it is not well managed, or if it is used in a waywhich is beyond its potential, some form of soil degradation inevitably occurs. At present, as thepressure on small scale farming land increases, large areas are being misused. The results ofpoorly managed land can be seen in various forms of soil degradation such as desertification,erosion, salinization, toxicity and water logging. The issue of soil degradation has increasinglydrawn the attention of many international development and research institutions, planners, policymakers, scholars and donors particularly concerned with the challenge posed on productionsystems in Africa.

The World Bank (1988) estimated that 100 million people in Africa are food insecure andnoted that Africa’s food situation is not only serious, it is deteriorating. Soil degradation, througherosion, has been identified as one of the major causes of declining food production and thereforeof the increasing inability of people to feed themselves. Brown (1991) also pointed out that soildegradation has continued in spite of the environmental protection efforts of nationalgovernments, the creation of numerous environmental agencies, the thousands of protective lawspassed, the activities of tens of thousands grassroots environmental groups and the production ofenvironmental issues. The World Bank (1989) showed that primary forests are disappearing at arate of 0.6% per annum across sub-Saharan Africa. These rates vary substantially amongAfrican countries. For example, the forests of Ivory Coast declined on average by 51% perannum from 1965 to 1984 (Elthel and Hertel 1989) and in arid areas annual rates of up to 25%were reported (Olsson K. 1985). In the context of the close correlation between populationgrowth, soil degradation and food production the following can be derived from the populationincreases (for various regions) estimated by the United Nations Fund for Population Activities(Table 1).

D. Tawonezvi and P.N. SitholeSenior Agricultural Economist and Senior Socio-economist of Agritex, Harare, Zimbabwe

Socio-economic aspects of soil management for sustainable agriculture and food security128

The world population is expected to stabilize at about ten and half thousand million by theyear 2110, and the African population at 2,193 (about 21% of the world population) (Table 1). Inthe table the expected population increases are shown in relation to 1980 population together withthe number of years over which they will take place to emphasize how great a food productionincrease will be needed within a short period of time. The world has to more than double its foodsupplies over the next 130 years. The figure for Africa is significantly higher with over four timesmore food being required 130 years from 1980 just to maintain the 1980 standard of nutrition.This presents a challenge to Africa as a whole, to put in place mechanisms which facilitate theattainment of the above levels of food production. This may call for continued expansion of landunder cultivation or improving of technology which allows higher productivity per unit area. Thepresent outlook in both respects (land expansion and improved productivity) gives a cause forconcern. Africa’s soil resources are being destroyed much faster than ever before. The presentproduction base tends to occupy the best land. The remaining areas are more marginal, generallypossessing a lower production potential and a more fragile ecological regime. Their cultivationwould require the most immense development programme. On the basis of current development,soil management (soil degradation in particular) needs close attention if Africa is to meet itsfuture food requirements.

TABLE 1Expected population increases

Region 1980population(millions)

Stablepopulation(millions)

Stable population inrelation to 1980

population

Year ofstabilization

Period(years)

World 4.434 10,529 +137% 2110 130Africa 470 2,193 +367% 2110 130Latin America 364 1,187 +236% 2100 120North America 248 318 +28% 2060 80East Asia 1,059 1,725 +63% 2090 110South Asia 1,405 4,145 +195% 2100 120Europe 484 540 +78% 2030 90Oceania 23 41 +120% 2070 80USSR 265 379 +43% 2100 120

Source: FAO, 1983.

OVERVIEW OF SOIL DEGRADATION IN ZIMBABWE

Environmental deterioration accompanied by soil loss and soil depletion pose tremendousimplications for agricultural development in Zimbabwe. The potential productivity of the soils isdeclining steadily on a national scale. Year by year the inherent fertility of Zimbabwean land isbeing depleted, soil profiles are shallowing and rills and gullies are encroaching into every cornerof the catchment areas.

The following is a summary of the state of soil resources in Zimbabwe:

• Current rates of soil loss from annual ploughed land are of the order of 50t/ha/yr. About onethird of the seasonal rainfall is lost as surface runoff and up to 50% of the applied fertilizersis washed off the land (Elwell and Stocking 1988).

• As a by product of soil erosion the country is estimated to be losing $1.5 thousand millionworth of nitrogen and phosphorus each year from the arable land and 2.5 million tonnes oforganic matter essential for soil stability and fertility (Stocking 1986).


• Thirteen percent of the total area of Zimbabwe and 27% of communal land is classified asseverely eroded (Whitlow 1988).

• The soil in most agricultural land has been reduced to its minimum agricultural potentialthrough degradation of soil structure, seriously limiting yields and substantially increasinginputs (Elwell 1989).

• Virgin soil is being reduced to its minimum yield potential within five to ten years after landhas been first opened up and many lands become totally unproductive and non-reclaimablewithin thirteen years.

• Marked changes have occurred to the hydrological balance of our catchment areas such thatrainfall amounts and distribution are being adversely affected. Groundwater levels aredeclining and the nation’s water supplies are jeopardized by siltation and drought.

TYPES OF SOIL DEGRADATION IN ZIMBABWE

Soil degradation is a complex process in which several features can be recognized as contributingto a loss of productive capacity. Generally, the processes are many and varied, and in Zimbabwethey include soil erosion by water and wind, soil fertility decline, salinization, water logging,lowering of water table, deforestation, forest degradation and rangeland degradation.

Soil erosion by water

In Zimbabwe forms of soil erosion by water include sheet, rill erosion and gullying. Human-induced intensification of land caused by vegetation clearance and construction, etc., is alsoincluded. Sheet erosion alone has been found to be causing soil losses of the order of 50 t/ha/yearin the communal lands. The major physical factors controlling the rate of erosion by water inZimbabwe are rainfall, vegetation or soil cover, topography and soil types.

Rainfall. The effect of rainfall (erosivity) is directly related to its amount, intensity anddistribution. The erosivity of rainfall in Zimbabwe is at its greatest at the beginning of the rainseason when the soil is largely unprotected. Research has shown that up to 20 tonnes per hectareof soil can be removed following a heavy storm and up to 100 t/ha over the whole season. Muchof the silt being carried in runoff water ends up in dams reducing yields (Elwell, 1990). This is incontrast to the rate of soil formation which is about 1 mm per year (IFAD 1991).

Vegetation and Soil Cover. Vegetation cover influences the effect of runoff on the soil surfaceand this in turn affects its erodibility. Where there is growth of vegetation, the force of rainfall isintercepted by the above ground part. In addition, plant roots protect the soil and improve itsstructure, infiltration rate and moisture storage capacity and runoff. When sandveld on 4 %slopes denuded of vegetation by overgrazing, annual soil loss increase by 21 times and runoff by8 times that from veld with 70% total vegetation cover (Elwell and Stocking 1974).

Topography. The degree of land slope has a very strong influence on amount of erosion. Soillosses from steep slopes are much greater than from gentle slopes. The undulating topographyover most of Zimbabwe coupled with frequent storms make the lands susceptible to sheet erosion.

Soil. Soils vary in their resistance to erosion. Heavily textured fertile soils are more resistant toerosion than light infertile soils.


Soil erosion by wind

Wind erosion refers to loss of soil by wind, occurring primarily in other parts of the country andduring dry seasons. It has not been possible to obtain quantitative estimates of the extent andseverity of wind erosion. There is no doubt however, that the problem is wide spread in mostparts of the country. Generally, wind erosion in Zimbabwe is pronounced :

In Natural Regions 111, 1V, and V, where rainfall is low, poorly distributed and variable,thereby making the soil dry, dusty and easily blown away. Wind erosion is also a problem in allareas during the drier months of August to October.

• In marginal areas of the country where vegetation cover is poor or heavily grazed, winderosion is also enhanced by human practices of cultivation and burning.

• In smallholder areas where there is a high proportion of fine silt in the soil.

Soil fertility decline

Soil fertility decline refers to the deterioration in soil physical, chemical and biological properties.The process involves lowering of organic matter, degradation of soil physical properties(structure, aeration, water holding capacity), as brought by reduced organic matter and adversechanges in soil nutrient resources (phosphorus, nitrogen potassium). Most soils in Zimbabwe arelow in organic matter and inherently infertile. Nitrogen is the most limiting nutrient as it is rapidlydepleted in cultivated soils (without replacement). Many soils are also deficient in phosphorus,potassium and sulphur (particularly in soils that have been heavily cropped without nutrientreplacement). Population pressure has reduced the fallow period and contributed to a decline insoil fertility. Erosion from such infertile soils is quite pronounced because of their poor physicalproperties.

Waterlogging

Waterlogging is the lowering in the land productivity through the rise in ground water close to thesoil surface. Also included under this heading is the severe form, termed ponding, where the watertable rises above the surface. Water logging is common in poorly managed smallholder irrigationschemes.

Salinization

Salinization refers broadly to all types of soil degradation brought about by increases of salts inthe soil. It thus covers salinization (build up of salts) and sodification (the development ofdominance of the exchange complex by sodium). In Zimbabwe, there are very areas of naturallyoccurring saline and sodic soils. Saline soils have been found in Matibi II communal area, alongthe Mwenezi river, at Malipati and on alluvial soils along the Save river below BirchenoughBridge. There are also some few irrigation schemes on which soil salinity has developed as aresult of poor management. Examples are:

• Mutema irrigation scheme in the Save Valley which is based on the use of groundwater.Salinity occurs because of insufficient application of water to leach salts from soil profile.

• Ingwezi irrigation scheme where patches of saline soils developed due to inadequate leachingof salts from soil profile.


It was not possible to get information on the extent of sodicity on Zimbabwean soils.However, it is known that the development of sodic soils under irrigation have not been extensive,mainly because of strict standards of soil and water testing for irrigation.

Lowering of the water table

This is brought about through pumping of groundwater for irrigation exceeding the naturalrecharge capacity. This has the effect of lowering land productivity. This has occurred in theNyamandlovu aquifer in Matabeleland North province during the 1992/93 drought season.

Deforestation

Deforestation is a widespread and extremely serious type of land degradation in the country. Atthe same time, it is a major cause of other types of degradation, particularly water and winderosion. According to forestry Commission over 70,000 hectares of land are deforested everyyear. According to Whitlow (1980) reserves of timber in Zimbabwe are shrinking rapidly. Treesare being cut down at an unprecedented rate to supply the basic needs of shelter and fuel for theexpanding population. Quoting Zvimba communal land as an example of the effect of populationpressure on deforestation, Whitlow pointed out that it had taken only 20 years for the region tohave been transformed from a predominantly woodland landscape to one almost devoid of trees,to the extent that the rural population was having to resort to burning crop residues and dung forfuel.

Rangeland degradation

This is the lowering of the productive capacity of grazing lands to support livestock. It occurs asa result of excessive livestock populations, inadequate pasture management, or both. Currently,the smallholder livestock population stands at a stocking rate of 5.5 hectares per Livestock unit(including cattle, goats, sheep and donkeys). The recommended stocking rates vary from 4hectares per Livestock Unit (LSU) in Natural Region II to 10 hectares per LSU in NaturalRegion IV, but higher for degraded land. It is quite clear from these figures that the grazing landsare overstocked by several times the recommended rates.

SOCIO-ECONOMIC CAUSES OF SOIL DEGRADATION

In Zimbabwe, farmers are rapidly destroying the soil which they depend on for existence (asalready indicated), though some knowledge is available on the causes and processes of soilformation, degradation and erosion and on the methods and techniques of conservation andreclamation. Land use pattern is affected by socio-economic factors such as land tenure,population pressure, economic conditions, social structure and educational standards. Only whenthese controlling factors are identified and their linkages and interactions recognized and takeninto account is it possible to formulate a programme which has any possibility of producingoptimum production potential and at the same time preserve or even increases resources of soiland vegetation. This section assesses the social, economic, political and institutional policyenvironments in the context of soil degradation in Zimbabwe. It then examines the fundamentalrelationships between the above factors in the context of cause and effect relationship or causalnexus.


Land distribution

Zimbabwe has a relatively large agricultural base. Approximately 82% of the total land area of39 million hectares (i.e. 32 million hectares) is classified as agricultural land. The rest ismountains and National Parks. The distribution of this agricultural land is the result of historicalevents which saw the peasant population being pushed off the better land into areas that areunproductive. There are about 4,500 large-scale commercial farmers on 11 million hectares ofland, who use capital intensive, high cost technologies to produce over 70% of the value ofagricultural output in most years. The smallholder sector is largely traditional (i.e. uses low costand inefficient technology) with nearly 6 million households living on about 22 million hectares ofland that has the lowest agricultural potential. Table 2 shows land distribution by farming sectorand by Natural Regions. The five regions commonly referred to as Natural Regions or Agro-ecological regions are based on moisture availability for agriculture.

TABLE 2Major features of farm sub-sectors in Zimbabwe

Small-scale farms Large-scale farms

Communalarea

Resettlementarea

Small-scalecommercial

Large-scalecommercial

ParastatalGovernment

Number of farms 1,000,000 56.794 8,500 4,832 55Total area (million ha) 16.34 3.29 1.38 10.74 0.42Share of total agriculturalland (%)

50.8 10.2 4.3 33.4 1.3

Average farm size (ha) 18 58 162 2,223 7,644Of which is arable (ha) 3-5 3-5 10-40 highly varied highly varied% of land in:NR I 0.86 0.9 0.7 1.8 2NR II 7.8 17.9 17.4 32.9 2NR III 17.2 37.7 38.4 21.5 32NR IV 44.9 24.6 36.2 21.7 12NR V 29.2 18.8 7.2 22.2 52Irrigated area (000 ha)5 7.2 3.6 126 13.5Share of nationalwoodland area (%)

21 44 35

Estimated population(000)7

5.327 421 166 1,160 38

Pop. density (P./sq km) 32.6 12.8 12.0 10.8 9.0Cropping intensity(Planted area/Totalarea)(%)8

14.0 5.8 4.3 4.2 2.3

Livestock stocking rates(Ha/LSU)9

5.5 8.2 6.4

Notes. Community cited estimate; A. As for April 30, 1994; B. CSO, 1994; C. CSO (1993); D. FAO(1993); E. Bradley and McNamara; F. Census (1992); G. Masters (1991); H. Cattle = 0.7 LSU :Sheep/goats= 0.15 LSU; I. For 1989/90 from Masters (1991)

Most of the land suitable for intensive farming, in regions I, II and III, was allocated tocommercial farmers and the less productive regions IV and V were allocated to small-scalefarmers. In fact over 70% of the smallholder farmers occupy the marginal regions IV and V.

The misallocation resulted in efficient use of land and low per caput income for thesmallholder farmers. Because of the relatively small areas of land allocated and consequentpopulation pressure in smallholder areas, the poor quality of the land and poor agriculturalsupport services resulting in relatively unimproved traditional farming practices, the productivityof the land progressively declined over the years. This situation, coupled with the discrimination


in the provision of infrastructure, combined to restrain production and increase land degradationin the smallholder sector. With 70% of the rural people residing on land mostly of poor tomarginal potential, population densities have long exceeded the land’s carrying capacity, resultingin serious degradation of land and land resources. The bulk of Zimbabwe’s population is exertingpressure on land that is naturally fragile and prone to soil erosion, fertility depletion anddeforestation.

Land tenure

Land tenure is important to soil management because it governs the size and quality of landavailable to agriculture and hence the scale of its economic potential and capacity for resourceinvestment. The type of land tenure may be important in determining the availability of bank orother funds for financing of agricultural inputs. Land tenure may affect the scale of soilconservation investment. Confidence in ownership may tend to promote soil management whilstlack of assurance may not.

With regard to Zimbabwe, land tenure coupled with distribution have been the dominantfactors in the pattern of agricultural production and the most important cause of soilmismanagement. Four main types of land tenure systems prevail as defined by who has the rightsover the land. These are :

• Communal, where a defined group of smallholder farmers has the right but no title to the land(found in the communal areas).

• Private, where an individual legal entity has the rights (common in large -scale farms).

• State, where the public sector has the right.

• Resettlement, where tenants have the permit to live and cultivate but have no legal rights overthe land.

The communal tenure system is composed of traditional villages comprising a defined groupof households with defined village boundaries. In each traditional village land falls into twocategories:

• Traditional Freehold Land: for arable and residential land allocated to a family, which willhave the right to bequeath and subdivide amongst family.

• Village Communal Land: includes grazing, forests and sacred areas administered throughtraditional heads.

The traditional heads also administer any changes on traditional freehold land. The communalarea freehold system is ideal for investment and any form of development as evidenced by theexistence of orchards, boreholes, fences, modern tile or brick houses, etch in the homesteads. Theissue of land degradation emanates mainly from the management of village communal properties(grazing, forests, rivers and dams). These resources are utilized as “commons”, and this approachdoes not lend itself to effective management of these resources. Over-exploitation and poor landhusbandry are common practices in such areas leading to problems such as overgrazing andsiltation of dams. Local heads lack the powers to legally administer the use of the commonresources. A person can cut down trees at will without any punishment. There is no limit to thenumber of cattle a household can own and in most cases livestock numbers exceed the carryingcapacity, thus putting pressure on the land. The tenure system in the resettlement areas is such


that participants enjoy precarious tenure at the pleasure of the state. Households have the permitto cultivate, but there is no right to bequeath and subdivide amongst family members. The settlersare viewed as Zimbabwe’s first tenants, growing cash crops under public supervision on stateland. The farmers are directly supervised by a resident Resettlement Officer, who has the right tocancel off the permit at any time if the settler does not comply with the rules and regulations ofresettlement farming. Grazing lands, forests and water resources are communally owned by thesettlers and usually over-exploited, just like in the communal areas. Most of the resettlementschemes have experienced indiscriminate cutting of trees, overgrazing of rangelands and siltationof dams and weirs.

Although there is little evidence that farmers would rather leave the resettlement schemes thansubmit to the climate of over-regulation that prevails there, there is a disturbing tendency amongsome settlers to sit back and wait for the state to deliver services rather than provide forthemselves through entrepreneurship or collective action. The system discourages farmers toinvest in land conservation measures since their future rights to use the resources are not secure.Land tenure is also an issue affecting soil management in smallholder irrigation schemes.Irrigation schemes by their nature require huge investments in implements (e.g. tractors, watermeters, conservation, labour and inputs). This investment can only be possible if farmers haveconfidence in security over the land. Furthermore most of these investments need financialsupport from banks, who demand collateral or security of tenure. The prevailing system in thesmallholder schemes (i.e. direct control by the government) does inhibits farmers fromcommitting themselves into huge investments and disqualifies farmers from getting bank loans.Private ownership facilitates private investment in technologies which prevent or address theeffects of soil degradation, as evidenced by high levels of management and productivity in thecommercial farms.

Land shortage

It has always been recognized that land is a finite resource, but only recently (at the turn of the20th century) has the full impact of this fact occurred. Food shortage or poverty by smallholderscould be combated by taking new, unused land into cultivation (a system called shiftingcultivation). As soon as the fertility of the soil was exhausted a new piece of land was opened upand the old one was left fallow to regenerate. The extent and type of agriculture was thus inharmony with nature. By about 1920 - 1930, this situation was no longer possible as a generalpractice in Zimbabwe and is virtually unknown today. The rapid increase in population over theyears (at a rate of 2.5 - 3% per annum) coupled with the colonial government’s confiscation oflarger proportions of available land area for large-scale commercial farming, created landshortages in the smallholder sector, thus making shifting cultivation impossible. The smallholderfarmers were forced to continually cultivate the same piece of land as a way of contending withland shortage problems. With this system soil erosion began to increase and by the mid nineteenseventies, overgrazing, deforestation, soil erosion, declining soil quality, siltation of riversdeclining groundwater reserves and general signs of desertification had reached alarmingproportions (Elwell, 1974, 1983).

Today there is almost no unused but usable land in the smallholder sector. All of the bestland is already taken up and that which is not cannot be used agriculturally on a sustainablebasis. Farm sizes range from an average of 18 hectares for communal areas, 58 hectares forresettlement areas and 162 hectares for small-scale commercial farms. (These figures contrastwith an average of 2,550 hectares possessed by large-scale commercial farmers). With regard toarable lands, average farm sizes for communal lands and resettlement areas are 3-5 hectares and


10-40 hectares for small-scale commercial farmers. These small land holdings lead to severeeconomic pressures on farms (especially in the communal areas)to obtain sufficient needs.Because of such pressure in the short term, labour, land and capital resources can not be sparedto care for the land, for example soil conservation structures.

A 1991 survey of households in three communal lands in the Mashonaland West Provincereveals the land degradation impact of increasing population density (land shortage) in communallands (Mehretu and Mudima, 1991). The findings from three communal lands : Zvimba inNatural Region I, Mhondoro in Natural Region II and Mupfure in Natural Region IV are given inTable 3. Households were interviewed to get their views on the changing land quality. A majorityof households in all three communal lands reported that their lands were undergoing severe stressfrom over cultivation (Table 3). Over 50% of the households reported a decline on maize yieldsover the last ten years. 30% of the households reported that grasslands have become poor anddepleted. Forest land depletion is high in communal lands with high population densities asexperienced by Zvimba in Natural Region II. Mupfure, located in Natural Region IV (NR IV)suffers the least amount of deforestation because of low population density. Ten years ago, abouta third of households in Zvimba (NR II) met their domestic fuel requirements from collectedwood as compared to only 16% today. In Mupfure (NR IV), which has the lowest populationdensity of the three communal lands, all households still collect domestic fuel wood from forestedareas.

Table 3 reveals that one third to half of the households in a communal land cut downstanding forests to meet their fuel requirements. Most households in high density Zvimba havebegun buying wood for domestic needs, The overall pattern is one of continuing degradation ofthe land resources, including soil, under increasing population density. The last 5 rows of Table 3clearly demonstrate how forest depletion is a direct function of population density (refer to Table4 for density figures). High population densities are accompanied by a high degree of forestdepletion, reduced availability of collected wood, high incidence of chopping down of forests andincreasing need to buy wood for domestic use.

TABLE 3Household views on changes in land potential in communal lands (percentage of householdreporting)

Communal Lands Zvimba Mhondoro Mupfure

Natural region II III IVReduced land capacity 86.4 70 75.0Farm land over cultivated 56.6 66.7 60.0Experiencing land deficit 37.7 28.5 32.5Land under pressure 70.8 52.3 55.0Decline in maize yields 59.7 42.0 57.5Poor (over-grazed) pasture 77.3 65.4 82.5Poor (depleted woodlands) 77.4 64.6 10.0Fuel wood used to be collected 10 years ago 58.8 96.9 100.0Fuel wood still collected at present 16.2 61.1 100.0Wood fuel obtained from tree cutting 28.6 55.3 40.0Wood fuel purchased 53.2 10.0 00

Source: Mehretu and Mudimu (1991).


TABLE 4Household profile in three Communal Lands, 1991

Communal Lands Zvimba Mhondoro Mupfure

Natural Region 11 111 1VPopulation density 56.1 50.5 11.3Land holding per household (has) 2.4 2.0 2.3Changes in acreage over last 5-10 years% reporting no change 89.6 87.7 82.5% reporting increase 5.8 6.2 12.5% reporting decrease 4.5 5.4 5.0Average household size, all membersResident members 4.6 4.2 4.2Non resident members 2.5 2.2 2.9Average age of residence 19.2 16.4 27.5Average age of resident females in years 24.1 21.0 22.5No of years of schooling 6.5 6.4 6.6% households in agriculture 95.5 93.1 87.5% households with small enterprises 12.3 25.2 7.5% households with other non-farmingactivities

53.9 64.1 75.0

% households experiencing food deficit 9.7 24.4 42.5% households reporting :Resettlement as immediate solution 42.9 23.7 17.5Occasional or no use of extension 68.2 83.1 82.5Extension inputs not affordable 42.9 39.2 42.5Mean annual household income (Z $) 4,365 3,020 2,052

Source: Mehretu and Mudimi (1991) ; CSO (1990).

Poverty

Smallholder areas have few economic opportunities due to low agricultural production and poorinfrastructure. Most of these farmers are resource poor and cannot afford to purchase thenecessary inputs to increase production. The low levels of agro-industrial development and nonagricultural activities result in few alternative forms of employment and income generation inrural areas. Farmers are therefore caught in a cycle of poverty, defined as access to basicnecessities of life. Poverty leads to soil degradation. It can be shown that richer farmers maintaintheir soils in better state than poor farmers. The 1994 enormous survey of the state of arablelands in the commercial sector, where management is generally high, showed that the croppingpotential of 12% of the available arable land has been damaged (Elwell 1988). This is lower than23,2% recorded for the poverty stricken smallholder farmers.

Population

According to the 1992 population census, the estimated total population for Zimbabwe at the endof the year was 10,4 million. This implies a total population of 12 million in 1997 (at a growthrate of 3%) and 293,5 million in 2110 when the population is expected to stabilize. The totalpopulation density for the country, according to 1992 census results, measured in persons persquare kilometer is 26. For communal areas farms, it is fairly high, more than 32 while incommercial farms it is only 9. With the above rate of population growth, Zimbabwe will have toincrease its food supplies 28 times over the next 113 years just to maintain the 1992 standard ofnutrition.

This can be achieved through increase in land under cultivation and/or increase in averageproductivity of land. The present state of affairs for both strategies looks impossible for


Zimbabwe. A research by Whitlow (1988) seems to justify this point. He found a correlationbetween erosion damage and population density with high density of settlement almost invariablyassociated with widespread soil erosion. He found 57% of communal lands to be overpopulated,some grossly so, and pointed out that this inevitability resulted in a cycle of ecologicaldegradation having adverse effects on living standards, which in turn, limits the ability of peopleto reverse the downward trend. It can be assumed therefore that the increase in degradation perhead of population is not linear but probably exponential in form. In view of Zimbabwe’spopulation growth rate, future prospects are grim.

Changes in attitudes

This is a contributory factor not always appreciated by outsiders. Prior to independence in 1980,most smallholder farmers accepted the situation into which they were born (i.e. subsistencecultivation of annual crops) even if it was one of relative poverty. With the improvement of ruralinfrastructure (roads, communication etc.) smallholder farmers were influenced to have greateraspirations (e.g. expansion of maize production), thus increasing area under cultivation. This wasa transformation in line with changing economic environment. This had an effect of exerting morepressure on the already cultivated land, thus leading to degradation.

Lack of resources

Smallholder farmers lack almost all basic factors of production (i.e. land, labour, capital andentreprenuership). Lack of land resources result in excessive local population pressure which putsthe ecosystem beyond its carrying capacity at the level of inputs and technology currently beingpracticed.

Capital. This is a major constraint in that smallholders have very low incomes to allowpurchasing of farm inputs. This lack of capital prevents smallholders from carrying out work todeal with the problem of soil degradation. Lack of adequate financial resources also prevents thegovernment from practicing methods which would solve soil degradation problems.

Labour. Smallholder farmers usually experience labour shortages for intensive activities such ascontour ridging, reclamation of gullies, etc.

Entrepreneurship

Lack of adequate technical knowledge and extension support limit farmers from practicingmethods which would solve the soil degradation problem.

Defective organization or policy

In the period following Independence, (1980-1988) the new government adopted a reconstructionpolicy for the agricultural sector with the emphasis placed on providing agricultural services andsupport for the smallholders. These services and support policies covered marketing and pricingprogrammes including the provision of marketing infrastructure such as depots at variousdistricts to cater for the smallholders. In response to the favourable conditions, smallholdersincreased their agricultural output (particularly maize and cotton.) This growth in output wasachieved through expansion of planted area. Because of the relatively small areas of arable landavailable, the smallholders expanded into marginal areas thus initiating destruction of landresources.


Defective planning of agricultural projects

Over the past decades, to date, all agricultural projects (e.g. smallholder irrigation schemes), wereprimarily predicated on financial, economic or social grounds, with most of the developmentaimed at achieving self sufficiency, production of export crops and raw materials for theindustrial sector. There was no legal requirement for some form of environmental impactassessment in the feasibility studies of these projects. Environmental considerations were purelyat the discretion of the planners involved. As agricultural development proceeded in the country,new areas of development began to encroach areas that are marginal for agricultural developmentand where risk of environmental damage is great. Examples of such areas are those with soils thatare marginally suited for irrigation, areas of poor water quality, or areas that are marginal in bothrespect (see under Salinization).

LAND SHORTAGE, POPULATION, POVERTY AND SOIL DEGRADATION: THE CAUSAL NEXUS

The socio-economic causes of soil degradation are linked by a chain of cause and effect or causalnexus (Figure 1). The two exogenous driving forces are limited land resources and increase inpopulation in the smallholder areas. This means there are no longer substandard areas of usable,unused land in the smallholder areas, but the number of people supported from this finite land isincreasing every year (at a rate of 3%). These two primary forces combine to produce landshortage. This refers to increasing pressure of population on land (marginal lands for mostsmallholders), resulting in small farms, low production per person and increasing landlessness. Aconsequence of land shortage is poverty. Land shortage and poverty, taken together, lead to nonsustainable soil management practices, meaning the cause of degradation. For reasons outlinedabove, poor smallholder farmers are led to clear the forest, cultivate steep slopes withoutconservation, over graze range lands and make unbalanced fertilizer application. The nonsustainable management practices lead to degradation. This leads to reduced land productivity; alower response to some inputs or, where farmers possess the resources, a need for higher inputsto maintain crop yields and farm incomes. This has the effect of increasing land shortage, thuscompleting the cycle.

Other causes

Under this heading are the direct causes of soil degradation (unsuitable land use andinappropriate land management practices), which include: deforestation of unsuitable land, overcutting of vegetation and overgrazing.

Deforestation of unsuitable land. Deforestation becomes a cause of degradation when the landthat is cleared is steeply sloping, or has shallow or easily erodible soils and where the clearance isnot followed by good management. The extent of deforestation as a type is given in Section 3. Itis the leading cause of water erosion in steeply sloping environments and also a contributorycause of wind erosion, soil fertility decline and salinization.

Over cutting of vegetation. Communal and resettlement people cut natural forests, woodlandsand shrublands to obtain timber, fuelwood and other forest products. Such cutting becomesunsustainable where it exceeds the rate of natural regrowth. This has happened widely in denselypopulated areas, where fuel wood shortages are severe (see section on land shortage).Impoverishment of the woody cover of trees is a major factor causing both water and winderosions.


Overgrazing. Overgrazing is the grazing of natural pastures at stocking rates above the livestockcarrying capacity. It leads directly to decrease in the quantity and quality of vegetation cover.This is a leading cause of wind erosion and also water erosion in dry lands. Both degradation ofthe vegetation cover and erosion lead to a decline in soil organic matter and physical properties,and hence in resistance to erosion. The stocking rates for the communal areas are given inTable 2 under Rangeland degradation.

CONSEQUENCES OF SOIL DEGRADATION

The consequences of soil degradation are many and varied. Some are quantifiable and some arenot. The effects can be considered at two stages; effects upon production and consequences forthe people.

Effects upon production

Soil degradation affects crop, livestock and forest production. The effects depend on type andextent of degradation. The effects in Zimbabwe are as follows:

Land abandonment. The exact area which has been abandoned for cropping because of decliningfertility or any other form of soil degradation is not known. However, there is no doubt that itforms a significant proportion of what was once the potential arable areas. Abandoned arablelands can be seen in all parts of Zimbabwe and some very extensive stretches occur in Mutokoand Sabi Valley areas (Elwell 1990). These areas are characterized by very gravelly surface orby compact partially weathered sub-soil (Elwell, 1990).

FIGURE1Cause and effect of land degradation

Causal nexus between land, population, poverty and soil degradation

Increase in smallholderpopulation

Limited landresources

Land shortage

PovertySoil degradation

Non-sustainablesoil management practices

Source: FAP (1994). Land degradation in South Asia: Its severity, causes and effects (Rome, Italy)


Reduced productivity. Declining soil fertility in smallholder areas is leading to unsustainableproduction levels. (e.g. maize yields in Zvimba, Mupfure and Mhondoro area). There is a closerrelationship between the depth and humus content of the soil and crop yields. When the rich topsoil is removed or degraded, productive capability falls rapidly. Some other factors contributingto lower yields are:

• Leaching and washing out of plant nutrients and fertilizer particularly potassium andnitrogen.

• Deterioration of soil structure and texture due to reduction in organic matter, the washingdown of finer particles and exposure of sub-soil.

• Reduction of soil depth so that there is less soil available to plant roots, greater loss of waterdue to runoff and decreased moisture availability during dry periods.

• Poor aeration of soil during rainy season because of poor structure and reduced depth.

• Chemical imbalance such as increasing salinity.

Livestock production levels are also affected by soil degradation since the quality of rangelands is a function of how well the land is managed.

Greater need for agricultural inputs. The level of poverty of many smallholder farmers inZimbabwe is such that they cannot accept the consequences of reduced crop yields or lowerlivestock production. Instead, they try to maintain their crop production levels by means ofincreased inputs (soil from anthills and manure from forests) and in the case of livestock theyattempt to maintain livestock numbers despite a reduced carrying capacity of pastures, thusleading to a vicious circle of further degradation. The other reasons for wanting increased inputsare:

• Less favourable soil texture and structure increases energy requirements for cultivation anddecrease the range of moisture content within which the soil can be worked.

• Increase in the number of rocks and stones on the surface impedes cultivation and leads towear and breakage of implements.

Reduction in the value of land, loss of land. As soon as erosion or any form of soil degradationbegins, the productive capability of the land starts to fall, and with it the value of the land. Ifdegradation continues the area loses all capacity to produce and becomes a desert, having almostno value. This is a financial loss to the owner and a permanent loss of resources to the communityand the nation.

Reduced responses to inputs. It is conventionally accepted that fertilizers are best utilized byapplication of low to moderate amounts, whilst seeking to obtain high responses. Landdegradation, particularly lowering of soil organic matter, has the opposite effect, that of loweringfertilizer responses.

Loss of flexibility in cropping pattern. Reduced crop yields force smallholder farmers to growonly staple food crops (e.g. maize, sorghum, and millet). Again this has an impact on soilmanagement, since continuous grain production causes further decline in soil fertility.

Greater risk. Smallholder farmers are risk averse when it comes to agricultural production(especially in dry areas such as natural regions IV and V). The recurrence of drought in these


regions make crop production a risky business and because of this, farmers tend to be reluctant touse scarce capital or fertilizers.

Reduced productivity on irrigated land. A specific case of lower crop yields and reducedresponses to inputs occurs on smallholder irrigation schemes which are widespread in thecountry. These irrigation schemes have been established at high cost, whether capital, as insurface and sprinkler systems, or labour, as in the case of hand-dug small earth dams. Loweredproductivity as a result of soil fertility decline and waterlogging reduces output from smallholderirrigation schemes, leading to inefficient utilization of scarce capital and labour resources.

Siltation. Vast quantities of soil eroded from fields and hills are washed into rivers dams or weirs.Deposition of such large quantities of soil in rivers and dams has adverse effects. Storagecapacity is reduced far more quickly than expected, and dams designed to last 100 years or morebecome almost useless in twenty or thirty years. If there is an irrigation scheme associated withthe dam, this means there is less water for irrigated crops, incomes fall and they must eventuallybe abandoned. Figures from measurement of siltation in 1974 revealed that silt load in theMazowe river is causing a loss equivalent to 6-7 hectares of top soil each day the river was inflood. A random survey of 16 importantdams contacted in 1983 in Masvingo andMatabeleland Provinces showed five ofthem to be more than 100% silted and 8 tobe more than 50% silted. A more detailedsurvey of 132 small to medium size damsin Masvingo province (1983) showed 16 tobe fully silted and more than half to beover 50% silted. Thus, these figures wouldindicate that by 1983 some 12-13% ofdams in this region were totally useless and50% of structures had less than half their capacity (Elwell, 1985). A silt survey of Sheet Dam (inMatabeleland South Province) carried out in July/August 1990 also gives some striking resultsabout the state of reservoirs in Zimbabwe. The results of the survey are given in Table 5.

The original full capacity of the dam was 1.149 * 106m3 and the present capacity is 0.658 *106m3. There has been 42.75 reduction in capacity due to siltation over a period of 45 years. Bothhuman activities and natural factors had a significant effect on this high rate siltation. The resultsof these surveys are by no means a complete reflection of the state of siltation in Zimbabweandams. They only represent merely the foreboding tip of the iceberg. Large numbers of dams andweirs throughout the country in both commercial and communal areas are already full of silt.There is no practical way of reclaiming them. Alternative sites being second choices, are bound tobe more expensive and less effective than the first choices: and they too will inevitably fill withsediment. The only feasible solution is to remedy the cause of the problem (i.e. control theerosion).

Effects for the people

The effects of land degradation have impacts on the living conditions of the smallholderpopulation and these include:

TABLE 5Details of sheet dam and its catchment

Catchment Area 464.75 km2

Impounded Date 13/9/46Mean Annual Rainfall 500 mmOriginal Capacity 1.49 * 106 km2

Present Capacity 0.658 * 106m3

Decrease in Capacity 0.491 * 106 or 42.7%Annual Rate of Siltation 0.0109 * 106 or 0.95%


• Food insecurity. As the soils deteriorate in quality, food security becomes more and moredifficult to ensure; in fact no longer guaranteed (Elwell 1992). Lowering of crop yields meansreduced production of food crops and subsequent food insecurity.

• Increased labour requirements. Reduced crop yields means low returns to labour. Labourused in reclaiming or rehabilitating the soil environment is labour lost from production.

• Lower incomes. Lower incomes is the most serious consequence of soil degradation in thesmallholder areas. These result from either increased inputs or reduced output or both. Withsoil degradation all the factors of production, of capital and labour are inefficiently appliedand productivity and subsequent incomes are lowered.

CONSTRAINTS AFFECTING SMALLHOLDER TECHNOLOGY ADOPTION

Adoption of modern technology for soil management by smallholder farmers is influenced bypersonal attributes of the farmer, farming systems and resource characteristics, institutional andinfrastructural and environmental factors. Personal attributes of the farmer include age, level ofeducation and sex. Farming systems and resource characteristics comprise cultivated area, familysize, and availability of appropriate inputs such as fertilizer, seed, machinery, equipment and theliquidity position of the farmer. Institutional and infrastructural factors cover laws andregulations governing the supply and accessibility of credit, extension advice, training and inputmarkets. Environmental factors, basically agro-ecological potential and capacities, give farmersand input suppliers incentives to participate subject to extended gains.

Personal attributes

Older farmers and the less educated are less likely to adopt new technology. This could be due toinability to fully understanding the technology and the associated risk. Sex has also been found tobe a factor in technology adoption with women being less likely to adopt than men. None or lateadoption by women is related to tendency to consult absentee husbands as well as lack of controlof the little available household income. Personal attributes were found to be pertinent in adoptionof technologies for soil fertility management in Resource Integration Research undertaken inZimbabwe, Kenya and Zambia and funded by EU and Danida (TSBF, 1996).

Awareness, perceptions and interpretation of land degradation

Soil degradation is a very slow process and almost invisible, e.g., sheet erosion. Therefore it maynot be perceived as an immediate problem. According to observations from many Africancountries, farmers attribute deterioration of crop yields to declining rains (TOIT 1995). There isclear evidence that during the past 20 years droughts occurred more often than the decadesbefore. However, soil degradation may also have affected the water holding capacity and therebyreduced the soil’s ability to overcome situations of stress. Very likely, this process may also havecontributed to the decline of yields. As long as farmers do not perceive soil degradation as amajor determinant of decreasing yields this trend will certainly not be reversed (Shaxson, 1985).

Farming system and resource characteristics

Small-scale farmers usually control limited quantities of land. Because of small land size, theyare not able to take advantage of improved technology, new managerial practices and adopt theuse of more profitable enterprise combinations. Communal area farms, because of small arableland holdings, do not have adequate land to set aside for two to three years under legume tree


improved fallows which has been shown to increase maize yields. Size of family has an impact onlabour availability. Where the household comprises mainly school going children this negativelyaffects adoption of soil management practices. Application of top dressing fertilizer, manure andant hills are all labour intensive. In research carried out in Northeastern Zimbabwe, resourceendowment was found to influence farmers’ choice of soil fertility management techniques.Farmers with many cattle were found to use termitarium soil. Farmers who had scotchcarts andwere on rich soils were found to use compost (TSBF, 1996). The liquidity position of the farmeraffects his ability to invest in soil improving technology. A substantial proportion of availableincome is invested in non-production activities i.e. education (in the form of school fees, textbooks and uniforms) and household consumption. Education is the largest investmentexpenditure. There is little cash income to meet adequately the investment required in agriculturalproduction. As a result farm households are not able to purchase sufficient yield increasing inputsneeded to improve crop productivity.

Institutional factors

Lack of coordination among implementing agencies: The management of natural resources inZimbabwe is the responsibility of several government departments, parastatals and non-governmental organizations (NGOs). Government departments include the Department of NaturalResources, through the Natural Resources Board (NRB), with the responsibility of policing andadvising government on the implementation of natural resources management strategies, Agritex(which provide technical knowledge on soil conservation and management) and the Department ofWater Resources (responsible for catchment management).

The Forestry Commission through the Rural Afforestation Division plays a crucial role inafforestation activities including the establishment of village nurseries and woodlots. The DistrictDevelopment Fund (DDF) implements water related projects (including boreholes, dams,irrigation schemes) in the smallholder areas. NGOs are quite numerous and they includeCAMPFIRE, SAFIRE, and ENDA Zimbabwe among others. This multiplicity of institutionscreates problems in that priorities in terms of resource allocation between agencies are notcoordinated. For example construction of an irrigation project by a NGO is not accompanied withthe allocation of funds for conservation works. There is a number of smallholder irrigationprojects which were developed by NGOs without conservation works, due to the fact that theyconsider conservation to be Agritex’s responsibility. But in most cases Agritex is not informedabout the need for conservation works and in some instances, even if they are informed, they lackfinancial resources to undertake the works.

Another shortfall in agricultural project development is the lack of coordination between theimplementing agencies and the beneficiaries. Farmers are usually not involved in the overallplanning and management of projects, yet they are expected to produce on a sustainable basis. Aslong as the proposed project or improvement is not demonstrated to serve farmers’ interests theywill not participate in proper resource management.

Agricultural research and extension: Up to 1980, the national research system focused ongenerating technologies for the large scale commercial farms located mainly in high rainfall areas.The thrust after 1980 was to develop sustainable crop and livestock production systems suited tothe low rainfall areas. But to this day, the recommendations on soil fertility improvement aregeneral. There is no close contact between the researchers and smallholder farmers in terms ofspecific recommendations. The soil testing facility that is available to farmers is inaccessible to a


communal farmer in the remote areas with poor access to information and communicationfacilities. Another area which needs attention is the identification of research areas. Generallyresearch work is done in areas which are accessible to researchers and in many cases far awayfrom the beneficiaries. Results obtained from such research can not by any means address theproblems of smallholder farmers. Their direction and contents tend to reflect the interests andprofessional goals of the researchers. In most cases, the results are published in the form which isunusable by the extension worker at grassroots level. It is helpful to have farmer based research,which involves the identification of problems together with the farmers and the collectiveimplementation of the research work.

In Zimbabwe, delivery of technology was improved by adopting alternative extensionstrategies with emphasis on farmer groups. Mobility of extension staff was also improvedthrough provision of motor cycles (AEWs) and cars (Officers) through World Bank loan in 1990.More staff, particularly farm level AEWs were hired to reduce the AEW: farmer ratio from 1:2,000 before 1980 to 1: 500 - 800 after independence. These were posted to ward and villagelevels. Of late, with the pressure to reduce public spending, the extension services is no longerwell provided for. Salaries are low compared to the private sector. The budget for field dutyallowances is very small virtually grounding extension staff for weeks if not months. Coursesdesigned to train extension staff and keep them up to date with the latest technology are oftentimes canceled due to lack of funds. The pool of vehicles and motorcycles given to Agritexthrough World Bank in 1990 have already surpassed their economic lives, therefore needreplacement. Extension officials sometimes have to use buses or bicycles to go to work. This isnot an ideal situation for sound agricultural development.

All these factors negatively affect extension delivery and therefore limit smallholder farmers’ability to adopt improved technological innovations.

Local Traders. There are inadequate inputs at the local level. Farmers are forced to source inputsfrom urban based suppliers. Local traders fail to stock adequate levels of agricultural inputs dueto cashflow problems, lack of transport facilities as well as lack of storage. This lack of inputslocally is problematic because farmers have to pay a lot to transport inputs from far awaycentres. When farmers organize themselves and purchase in bulk inputs are never delivered intime. Large input suppliers do not give priority to low income farmers. They deliver last and onlywhen high volumes of inputs have been ordered.

Credit. The Zimbabwean experience after independence shows a direct relationship betweenavailability of credit to smallholder farmers and increase in agricultural input use. With theextension of the AFC’s mandate in 1979 to cover the smallholder sector, the number of loans tocommunal farmers rose from 18 000 (valued at Z$4.2 million) in 1979/80 to 76 000 loans with anominal value of Z$40 million in 1985/86. This stimulated quantity of purchased inputs such asfertilizer and improved seed. The quantity of fertilizer purchased increased from 25-30 thousandtonnes in 1978/79 to 130,000 tonnes in 1985/86. Delivery of improved seed to the small farmsector rose from 4,250 tonnes in 1978/79 to 22,000 tonnes in 1985/86. Thus the expansion incredit facilities in the communal lands enabled more farmers to have access to yield augmentingresources. The 1985/86 season was the peak in terms of credit extension to the smallholdersector. By 1992/9 season the number of loans was down to 15,221. The major reason for the fallin loan extension to the smallholder sector was high default rate. The AFC would generally notlend to farmers in default. Reasons given by farmers for having failed to repay as scheduledincluded drought and low repayment capacity. Farmers complained that in cases where they


decided to honour their debts, they remained broke and could not pay for their other commitmentslike school fees, clothing and other household costs. While the majority of non current borrowersstopped borrowing because AFC would not lend to farmers in default, there are some who paidup and yet did not want to borrow again because of what they term poor service from the AFC.This poor service included failure by the institution to give farmers correct loan statements. Somesmallholder farmers have limited information about available sources of credit, terms of loansand correct structuring of farm debt. Some farmers observed neighbours or relatives who werefinancially stressed from borrowing lose their farms and /or equipment because they were notable to repay the debt. This has resulted in the farmers wanting to remain debt free because offear of farm closures. Without adequate credit, the farmers cannot invest in productivityenhancing technologies such as fertilizers. Credit finance is important in the purchase of capitalequipment such as tractors and scotchcarts. Other sources of finance include crop sales, livestocksales, remittances and other non form activities. But these sources are not significant enough forthe purchase of capital equipment. Low outputs due to low inputs means that there is little left forinvestment once the living expenses of the farmer have been deducted from farm income. Lowinvestment in livestock, machinery, buildings, conservation, and so on will keep the farm’sincomes low, and so the cycle conditions. In a study of smallholder credit situation in Zimbabwecarried out in 1993 by Vudzijena, non borrowers ranked their sources of money for inputspurchase as follows :

Crop sales 80%Livestock sales 28%Remittances 15%Local job 4%Personal savings 28%

This means that in the event of a drought, the average non borrower needs credit to financethe next season’s inputs to maintain his usual productivity.

Marketing. Smallholder farmers are generally long distances away from markets. Because of thisthey suffer from poor market information. The situation is aggravated by the lack of marketingintelligence system and storage and packaging facilities. With the opening of the economy,marketing has become central in production economics, especially on the aspects of what toproduce, how to produce and how much to produce. Without markets there is no point producingand even managing the factors of production (e.g. soil resources).

Transport. Shortage of transport in communal lands where the majority of smallholders are,restricts the operation of private market, raises marketing costs and diminishes farmer access tooutlets. Improved transport systems and in particular the development of a comprehensive andflexible private network of medium and small trucks is likely to be a pre-requisite for effectiveexpansion of private sector marketing systems for both agricultural inputs and outputs.

Infrastructure. While the Zimbabwe rural road system is generally well developed, the feederroad system in most communal, resettlement and small scale commercial farming areas is in adeplorable state with most of the roads impassable during the wet season. The inadequate ruralroad system is one of the main factors affecting the growth of the rural transportation system andhas given rise to inefficient input supply and produce marketing systems.

Smallholder farmers in a majority of cases, do not receive inputs at the right time and in therequired quantities. Inputs such as fertilizer and seed are often delivered as late as


November/December. In addition, because crops cannot be transported to the market on time,high post harvest losses are incurred. The inefficient input distribution system and producetransportation systems severely affects the competitiveness of the smallholder farmers asmarketing costs represent at least 25% of total costs per tonne produced in the smallholder sectoras compared to 12% for commercial farms (Vudzijena, 1993).

Rural areas are characterized by poor postal and telecommunication systems. Survival in thenew economic environment requires farmers to be constantly in touch with the market in order tomake timely decisions on what inputs to use, at what levels compared to value of outputs.Smallholder farmers are constrained in their decision making on profitability of enterprises due topoor telecommunication system in rural areas.

Unfavourable trading position

Maize is the major crop in communal areas both in terms of numbers of farmers who grow thecrop and the proportion of land allocated to the crop. Generally, looking at data from 1986 to1996 (Table 6), prices of fertilizer have been rising faster than prices of crops produced byfarmers. The net result is that farmers have been facing a price squeeze. The price squeezeadversely affects the communal farmers’ income position and their ability to invest in agriculturalinputs the following season.

TABLE 6Fertilizer to maize price ratios in Zimbabwe (1986-1996)

Harvest year Compound D Ammonium nitrate Maize (Grade A ) Fertilizer/Maizeprice ratio

1986 355.6 406.0 180.0 2.11987 355.6 406.0 180.0 2.11988 416.6 415.4 195.0 2.11989 416.6 415.4 215.0 1.91990 463.8 416.0 225.0 2.01991 655.0 613.0 270.0 2.31992 1,048.0 981.0 550.0 1.81993 1,048.0 981.0 900.0 1.11994 1,296.0 1,222.0 900.0 2.81995 1,296.0 1,222.0 950.0 2.71996 1,604.0 1,970.0 1,200 1.5

Source: Oni 1997.Note: Fertilizer price changes occur at various times of the year. Prices quoted are generally those rulingat the end of the planting period. The fertilizers/maize price ratio refers to a 50:50 blend of Compound Dand Ammonium nitrate.

Technology constraints

Available machinery technology for working in the soil is not adequately scaled down to meet theneeds of the small farmers. The available machinery requires substantial capital outlay. Thisresults in over-investment and increase in fixed costs of production. The alternative forsmallholder farmers has been buying used equipment. However, this means high repair andmaintenance costs and increased down time. The machinery technology appropriate for the smallfarmer should be easy to maintain and free of some luxury gadgets. The equipment should besized to suit the small farmers’ production systems as well as managerial and technical skills.


CONCLUSION

We are living in a challenging period which may even become more and more challenging in thehistory of agricultural development in Zimbabwe, Africa and the world. If we continue along ourpresent pattern, ignoring the warning signs, the environment is constantly signaling to us, we aredoomed for a certain disaster.

From the analysis it is clear that land degradation has reached serious levels in Zimbabwe. Ithas taken place within the context of a high population density in relation to available land, lackof resources in the small-scale sector, poverty and defective policies.

At this moment, erosion is costing the farmers and the nation vast amounts of money interms of reduced yields, higher inputs and loss of moisture, nutrients and fertilizer, not to mentionthe cost of food damage, the siltation of dams and the growing area of barren land.

Radical changes are inevitably needed in our attitudes and practices. The problem should nolonger be regarded as one for the future generations.

Attempts to combat land degradation directly by conservation measures have beenundertaken in Zimbabwe but with limited success. In fact, this strategy has had provided shortterm effects. It is clear that the problem will continue unabated unless technical measures areaccompanied by efforts to tackle the underlying causes of degradation. These lie in the causalnexus between population increase, limited land resources, land shortage, poverty, non-sustainable management and land degradation. In the prevailing situation in Zimbabwe, in whichthere is no spare land in the smallholder sector, population increases will largely or entirelycounteract the effects of measures for improvement.

A prerequisite for effective action is recognition by the government of land degradation andits effects upon the people, the agricultural sector and the natural economy. It is necessary but notsufficient to pay service to environment or to write reports. There must be allocation of staff,budget and resources.

RECOMMENDATIONS

Protection of natural environment is as important to the government as defense of its borders forsustainable socio-economic development. Because of this, the government should ensure that itcreates an enabling environment in which the soil user can employ production and managementsystems which do not lead to degradation of soil resources. In addition the government should putin place an appropriate institutional framework for enhancing farmers’ capacity towards adoptionof improved technologies for soil improvement, conservation and sustainable land use andproduction.

Institutions for environmental management exist in Zimbabwe, but there is need for reorientation and strengthening of their current capacities. In this context, the organizational andinstitutional framework should enhance linkages between different participating agencies, provideresources and where need be, create new organizations.


Some of the important aspects which need special attention in the process of transformingsoil management include appropriate land tenure systems, efficient credit facilities, research,extension and training, etc.

This section of the paper proposes a conducive socio-economic and policy measures(including the above). as they relate to the limitations and problems previously illustrated.

Guarantee security of tenure

The farm productive potential of smallholder lands will be realized only when farmers feel it istruly theirs (an aspect that is lacking in the present system). Farm operators make long terminvestments to optimize land productivity only when they own the property or have security oftenure. Security of tenure is associated with four main sets of rights: rights to use, transfer rights,exclusive rights and enforcement rights. Tenure security to safeguard communal resources ofgrazing forests etch in communal areas can be improved through strengthening the powers oftraditional leaders and the administering of village communal lands through the traditional villagecourt system. It is recommended to have individuation of rights on a community basis where eachcommunity has a well defined territorial boundary over which it has monopoly rights overresource utilization under its control. The grazing land and the common resources should bemanaged by a local board whose membership would include the local chiefs, headmen, kraalheads, councilors and Village Committee chairperson. Any one found cutting trees or doing anyactivity which causes degradation should be punished accordingly.

Tenure security on resettlement can be secured by replacing the permit system with twooptions:• Leases with option to purchase.• Long leases of up to 99 years.

These options can encourage farmers to undertake long term investments suitable forsustainable agricultural production and natural resource management. For new resettlementschemes it is recommended to have individual tenure system, whereby each individual is allocated60 or so hectares which are demarcated into grazing, arable and residential areas. The individualwill have the right over the land under any of the two options given above. This systems canencourage investment and proper management of resources.

Improving the extension service

The declining real operational budget for Agritex is a major policy issue requiring urgentattention. Budgeting provisions should be aimed at progressively improving operating exercises.This improvement is necessary to prevent extension officials from becoming office bound becauseof shortage of funds. The extension service should also have access to reliable vehicles andmotorcycles. It is unsustainable to have staff travelling by bicycle, bus service or by old and wornout vehicles liable to frequent breakdowns. The extension service should go beyond productionadvise and focus on other important elements such as marketing, financial management andleadership. Farmers have realized it’s quite important to have marketing included in the extensionthrust. The marketing system of smallholders can be enhanced through the setting up of amarketing intelligence system or marketing information system. The private sector can alsoparticipate towards the establishment of such systems if a workable environment is created forthem. This system can facilitate the farmers decision making process and even allow them to takerisks in their day to day management practices, including managing of soils.


Creation of enabling environment for private traders

A key strategy in soil management is to provide incentives which enable private sectorparticipation in the small-scale agricultural sector. This could be done in several ways and theseinclude :

• AFC extending loans (at concessionaire rates) to rural traders to allow the purchasing oftrucks for transporting inputs and outputs.

• Short term loans for restocking are particularly important in alleviating the trader’s cashflowproblems.

With a reliable input supply and output delivery system farmers will be motivated to embarkon full-scale sustainable production.

Rural infrastructure

The government should improve rural infrastructure i.e. road (for input and output delivery),communication (for marketing information and ordering) to help the farmer make rationaldecisions on what to produce, when to produce, how much to produce.

Mobilization

Farmers as a group can do a lot themselves if a conducive atmosphere is put in place. Forinstance, if farmers are trained and some initial capital is injected by say government or donoragency, farmers can get motivated to take the lead. They can build warehouses for inputs/outputs,can get discounts through bulk purchasing and can enjoy other economies associated with large-scale production. A strategy like this was implemented in the Wedza district of Mashonaland EastProvince. Farmers were given a revolving fund by a donor to buy stocks for inputs. A lot oftraining, related to general and financial management was given to the participants to allowsmooth running of the business. The farmers operated as traders, buying and selling inputs at aprofit. The scheme proved to be successful and until now the farmers are enjoying its benefitswhich include no transport costs, timeliness of inputs, among others.

Research improvement

Zimbabwe has a well developed research system which however, needs some reorientation in anumber of aspects. There is need to strengthen research/extension/ farmer linkages to facilitatethe flow of information to the farmer. Furthermore the research should be farmer based and notbe conducted in areas which suit the researcher. To facilitate the implementation of this strategy,research and extension officials should be thoroughly trained in Participating Rural Appraisal(PRA). This approach is important in fostering communication between the government agenciesand the community.

Training

Problem solving requires both the will and the intention and capability or expertise. Many of therelationships and processes which result in soil degradation are more or less technical in nature,and may even be difficult for a lay-person to recognize. It is impossible to devise and applysolutions to the soil degradation problem unless both the farmer and technical officials havesufficient knowledge about the subject. It is only through environmental education thatcommunities and staff can acquire knowledge, skills and commitment to adapt to pursue


development activities in harmony with the environment. Environmental education should also beincluded in the schools curricula and environmental magazines, and other publications for bothchildren and adults. It should also be broadcast on radios and television. Regular workshops andseminars with school teachers and farmers can also help to address the problem of landdegradation. It is also important to suggest alternatives when it is felt that one resource is beingoverused. For instance, instead of firewood farmers can be advised to use other sources of fuelsuch as biogas and “tsotso” stoves which use little wood.

It is also encouraged to carry out environmental impact assessment before embarking onmajor developmental projects (e.g. irrigation projects) to reduce negative impacts on the land andsoils. The main purpose of carrying out environmental impact assessment is to ensure thatenvironment, socio-economic costs and benefits of developmental projects are properly accountedfor and that unwarranted negative impacts (e.g. salinity in irrigation projects) are avoided. Thefollowing is a summary of recommendations for remedying the situation:

• Study of the causes of land degradation.

• Study of the economic and social effects upon the people.

• Translation of the problem into policy objectives and national programmes.

• Research into measures to combat degradation.

• Research into cropping systems, soil and water management, husbandry and techniques thatcan be affordable and accepted by the farmer.

• Improved educational and training opportunities for farmers to enable small farmers to adoptpractices which improve and maintain soil fertility.

• Financial support for necessary inputs to stop fertility decline and improve yields.

• Infrastructure development to facilitate the ordering and delivering of inputs and outputs.

• Improved institutional, economic, environmental and social conditions associated with smallholder farmers.

When the above strategies and proposals are achieved, a balance will have been achieved inland use development. Man and environment will have seized fire in their perpetual struggle andwill be working in harmony

REFERENCES

Elwell. H.A. 1980. Soil, The Basis of Life. Harare: Institute of Agricultural Engineering.

Elwell. H. A. 1983. The degrading soil and water resources of the communal areas Harare: TheZimbabwe Science News. Vol. 17. Nos 9/10.

Elwell, H. A. 1990. Soil Erosion in Post Production activities and marketing in small-scale farmingareas of Zimbabe. Harare.

FAO. 1983. Guidelines for the control of soil degradation. Rome.

FAO/Government Cooperative Programme. 1986. Regional Soil Conservation Project for Africa, Phase1. Rome.

FAO. 1994. Land Degradation in South Asia: Its Severity, Causes, and Effects upon People. Rome.


Mehretu. A. and Mudimu. G. 1991. Dimensions of Cognitive Behaviour on Conservation of LandResources in Selected Communal Areas: Preliminary Survey Findings. Harare: University ofZimbabwe.

Ministry of Agriculture. 1995. Zimbabwe’s Agricultural Policy Framework: 1995-2020. Harare.

Oni. S. A. 1997. Impact of ESAP on the Communal Areas of Zimbabwe. Harare: University ofZimbabwe.

Rukuni. M. and Eicher. K. 1994. Zimbabwe’s Agricultural Revolution. Harare: University of ZimbabwePublications.

Sithole. G. 1995. The Food, Agriculture and Natural Resource Policies of Zimbabwe Harare.

TSBF. 1996. The Biology of fertility of Tropical soils: Report of the Tropical Soil Biology and FertilityProgramme.

Vudzijena. 1993. Study, Analysis and Recommendations of the credit situation for smallholder farmersin Zimbabwe. Harare.

Whitlow, J.R. 1988. Deforestation in Zimbabwe: Some Problems and Projects. Harare: Natural ResourceBoard.

Whitlow, J.R. 1979. The Household Use of Woodlands Resources in Rural Areas. Harare: NaturalResources Board.

Whitlow, R.J. 1980. Agricultural Potential in Zimbabwe: A Factorized Survey Zimbabwe AgriculturalJournal, 77 (3):97-105.

Zegeye, H. and Runge-Metzger, A. 1992. Sustainability of Land Use Systems. Verlag Josef MargrafScientific Books.



Soil and water conservation, soil moisturemanagement and conservation tillage in

Zimbabwe

GENERAL DESCRIPTION OF ZIMBABWE

Zimbabwe is a tropical country which lies between 15° 30' and 22° 30' South latitude and between 24°and 33° East longitude. The country stretches over a total surface area of 390 000 km2 sharingcommon borders with Botswana to the West, Zambia to the North, Mozambique to the East and SouthAfrica to the South. The land mass is apportioned into the following categories; communal lands(163 600 km2), resettlement farming lands (26 400 km2), commercial farming land (142 400 km2),national parks (47 000 km2) state forests land (9 000 km2), urban and state land (22 000 km2). Thepopulation of Zimbabwe is approximately 11.9 million people, of which approximately 75% reside inthe communal areas. The physical features of Zimbabwe are characterized by three broad relief regionsnamely; the lowveld (300-900 m) the middleveld (900–1 200 m) and the Highveld (1 200 – 2 000 m).In addition, a narrow belt of mountains known as the Eastern Highlands, stretches some 250 km,running from north to south along the eastern boarder with Mozambique. The greater part ofZimbabwe experiences a tropical climate with the exception of the Highveld and Eastern Highlandswhich experience a sub-humid to temperature climate owing to the modifying effect of altitude.Rainfall is highly variable, with mean annual rainfall ranging from below 400 mm in the extreme southof the Lowveld to above 2 000 mm on isolated mountain peaks in the Eastern districts. Rainfallreliability generally increases with elevation and from the south of the country to the north. Coefficientsof variability range from more than 40% south of Bulawayo at the boarder with Botswana, to less than20% in the highveld and parts of the Eastern Highlands. Rainfall distribution and reliability aregenerally of more importance to dryland cropping than the annual average (Anderson et al., 1993). Inthe driest parts of the country, where mean annual rainfall is less than 400 mm, even if well distributed,the rainfall is insufficient to support crop production other than the most drought tolerant crops such assome millet varieties.

Agro-ecological zones and their characteristics

In Zimbabwe, rainfall has been used as the single most important parameter in defining agro-ecologicalzones and their suitability for agricultural production (Vincent and Thomas, 1960). A description of theagro-ecological zones or Natural Regions (NR) as they are known in Zimbabwe, and their distributionis given in Table 1.

Godfrey NehandaInstitute of Agricultural Engineering, Harare, Zimbabwe

Soil and water conservation, soil moisture management and conservation tillage in Zimbabwe154

TABLE 1Land distribution by agro-ecological zones

Region Land area(km2)

Percent oftotal area

Description

I 7,000 1.8 Specialized and diversified farming. Very high rainfall, often inexcess of 1000 mm with comparatively low temperatures (under150C). Region is suitable for afforestation, dairying, tea, coffee,fruits and intensive livestock production.

II 58,600 15.1 Divided into two sub-regions (sub-region IIa and Sub-region IIb)Sub-region IIa - suitable for intensive farming based on cropsand/or livestock production. Experiences moderately high rainfall(750-1,000 mm) confined to the summer season. Normally enjoysreliable rainfall conditions with low chances of severe dry spells insummer.Sub-region IIb-experiences the same amount of rainfall as IIa, butcharacterized by severe dry spells during the rainy season. Suitablefor intensive farming based on cropping and/or livestock.

III 72,900 18.7 Semi-intensive farming region. Annual rainfall is 650 - 800 mm.Region is subject to fairly severe mid-season dry spells whichrenders it marginal for enterprises based on crop production alone.Farming systems should therefore be based on both crops andlivestock.

IV 147,800 37.8 Semi-extensive farming region. Annual rainfall is 450 - 650 mm.Region is subject to periodic seasonal droughts and severe dryspells during the rainy season. Farming systems should be basedon livestock production.

V 103,700 26.6 Extensive farming region located in the very hot low lying areassuitable for extensive animal production with crops under irrigation.Rainfall is generally under 450 mm, which is too low for rainfedagriculture.

National rainfall trends over the last three decades

Natural Regions become increasingly marginal for dryland crop production as one moves from NaturalRegion III to Natural Region V and the risk of getting poor yields also increases accordingly. Hussein(1987) gives the probabilities of normal seasons occurring in Natural Regions III, IV and V as 60%,40% and 35% respectively. A normal season has been defined as the season when rainfall (in terms ofboth quantity and distribution) is adequate to sustain plant growth over the entire growing seasonwithout any adverse mid-season droughts. On a national scale, seasonal quality has tended to decline inrecent years, with the frequency of agricultural droughts being significantly higher over the last 20years when compared to the long term (1910 - 1997) period (Vhurumuka and Eilerts, 1997). Drylandcrop production is strongly influenced by rainfall trends and seasonal quality as shown in Figure 1.

THE STATE OF SOIL AND WATER CONSERVATION IN ZIMBABWE

The main source of soil and water conservation problems in the LSCFS are related to intensive use ofagricultural machinery for annual ploughing; which pulverize the soil and renders it prone to erosion.Ridging up and down the slope in tobacco growing areas is also a major problem which acceleratessheet erosion. Rill and gully erosion on many farms have been checked by installation of efficientmechanical conservation systems (Table 2). Most communal areas on the other hand, are situated inmarginal regions, where rainfall is erratic rendering the areas susceptible to periodic droughts. The soilsare predominantly granitic sands, which have low inherent fertility, low cation


TABLE 2Conservation tillage techniques under evaluation

Tillage

technique

Description Location Responsible

Institution

Residue ormulchfarming

- Requires 30% residues to be left on the soilsurface.- Soil may be ripped (Mr) or not (zero tillage)

Art Farm (NRII) AgriculturalResearchTrust

Rippingbetweenrows intoresidues(mulchripping)

Similar in many ways to mulch farming.Involves ripping between previous year rowsto open planting lines

Domboshawa Farm (NRII)Makoholi Experimental(NRIV) StationInstitute of AgriculturalEngineering (NR II)

Agritex/GTZ

Agritex

No-till-tiedRidging

Involves deep ploughing and making ridgeswith cross ties across the slope at approx.1% grade. No tillage will be required insubsequent years except for maintenance ofthe ridges. This system harvests water in dryyears and facilitates drainage in wet year.Planting is normally on top of the ridge.

Domboshawa Farm (NRII)Makoholi ExperimentalStation (NRIV)Institute of AgriculturalEngineering (NRII)Cotton Research Institute

Agritex/GTZ"

Agritex

CRI/SRI

No-TillStripCropping

Involves planting narrow strips of row cropsalternating with dense cover crops tominimize soil loss and run off. The land isnot tilled and only compost manure is usedas a fertilizer. The strips of crops (70%maize, 20% legume, 10% rapoko) arerotated every year

Institute of AgriculturalEngineering (NRII)

Domboshawa Farm (NRII)

Makoholi ExperimentalStation (NRIV)

Agritex

Agritex/GTZNo-Till TiedFurrow

Land is planed into a series of shallow veeshapes drawn across the slope. Duringintense storms, rainfall runs down the sidesof the vees into the furrow where the crop isplanted. Ties are built across the vees tostore excess water

Chiredzi Research Station(NRV)

DR&SS

FIGURE 1Rainfall and communal area maize production trends for the 1969/70 season


exchange capacity and low water holding capacity. They therefore require a very high level ofmanagement to sustain crop production.

The LSCFS is made up of farms which are owned and operated on freehold title basis. Thesefarms occupy approximately one third (1/3) of Zimbabwe's land area, and are dominated by about 4500 highly skilled mainly white commercial farmers. Thirty-two percent of these farms are in agro-ecological zones I and II, which constitute the most productive zones in Zimbabwe, with good soils andhigh natural rainfall. Individual holdings in this sector are generally large (1,000 - 4,000 ha on average)and this has in some instances led to the under utilization of land. The sizes of farms becomeincreasingly bigger as one moves from the high potential areas in Natural Regions I and II, to the moremarginal areas in Natural Regions III to V. This state of affairs, in addition to a wide resource pool anda reasonable knowledge base, offers opportunities for good land management systems to be applied,thereby protecting the land and minimizing erosion related problems. In fact 48.7% of commercialfarming areas have been described as having negligible erosion and only 2% of the land has beendescribed as being severely eroded (Whitlow, 1988). This data however relates to gully and rill erosionand does not reflect on the extend of sheet erosion in the LSCFS, which may be quite considerable.

Low levels of agricultural productivity and poor access to essential resources (e.g. draughtanimals, finance, etc.), compounded by inadequate socio-economic infrastructure to supportagricultural development, have led to exploitative land use and extensive cultivation to meet basic foodrequirements. This situation is worsened by an ever-increasing population in the communal areas. Ofthe 11.9 million people in Zimbabwe, 75% derive their livelihoods in the communal areas. Total area ofland cultivated has been expanding over the years in response to population pressure, and thereforecorresponding demand for land to grow more food crops. Since land is a static resource, previouslyuncultivated non arable lands have been opened up for cropping purposes, and land cultivated percapita has declined in response to population growth. The overall land per household within thecommunal areas declined to 4.1 ha in 1982, Compared to 6.0 ha in 1979 and 18.9 ha in 1931(Zinyama, 1986). More recent studies show that total area cropped to maize, millet and cash crops inthe 1980s stood at 1.97 ha per household. This dropped further to 1.63 ha per household in the 1990's(Vhurumuku and Eilerts, 1997). This decline in per capita land holdings has a strong bearing on theincreased vulnerability of communal areas to soil erosion and land degradation as continuous ploughingand cropping with little or no rotations becomes the norm. Elwell (1992 and 1993) reported that allland that has been annually ploughed in Zimbabwe for more than 5 - 10 years can be expected to bestructurally degraded. In sandy soils, which are predominant in the communal areas, soil degradation isreflected in almost total loss of organic matter, increase in acidity, decline in fertility, decline in waterholding capacity; and increased runoff and soil loss (Norton, 1995).

The environmental factors, and the socio-economic circumstances prevailing in the communalareas, have created a vicious cycle of poverty which makes it difficult for the farmers to uplift landmanagement standards, based on currently available technologies. Most of the technologies availabletoday, were developed for the large-scale commercial farmers. Inspite of their lack of reference to thesmallholder sector, they are still being recommended for adoption by smallholder farmers. Farmershave responded by largely ignoring these technologies because of their inappropriateness to theirnatural and socio-economic environments. In most communal areas, where these technologies havebeen partially adopted, the result has been widespread land degradation, increased surface runoff andconsequently massive soil erosion. Annual soil and runoff losses from conventionally tilled lands in thecommunal areas have been estimated at 50t/ha and 30% of seasonal rainfall respectively (Elwell andStocking, 1988). In an erosion study in Southern Zimbabwe carried out in the 1992/93 season,Hagmann measured soil loss rates in rills of 59t/ha (Hagmann, 1996). He also concluded that years


following severe droughts, during which communal grazing eliminates litter and vegetation cover,provide the most favourable conditions for soil erosion and land degradation in general. Whitlow,(1988) estimated that up to 27% of the land in communal areas is severely, to very severely eroded onthe basis of visible erosion.

The above scenario therefore calls for investment in the development of land management systemsthat are effective at reducing soil losses and runoff, improving soil conditions for crop production;which in turn will stabilize yields and productivity. The technologies must be developed with the fullparticipation of the end users, with the objective of adapting them to suit the farmers prevailing socio-economic circumstances. Conservation tillage techniques are one such group of technologies which canhave major impacts in checking soil and water loss problems, and alleviate the effects of recurrentdroughts on crop yields.

TILLAGE, CONSERVATION TILLAGE AND MOISTURE MANAGEMENT

The history of the western type of tillage in Zimbabwe dates back to the early twentieth century whenagricultural machinery and implements were introduced from Europe by the white settlers following thecontroversial, but successful land appropriation of the late nineteenth century. The tillage systemintroduced, which is now commonly termed conventional tillage, involves annual ploughing, turningsoils using a disc or mouldboard plough to perform primary operations of preparing a desirableseedbed which is weed free using tractor or animal draught power. Application of the conventionaltillage system, in conjunction with the use of hybrid seed, fertilizers and agro-chemicals to control pestsand diseases, assisted the country to achieve high economic growth during the green revolution period.This practice was extended to the smallholder sector in the 1920s when the ox-drawn mouldboardplough was introduced in the communal areas. The extensive extension drive that ensued, resulted inwidespread adoption of the plough in the smallholder sector. To date, over 90% of households in thesmallholder sector own a mouldboard plough. Continuous use of the plough, and poor agronomicpractices are now generally believed to have contributed significantly to the land degradation dilemmacurrently prevailing in the communal areas. Although the recommended ploughing depth is 23 to 30 cmfor a good cropping environment to be created, most smallholder farmers have never been able toachieve these depths. This is due to a variety of problems which include among other things, lack ofproper knowledge on the use of the plough and general poor draught animal condition which limit theability of the animals to pull the plough. Plough pans have therefore developed at shallow depthscreating impeding layers which limit water infiltration, root development, aeration and nutrient uptake,consequently contributing to poor yields. Conventional tillage which has been widely practised inZimbabwe, is therefore now increasingly being recognized to have deleterious effects on soil conditionsand is regarded as unsustainable (Elwell, 1991). After several years of continued conventionalcultivation, soils become depleted in organic matter; soil structure deteriorates and losses of soil andnutrients by erosion and runoff start to spiral. The soil profile then holds less nutrients and moisture(Elwell, 1989, 1991; Norton, 1987). Conservation tillage techniques which have now gainedconsiderable ground in the large scale commercial farming sector, are now being promoted as viablealternatives to conventional tillage (McClymont and Winkfield, 1989).

Development of conservation tillage systems

Conservation tillage systems in Zimbabwe are generally defined as any tillage practice that leaves alarge proportion of crop residues on the soil surface after planting (McClymont and Winkfield, 1989).There is however another group of conservation tillage techniques such as the no-till tied ridging system(Elwell and Norton, 1988) and the no-till tied furrow system (Nyamudeza and Nyakatawa, 1995)


which do not conform to the definition above, as surface mulching is not necessarily a requirement.These two systems are better adapted to the smallholder sector, where residues are scarce, as they arenormally fed to livestock during the dry season. Conservation tillage systems were first introduced intoZimbabwe during the 1960's in response to escalating fuel, machinery, repair and maintenance costs(Smith, 1988; Winkfield, 1992) Since then, experiences at the Agricultural Research Trust (ART)Farm, the Institute of Agricultural Engineering (IAE), Chiredzi Research Station, Cotton ResearchInstitute (CRI), Makoholi Research Station and Hinton Estates, have demonstrated that conservationtillage systems have a marked influence on soil properties, moisture conservation and yield parameters.The specific benefits attributed to conservation tillage are as follows (McClymont and Winkfield,1989):

• reduced soil erosion and surface sealing,• increased water resources for plant growth,• moderation of extreme temperatures,• increased water infiltration,• increased soil fauna activity,• reduction in crusting and compaction,• a better developed rooting system. History of conservation tillage research

The conservation tillage research programme reported on by Smith (1988) began in the 1970'sfollowing concerns over machinery costs and the need for increased output per tractor and reducedoperation costs per ha to sustain production at previous levels. The trials were mostly conducted usingtractor draught as they were designed to meet the needs of Large Scale Commercial farmers. Theprogramme compared the effects of reduced tillage techniques such as rough ploughing, wheel trackplanting, rip and disc, harrowing, "badza" holing out and tine planting on yield parameters to thestandard conventional tillage practice. Some of the interesting results that came out of this programmeare summarized below:

Mulch effects from type of tillage trials. Planting into crop residues at Henderson and IAE resulted inincreased water infiltration than on conventional tillage treatments. The increased water infiltrationtended to produce higher yields in mulch treatments than ploughed treatments in drier years. In wetseasons, when moisture was not a limiting factor, the increased infiltration resulted in lower yieldsunder mulch tillage. This effect was attributed to higher leaching losses, and water-logging forsusceptible crops. Run-off losses and soil losses were also lower under reduced tillage treatments thanunder conventional tillage systems.

Frequency of tillage trials. These trials involved a system of alternating ploughing in one season withreduced tillage on a three year rotational basis. Generally, yields were gradually reduced during thereduced tillage phase, possibly due to the reduced soil rooting volume and increased pest and diseaseincidence. However, the "bonus" effect experienced in the ploughing season of the rotationcompensated for the losses during the reduced tillage seasons, making the mean yield over severalseasons comparable to continuous ploughing.


Current Conservation Tillage Research Programmes

This section reviews research work which was initiated after 1980 and is still in progress. Followingindependence in 1980, research focus by government institutions and donor organization was turned tothe smallholder sector. A number of programmes to develop conservation tillage techniques based onanimal traction and designed to suit smallholder farmers were initiated. The research programmes wererelated to dryland cropping to cover the needs of farmers in marginal areas (Natural Regions III to V)as well as those in the wetter areas (Natural Region II). The responsibility for developing conservationtillage trials pertaining to large scale commercial agriculture has largely been taken over by theAgricultural Research Trust (ART), which is a non-governmental organization set up to service theneeds of commercial producers. Table 2 summarizes the tillage techniques being evaluated by differentinstitutions under the current research programme.

Agritex/GTZ Conservation Tillage for Sustainable Crop Production Project (Contill)

The Contill project began in the 1988/89 season as a collaborative research project between Agritexand GTZ (Germany Technical Agency). Although GTZ support has now been withdrawn, the trialshave continued to run with government resources. The trials are being conducted at the Domboshawasite (NRII) and the Makoholi site (NR IV). The main objective of these trials is to test severalalternative conservation tillage systems by comparing their yield, soil loss and runoff merits toconventional tillage.

The most important conservation tillage techniques that are being compared to conventionalmouldboard ploughing are ripping between rows into residues and no-till tied ridging (Table 2). Theresults from Domboshawa presented in Table 3 show that both mulch ripping and no till tied ridgingwere effective at controlling soil loss and runoff as compared to convention tillage. Similar results wereobtained for the drier region, at Makoholi (Table 4). The Annual soil loss figures recorded for the twoconservation tillage treatments at Domboshawa and Makoholi were below the maximum acceptablelevel of 5t/ha/year (Elwell, 1980). Soil loss from sheet erosion at Domboshawa was consistently below1.0 t/ha with the exception of one odd situation in the 1989/90 season, when losses went up to 2.2 t/ha.On the other hand, soil loss from conventional tillage was as high as 11.8 t/ha in the 1992/93 whichfollowed a severe drought in the 1991/92 season. No till tied ridging treatments consistently yieldedbetter than conventional tillage at the Domboshawa site, except for the 1991/92 season, which was avery dry year. Yields on mulch ripping plots tended to fluctuate, but show signs of stabilization asmulch continued to accumulate over the seasons.

Conservation tillage trials at the Institute of Agricultural Engineering (IAE)

From the 1993/94 season to the 1995/96 season, mulch ripping treatments performed better thanconventional tillage treatments. This shows the positive long term effects of conservation tillagesystems on the production base. In the semi-arid south (Makoholi) mulch ripping showed greatpotential when compared to no-till tied ridging and conventional tillage. For the first six years of thetrials, average yields of maize were highest for mulch ripping (3.6 t/ha) and lowest for no-till tiedridging (2.5 t/ha). Yields of conventional tillage (2.9 t/ha) were marginally better than no till tiedridging. Profile moisture contents on sandy soils have shown that no till tied ridging, despite itsoutstanding water harvesting benefits through effective runoff reduction, does not overally increase thesoil water content within the rooting zone (Vogel, 1993). This has been attributed to low water holdingcapacity of the sands, which results in water losses through deep percolation. The plant available waterof the Domboshawa sands is only about 10% by volume.


TABLE 3Grain yield, surface runoff and soil loss over an eight-year trial period (1988/89 to 1995/96) atDomboshawa

Convent tillage

1988/891989/901990/911991/921992/931993/941994/951995/96

3.822.763.061.165.104.592.383.10

62.9274.3 15.0 9.4

105.0 13.0 99.5

*

1.7 9.5 1.1 1.011.8 1.510.3

*

Tied ridging

1988/891989/901990/911991/921992/931993/931994/951995/96

5.034.564.560.756.575.952.393.37

2.3116.5 1.4 0.1 13.0 0.7 5.9

*

0.22.20.30.10.90.20.7*

Mulch ripping

1988/891989/901990/911991/921992/931993/941994/951995/96

3.812.073.960.344.255.693.463.86

86.2109.1 4.8 1.0 15.2 1.7 4.4

*

2.02.60.60.31.10.60.6*

TABLE 4Grain yield, surface runoff and soil loss over seven years of trials (1988/89 to 1994/95) at Makoholi

Tillage treatment Season Grain yield(t/ha)

Surface runoff(mm)

Soil loss (t/ha)

Conventional tillage

1988/891989/901990/911991/921992/931993/941994/95

2.86.61.90.05.82.40.9

79341 1929549

0.7 1.3 5.8 0.711.840.2 6.8

Mulch ripping

1988/891989/901990/911991/921992/931993/941994/95

3.27.13.00.07.02.62.2

528 2 135 5 4

0.5 1.0 0.6 0.3 3.7 0.2 0.1

No-till tied ridging

1988/891989/901990/911991/921992/931993/941994/95

2.13.01.50.04.83.01.1

0.3 26 0.2 0.1 34 16 4

0.02 0.09 0.12 0.11 2.68 3.00 0.14

The Institute of Agricultural Engineering (IAE) site is on deep well drained fersiallitic red clays innatural region II. The on-going tillage trials at IAE were first established in the 1991/92 season. Themain objective of the trials is to establish the sustainability of ripping into residues, no till tied ridgingand no-till-strip cropping by comparing rates of soil loss, runoff and soil structural changes toconventional tillage. The test crop used on all treatments is a medium season maize variety called


R215. The results in Table 5 confirm the superiority of conservation tillage systems in reducing soilloss and runoff over conventional tillage.

TABLE 5Maize grain yield, surface runoff and soil losses over a five year trial period (1991/92 to 1995/96seasons) at the Institute of Agricultural Engineering (IAE)

Tillage treatment Season Grain yield(t/ha)

Surface runoff(mm)

Soil loss (t/ha)

Conventional tillage1991/921992/931994/951995/96

1.53 7.49 4.42 6.54

36.6 86.6 66.9238.3

4.733.813.206.86

Mulch ripping 1991/921992/931993/941994/951995/96

1.678.749.904.476.77

10.8 8.8 3.4 2.3 5.9

0.480.520.200.320.39

No-till strip cropping 1991/921992/931993/941994/951995/96

1.899.299.442.956.86

8.82.31.41.54.6

0.400.110.250.101.42

No-till tied ridging 1991/921992/931993/941994/951995/96

2.639.849.512.407.32

0.09.71.218.812.3

0.000.530.251.481.08

Improved soil conditions, and better infiltration allow soils on mulch ripped plots to capture earlyrains and wet up their profiles much faster than conventionally tilled plots. This gives the crop onmulch ripped plots the advantage of early crop establishment as compared to conventional tillage,particularly when erratic rains are experienced at the beginning of the season. The yield results for the1991/92 to 1995/96 seasons (Table 5) show that there are no clear trends, and no significantdifferences in terms of crop yield responses to tillage treatments. When averaged over the five seasons,however, No till tied ridging gave the highest yield (6.34 t/ha), followed by mulch ripping (6.31 t/ha).No-till strip cropping gave the third highest yield (6.09 t/ha) and conventional tillage gave the lowestyield (6.01 t/ha). What is more important, however, is that conservation tillage treatments do notadversely affect yields, and they exhibit tremendous potential to stabilize yields through their positiveimpact on soil structure, increased infiltration and reduced soil loss and runoff.

No-till tied furrows technique - Department of Research and Specialist Services (DR&SS)

Research on the no-till tied furrow technique was initiated by DR&SS at its Chiredzi Research Stationand Chisumbanje Experiment station in the 1982/83 season (Nyamudeza and Nyakatawa, 1995).These two stations are located in natural region V, in the South east lowveld of Zimbabwe. The soils atChiredzi Research station and Chisumbanje Experiment station are sandy paragneiss and vertisoils(heavy clays) respectively. The objective of the research programme is to determine the effects ofreducing run-off on soil water and crop yields. Tables 6, 7, 8 and 9 show the effectiveness of tiedfurrows in conserving moisture down to a depth of 0.75 m when compared to the flat. At the Chiredzisite soil, water content in the furrows of tied furrows was up to 33% more than on the flat.


TABLE 6Total soil water (mm) to a depth of 0.75 m under tied ridges and on flat land from 8 to 21 days aftersowing during 1985/86 season.

Days after sowing8 22 36 50 53 64 79 93 107 121

Rainfall 89 0 34 33 45 80 85 8 27 0Treatment TiedRidgesFlatDifference

1751750

148147+1

152145+7

141135+6

185162+23

175141+33

163123+40

130115+15

120117+23

120111+9

S.E DifferenceSignificanceCV (%)

6.6N.S14

6.6N.S15

7.2N.S18

4.7N.S12

6.9**15

6.4**15

6.0**15

4.9**15

5.8**17

4.9N.S16

Source: Nyamudeza and Nyakatawa,1995Note: N.S. not significant, ** P< 0.01

TABLE 7Total soil water (mm) to a depth of 0.75 m under tied ridges and on flat land form 20 days beforesowing to 99 days after sowing during 1986/87 season

Days after sowing-12 15 29 43 57 71 85 99

Rainfall (mm) 431 67 0 47 23 26 2 21TreatmentTied RidgesFlatDifference

214197+17

212189+23

184164+20

186162+24

171155+16

142132+10

130121+9

122113+11

S.E differenceSignificanceCV (%)

7.2**14

8.8**16

6.9**15

6.4**13

6.2**14

5.7**15

5.4N.S16

4.2N.S16

Notes:N.S not significant, * P < 0.05, ** P < 0.011158 mm of rainfall fell in eight days in April 1989 on bare soil and the soil was kept bare through the winter; 43mm fell from 1st October to 20 days before sowing.

TABLE 8Total soil water (mm) to a depth of 0.75 m under tied ridges and on flat land from 11 to 104 days aftersowing during 1986/87 season

Days after sowing11 17 25 39 53 67 81 95 104

Rainfall (mm)TreatmentTied RidgesFlatDifference

133119+14

95

166127+39

56

141117+24

1

163133+30

24

158131+28

56

137122+15

56

111103+8

25

108110-2

32

104103+1

S.E.DifferenceSignificanceCV (%)

4.2N.S14

4.7**9

4.4**16

4.4**15

4.4**13

4.2**14

3.4N.S15

3.5N.S16

3.5N.S16

Source: Nyamudeza and Nyakatawa, 1995 (Tables 9 & 10)Note: N.S. not significant, ** P < 0.01.

Tied furrows also increased maize and cotton yields by 27% and 35% respectively over six yearsand sorghum yields by 44% over seven years. (Table 9).


TABLE 9The effect of growing sorghum, maize and cotton in tied furrows and on flat land on grain yield (kg/ha)of the crops at Chiredzi Research Station from 1983/84 to 1990/91

Crops Seasona) Sorghum 83/84 84/85 85/86 86/87 87/88 89/90 90/91

Mean

TreatmentTied furrowsFlatS.E. differenceSignificanceC.V. (%)

631413 42 *36

2,8922,771 131N.S14

2,6302,018 91*

12

755465131

*30

687 50---

2,7711,865 80 ** 18

1050 369 100 ** 29

1,6311,136

b) MaizeTied FurrowsFlatS.E. DifferenceSignificanceC.V. (%)

00---

3,6343,537 217N.S 6

3,1002,302 333

* 9

162 0 - - -

00---

2,7411,745 168 ** 26

-----

1,6061,264

c) CottonTied furrowsFlatS.E. DifferenceSignificanceC.V. (%)

487301 54 ** 15

2,8502,427 188

* 7

1,4331,320 200 N.S 14

862 564 77 *

10

899672 53 *

24

1,565 704 38 ** 13

-----

1,349 998

Note: N.S., Not significant, * P < 0.05, ** P < 0.01Source: Nyamudeza and Nyakatawa, 1995

FEASIBILITY OF IMPLEMENTING CONSERVATION TILLAGE SYSTEMS IN THESMALLHOLDER SECTOR

Minimum tillage systems involving shifting cultivation and use of the hand hoe to open up plantingstations were commonly practiced in Zimbabwe during the pre-colonial period. The western style ofagriculture, which emphasized ploughing as a necessary technology for good seedbed preparation andweed control was introduced and vigorously promoted in the smallholder sector during the colonial era.Promotion of the ox-drawn mouldboard plough as a tool for good land preparation, which was part ofthe ploughing campaign, was highly successful and resulted in widespread adoption of the western styleof tillage. To date more than 90% of smallholder farmers own an ox-drawn mouldboard plough invarious states of repair. Minimum tillage systems were therefore depopularized and regarded asbackward technologies which could only be practiced by the poor who did not own draught animalsand could not afford to purchase a plough. The concept of minimum tillage literally disappeared fromsmallholder agriculture over the years with the exception of areas where livestock development washampered by the impacts of severe droughts and animal diseases in areas such as the Zambezi Valleywhere tsetse flies are rampantly present. Conservation tillage has therefore become a relatively newconcept to most of the present generation smallholder farmers which needs to be reintroduced as apractice that offers the best alternative to conventional tillage in a scenario where:

• Farmers are losing draught animals due to more frequent and severe droughts,• Draught animals are much smaller than they were a few decades ago due to inbreeding and

declining grazing,• Poor animal condition at the beginning of the season resulting in delayed land preparation and

planting,• Soil fertility and yields are declining,• Soil loss and runoff have increased resulting in man induced droughts.


Development and promotion of conservation tillage systems for the smallholder sector was onlyintensified recently in the late 1980's into the 1990's following realization that there was a need tourgently deal with the rampant soil degradation problems in the smallholder sector. The programme isstill in its infancy and although the concept has been enthusiastically received in some areas, it wouldbe too early to expect widespread adoption of the technologies at this stage. As was the case with largescale commercial farmers, a slow change process would be expected at the beginning and thenaccelerate as more information becomes available and the farmers develop confidence with the systems.An important development in the programme however, has been the recognition of the farmer as animportant partner in the development, evaluation and dissemination process of all technologies. Allcurrent conservation tillage programmes have therefore either adopted a two pronged approachinvolving complementary on-station and adaptive on-farm research or they have gone whole sale on-farm.

The collaborative Agritex/GTZ Contill project initiated complementary adaptive on-farm trials inthe 1990/91 season as a way of ensuring that generated technologies would be relevant to the socio-economic circumstances of the end users, the smallholder farmers. The approach was further adaptedto embrace participatory approaches in the experimentation process (Hagmann, 1993). The currentapproach is based on the hypothesis that only farmers themselves can develop and/or adapttechnologies to their specific needs and requirements. The new approach which focuses on research andparticipatory development of agricultural innovations seeks to empower farmers and enable them toanalyze their problems, to define and to develop appropriate interventions and to express their demandsfor support in-order to achieve self reliant development (Hagmann et al, 1995). From the on-farmresearch programme, it has so far been concluded that mulch ripping is the only conservation tillagetechnique that can be considered to be ecologically sustainable for the semi-arid environments (NaturalRegion IV). No-till tied ridging has excellent soil and water conservation and drainage properties, andhas performed much better in the higher rainfall areas.

Performance of the different tillage techniques in the semi-arid region (NR IV) and the sub-humidenvironment (NR II) has proved to be highly variable depending on soil, site and farmer specificconditions. To address the problem of high variability of conditions, it was concluded that differenttechniques and systems should be promoted as options rather than blanket recommendations and thatfarmers should be encouraged to select, test and experiment with options in order to adapt techniques totheir specific needs and conditions (Chuma and Hagmann, 1995). The success of participatoryapproaches in technology generation and dissemination will rely on the ability of scientists to adopt andaccept farmers as research partners; and the ability of extension organisations to transform their rolefrom that of teachers to facilitators. Change of attitudes, particularly in organisations that have builttheir reputation on the basis of top - down approaches, can only be expected to be a process rather thanan event. It is important however to underline that participatory approaches appear to be takingresearch and extension in the right direction, being based at the level of the farmer himself.

Opportunities for practicing conservation farming

The most important component of residue farming is the availability of residues to give surface coverof at least 30% when the crop is planted. The problem with the communal area situation is thatresidues are normally fed to livestock and there is not much left at the beginning of the season to allowfor conservation farming to be practiced. The best opportunities for practicing residue farming do existin the resettlement and small scale commercial farming areas, where per capita land holdings are muchbigger than in the communal areas. The government is currently in the process of acquiring 5 millionhectares of land from the LSCFS for resettlement purposes under the land acquisition act of 1990.Whilst it is not clear how the land is going to be redistributed, subdivision of land into smaller units,


but offering people bigger land parcels than those currently prevailing in the communal areas in certain.Bigger land parcels in both resettlement areas and small scale commercial farming areas offer betteropportunities for implementing effective grazing management systems, hence offering better chancesfor preserving stover on arable lands which is a pre-requisite for conservation farming to succeed.Conservation farming is also possible in the communal areas where large numbers of livestock havebeen lost due to severe droughts, such as the one that was experienced in the 1991/92 season.

Development of conservation tillage technologies must also run concurrently with development ofappropriate tillage equipment. The most commonly available implement in the smallholder sector is theox-drawn mouldboard plough. Conservation tillage equipment development must be based on the mainframe of the plough so that additional attachments for specific operations can easily be attached andremoved from the beam of the mouldboard plough. This will ensure minimum investment on the part ofthe farmers thereby making the technologies attractive and more easily adoptable. Feasible solutionsalso need to be found to weed control problems if the technologies are to be attractive. Overall,however, there is great scope for implementing conservation tillage technologies in the smallholdersector, with appropriate steps being taken to create a favourable environment for such technologies tobe adopted.

CONCLUSIONS

The research data from different agro-ecological zones show that conservation tillage techniqueseffectively reduce soil loss and runoff. The systems also offer opportunities for improving availablewater in the soil profile to support crop growth under dryland cropping, especially on medium to heavytextured soils. This property becomes even more important during drought years and during mid-season drought periods where they provide a buffer, and reduce the chances of crop failure.

Conservation tillage technologies would therefore make substantial contributions in addressing theproblems of widespread land degradation and soil erosion that are destroying the agricultural base,particularly in the communal areas.

It is important to ensure that the technological and socio-economic constraints that hinder theadoption of conservation tillage techniques are addressed. One way of doing this, would be to employparticipatory approaches in the technology developmental process as well as at the disseminationphase. Adoption of participatory development approaches can only succeed with full commitment fromresearch organizations, extension organizations and farmers.

REFERENCES

Anderson, I.P., Brinn, P.J., Moyo, M., and Nyamwanza. B. (1993) Physical Resources Inventory of theCommunal Lands of Zimbabwe. An Overview. NRI Bulletin. No. 60 O.D.A.

Chuma, E. (1994) The contribution of different evaluation methods to the understanding of farmer decisionsand adoption and adaptations of innovations. Experiences from the department of a conservation tillagesystems in Southern Zimbabwe. Project Research Report No. 12. Agritex/GTZ, Harare.

Ellis-Jones, J., and Mudhara, M. (1995) Factors Affecting the Adoption of Soil and Water Conservation insemi-arid Zimbabwe: In: Soil and Water Conservation for smallholder farmers in semi-arid Zimbabwe.transfers between research and extension. Proc. of a Tech. Workshop, April, 1995. Masvingo: 106 - 117.

Elwell, H.A. (1980) Design of safe rotational systems Agritex Handbook, Harare.


Elwell, H.A. (1989) Soil Structure under conservation tillage. In: Conservation Tillage. Communal GrainProducers Association Handbook, Harare. Cannon Press, Harare: 33-39.

Elwell, H.A. (1991) A need for low-input sustainable farming. The Zimbabwe Science News. 25: 31 - 36.

Elwell, H.A. (1992) Cropland Management options for the future. Proc. of the 3rd Ann. Sci. Conf. SADC -Land and Water Management Research Programme, October 1992, Harare: 278 - 289.

Elwell, H.A. (1993a) Report on the measurement of soil erodibility indices 978 - 1990. Report of the I.A.E.Agritex - Harare.

Elwell, H.A. and Norton, A.J. (1988) No-Till Tied Ridging: A recommended sustainable crop productionsystems. I.A.E handbook, Harare.

Elwell, H.A. and Stocking, M.A. (1988) Loss of Soil nutrient by Sheet erosion is a major hidden cost. TheZimbabwe Sci. News, 22(7/8),: 79 - 82.

Hagmann, J. (1993) Farmer Participatory Research In Conservation Tillage and Approach, Methods andExperiences from an Adaptive On-Farm trial programme in Zimbabwe. Project Research Report, No. 8.Agritex/GTZ

Hagman, J. (1996) Mechanical Soil Conservation with contour Ridges: Cure for, or cause of, Rill Erosion?Land Degradation and Development. Vol 7 (2): John Wiley and Sons, Ltd.: 145 - 160.

Hagmann, J., Chuma, E., Murwira, K., and Moyo, E. (1995). Transformation of Agricultural Extension andResearch Towards Farmer Participatory; Approach and Experiences in Masvingo Province, Zimbabwe.In: Soil and Water Conservation for Smallholder farmers in semi-arid Zimbabwe. transfers betweenresearch an extension. Proc. of a Tech. Workshop, April, 1995. Masvingo, GTZ - ARDA/PPU: 135 -145.

Lineham. S. (1978) the onset and end of the rains in Rhodesia. Notes on Agricultural Meteorology No. 24.Department of Meteorological Services.

Mashavira, T.T., Hynes, P, Thomlow, S. and Willcocks, T. (1995) Lesson learned from 12 years ofConservation Tillage Research by CRI under semi-arid smallholder conditions. In: Soil and WaterConservation for smallholder farmers in semi-arid Zimbabwe. transfers between research and extension.Proc. of a Tech. workshop, April, 1995. Masvingo GTZ - ARDA/PPU 22 - 31.

McClymont, D. and Winkfield, R. (Eds) (1989) Conservation Tillage, Commercial Grain ProducersAssociation Handbook Cannon Press, Harare.

Nehanda. G. (1996) A comparison of the effects of two tillage systems on maize crop growth and performanceon a red clay soil at IAE. Paper presented at the Rockefeller Foundation Second Forum GranteesMeeting. Nairobi, August 1996.

Norton, A.J. (1987) Improvement in Tillage Practices. Paper for FAO/SIDA sponsored seminar on IncreasedFood Production. Through Low-cost Food Crops Technology, Harare, Zimbabwe, March, 1987.

Norton, A.J. (1995) Soil and Water Conservation for smallholder farmers in Zimbabwe. Past, present andfuture: In: Soil and Water Conservation for smallholder farmers in semi-arid Zimbabwe. transfersbetween research and extension. Proc. of a Tech. workshop, April, 1995. Masvingo. GTZ -ARDA/PPU. 5- 21

Nyagumbo, I. (1993) Farmer participatory research in conservation tillage. Experiences with no-till tiedridging in communal areas lying in the sub-humid north of Zimbabwe. Project Research Report No. 8.Agritex/GTZ Harare: 17 - 30.

Nyamudeza, P. and Nyakatawa, E.Z. (1995). The effect of sowing crops in furrow of tied ridges on soil waterand crop yields in NRV of Zimbabwe: In: Soil and Water Conservation for smallholder farmers in semi-arid Zimbabwe. transfers between research and extension. Proc. of a Tech. Workshop, April, 1995.Masvingo GTZ - ARDA/PPU 32-40.


Sarupinda, C.D. (1992) Preliminary study of the adoption of no-till tied riding systems in Musana,Chinamhora, Mutoko and Chiweshe communal Lands. Agritex M & E Section, Harare.

Smith, R.D. (1988) Tillage Trials in Zimbabwe 1957 to 1988. Institute of Agricultural Engineering Report.November 1988.

Vincent, V. and Thomas, R.G. (1960). An Agricultural Survey of Southern Rhodesia. Part 1. The Agro-Ecological Survey. Salisbury: Government Printers.

Vhurumuku, E., and Eilerts, G. (1997). Zimbabwe Food Security Reference Manual for Early Warning.1996/97. USAID (Fews) Project - 698 - 0491 - 5615903.

Whitlow, R. (1988) Land Degradation in Zimbabwe. A geographical study. Geography Department, Universityof Zimbabwe. Natural Resources Board Publication.

Winkfield, R. (1992) Minimum and zero tillage versus conventional tillage. In: Improved Land management -The lessons learned. Proc. from a two day conference. April, 1992.

Zinyama, L.M. (1986) Rural Household Structure, Absenteeism and Agricultural labour: a case study of twosubsistence farming areas in Zimbabwe. Singapore, J. Trop. Agric. Vol 7 (2).



Summary analysis of the country papers

Out of the 21 countries covered by the FAO Subregional Office for Southern and East Africa, 11were given the opportunity to participate in this important Expert Consultative Workshop onIntegrated Soil Management for sustainable agriculture and food security. The main objectivesfor organising this workshop were:

• Discuss the status of land degradation under contrasting agro-ecological and socio-economicconditions.

• Exchange experiences on constraints for controlling land degradation and examine possiblesolutions to overcome these constraints.

• Develop national and sub-regional programmes in support of land development schemes toenhance productivity in support of food security in the region.

Reversing the process of soil degradation and sustaining crop productivity through soilmanagement and biodiversity conservation are important aspects of food security. Although costeffective options are available, there is a need to increase the awareness campaign at high policy-making level as well as maintain the determination of agriculturalists to achieve their goals. It is,therefore, important to document the information on the extent of soil degradation, its bio-physical, economic and social impacts as well as successful examples of soil improvementprogrammes within the region.

FOOD (OR CEREAL) PRODUCTION AND REQUIREMENTS

Most of the rural community in Eritrea live on subsistence agricultural (mainly on crop andlivestock production), the majority of whom are in a low socio-economic status and vulnerable tofood shortages. In general, there are constant crop production deficits, and for the last threedecades, basic food requirements have not been met. The emphasis should be to improve themanagement aspect of agricultural production, water use efficiency, agricultural inputs, highyielding varieties and cultural practices.

In Ethiopia, the performance of the agriculture sector in the last few decades has been poor.The total area under crops and the total production has remained stagnant for several years. As aresult, the country became a net importer of food grain since 1981. For generations, Ethiopianfarmers have been producing at subsistence level, mainly because of limited access to modernresearch-led agricultural technologies, including inputs such as commercial fertilizers and organicmatter. Even though extensive areas of land are cultivated each year and the size of thepopulation engaged in the farming activities is very large, the total annual food production isalways substantially much below the national requirement.

C.F. MushambiChemistry and Soil Research Institute, Harare, Zimbabwe

Summary analysis of the country papers170

Between 1987 and 1997, the food production in Uganda increased by 18.8 percent whilst thepopulation increased by 42.9 percent. Hence the population is increasing much faster than thefood production. Therefore, the food requirements versus food production situation in Uganda arelikely to become alarming in the near future.

The population growth rate of Malawi is currently estimated at 3.3 percent per annum, andabout 90 percent derive their livelihood from Small Land Holdings. High population densities andgrowth rates limit available land for agricultural expansion. Most small holder farmers lack basicneeds such as adequate food. The future prospects in meeting the national basic food demands fora growing population are bleak and worrisome.

Zambia has faced food deficits in the past, mainly due to droughts and unfavourableagricultural policies. The growth in agricultural production has not kept pace with the populationgrowth rate (estimated at 3.2 percent per annum) in recent years. Accordingly, Zambia facesserious and chronic food deficits in the coming years, unless measures are taken to reverse theadverse trends.

Crop production in Zimbabwe has a tendency to vary with agro-ecological zones and alsowith seasonal variations in weather patterns. Rainfall has been used as the single most importantparameter in defining agro-ecological zones and their potential for agricultural activities. Otherfactors involved in the levels of crop production, particularly in the smallholder sector, are levelsof agronomic management, access to inputs, availability of credit, and marketing facilities. Givena good rainy season, Zimbabwe produces surplus food in relation to its requirements.

The cereal production in Namibia varies significantly according to rainfall. National cerealproduction has varied in recent years from low yields (33 100 t per year) in drought years tomedium yields (118 900 t per year) in good years. With an estimated national demand for cerealof 201 900 t per year, Namibia has to import a significant amount of its cereal requirements.

South Africa produces a wide variety of food crops which take full cogniscence of thepeople's nutritional needs. In terms of value and quality, South Africa does not only meet its ownfood requirements, but is also a major exporter of cereals and other agricultural products.

Tables 1 and 2 show the summary of food production and requirements as well as deficitsand surpluses for the ten (10) countries represented at this Consultative Workshop.

TABLE 1Summary of food (cereal) production and requirements

Annual Production Annual RequirementsEritrea 220 000 - 250 000 MT About 384 600 MTEthiopia 8 000 000 MT 9 000 000 MTUganda 13 219 000 tons in 1987

15 703 000 tons in 1997Not Available

Tanzania 7 500 000 tons in 1988/89 Not AvailableZambia 1 020 749 tons in 1994 1 220 935 tons in 1994Zimbabwe 70's 1 814 481 tons

80's 2 176 012 tons90's 1 807 004 tons

Not Available

South Africa 11 086 800 tons per yearduring 1975/76 - 1994/95

Not Available

MT-Metric ton


TABLE 2Summary of food (or cereal) deficits or surpluses for ten African countries

Country Deficit in DomesticFood Requirement

Sufficient in DomesticFood Requirement

Surplus inDomestic FoodRequirement

Eritrea *Ethiopia *Kenya *Uganda *Tanzania *Malawi *Zambia *Zimbabwe *Namibia *South Africa *

* Sourced from country papersNote: Surplus figure are dependant on the impacts of weather patterns and/or drought.

Given the size of agricultural land resources available in these African countries, the fooddeficit scenario is not a healthy one. It is the responsibility of each government to reverse thissituation and be able to efficiently utilise the agricultural production sectors.

EVALUATION OF PER CAPUT CULTIVATED LAND AND TRENDS IN CEREAL CROP

Africa's food crisis can be defined as the steady decline in agricultural production per person.Between 1965 and 1982, Africa's food production per person fell by 12 percent in 33 of the sub-Saharan African countries. During the same period, Southern Africa's per caput food productionfell by 19 percent.

There are several factors contributing to this decline, such as the high population growth ratewhich, on average, is approximately 3 percent per annum, and the continued land over-utilisationwhich leads to low agricultural productivity.

Over the past two to three decades, the increase in food supply in most regions of the worldwas gained through increasing yields per hectare, but in sub-Saharan Africa, the increase in foodsupply has occurred through expansion of cultivated land and/or shifting cultivation. BecauseAfrica is facing a high population growth rate and the arable land per caput is constantly beingreduced, emphasis must be placed on increasing yield particularly through maintenance of soilproductivity, rather than concentrate on the expansion of cultivated land areas.

Although there is a potential for increasing food productivity in Ethiopia, while, theexpansion growth for the same period in the area of cultivated land is small compared topopulation growth. Available data indicates that the increase in the area of cultivated land from1961 to 1991 was about 20 percent, however, that of population growth for the same period wasabout 150 percent. As a result, the per caput land area decreased by more than half. Furthermore,yield per unit area also decreased, due to excessive soil degradation and nutrient depletion.

The same scenario is also experienced in Eritrea, Uganda, Kenya, Tanzania, Malawi,Zambia Zimbabwe and Namibia, where the cultivated land per caput is decreasing fast, and is notbeing compensated with an increase in crop yields. Therefore, corrective measures are longoverdue.


In South Africa , the annual population growth rate is 2.7 percent. Land per caput ratios areworsening, and it is estimated that the area of arable land per caput will drop well below theaccepted minimum of 4 ha before the year 2010. At present, food production per caput issufficient but agricultural output has to be expanded to maintain and conserve the naturalresource base. Over the last two decades, South Africa has more or less maintained itsagricultural production under the harsh population pressure, scarcity of land, and unfavourableclimatic conditions.

Per Caput Cultivated Land

Eritrea: The per caput arable land declined from 4.3 ha in 1943 to 1.10 ha in 1996.

Ethiopia: The per caput cultivated land decreased from 0.574 ha in 1961 to 0.279 ha in1991.

Uganda: The per caput cultivated land decreased from 0.27 ha in 1990 to 0.25 ha in 1997.

Kenya: Population increase has led to a big land pressure. This implies that the per caputcultivated land is decreasing (figures are not available).

Tanzania: Population increase has led to pressure on land. Therefore, per caput cultivatedland is decreasing (figures are not available).

Malawi: As a result of increasing population on limited land area, the per caput cultivatedland is decreasing (figures are not available).

Zambia: The declines in per caput cultivated land are a result of high population growthrates (figures not available).

Zimbabwe: The per caput cultivated land in the 1980's was 0,393ha, but in the 1990s thisfigure dropped to 0.325 ha.

South Africa: Person-to-land ratios are worsening fast. It is estimated that cultivated land percaput will drop well below the accepted minimum of 4 ha before the year 2010.

In summary, the per caput cultivated land is decreasing fast for all the countries representedon this Workshop. Therefore, emphasis must be put on increasing yield as opposed to landexpansion or shifting cultivation.

EXTENT OF SOIL DEGRADATION AND ITS BIOPHYSICAL AND SOCIO-ECONOMIC IMPACTS

The basic challenge facing agriculture and food security in many developing countries today isthe steady loss of plant nutrients leading to decline in plant biomass, organic matter, microbialactivity, and finally crop yields. These processes in combination with bad soil managementpractices, overgrazing and deforestation, cause large scale soil degradation. Soil degradation canbe described as a loss of soil productivity brought on by various physical and chemicaldepletions. Soil degradation is the end result of a combination of factors, which damage the soiland vegetation resources, and restrict their use or productive capacity. Major forms of landdegradations include soil organic matter depletion, acidification, salinization and high population


pressure (human and livestock). The processes of soil degradation are more prevalent and moreintense in the smallholder and resource poor farming sectors of the community, which arecharacterised by fragile environments and have the highest population densities.

Research indicates that soils in sub-Saharan Africa are low in organic matter due to lessplant residue materials recycling back to the ecosystem. At the beginning of this century, thevegetation cover in Eritrea was estimated at 30 per cent. Presently it is less than 1 percent.Similarly, in all the African countries, the area covered by forests has drastically been reducedsince the turn of the century. This situation has created agricultural soils that have very lowfertility status and are subjected to accelerated erosion. One of the serious crop yield limitingfactors to the majority of farmers in sub-Saharan Africa is lack of inputs either through residueincorporation in the form of organic matter or through the addition of inorganic fertilizers. Inplaces, which have been settled for decades, the soils have been continuously "mined" of nutrientsthrough harvests and soil erosion resulting a decline in the crop yield.

The over exploitation of land resources by man, through inadequate soil and waterconservation and, at times, inappropriate farming practices, are the underlying causes of landdegradation in Africa. Dissemination of research information in the areas of soil, water andbiodiversity conservation by researchers to the extension workers and farmers is also limited. It isimportant to have a multi-disciplinary approach that involves everybody in the definition of theproblem and the identification of possible solutions regarding soil degradation. Similarly thecauses and types of degradation processes are very much related between these countries. It is notsurprising, therefore, to note that these soil degradation types are the same among the countries ofthe region.

Table 3 highlights the major types of soil degradation in each country and also indicatingclose similarities between them. It should be mentioned here that wind erosion is more prominentin Eritrea, Ethiopia and Namibia; whereas, water erosion is prominent in Malawi, Zambia,Zimbabwe, and South Africa.

TABLE 3Major types of soil degradation by countryType ofdegradation

Eritrea Ethiopia Kenya Uganda Tanzania Malawi Zambia Zimbabwe Namibia SouthAfrica

Erosion (wind& water)

**** **** **** **** **** **** **** **** **** ***

Fertilitydecline

*** *** *** *** *** *** *** *** *** ***

Acidification * * * * * ** - ** * ****Sodicity/Salinity

** ** ** ** ** ** ** * **** *

Compaction * * * * * * * * * *Crusting * * * * * * * * * *

Key : **** Very high (major) *** High (2nd major) ** Medium * Low


AVAILABLE TECHNOLOGICAL OPTIONS FOR CONTROLLING SOIL DEGRADATION ANDENHANCING PRODUCTIVITY

The challenge facing scientists at the moment is to develop and test more technologies that willcontrol soil degradation and enhance crop productivity. These technologies should be affordableand easily sustainable to the ordinary smallholder farmer.

Summary information based on country papers

Types of Degradation Causes of Degradation

• Wind /Water erosion: - Lack of vegetation cover, due to deforestation and overgrazing

• Soil fertility decline: - Exhaustion of nutrients through continuous cropping without inputs.- Leaching of plant nutrients- Poor farming practices

• Acidification: - A combination of factors which include- depletion of soil pH- availability of toxic elements such as Al, Mg and Fe.- deficiencies in P, Ca, Mg and K- low water holding capacities resulting in excessive leaching in

bases

• Sodicity/Salinity: - Accumulation of dissolved salts.

Some of the technologies currently being applied to control soil degradation (and indeed manyothers not listed here) are highlighted in Table 4 and have a role to play in the overall search forgood management options for improving soil fertility in Africa. Due to the new soil and waterconservation programmes in Eritrea, the vegetation is regenerating well and earth dams and pondshave made significant contributions to water harvesting. Other success stories about varioustechnologies that are being carried out are mentioned in the country papers.

TABLE 4Technologies Utilized to Control Soil Degradation.Programmes inPlace

Eritrea Ethiopia Kenya Uganda Tanzania Malawi Zambia Zimbabwe Namibia SouthAfrica

Soil and WaterConservation

+ + + + + + + + + +

Minimum Tillage + + + + + + +InorganicFertilizers

+ + + + +

Lime and Liming Materials

+ + + + +

Manures andOtherOrganicFertilizers

+ + + + + + + + +

BiologicalNitrogenFixation

+ + + + + +

AgroforestryTechnology

+ + + + + +

Based on country papers (see this issue)


In the future, it is hoped that all researchers will take the participatory type of approach,where farmers and extensionists are fully involved throughout the duration of the programme.

CONCLUSION

Sub-Saharan Africa can no longer sit back and watch its natural resources (soil, water,vegetation) disappear through mismanagement and unfavourable policies. Strategies andconservation programmes must be formulated and action plans drawn up in order to overcomeproblems of soil degradation.

This workshop is being held at an opportune moment. It is hoped that each country willrevisit its activities on the natural resource conservation and then concentrate on those areas thatrequire strengthening; then work on the practical solutions concerning land degradation. Theultimate goal being to sustainable increase the yields of food crops whilst at the same timeconserving the natural resource base.

REFERENCES

Country Papers from: Eritrea, Ethiopia, Kenya, Uganda, Tanzania, Malawi, Zambia,Zimbabwe, Namibia and South Africa (see this issue).



Country reports

178


Eritrea

COUNTRY FOOD PRODUCTION AND REQUIREMENT

Food balance

The total national area is around 125 020 square kilometres. It is part of the Sahelian belt ofAfrica and has an estimated population of about 3 million. Eritrea is divided into six agro-ecological zones namely the Central Highland Zone (CHZ) with sub-zones SML, NML and H,Escarpment Zone (WEZ), North-Western Lowland Zone (NWLZ), South-Western Zone (SWLZWestern), Green Belt Zone (GBZ) and the Coastal Plain Zone (CPZ).

The agricultural sector occupies about 80% of the labour force. It contributes about 26% ofthe GDP (World Bank, 1994). Most of the rural community live on subsistence agriculture(mainly on crop and livestock production) out of which 78% (Cliffe, 1991) are in low socio-economic status and are vulnerable to food shortage. Besides, few of the population depend onfisheries. Agricultural production in Eritrea ranges from nomadic pastoral systems to small scaleirrigated horticultural production. Cliffe (1991) recognizes three major systems: pastoral (11%),agro-pastoral (22%) and agricultural (67%). Survey studies in the highlands of Eritrea (Haile etal., 1995, Azbaha et al., 1996), show that the population is predominantly agro-pastoral. Purecrop cultivators without livestock are of a rare occurrence, since crop production is dependent onanimal traction. Owing to its ecological diversity, Eritrea produces a wide range of cereals,vegetables, pulses, fibber crops are grown (Mesghina and Bissrat, 1997; Araia et al., 1994).Subsistence farmers in the highlands grow taff, barley wheat oil seeds and legume. In thelowlands the main crops grown are pearl millet, sesame, groundnuts, cotton, sorghum, fruits andvegetable. Sorghum is the most important crop and accounts for about 46% of annual yield in thecountry (Cliffe, 1988; World Bank, 1994). Next to sorghum, are pearl millet (16%) and barley(15%) (Araia et al., 1994). Commercial agriculture also played a significant role before the war.It included rain-fed cereal and cotton production as well as large scale irrigated agriculture for theproduction of fruits and vegetables mainly for export. The potential for expansion of small andlarge-scale agriculture is still there. It is estimated that the area under horticulture is about 7 000ha (World Bank, 1994). This figure appears to be on the low side.

The food requirement of a person per year is 0.145 Mt (World Bank, 1994). Table 1 andFigure 1 show that the basic food requirement was not met during the last three decades.However, the south mid altitude and the coastal areas do produce enough food to support thelocal population as well as export it to other regions of the country. Food deficit periods in thehighlands and lowlands differ. In the green belt and eastern coastal areas, there is food deficitfrom October-January. In the highlands and the western lowlands, it is between May andSeptember, which is the time of land preparation, sowing and the beginning of crop maturity.

Woldeslassie Ogbazghi and Anwar ul-HaqCollege of Agriculture and Aquatic Science, University of Asmara

Eritrea180

TABLE 1Food production and annual deficits in percentage (1976-1996)

Year Production000 tonnes

Self-sufficiency%

Deficit%

Sources

1975-76 188 42 58 Araia et al., 19941988 100 N/A. N/A. World Bank, 19941990 170 N/A. N/A. World Bank, 19941991 70 16 84 Tesfay, 19921992 278 64 36 Appleton et al., 19921993 90 16 84 UNICEF, 19941994 265 60 40 FNSP, 19961995 142 32 68 IGAD, 19961996 97 20-25 75-80 MOA, 1996

Some coping strategiesduring food shortage periodsinclude sale of livestock andlivestock product, collection ofwild fruits like Cactus, Balanitesspp. doum palm and Zizyphusfruits. Under such circumtances,wild plants constitute almost themajor dietary part during thesemonths. Although the nationalpicture seems to be deficient infood production the southwesternlowlands, southern midlands andcoastal areas with spateirrigation are self sufficient interns of their grain requirement.

Historic records reveal that there is constant crop production deficit in Eritrea. Cliffe (1991)estimates a normal harvest under non-disastrous situations to be between 220-250 thousandmetric tons covering between 55-65% of the annual need only. Consequently, during the strugglefor liberation, and immediately after, most of its people were dependent on food aid. It wasestimated that 72% of the Eritrean population during 1992, was food-aid dependent (Appleton etal., 1992). Since liberation(1991), government focus was to shift from food-aid dependency tofood security. Pre-liberation statistics regarding food production are scarce and unreliable. Recentsources, however, indicate that food production follows a similar pattern as before (Figure 1).

Food requirements projections (1996 -2010)

Food requirement projections are made based on 1992 food production estimated to be 278,000metric tons which covered about 64% annual food demand for that year. The population size ofEritrea in 1996 is taken 3 million with per caput food requirement of 0.145 tonnes per annum.The annual growth rate has been taken as 2.9% per year. The yield of cereals is estimated to be0.74 MT/ha (World Bank, 1994).

FIGURE 1Food production 1986-96 (000 Mt)

0

50

100

150

200

250

300

1986 1988 1990 1991 1992 1993 1994 1995 1996

Years

Prod

uctio

n


By the year 2010, the population of Eritrea is expected to be about 4.5 million and theannual food requirement by that year is estimated about 649 089 metric tons. If the 1992 grainproduction figures (278 000 tonnes) are taken as base, then production will have to increase byabout 133%; the required crop area would be 877 147 ha (Figure 2).

If the additional requirement in grain of 371 089 tonnes were to be achieved by putting moreland under cultivation, an additional 501 471 ha of land would have to come under production.This would require 1.3 times more than the area under production in 1992. If average yield wereto increase by 50%, an additional 337 353 ha of land would be required. NEMP-E, (1995),estimates, about 2 million ha of land are available for rainfed agriculture mainly in thesouthwestern lowlands of Eritrea. By looking at the potential arable land, it is tempting to saythat Eritrea would satisfy its annual food requirement by putting more land under cultivation. Inspite of Eritrea’s arid and semi-arid climate, the challenges of achieving this objective is notbeyond the reach of the country’s capacity.

It is estimated that about 600 000 ha is potentially suitable for irrigated agriculture. WorldBank (1994) estimated that 22 000 ha were already under irrigation and suggested to expand thisto 60 000 ha. Attaining the objective would be feasible if the yield of rainfed agriculture for 1992is maintained and at the same time the yield in irrigated agriculture is increased to 1.2 tons per ha.Although the potential for expansion of arable land is there, it should be done at slower pace. Theemphasis should be to improve the management aspect including irrigation, water use efficiency,agricultural inputs, high yielding varieties and improved cultural practices. This is particularlyimportant in protecting the environment and adopting sustainable agricultural productionstrategy.

EVOLUTION OF PER CAPUT CULTIVATED LAND AND TRENDS IN CEREAL CROP YIELDS

Eritrea has a total area of 12 167 697 ha (Table 2) out of which 1 084 821 is cropped land whichis 8.9%. The unproductive and currently unutilized land is 2.0% and 33.1% respectively. A totalof 3.2 million hectares is suitable for production which could allow expansion by 17%.

FIGURE 2Projected food demand and food crops required area

0

200

400

600

800

1000

1996 1998 2000 2002 2004 2006 2008 2010

Years

000

Mt a

nd 0

00 h

a

Food demand Required area

Eritrea182

Land use and land cover

The population of Eritrea has quadrupled during the last six decades. The per caput total area hasdecreased from 16.3 ha in 1943 to only 3.4 ha in 1996. The per caput potential arable land hasalso declined from 4.3 ha in 1943 to 1.10 ha in 1996. The expected yield from per caput of arableland is shown in Table 2. By the 2010, the population of Eritrea will grow by 49.2% using the1996 as a base line. As a consequence, the per caput cultivated area and potential arable land willbe decreased by 34.5% as shown in Table 2.

TABLE 2Per caput total area, current arable land and potential arable land of Eritrea

Land per caput

Year Population

(000)

Total area

(ha)

Potential arableland(ha)

Expectedyield

(tonnes)

Currentarable land

(ha)

ExpectedYield

(tonnes)1943 (a) 750 16.3 4.30 3.18 1.50 1.101952 (b) 1,031 11.8 3.10 2.30 1.10 0.811964 (c) 1,500 8.10 2.10 1.60 0.72 0.531996 (d) 3,000 3.40 1.10 0.81 0.36 0.272010 (e) 4,476 2.70 0.71 0.53 0.24 0.18

Sources: a) Longridge, 1943 b) Trevaskis, 1975 c) Aradom, 1964 d) World Bank, 1994, e) projection

CONSTRAINTS TO FOOD PRODUCTION

Drought. Most parts of Eritrea are affected by drought and the erratic nature of the rainfallpattern. The climate of Eritrea ranges from sub-humid in the green belt agro-ecological zone toarid in the coastal areas. In the highlands and the western lowlands, the rainy season is fromJune-September. In the eastern escarpment, however, it is from October to March (winter rains).Owing to diverse topography and altitude, annual precipitation varies between 100 mm in thelowlands to more than 1000 in localized areas in the green belt that benefit from bi-modal rainfallregimes. The temperature in the lowlands is very hot and cool in the highlands. In the lowland, theclimate is hot or very hot with annual mean temperature between 26.5 and 29.0 °C. Areas locatedbetween 1 000 and 1 500 m of altitude are warm to mild and their temperature ranges between 19and 22 °C. The highlands (above 2 000 m) are cool, with mean annual temperature of 19 °C(FAO, 1994).

Impact of war. The gap in food production was widened due to the protracted war of liberationwhere the country lost a great proportion of its labour force. During the war, draught animalswere killed, irrigation canals and dams were destroyed together with farm tools and implements(Araia et al. 1994). As a consequence, the ability of farmers to save seed from stock has becameimpossible. The war also caused food deficit because villages were abandoned and burned and thearea under production was limited (Cliffe, 1988).

Lack of agricultural infrastructure. The Government of Eritrea has invested to build roads andagricultural infrastructure. However, due to the topography of Eritrea, it is still very difficult tocommunicate between the major production areas and the market centres of the country. Most ofthe productive areas are located a long distance from the major roads

Land degradation. Low food production in Eritrea is the result of progressive loss of fertility anderosion. Although land degradation is widespread throughout the country, the areas of greatconcern are located in the highlands where majority of the population live. In most cases, the


topsoil is removed and the soil fertility is very poor to support cultivation without significantintervention to improve its quality. Under the present situation, increase in crop productivity islikely to be difficult without extensive rehabilitation efforts. In the highlands, soil degradation isassociated with the removal of the vegetative cover (Jones, 1991; Azbaha et al., 1996).Deforestation in Eritrea is the result of removal of the vegetative cover for grazing, cultivation,construction and fuelwood. Land degradation was also worsened due farming on steep slopes aswell as the shortening of the fallowing period due to population pressure. This resulted inaccelerated soil erosion that washes away topsoil almost within a season.

Land tenure. The major constraints of food production in Eritrea include the counter productiveland tenure system. The land tenure varies from place to place (Nadel, 1946; Zekaria, 1964;Jordan, 1989). The Diessa land tenure system does not guarantee tenure right and farmers arereluctant to make efforts in terracing, planting trees or invest in improved cultural practices.

Lack of research outputs. Although agricultural research stations were established as early as1901 (Yemane, 1988), their contribution to the enhancement of agricultural productivity in thecountry is limited. This is because research activities failed to address relevant productionproblems in the country. During the war, research activities were confined to limited areas andresearch finding did not reach the farmers. This gap between research findings and theirdissemination to the farmers is still wide

Lack of marketing and storage facilities. The cost of food in Eritrea is high because farmersconsume little less than three quarters of their produce and the rest is sold in the market (Araia etal., 1994). Most farmers produce what they consume and consume what they produce (Tesfay,1992). Insufficient storage capacity on the farm and marketing facilities discourage farmers fromproducing surplus. In addition, it is estimated that lack of storage facilities causes substantial lossof agricultural produce. Moreover, farmers are also discouraged from producing perishablehorticultural crops primarily due to lack of marketing and storage facilities.

EXTENT OF SOIL DEGRADATION AND ITS BIO-PHYSICAL & SOCIO-ECONOMIC IMPACTS

Types of land degradation

Water erosion. Reliable data on the extent and impact of soil erosion in the country are notavailable. Limited research findings conducted in Afdeyu (Central Zone) of Eritrea shows thatsoil loss is on the average 15 tonnes/ha/year equivalent to over 50 years to remove 4.5 cm topsoil. This is estimated to result in annual crop failure of 0.2 - 0.4% and a decline in the livestockof about 0.05 - 0.1% annually (World Bank, 1994). During few rains occurring in the Eritreanhighlands runoff is extremely high, flooding whole fields (Grunder and Karl, 1997).

Wind erosion. To date, there are no quantitative data on the magnitude of wind erosion in Eritrea.However, wind erosion is frequently observed particularly in the southwestern, northwestern andcoastal areas of the country. This is because of lack of vegetative cover during dry season. Windblows fine soil particles and organic matter from the surface soil. Moreover, wind erosion causescontinuous movement of sand dunes in the coastal areas accelerating the process of landdegradation. The lowlands are subject to strong winds and it is common to find aeolian deposits(Murphy, 1959).

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Salinity and alkalinity. In the western and coastal areas of Eritrea, the soils are deeper comparedto those the highlands. The surface texture is mostly sandy, loamy sand and sandy loam. The soilreaction generally varies from slightly alkaline to strongly alkaline. In some places, the soilreaction is reported as high as 9.5. The organic matter content extends from 0.6-2.5. Under aridconditions, there is accumulation of salts on the surface, and there is high potential for thedevelopment of saline alkaline, and calcareous soils (Maskey, 1985). This problem is particularlyserious in the coastal areas where the annual rainfall is less than 200 mm with evapotranspirationexceeding 2,000 mm/year. In the highlands, there are indications on the development of salinesoils in irrigated areas using water from deep wells.

Physical degradation. The extent of physical degradation in Eritrea is not well documented.However, (Jones, 1991) pointed out that livestock causes physical soil degradation in RoraHabab area. In the highlands, during rainy season, livestock are confined to limited grazing areas.This exerts tremendous pressure on the soil through trampling that reduces infiltration.Consequently, it is common to observe the creation of gullies caused by runoff. Besides, theremoval of organic matter (animal dung and crop residues) from agricultural fields as well asover tillage contribute to physical degradation of soils. In the highlands, land preparation is donefive times per year (Azbaha et al., 1996).

Extent of land degradation

Eritrean farmers equate soil degradation to land degradation. It is perceived as the reduction inthe productivity of land by biological, chemical, or physical processes (NEMP-E,1995). Landdegradation is a process and phenomena (Azbaha et al., 1996). As a process it is continuous andincremental. It is an increasing weakening of the physical, biological, and economic potential ofland thereby reducing the overall capacity of the productivity of the land. Land degradation is aprocess that lowers the productivity of land assuming all other factors such as technology,management and weather held constant (Bojo, 1995). As a phenomenon, land degradation is theend product of a long process that is manifested by decrease in cultivable land per peasanthousehold, decrease productivity of a unit land per specified in-put, decline in livestockpopulation, loss of vegetative cover and shortage of fuelwood, wood materials, loss of top soil,and generalized ecological disturbances (Biswas and Biswas, 1980, Azbaha et al., 1996). Thesoils of most parts in Eritrea are very poor in organic matter content (Murphy, 1959; Azbaha etal., 1996; Haile et al., 1995, Jones, 1991). A general picture of some soils in Eritrea is givenbelow.

Central Highland Agro-ecological Zone, Debubawi Anseba. Debubawi Anseba is located in thecentral highland of Eritrea. The area is mountainous and densely populated with little potentialfor expansion of rainfed agriculture. The altitude of the highest peak is about 2300 m above sealevel. It has a cool semi-arid climate (FAO, 1994) with mean annual temperature of 18 °C andmean annual rainfall of 400 mm per annum. During the past three decades, rainfall has showngreat fluctuation in terms of distribution and amount. The soil are angular to subangular instructure. The consistence of dry moist and wet soils is soft, slightly hard and wet friablerespectively. The mean soil depth is about 62 cm and ranges from 30 to 160 cm. The deeper soilswere from valleys and agricultural areas. Out of a sample of 32 surface soils, 18.77%, 62.50%,9.38%, 9.38% were loamy sand, sandy loam, loam, and silt loam respectively. The soil colour islight yellowish brown to yellowish brown. In many places soils are shallow or very shallow dueto erosion (Murphy, 1959; Maskey, 1985). In some areas, especially in depressions, the soils arerelatively deeper The soils are coarser in texture due to slow weathering process and parentmaterial i.e. schist. However, in depressions with colluvial materials the soils are of medium


texture and are deep. The soil reaction is mostly neutral and organic matter (1.07%) andphosphorous (2,76%) content is low, whilst no particular salinity problems is recorded.

South Mid Altitude Zone, Egela Hatsin. Egela-Hatsin is located in the southern midland agro-ecological zone of Eritrea. The topography of the area has gentle slope, steep and almost flat atthe upper, middle and lower parts of the catchment respectively. The elevation of the area rangesbetween 1400- 2000 m above sea level. Annual rainfall ranges between 400 mm/annum. Themean annual temperature is 270 C. The soils in the area are angular to subangular in structure.Dry soils are soft to slightly hard; moist soils are friable to firm and wet soils non-sticky to stickyconsistence. Out of a sample of 37 surface soils, 54.05%, 40.54%, 2.70%, 2.70% were sandyloam, loam, silt loam and clay loam respectively. The mean soil depth is about 54 cm rangingfrom 40 to 150 cm. The soil colour is light yellowish brown to yellowish brown. The soil reactionis slightly acid and organic matter (1.00%) and available phosphorous (2.23%) content is low,whit no salinity.

Coastal Plains Agro-ecological Zone, Ghatelay. Ghatelay area is located in the coastal plains ofEritrea. The altitude of the area ranges between 200-400 m above sea level. It is a flat area withsome hills here and there. The area is hot and dry with mean annual rainfall of 200 mm andtemperature 350C with maximum range of 45 °C. The soil structure is angular to sub-angular.The consistence of dry, moist and wet soils is soft, friable to firm and slightly sticky respectively.The soil depth ranges between 15 - 100 cm with mean value of 75 cm. The soil texture is sandyloam or silt loam and has brown colour. In the coastal areas of Eritrea, there are sand dunes andaeolian deposits and in many places these are very deep. Alluvial materials brought up from thehighlands are good for many of the spate irrigation systems. Analyses of soils from these areasindicate that the soils collected from areas which don't receive seasonal floods are affected bysalinity problems. However, the salinity levels of the soils in fields under spate irrigation are low.These soils are characterized by low organic matter (1.10%) and phosphorus (2.10%) that limitagricultural productivity in the area. The soils are alkaline in reaction. Owing to the dry climatein the area, there is a very high possibility for the development of saline and alkaline soils.

Northern Mid Altitude Agro-ecological Zone, Rora Habab. Roral Habab is an area located in thenorthern mid land agro-ecological zone of Eritrea. The elevation of the area ranges between 1,900- 2,200 m above sea level. Annual rainfall ranges between 300-400 mm and temperature rangingfrom 15 - 23 °C. Previously the area was covered with dense forest and deforestation is closelyassociated with erosion and nutrient impoverishment. Land clearing resulted in decline of organicmatter and essential plant nutrients due to decreased litter returning to the soil (Jones, 1991). Thearea comprises of hills and mountains and erosion due to water remains a very serious problem.Most of these places are left devoid of the topsoil. Surface soils are clay loam, loam, or sandylooms with clay content ranging 9-48% (Jones, 1991). Valleys have deeper soils owing tosedimentation from the hills. The soil reaction is ranges from neutral to moderately alkaline. Theorganic matter content varies from 0.80 - 4.0% in which the higher values were reported fromnon-cultivated areas. The soils in cultivated areas have less N, organic carbon, exchangeable Ca,clay, CEC and sum of bases than soils in grazed areas and woodlands. The total nitrogen andorganic carbon in cultivated areas have on the average 22 - 31% less total nitrogen, organiccarbon, exchangeable Ca, CEC and sum of bases than grazing and woodlands (Jones, 1991).

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Causes of soil degradation

Soil degradation is the result of prolonged combined effects of intricately related factors. Thesefactors could be categorized as biophysical and socio-economic factors (Azbaha et al., 1996).The biophysical factors include the inherent topography of the country, climate, drought. Socio-economic factors are essentially related with the traditional land tenure, population growth andlegacy of war. Given Eritrea's topography, geological instability and steep slopes, some levels ofnatural soil erosion are inevitable. Erosion in the highlands results in few depositions andsedimentation opportunities in the lowlands. However, the natural erosion has been substantiallyaccelerated by human interaction. The intensive bombardment during the thirty years war ofliberation, the demand for fuelwood, construction materials and clearing of land for timber,fuelwood, and cultivation have contributed the widespread destruction of forests and of vegetationcover (Azbaha et al., 1996; World Bank, 1994). This in turn has affected the structural stabilityof the soils. The loss of tress and hence foliage also meant that less nitrogen returned to thesystem. With the declining availability of fuelwood, many rural communities use animal dung assource of domestic energy.

Deforestation. Studies on the natural vegetation of Eritrea are scarce. Most of the literature onthis topic are in Italian and generally are descriptions of broad vegetation types and formations.Nevertheless, it is now known that vegetation cover of the country has been greatly reducedduring the last century. The forest cover at the beginning of the century was estimated to be about30%. In 1952, it had declined to 11% (NEMP-E, 1995) and in 1960, to 5% (MOA, 1994).Recent estimates by FAO (1994), and the MOA (1994) show that this is now reduced to 0.4%.The major causes of the disappearances of the vegetation include land clearing to extractfirewood, agricultural implements and construction materials. In addition, over-grazing, improperland use, lack of improved agricultural practices, shifting cultivation and burning of grasslandshave substantially accelerated the process. The widespread destruction of vegetative cover hasaffected the structural stability of the soils. The loss of trees results in the loss of nitrogenreturning back to the system. With the decline of fuelwood, many rural communities resort to useanimal dung and biomass residues for household energy requirement thus, depriving the land ofnutrients. This loss is not in all cases replaced by either the addition of fertilizers or the plantingof leguminous plants.

Overgrazing. Livestock is an important component of the agricultural sector (FAO, 1994). Theindigenous livestock population is estimated about 1.65 million Tropical Livestock Unit(1 TLU = 250 kg). These comprise of 1,258,000 cattle, 4,153,000 goats, 851,000 sheep, 268,000equine, 185,000 camels and 2.5 million backyard chickens (Azbaha et al., 1996). FAO estimatesabout 40% of the livestock are found in the highlands. These comprise mainly of oxen used toplough the land and the rest are kept in the lowlands. The overall livestock size expressed by TLUis not markedly different from the estimated FAO carrying capacity. The issue of overgrazingamong pastoral herd remains debatable. Azbaha et al. (1996) argues that using carrying capacityand stocking rate used to determine the number of animals that theoretically can be supported onrangelands. This useful only in providing a generalized description of the ecosystem, averagedover space and time. In the Eritrean context, space and time are important indicators rather thanthe number of animals that determines the sustainable carrying capacity of the system. In thehighlands sedentary agriculture, livestock have contributed substantially to land degradationprimarily because of lack of mobility and lack of feed during the dry season. During the rainyseason, most of the southern and central highlands are cultivated and animals do not get enoughgrazing areas. Consequently, in localized areas (water holes, routes etc.), trampling the soilduring the wet season results in localized compaction. The same is also reported by Jones (1991)


in the northern midlands agro-ecological zones of Eritrea. Compaction results in poor infiltrationand causes accelerated runoff. The net result is creation of gullies and poor regeneration ofvegetation.

Soil mismanagement. In Eritrea, the traditional land tenure varies from place to place (Nadel,1946; Ambaye, 1964; Jordan 1989; Kidane, 1992). Until recently, there were three main systems:Resti (family ownership), the Diessa (village or collective ownership) and Demaniale (stateownership). In Resti system, land is acquired by occupation, purchase or grant by rulers andcould be individual or institutional such as the church. The ultimate ownership resides onextended family who have pioneered the earliest settlement in an area. An individual landholdercan cultivate the land and arrange share cropping but cannot sell to an outsider without theconsent of his extended family (Azbaha et al., 1996). In this land tenure system, unlikeagricultural land, pasture land is communally owned. Diessa land tenure system is village-wideownership of land (Azbaha et al., 1996) and prevails mainly in the highlands of Eritrea. Landbelongs to the village community and is managed by a committee of village elders that establishcriteria for eligibility for the full share of crop fields. The crop fields are subject to redistributionevery 5-7 years. To ensure equitable distribution of land, the various land categories areclassified into very fertile, fertile and poor soils. A household is entitled for a field in each groupwhich could be located in different sites. These have resulted into an increasingly fragmentedparcels of land that are difficult to manage.

The increasingly small sized parcels, also force farmers to plough against the contourexacerbating the risk of soil erosion. Moreover, it has also diminished the willingness of thefarmers to practice effective soil and water conservation. In the current situation, it is difficult toshare water channels. Village ownership of land does not favour the integration of multi-purposeperennial trees and crops. Besides, integration of livestock into the system is difficult essentiallybecause the grazing resources are communally managed. This hinders the potential benefit of thelivestock to soil fertility. These happen because the community members are aware that their landwould be given to another farmer in the following land redistribution. Demaniale refers to stateownership of land. Italians introduced Demaniale by confiscating holdings of the indigenouspopulation. In the lowlands, all areas were declared as Demaniale. During the British rule,confiscation of land was in favour of demobilized Italian soldiers (Mesghina, 1988). TheDemaniale lands have been open to access to every body. Open access and unregulated land usesystem is believed to have subjected land to abuse. While Demaniale opens land to abuse Diessaand Resti lead to land mismanagement. In addition, land in Resti and Diessa suffers from poormaintenance, lack or shortening of the fallowing period and has a negative impact on theagricultural productivity of the soil. Furthermore, the rapid population pressure has led tosuccessive fragmentation of arable land and the unscrupulous cutting of trees which are typicalevidences of land mismanagement.

Population pressure. Above sixty percent of the Eritrean population live in the highlands thataccounts only to about 5-10% of the total land mass of the country. This area was once verysuitable for the production. However, steady increase in human population over the past decadeshas led to the fragmentation of holdings and the pressure to move into marginal land. Period offallowing have been reduced while the continued use of low level of technology and inputs havecompounded the depletion of soil fertility in most parts of the highlands.

Biophysical impacts

The biophysical impacts of land degradation are reduction in the organic content of the soil andloose soil structure. Moreover, erosion by water creates huge gullies and results in the reduction

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of agricultural lands. Poor organic matter in the soil accelerates leaching of the essential elementsthat is essential nutrient to crop and thus results in decline of productivity. Losses of vegetativecover and grazing areas have also equally important consequences on the overall production.

Economic impacts

Reliable data on the economic impact of land degradation in Eritrea are scanty. However, Thereis a decline in agricultural production in all parts of the country owing to loss of fertility. Yieldhas dramatically declined by 1/3 during the past three decades. Consequently, farmers dependlargely on sale of animals, animal products and other off-farm activities. Currently the trend ismost families are not self sufficient with their domestic grain demands. The constant food deficitis exerting more pressure to the resource base of the country. The average yields of the majorcrops in the Central Zone are shown in Table 3. The data presented in this table show also thatthe there is a gradual decline in yield of all the cereals grown in the highlands. This could becorrected in the short term by applying commercial fertilizers.

TABLE 3Yield of crops on farmers’ fields without fertilizers in Central Zone (quintals/ha)

Crop 1992-93 1994 1995 Average

Barley 11.70 9.40 8.96 10.10Wheat 9.63 7.11 7.28 8.00Maize 8.45 10.00 5.88 8.11Sorghum 4.90 7.97 1.32 4.72Taff 2.89 4.80 1.72 3.17Pearl Millet 5.90 10.70 0.68 5.76Finger Millet 8.24 4.80 2.00 5.01

Source: Azbana et al., 1996

The data in Table 4 show that there is a potential to enhance production by addingcommercial fertilizers. Yield has increased by 40.7%, 42.2% and 45% in barley, wheat andsorghum thanks to the application of 50 kg of DAP.

TABLE 4Yield increase of fertilized wheat, barley and sorghum in two locations (quintals/ha)

Crop Yield withoutfertilizers

Yield withfertilizer

Difference Increase

quintals/ha quintals/ha quintals/ha %Barley 14.46 20.35 5.89 40.73Wheat 13.50 19.20 5.70 42.20Sorghum 23.18 33.75 10.57 45.59

Source : Azbana et al., 1996


National activities

The technological options so far are limited. Since independence, the Government of the State ofEritrea has taken top priority activities related to soil and water conservation as shown inTable 5. Most land rehabilitation and the soil and water conservation activities are on hillsides.Local farmers do the work in turn of Food for Work (FOP) and Cash for Work Programmes(CFW). At the moment, there are no scientific evidences on the impact of these activities on theagricultural productivity. In spite of this however, the vegetation in enclosures is regenerating


well. Earth dams and ponds have made significant contribution to alleviate the shortage ofpotable water. However, many of the earth dams in the country are not fully exploited forirrigation purposes. In recent years, terracing, earth bounds and soil conservation measures havealso been expanded to agricultural fields. The success of such initiatives will depend eventuallyon the land tenure reform. Personal observation indicates that fields with earth bounds, checkdams and terraces have improved yield owing to better moisture holding capacity. However, thisrequires to be substantiated with quantitative data and hence a detailed study.

TABLE 5Soil and water conservation activities so far undertaken in Eritrea

YearActivities1992 1993 1994 1995 1996 Total

Hillside terraces(km)

55 891 25 276 11 678 12 010 4 223.5 109 078.5

Check dam (km) 1 183 606 174 347 72.5 2 382.5Microbasins 145 174 208 888 241 757 177 821 7 000 780 640

Seedling produced 18 918 622 18 966 312 10 021 137 13 577 096 8 621 373 70 104 540Planting & replantingnurseries

17 644 893 17 166 642 7 790 116 11 870 528 4 164 165 58 636 344

Nurseriesestablished

10 19 11 4 2 46

Closures (km) 49 942 22 589 4 503 34 966 9 805 121 805Earth dams 51 24 11 30 15 131Ponds 19 54 18 17 5 113Wells 33 34 22 13 3 105Embankments (km) 171 119 103 105 2 500Canals (km) 0 7 3 2 28.6 40.6Diversions (km) 0 1 3 4 - 8

Source: MOA, 1997

Research station activities

There are attempts to measure runoff and rate of erosion at experimental station in Afdeyu,Eritrea. Assessment was made to study the impact of different land use systems on the rate oferosion. Some results of these experiments are shown in Table 6. These show that the traditionaltest plot 2 was able to adequately control soil erosion and runoff, since the erosion level remainedat tolerable rate. Test plots 1, and 4 experienced significant differences mainly due to slope. Allwere similar to vegetative cover (Gunder and Karl, 1987).

TABLE 6Test plot (2m x 15 m) runoff and soil loss results, Afdeyu

Slope Test Plot Cover Soil Loss Runoff Runoff

(%) (No) (T/ha) (mm) (%)2 2 maize 8.30 34.10 8.910 3 grass 23.7 165.80 43.131 1 grass 44.50 188.90 49.165 4 grass 33.2 150.90 39.2

Source: Gunder and Karl, 1987

Traditional activities

In Eritrea, the different groups have adopted methods to combat soil erosion. These methodsinclude stone bounds, earth bounds, stone walled diversions, structure across slopes, ridgingalong contour and leaving stand trees in agricultural fields. However, the level of application of

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the technique or group of techniques varies from one socio-economic groups to another as shownin Table 7. In addition to combating the adverse effects of erosion, farmers in Eritrea have alsodeveloped various methods to tackle decline in soil fertility. Gaim (1996) indicated that none ofthe socio-economic groups in Eritrea use forest fallow. Except for the Maria, none of the groupsused commercial fertilizers. The different coping strategies across the different groups are shownin Table 8. In some areas in Eritrea, where land was periodically redistributed, most people livedwithin the margins of subsistence. In order to catch up the annual subsistence, every farmer hadto increase its labour.

TABLE 7Common methods applied to counter soil erosion by socio-economic groups of Eritrea

Methods II III IV V VI VII VIII IX

Stone walled terraces ++++ +++ - ++ + ++++ - +++Earth bunds ++++ ++ - + + +++ + +++Stone walled diversions ++++ ++ - + - ++++ - ++Structures across slopes ++++ ++ - + ++ +++ - +Ridging along the contour ++++ + - - - ++ - +Stand of trees ++++ + - + ++ +++ - ++Barriers of bushed toaccumulate debris in gullies

++ ++ - + + +++ + +

Source: Gaim Kebreab, 1996Notes: II = Tigringya, III = Saho, IV = Benamer, V= Maria, VI = Nara, VII= Bilen, VIII= Hedareb, IX=Beitjuk; ++++ = used by all respondents, +++= used by 75% of respondents, ++= used by 50% of therespondents, += used by 25% of respondents and - = not used or 0 -25%.

TABLE 8Traditional knowledge techniques applied to counter fertility decline in Eritrea

Methods II III IV V VI VII VIII IX

Forest fallow - - - - - - - -Bush fallow - - +++ ++ ++++ - ++++ -Short fallow + ++ ++ ++ ++ + ++ +Organic manure ++++ ++ - + ++ +++ + +++Fertilizer - - - + - - - -Crop Rotation ++++ ++ - - - +++ - ++Inter-cropping ++++ + - - - +++ - +++Vegetation burning + + + - ++ ++ + -

Source: Gaim Kebreab, 1996

SUCCESSFUL CASES OF IMPROVED SOIL MANAGEMENT

Large scale improved soil management schemes are not common in the country. Since 1995,however, there are some efforts aimed at introducing soil management packages. These includedistribution of fertilizers to farmers, Vertisol and spate irrigation management.

Vertisol management

The sub-zone of Adiquala is one of the agricultural potential areas in Eritrea. It is located in thesouth mid-altitude agro-ecological zone of the country. The main soil types in this area arevertisols that are characterized by poor drainage particularly during the wet season. Poordrainage hampers early seedling growth and development of crops grown in the area. Recently, totackle this problem, Vertisols management programmes were introduced on a small scale. Inaddition, commercial fertilizers are distributed to farmers on credit through SASAKAWA global2000. Although the programme is new, it is gaining wide acceptance by the farmers. In 1996, it


was launched at a pilot level and in the following year it was expanded to include a large numberof farmers interested in the scheme. The results from the last two concurrent years indicate thatyield of major cereal crops have almost tripled (Table 9).

TABLE 9Yield in Quintals/ha of Treated and Non-treated Fields in Sub-Zone, Adiquala

Yield (Quintals/ha)Crop

Fertilizer + VertisolManagement

No Treatment Yield Difference(%)

Taff 17 4 76.5Wheat 26 6 76.9Sorghum 30 7 76.7Maize 34 8 76.5

Source: Ministry of Agriculture, Sub zone Adiquala, Eritrea.

Vertisol management and application of fertilizers is now integrated at a pilot projectencompassing few farmers. In the future, there are plans to expand to other areas with similarproblem (Yemane, Head ministry of agriculture, Sub-zone Adiquala, personal communication).Having seen the extraordinary increase in yield, farmers are requesting for the technology. This isbecause application of fertilizer to the field improved the fertility status of their land. The result issignificant improvement on yield of cereals such as wheat, maize and taff as shown in Table 4.Higher yields are expected from combination of fertilizers with vertisol management. Thepossible reasons for the success of these activities are the:

• Use of simple and relatively cheap equipment to prepare drainage canals,

• Use of farmers’ experience and local knowledge and their involvement on voluntary basis inthe diagnosis and implementation of the programme,

• Conducting of on-farm demonstration and training and

• Access to credit for fertilizers and pesticides.

Management of spate irrigation

World Bank (1994) estimated the total irrigated area in Eritrea to be about 20 000 ha of whichabout 10 000 ha is under spate irrigation in the coastal plains agro-ecological zone of Eritrea.The major areas under spate irrigation are Sheeb, Wokiro, Shebah, Figret, Zula and Wadilo. Inthis system, the seasonal floods are diverted to grow sorghum, maize, pearl millet and variousvegetables. The major problems in this area include sedimentation of diversion canals anduncontrolled flow of floods. Occasionally field canals and diversion canals are destroyed andcause damage to agricultural fields. Farmers maintain the canals using branches of Acacia trees.For this purpose, a large area of the woodland is cleared resulting in land degradation. Efforts areunderway to improve the diversion canals and to construct reinforced concrete structures. In someareas, like Sheeb the diversion canal is already completed and in others it is in process. Theobjectives of these activities are to ensure a sustainable distribution of water to the agriculturalareas and environmental restoration.

INSTITUTIONAL FRAMEWORK AND POLICIES FOR LAND RESOURCES MANAGEMENT

Traditional Institutions

According to Gaim (1996) institutions influence human choices by influencing the availability ofinformation and resources, shaping incentives and establishing the rules and social transactions.

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In Eritrea, there were eight customary laws (Gaim, 1996). These laws included land tenure, landmanagement, civil law, family law, and penal laws. Today, these institutions are gradually beingreplaced by new laws. These institutions were created in response to severe competition for landamong the users group. The main functions of these laws were to regulate access to and use ofland, arbitration and conciliation forceful sanctions such as group morality and public opinion(Nadel, 1946b). The codes of customary laws contain a wealth of information regarding thetraditional resource management systems. Eritrea represents a wealth of mosaic tradition andculture originating from varied socio-economic background of the population. The diversity of thecountry in terms of ecology and topography is also considerable. It is therefore difficult to makegeneralized statements about the land tenure and land management practices. Nevertheless in allcases, decisions were made by consensus i.e. collective agreement on the utilization of scarce landand water resources. The Diessa land tenure system is which the land distribution is madeperiodically by the village council has been questioned by Gaim (1996). The author raised theissue of incentives to the farmers, investment on the land, over-use and under-investment becauseof the possibility of transfer to the next allocate”.

Government Institutions

The Government of the State of Eritrea is in the process of coordinating its activities. At themoment, soil management is dealt within two ministries namely the Ministry of Agriculture andthe Ministry of Land Water and Environment. The Government has fully recognized theeconomic importance of agriculture and the following objectives are set by the Ministry ofAgriculture (MOA, 1997):

• Food security through the promotion of improved technology,

• Employment generation through the establishment of labour intensive activities,

• Improve the supply of raw materials to domestic industries by encouraging the farmers toproduce industrial raw materials,

• Increased foreign exchange earnings through direct and indirect export promotion strategies,

• Environmental protection and restoration and

• Sustainable satisfaction on the demand for fuel wood and construction materials.

To date, there are no formulated comprehensive soil management policies. In the future, thereis a need to set soil management objectives with clear institutional responsibilities. Soilmanagement activities should be integrated with forestry, soil, water conservation and irrigation.Soil management should include both water resource management and rehabilitation of degradedlands. Hence, activities carried out by the Ministry of Agriculture and Land Water andEnvironment need to be coordinated. The Government of the State of Eritrea has promulgated anew land law (Government of The State of Eritrea, Proclamation 58/1994). The new law willeventually replace the traditional land tenure system. The proclamation guarantees all Eritreansabove 18 years of age irrespective of marital status or ethnic affinity usufruct right. The Ministryof land, Water and Environment is responsible for the allocation of land on equitable basis. Thisnew land law would confirm security of tenure and thus increase inputs environmental protectionsuch as planting of trees, building of terraces and application of fertilizers and manure. The newland law provides farmers with lifetime right of usufruct over currently held land thereby doingaway with periodic redistribution of land. The life time usufruct is expected to substantiallyimprove incentives favourable to sustainable use of land. Currently, soil management fallsbroadly under the Ministry of Agriculture and the Land Water and Environment. Both ministries


have baseline information and carry out field activities. The department of Environment has asupervisory role. The current situation in these ministries have limited effectiveness to soilmanagement. It is, therefore, imperative to introduce integrated soil management to boostagricultural production. The issue of soil management needs to be given due consideration. It isalso important that law is required to protect investment on land management (commercialinvestment or management infrastructure) as investors are rarely prepared in the absence of law.The present lack of law, policy and strategy on soil management in Eritrea is a severe constraintto the development of agricultural production. The present laws, proclamations and strategies areonly in draft forms and that the constitution is promulgated and gazetted for further gazettementof all legislation, policies and strategies should not be far.

Allocating soil management responsibilities. During the transition period, care should be takento avoid confusion on land management responsibilities. Allocation of responsibilities should beset in short and long-term perspectives. In the short-term, responsibilities could rest with thecentral government with grass root participation at village level. In the long-term, however,responsibilities may be transferred to the regional institutions. In the highland, land has beensubjected to heavy human and animal pressure over many centuries (Gaim, 1996). That it hasbeen able to support the growing population in the context of available technologies might be dueto our failure to understand the copping strategies adopted by the farmers. Gaim (1996) believesthat the rules were enforced and conventions methods have evolved over time in response to theneed to derive resources of livelihood from fixed or diminishing resources in the context ofunstable environment.

Legislation. There is a need for clarification and co-ordination of legislation related to soilmanagement. The need for effective and coherent legislation on soil management is immediatewith clear mandate to implement soil management. Other significant social factors like foodsecurity and land tenure need to be considered seriously. Integrated soil management legislationcould be implemented by the Ministry of Agriculture. In this regard, the role of the centralgovernment would be to provide skilled personnel, funds, technical assistance and equipment ifnecessary. At the same time, it could issue policies, legislation and working guidelines in co-operation with the local government. The role of the zones and sub-zones would be to implementthe national action plan in co-operation with local communities. Initiatives, however, would haveto be generated from the communities. At grass root level, the villages being the directbeneficiaries of soil management activities, implementation should be done with full participationof the villagers. The technical skills of personnel at the zones, sub zone and the villages levelsshould upgraded through on job training.

PROPOSALS OF PROGRAMMES FOR IMPROVED SOIL MANAGEMENT AND PRODUCTIVITYENHANCING

Most parts of Eritrea suffer from serious soil erosion and depletion of soil fertility. Integrated soilmanagement strategies should be adopted to eliminate the causes of land degradation. The currentsituation of food production trends in Eritrea could be improved if a combination of the followingimproved soil management enhancement programmes would be adopted.

• The new land law should be implemented so as to promote investment on land, trees, soil,water conservation structures and fertilizers. In addition, soil management and maintenancestrategies of soil and water conservation structures should be enforced at a village level.

Eritrea194

• Alternative sources of energy should be explored to alleviate the chronic shortage of domesticenergy. The use animal dung has detrimental effect on soil fertility and hence production.

• Introduction of multipurpose perennial trees and grasses to restore fertility status and reducesoil erosion.

• Reclamation of degraded lands (sand dunes, gullies and marginal lands) through constructionof mechanical structures and planting trees. In the coastal areas, drought and salinity tolerantmultipurpose trees should be identified and tested in multi-locational trials.

• Tree planting should be promoted at individual household levels. Appropriate tree selectioncould be done in collaboration with local farmers. These trees should include exotic andindigenous browse and fodder species.

• Studies on the indigenous soil and water conservation practices and soil fertility maintenancestrategies should be undertaken. This would provide baseline information for further studiesand action. Introduction of soil management practices should be based on the existing socio-economic and ecological setting of Eritrea. This would require a multidisciplinary researchteam and participatory research approach.

• There is an urgent need to assess the erodability of soils in catchment areas as well measurethe sedimentation process in down streams and reservoirs.

• Dissemination of improved soil management practices at farm level. Preferably, this could bean action-oriented research to address immediate farmers' problems.

• There is a dire need to undertake on-farm training and education particularly to farmers andextension workers. The training would include issues related to the importance of integratedsoil management practices in boosting agricultural production and environmentalrehabilitation. The effect of narrow grass strips, and conservation tillage on soil erosion andyield of crops should be assessed.

• In Eritrea, the conservation and rangeland management is usually overlooked whileconsidering soil management options. It is time to reconsider possible techniques to improvegrazing areas and reduce land degradation. Studies should be conducted to investigate theeffect of overgrazing on soil degradation.

• Under the arid situation in Eritrea, emphasis should be given to the conservation and efficientutilization of water resources. Focus should be given to spate irrigation and runoff harvestingnot only for crop production but also to improve the quality of browse to the pastoralcommunities.

• Provision of soft loans to needy farmers and reward to exemplary farmers who practicesustainable soil management in their fields.

REFERENCES

Appleton, J. A., M. S. Bellmans and Reynolds 1992. Observations on food Security nutrition anddemand for fish in Eritrea. Department of Marine resources and Inland Fisheries, Asmara, Eritrea.

Araia, W., M. K. Omer, A. Haile and W. Ogbazghi 1994. Resource-Base, Food Policies and FoodSecurity. In 'Inducing Food Insecurity Perspectives on Food Policies in Eastern and SouthernAfrica,' Ed. M.A. Mohammed Saleh, The Nordic African Institute, Uppsala, Sweden.

Awalom, H. 1996. A research proposal on food security in Eritrea: an overview. Unpublished MOAEritrea.


Azbaha et.al., G. Iyassu, W. Ogbazghi, K. O. Mohammed, W. Araia, Tesfaselassi and Ghiday 1996.Rehabilitation of Degraded Lands in Eritrea. University of Asmara, MOA and IDRC. Asmara,Eritrea.

Biswas, Asit K. And Biswas M.R. eds. 1980. United nations Conference on Desertification. Oxford,Pergamon Bojo 1995. Rehabilitation of Degraded Lands In Eritrea. World Bank Report.

Cliffe, L. 1988. Food and agricultural production assessment study: an independent evaluation of thefood situation Eritrea. Agriculture and rural development studies, University of Leeds.

Cook R. L. And Boyd G. E 1992. Soil Management, A World View of Conservation and Production.Krieger Publishing Company, Malabar, Florida.

FAO 1994. Agricultural Sector Review and Project Identification. FAO, Rome.

FAO/MOA 1996. Formulation of a national Food security and Nutrition Programme. A report onWorking sessions, Keren, Eritrea.

Fisseha, A. 1995. The role of Eritrean rural women in the fight against desertification. A paperpresented at the IGADD sub-regional workshop in Asmara, 1-3 August 1995.

Gaim, K. 1996. People on the edge of the horn. Red Sea Press.

Ghebru, B. and Asefaw Tekeste, 1995. A case of disaster Profile: The Eritrean Experience. UN DisasterManagement Training Programme for Africa. Eritrea-National Work shop 20-24 Feb. 1995.

GOE 1994. Proclamation of the State of Eritrea No 58/1994 on changes on land holding and useprocedures. Government of the State of Eritrea 1994. Macro-Policy.

Grunder. M. and Karl H. 1997. Soil Conservation Research Project. Vol. 8. Seventh progress Report.University of Berne, Switherlanl.

GTZ 1991. Integrated Food Security Programmes. Agricultural services and food security, OE 421.

Haile, A., W. Araia, M. K. Omer, W. Ogbazghi and M. Tewolde 1995. Diagnostic Farming SystemsSurvey in South Western Hamasien Eritrea. CAAS, University of Asmara, Eritrea.

IGADD 1996. Food Situation Report, No. 1/96, IGADD, Early warning and food information System,Djibouti.

Jones, P. S 1991. Restoration of Juniperus exelsa and Olea europaea sub sp africana in woodland inEritrea. A Ph.D. Thesis, Department of Biological and Molecular Sciences, University of Stirling,Scotland.

Leach M. and James Fairhed 1994. Natural Resource Management: The Reproduction and Use ofEnvironmental Mismanagement in Guinea's Forest-Savannah Transition Zone. ids bulletin 25 no 21994.

Maskey R. B. 1985. Soils their Fertility and management in Eritrea. University of Asmara. Unpublished.

MOA 1997. The State of Eritrea's experience on the implementation of UN-CCD

MOA 1992. Annual Report. Asmara, Eritrea.

Murphy H.F.1959. A report on the Fertility Status of Some Soils Of Ethiopia. Experimental StationBulletin No 1. Imperial Ethiopian College of Agriculture and Mechanical Arts.

Nadel. F. S. 1946b. Land Tenure in the Eritrean Plateau. Journal of International African Institute VOl.XII No1.

Nyborg, I. and R. Haug 1994. Food security indicators for development activities by Norwegian NGO'Sin Mali, Ethiopia and Eritrea. The SSE program, NORAGRIC.

Riley, Frank 1995. Addressing Food Insecurity in Eritrea. A report prepared for World FoodProgramme/ Eritrea Draft.

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Tecleab M. and B. Ghebru. 1997. Analytical Review of the National Agricultural Research SystemNARS in Eritrea.

Tesfay G. 1992. Agricultural Development in Eritrea. A Paper Presented at the Economic PolicyConference 15-19, July 1991, Asmara, Eritrea.

Thomas D. B. E. K. Biamah, A. M. Kilewe, L. Lundgren and B. O. Mochge 1986. Soil Conservation inKenya. Department of Agricultural Engineering, University of Nairobi and SIDA.

UNICEF 1994. Children and Women in Eritrea.

World Bank 1994. Eritrea options and Strategies for Growth Vol I-II reports No 12930-ER, WashingtonD.C. world Bank.

Yemane M. 1988. Italian Colonialism, the case Study of Eritrea 1869- 1934. Lund, Sweden.


Ethiopia


The total area of the country is 1.1 million square kilometres out of which about 79 millionhectares are suitable for agriculture, although only approximately 7 million hectares are used forcrop production in any one year (FAO, 1986). Economically, the highland zone is important asmost of the economic activities are concentrated in this zone. Although large portions of thehighlands are put under continuous cultivation, the total amount of grain produced every year isvery low. It is estimated that yields on the overall are about 10 q/ha for cereals, which isconsidered very low as compared to the potential yield of these crops. This is mainly due to theextremely low level of plant nutrients in the soil that does not allow the crops to express theirpotential yields, even in areas where there are no moisture limitations. In the majority of thehighlands that have been settled for several centuries, the soils have been continuously mined fornutrients through harvests and soil erosion. The yield of crops in most areas has continuouslydeclined and in some cases has reached a point where the soils can no longer support plantgrowth. Except in some alluvial plains, where the soils are recharged every year with top soilscarried away from over-lying areas, the productivity of the majority of the highland soils havereached the lowest level.

Ethiopia is the second most populous country in sub-Saharan Africa, with a population ofmore than 55 million and a growth rate of 2.4% per annum, of which 89% lives in the rural areas.The country's social indicators are among the lowest in the world, with over half the populationsuffering from chronic food insecurity. Out of the total potentially arable land, only 14.8% arecurrently under production of annual and perennial crops. In general, cereals are the mostimportant crops occupying about 76.3% of the total cropped area and 70% of the caloric intakeof the population. The remaining is occupied by pulse and oil crops (2.1%), coffee (5.1%), fruitsand vegetables (1%), and cotton (0.8%). Out of the estimated total annual cereal crops output(average of 9-10 million metric tons) the contribution of the small holder farmers is about 96%.Recurrent draught and consequent depletion of assets of peasant farmers have made theagricultural sector weak and vulnerable (World Bank, 1995).

Despite the enormous agricultural resource base, the country has been facing reduced cropproduction and food insecurity during the last two decades, since 1970. Recurring draughtperiods had significant effect on crop yields. By 1990, the balance between food production andpopulation growth had worsened. The per caput calorie intake per day had decreased dramaticallyfrom around 1 740 in 1983 to 1 550 in subsequent years. Considering the cereals contribution tothe national diet (70-80%), it was estimated that additional gross production of 5 million tons peryear were needed to meet the populations food requirement and avoid famine in the nineties(Bateno, 1997).

For generations, Ethiopian farmers have been producing at subsistence level. This is mainlydue to limited access to modern research-led agricultural technologies, including inputs such asfertilizers and organic matter.

Sahlemedhin SertsuNational Soil Research Laboratory, Ministry of Agriculture, Addis Ababa

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Traditional farming systems are low yielding due to excessive depletion of plant nutrient,and as a result farmers are continuously forced to expand their territory of cultivation to marginallands that are prone to excessive erosion. All these and other factors have resulted in low cerealcrops yield, hence, excessively lowering the total grain production of the country (Table 1).

The possibility of expanding the areas under crops in the central highlands is severelylimited, due to the growing population pressure and the large number of livestock herds. Landscarcity has led to increasing the cropped area at the expense of both fallow and grazing, withcrops being grown on more marginal, steep and poorly drained lands that are more susceptible toerosion. Moving to the sparsely populated lowland areas (expansion to virgin areas) is restricteddue to human and livestock diseases, and unavailability of public service facilities, etc. Estimatedfood production and requirement balances for the country from two sources are shown in Tables2 and 3.

TABLE 1Major cereal crops grown in Ethiopia: average area, total production and yield, 1990-92

Crops Area (hectares) Production (Mt.) Average yield(quintals)

Teff 1,318 1,028 7,8Maize 1,000 1,605 16.1Sorghum 813 899 11.1Barley 950 914 9.9Wheat 687 886 12.9

Source: FAO computer files AGROSTAT/PC (quoted by Belay, 1997)

TABLE 2Food production and requirement balance up to the end of the century

YearsItems Unit94 95 96 97 98 99

Population Projection @2.7%/year

Million 54.43 55.90 57.41 58.96 60.55 62.19

Per caput food grain requirement(cereals + pulses)

kg/year 134.00 136.00 138.00 142.00 146.00 150.00

Total net food grain requirement(row 1x2)1,000

milliontons

7.29 7.60 7.92 8.37 8.84 9.33

Gross food grain requirementincluding wastes & seed (@ 15%)

milliontons

8.38 8.74 9.11 9.63 10.17 10.73

Domestic output with incremental fertilizer useI) assumed growth rate % 3.00 3.00 3.10 3.20 3.30 3.40II) estimated production million

tons7.60 7.83 8.07 8.33 8.60 8.89

Estimated food sap (Row 4- 5 (II) milliontons

0.78 0.91 1.04 1.30 1.57 1.84

Source: World Development Report, 1993 (quoted by World Bank, 1995)

Even though an extensive area of land is cultivated each year and the size of the populationengaged in the farming business is very large, the total annual food production is always muchbelow the national requirement. Although a number of natural, socio-economical and politicalreasons could be attributed to the low crop productivity, the major ones are:

• Extreme exhaustion of nutrients and degradation of the soils as a result of several centuries ofcontinuous cultivation, particularly on the highlands, with little to no external inputs and verylow level of soil management thus exposing the land to extreme soil erosion and degradation,

• The total dependence of crop production on rainfall, which is very erratic from year to year inboth amount and distribution,


• Fast population growth as compared to the stagnant level of crop production, which alsoincreased the stress on agricultural land and decreased yield per unit area,

• Excessive land fragmentation, redistribution and tenure system which made farmersindifferent in utilization of improved land management techniques,

• Inability of the majority of farmers to purchase and use essential inputs like fertilizers andutilization of every farm residue for household purposes rather than adding to the soil.

There are a number of reasons for the low level of chemical fertilizer used by farmers, themajor one being the high fertilizer price. The data in Table 4 show the results of a socio-economicsurvey conducted in one region which indicated the reasons given by farmers for the limited useof fertilizers.

TABLE 3Food requirement and balance for the period between 1979-80 and 1988-89

Period Population Food production(tonnes)

Food production percaput per year (kg)

Calories percaput per day

1978-80 37 758 000 7 495 580 199 1 8541980-81 38 966 000 6 560 523 163 1 5181981-82 40 213 000 6 296 217 157 1 4631982-83 41 500 000 7 805 370 188 1 7511983-84 42 828 000 6 336 604 148 1 3791984-85 44 255 000 4 855 301 110 1 0251985-86 45 737 000 5 403 657 118 1 0991986-87 47 189 000 6 261 697 133 1 2391987-88 48 587 000 6 769 778 139 1 2951988-89 50 167 000 6 375 812 127 1 183Average 6 416 054 148 1 380

Sources: C.S.A. 1991. The 1984 population and housing census of Ethiopia, Analytical Report atNational level, pp 307, Addis Ababa; Wheat equivalent 340 calories/100g, ENI. Gunnor Agren andRosaline Gibson, Food composition Table for use in Ethiopia

TABLE 4Farmers view on fertilizer consumption

Reason for low use of fertilizers No. of households %Expensive 1 532 61.3Unavailable 284 11.4No difference in production 69 2.8Lack of knowledge about fertilizers 524 21.0Others 89 3.5Total 2 489 100.0

Source: UNDP, SAERP/WARDIS PROJECT in Tigray Region, January, 1997.


Cultivated land against population growth

The agriculture sector of Ethiopia accounts for 41% of the GDP, 90% of the foreign exchangeearnings and 85% of the employment. Although the total area of the potentially arable land isestimated to be about 79 million hectares, only about 14.8% of it is cultivated at present. Out ofthe estimated 3.5 million hectares of potentially irrigable areas, no more than 0.1 million hectaresare currently under irrigation (Berhe, 1995). In spite of such high potentials for increasingproductivity, the expansion in the area of cultivated land is very little as compared to populationgrowth. As a result of excessive soil degradation and nutrient exhaustion, yield per unit area is

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also decreasing rather than increasing. The size of the population, however, seems to increasesteadily at the rate of 2.7% per annum. Under such circumstances, recurrent famine and hungerare inevitable. In order to meet the food requirement of the growing population, crop productionhas to be increased through improved management technologies, appropriate land tenure, andagricultural policies. Evolution of land use and the change in cultivated land compared topopulation growth from 1961 to 1991 is shown in Table 5. These data indicate that the increasein the area of cultivated land is about 20% during the 30 years, while the population growth isabout 150% during the same period.

Irrigated land increased from 150 000 ha in 1961 to 162 000 ha in 1991, which is still verylow compared to the potentially irrigable area of 3.5 million ha. The increase in cultivated landarea does not keep pace with the population growth. As a result, the per caput land decreased bymore than half. The data also show that the 20% increase in the cultivated land area was at theexpense of the pasture and the forestland. The other significant shift as a result of populationgrowth is the increase by about 10% of the land in the "others" category, which is the wastelandthat increased as a result of degradation of the cultivated land.

TABLE 5Population growth, and of land use and cultivated land (ha) per caput evolution, 1961-91

Year Population Cultivatedland

Pasture Forest Others Cultivated landper-caput

1961 20 000 11 486a) 486b) 11 000

46 350 30 000 22 264 0.574

1991 50 000 13 930a)730 b)13 200

44 850 27 000 24 320 0.279

Variation + 3 000 + 2 444 - 1 500 - 3 000 +2 056 - 0.295Sources: FAO 1993 (Jassen and Willekens, 1994); 1991. Population and housing census of Ethiopia.Notes : (a) permanent land, (b) annual + irrigated

Major causes of low productivity

The majority of the farmers land holdings are too small to be economically viable through the useof inputs, mechanization and efficient utilization of time and labour. This affects highly theproductivity of farmland. The fact that the land belongs to the Government and continuousreallocations and redistribution of land have been taking place in the past and is still occurring atpresent, has taken away the sense of ownership from the farmers. Such lack of ownership resultsin less commitment for the conservation and better management of soils and other land resourcesthat are essential for improving agricultural productivity, hence, bringing about excessive landdegradation and continuously declining productivity. The lack of ownership to the land has amultiple effect on soil and land management and agricultural productivity. The fact that a farmernever feels sure of maintaining his land to be able to pass it to his children or to sell it any time hewants, prevents him from investing on his land for long-term rewards. Because, he always thinksthat the part or whole of his land could be passed to another person, if officials feel to do so. Thismeans, farmers have the tendency to make the land less attractive to others, i.e. less productiveand degraded. In other words, they try to use the land for a longer time with little investment andeffort, before the land is fragmented and passed to another person, without compensation forpermanent crops, if they at all have established one. The major land improvement incentives tothe farmers in Ethiopia, particularly for soil conservation works, are the grain and oil rations thatare issued as part of the food for work programme. Such programme, although, has run for along time, was not found to be successful. The lack of success was mainly because most of thefarmers consider the grain and oil incentives as a source of rations rather than soil management


incentives, resulting in piling and unpiling of stone-bund terraces on the same piece of land everyyear.

Research outcomes have shown that the majority of the cereal cultivated land on thehighlands are highly responsive to N and P fertilizers because of the high exhaustion of thesenutrients from the soils as a result of several decades of continuous cultivation. Althoughimproved seeds and N and P fertilizers are known to increase the yields of the majority of thecereal crops highly, the consumption of fertilizer in the country is still very low (not more than anaverage of 7 kg of nutrients per ha of cultivated land). The major reasons for the use of low levelof fertilizer are believed to be: (i) limited availability of fertilizers (all imported), ii) limitations ofroad infrastructure for timely supply of fertilizers to all corners of the country, iii) the lack ofknow-how from the farmers side, iv) limited extension services, and v) the high price of fertilizersas a result of elimination of fertilizer subsidy in recent years.

Traditionally, most farmers are aware about the importance of the common culturalpractices like crop rotation and fallowing for the maintenance of soil productivity. With theincrease of population that decreased the per caput land holdings, the practice of fallowing hasbeen gradually abandoned and the majority of the land is put under continuous cultivation.Moreover, the tradition of rotation of cereals with pulse and oil crops have also become less andless popular. This is because of the high demand for certain cereals on the market which force thefarmers to grow specific cereal crop year after year in order to get high market price and be ableto survive on their small piece of land. The result of elimination of fallow system, completeutilization of crop residues and the lack of rotation of cereals with pulses have caused excessivesoil nutrient exhaustion and the ultimate low yield. Unchecked population growth andoverstocking have resulted in encroachment to steep slopes and ecologically precarious areas tomeet the need for food and grazing. Such encroachment followed by removal of naturalvegetation and improper land use practices has resulted in the degradation of the cultivated land,eventually converting it to bad land. Such degradation poses the greatest long-term threat tohuman survival in Ethiopia and remains to be one of the greatest challenges facing the people andthe Government today. Under the traditional tenure system, land has been continuously sub-divided among farming members through generation inheritance claims. Reallocation of land bypeasant associations earlier and by Regional Government Officials lately, has also resulted in anever-decreased holding of parcels of land by the farmers. Traditionally, the grain-livestock mixedagriculture is mainly on the highlands, that are relatively free of human and livestock diseases.Although extensive area of land with sufficient rainfall are available in the warm and humidareas, because of the high infestation of human diseases like malaria and livestock diseasesthrough the vector, tsetse fly, expansion of cultivated land to such areas are very much restricted.

EXTENT OF SOIL DEGRADATION AND ITS BIO-PHYSICAL AND SOCIO-ECONOMIC IMPACTS

Types of soil degradation and causes of low agricultural productivity

Excessive exhaustion of nutrients from the soil through continuous cropping with little or noinput through residue incorporation or other external inputs in the form of organic and inorganicfertilizers has become a serious yield limiting factor to the majority of the highland farmers. Theresults of soil fertility and fertilizer studies in the past have indicated that the majority of theareas under cereal crops are highly responsive to nitrogen, about 25% of the areas, particularlythe red soils, are responsive to phosphorus and only few areas are responsive to potassiumfertilizers. The general landscape, unique topography, heavy deforestation, intensive rainfall andlow level of land management have resulted in heavy soil erosion, particularly in the northern andcentral highlands. The consequences being low content of mineral nutrients and low moisture

Ethiopia202

holding capacity of soils, hence low productivity.The majority of the soils occurring in the warm andhumid areas of the country are acidic in reaction as aresult of excessive leaching of bases. Theproductivity of such soils is low because of high Prequirements, Al toxicity and deficiency of the baseelements. The extent of the moderate to stronglyacidic soils (pH <5.5) in the country is around 13%.Most of the soils in the arid and semi-arid areas ofthe eastern and south-eastern parts of the country,particularly the irrigated and potentially irrigablelands are saline/alkaline and are prone to thisproblem. Approximately, about 4.5% of the totalland area of the country is believed to be saltaffected. As a result of poor irrigation and drainagewater management, about 7% of the 70 000 ha ofirrigated cotton farmland in the Awash valley (withinthe Rift Valley) is believed to be already salinized. Alarge portion of the area on the highlands and the alluvial plains are covered with Vertisol or soilswith vertic characteristics (10% of the total land area of the country). Such lands are notnormally utilized for crop production, due to the excessive waterlogging problem during the mainrain season. The water logged soils on level plains are usually used as grazing grounds or forgrowing crops at the end of the rainy season, particularly crops such as durum wheat and chick-pea that can strive on reserve moisture. High yields are not obtained from these crops due toinsufficiency of moisture and low soil fertility. The major soil fertility limitations under Ethiopianagriculture are outlined in Table 6. Among the arrays of yield limiting factors, soil erosion andproblems associated with the slope of cultivated lands seem to be the major problems on thehighlands.

Extent of soil degradation through erosion

Among the complex environmental problems the country faces today, soil erosion anddeforestation are the most serious ones that are believed to be the root causes of the recurringfood shortage and famine. Out of the estimated 60 million ha of agriculturally productive land(with more than 120 days of growing period), about 27 million ha are significantly eroded, 14million ha are seriously eroded and 2 million hectares have reached the point of no return; with anestimated total loss of 2 billion cubic metres of top soil per year (Fikru, 1990). Another reportalso indicates that as a result of such degradation, about 20,000 square kilometres of farm landare thought to have lost their fertility and productivity base (FAO, 1986). Although themagnitude of erosion and soil loss varies from place to place depending on the climatic condition,soil type, land use land cover, etc., the average annual soil loss from cultivated lands areestimated to be about 100 tons/ha (FAO, 1986). Results from experimental plot tests (SCRP,1985) have indicated that the rate of soil loss in extreme cases range from 0 to 300 metrictons/ha/year. An average soil loss observed from SCRP experiments conducted in six differentagro-climatic regions was 70 tons/ha/year, which is beyond the concept of any permissible soilloss. The Ethiopian highland reclamation study (FAO, 1986) predicts that, even if erosion ratesstay at their current level, it is projected that the area of farm lands on the highlands with a soildepth of less than 10 cm, which is estimated to be 20 000 km2 at the time of the study, is expectedto increase five-fold in the year 2010 and will cover an area of 10 000 km2 arable land. This

TABLE 6Major soil fertility limitations inEthiopian agriculture

Limitations Area%

Steep slopes (8-30%) 32Erosion prone soils 30Shallow soils 29Very steep slopes (>30%) 26Dry 18Basic reaction 17Acidic 11Low K reserve 9Vertisols 9Aluminium toxicity 5Salinity 5Low moisture holding capacity 3Low CEC 1

Source : Janssen and Willekens, 1994


means all the essential soil properties and constituents will be lost and the land becomesunproductive.

Estimated nutrient loss through erosion

Soil fertility is intricately and insidiously related to soil erosion. High amount of plant nutrientsand organic matter are lost along the removal of topsoil by erosion. The magnitude of such lossesvary from place to place depending on the degree of erosion and the nutrient content of the soil inquestion. The calculated range of nutrient losses per ha from the highlands of Ethiopia throughsoil erosion is given in Table 7. The bases for the calculations of these values are the actuallymeasured soil loss figures and the commonly reported nutrient content values for an averageshallow soil in the highlands of Ethiopia.

TABLE 7Calculated range of nutrient losses through erosion from the highlands of Ethiopia (kg/yr per ha)

Soil-loss range Total amount of nutrient lostPlant nutrient Nutrient contentof soil lowest highest lowest highest

Organic Matter (%) 2.0 18.0 214.4 360 4,288Total N (%) 0.2 “ “ 36 429Available P (ppm) 22.9 “ “ 0.412 5Exchangeable K (%) 0.0078 “ “ 1.40 17Exchangeable Ca (%) 0.16 “ “ 28.8 343Exchangeable Mg (%) 0.048 “ “ 8.64 103

Economic impact of soil degradation

The estimated range of losses in terms of maize and wheat yields as a result of soil erosion(nutrient loss) is shown in Table 8. The bases of the calculation in estimating these yield lossesare the loss in nutrient (N) through erosion at two extreme locations (Table 7) and the cropyield/fertilizer response ratio for wheat and maize (Bateno, 1997). The value of N lost througherosion is considered as fertilizer nutrient, because it is the most limiting nutrient to which cropsrespond highly in most areas on the highlands.

TABLE 8Calculated loss in grain yield due to losses in nitrogen through erosion

Crop Yield lost (kg)per kg N lost

Range of nutrient lossN (kg/ha)

Total yield lost (mg/ha)due to N lost

(Crop response ratio) low High low highMaize 9.6 36 429 0.345 4.12Wheat 6.9 36 429 0.248 2.96

The calculated economic impact of nutrient losses from the highest and lowest soil lossareas, in terms of monetary values of crop yield losses and in terms of replacement fertilizerequivalent values of the lost nutrients are shown in Tables 9 and 10, respectively.

The data in Table 7 show that the loss of major nutrients through erosion, including soilorganic matter, is very high, particularly in the high soil loss areas. The values of nutrients andsoil organic matter lost through erosion, in the low and high soil erosion areas, respectively, are:organic matter (360 and 4288 kg/ha/yr), total nitrogen (36 and 429 kg/ha/yr), availablephosphorus (0.412 and 4.9 kg/ha/yr), exch. potassium (1.4 and 16.72 kg/ha/yr), exch. calcium(28.8 and 343.0 kg/ha/yr) and exch. magnesium (8.64 and 102.91 kg/ha/yr).

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TABLE 9Monetary values of crop yield losses as a result of soil degradation

Crop Yield lost(Mg/ha)

Grain price(Birr/kg)

Total loss(Birr)

Lowest Highest Lowest highestWheat 0.248 2.960 1.60 396.8 4,736maize 0.345 4.118 0.80 276.0 3,294

TABLE 10Loss in terms of replacement fertilizer (N, P and K) equivalent values as a result of soildegradation

Price as fertilizer(Birr/kg)

Total loss in terms of cash(Birr)

Nutrient Nutrient loss(kg/ha)

Lowest Highest Lowest highestN 36 429 1.90 68.4 815.10P 0.412 4.9 2.00 0.82 9.80K 1.4 16.72 2.00 2.80 33.44

The magnitude of losses of nutrients in the rest of the areas is believed to be in between thisranges. Considering the low level of soil fertility and the extremely low crop yields obtained inmost of the highlands of the country, and where very little to no fertilizer is applied to the soils,the above estimated nutrients losses through soil erosion is considered very high. The impact ofsuch soil and nutrient losses, in northern Shoa, where soil loss values are the highest, is clearlyreflected in the real situation through the extremely low crop yields and the absolute poverty ofthe farmers in the area. Most of the sloping lands in this high erosion areas are completely devoidof soils and the bare rocks are exposed on the surface. The reclamation cost in order to bringthese soils back to normal production, if there is going to be any attempt at all, is going to be veryhigh in terms of physical management and the supply of nutrients.


Through national and international efforts during the last twenty years, agricultural research hasattempted to overcome the basic agricultural productivity constraints, giving more attention tocrop improvement programmes. Side by side with the crop improvement programme, though notintensively, research on soil conservation and soil fertility improvement have also beenundertaken. In terms of the research findings and development of technology packages, theachievement in agricultural research could be rated successful. The problem is the lack of transferof technology to the farmers to show significant impact in improving agricultural productivity atnational level. Some important and promising research findings and available technologypackages are summarized below.

Soil conservation techniques

Results of soil conservation research conducted on erosion susceptible farmers’ fieldsrepresenting the major agro-ecological zones, have indicated that any of the common techniquescould highly influence soil loss, if used by farmers. There are, however, high differences amongthe different types of conservation techniques in controlling erosion. Conservation techniquestested on farmers’ fields and their soil loss reduction effects are shown in Table 11.


Fertilizers (NP) and improved seeds

Since the inception of the fertilizer trials in thecountry some forty years ago, the high response ofmost of the cereals to N and P fertilizers has beenrealized. The majority of the crops and areas gavehigh response to N and about 25% to P, particularlyon red soils, while little or no response has beenobserved to K. Because of this reason, the extensionactivities are focusing mainly on N and P fertilizers.Although there are good responses to NP fertilizers,the farmers in most places did not realize the benefitsvery well. This is mainly because of lack of know-how on the usage, lack of proper cultural practices like weeding etc., lack of improved seeds, thehigh price of fertilizer and shortage of moisture. It has been proved to the farmer, however, thatcrop yields could be increased several fold if packages of technologies like fertilizers along withimproved seed and proper cultural practices are used. A number of technical reports andreferences on research findings could be cited as to the positive effects of technology packageslike fertilizers and improved seeds in increasing crop yields. The data on Table 12 show thedifference in grain yield of different cereals grown under the traditional practice and those grownaccording to the recent extension of fertilizers (NP) and improved seeds package in differentregions. It could be noted from these results that yield could be increased in several folds with theuse of the improved package if moisture is not a limiting factors.

TABLE 12Yield achievement by farmers 1994-95

Traditional average (Mg/ha) EMIP average (Mg/ha)Region maize wheat Teff sorghum maize wheat Teff sorghu

mTigray 1.0 0.7 0. 4 0.9 3.0 2.0 1.0 2.5Amhara 1.5 0.7 0.6 1.4 5.0 3.5 1.5 3.0Oromiya 1.6 1.1 0.6 1.1 4.5 3.4 1.35 3.1South 1.6 1.2 0.6 - 4.1 2.7 1.3 -Harari 1.2 - - - 2.5 - - 2.0Region 12 1.2 - - - 3.0 - - -

Source : Evaluation report NEIP/EMIP

Improved drainage

With an extensive area of poorly drained soils in the country, where the Vertisols (dark clay soils)alone represent over 10% of the total land area, drainage is an important soil managementtechnique for increasing agricultural productivity. Although most Vertisols on the highlandsreceive sufficient moisture during the rainy seasons, traditionally they are used mainly for freegrazing and very little for crop production. This is mainly because of their drainage problemwhich makes it impossible to grow crops during the rainy seasons. To a limited extent, these soilsare used for the production of chickpeas and durum wheat that are planted at the end of the rainyseason utilizing the reserve moisture in the soils. At experimental level, it has been demonstratedthat with the use of improved land preparation methods like camber-beds to reduce water loggingproblems and with the application of N and P fertilizers, cereals could be planted on Vertisols andother water-logged soils at the onset of the main rain season. Following such cultural practicesthat are followed on the upland soils, higher yields could be obtained on Vertisols. However, thepreparation of camber beds for draining excess moisture from Vertisols requires mechanization

TABLE 11Effect of different soil conservationtechniques in reducing soil loss atdifferent locations

Treatment Soil loss reduction(%)

Control 0Graded bunds 32Graded fanya-juu 54Grass Strip 66Level bunds 80Level fanya-juu 89

Source : Berhe, 1993

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and could not be easily done with traditional local plow which is pulled by a pair of oxen. Sometechnology packages on improved land preparation methods that are within the capacity of thefarmers, however, have been also tested and demonstrated to the farmers. These are the broad-beds and furrows (BBF) land preparation method with specially designed tools to fit the localplow system and be pulled by a pair of oxen. With the use of this drainage technique and theapplication of fertilizers (NP) along with improved seeds, crop yields on Vertisols could be highlyincreased at the peasant farmers’ level. Some tested technology package for improving theproductivity of waterlogged soils and are available for use by farmers are cited below.

Organic fertilizers and improved cultural practices

Experimental results have repeatedly shown that the application of fertilizers (organic orinorganic (N and P) in most cases increase yield at least where there is sufficient moisture. Someresult of experiments conducted with organic fertilizers, improved cultural practices, and withsoil amendment materials which could be disseminated to farmers, where situations permit.


The national agricultural research and extension systems have made a lot of effort in the past twoscores to overcome the major agricultural production limiting problems through differentapproaches. Although a number of promising research results have been obtained undercontrolled experimental conditions, the impact of these findings at farmers field level were verylimited due to numerous reasons, mainly related to cultural, socio-economic and policy factors.Out of the many agricultural research findings and recommendations taken to the farmers throughthe extension system the package that reached relatively a large number of farmers and showed ameasurable effect is the NP fertilizer. Particularly, through the recently started NationalExtension Intervention Programme (NEIP), it has been possible to cover large number of farmersthrough the fertilizer and improved seeds technology package, which also involves other improvedcultural practices.

Although a number of research based effective recommendation packages could be cited,two cases were selected for presentation in this paper. The first case is the National ExtensionIntervention Programme (NEIP) which involves Extension Management Training Plots (EMTP)based on the experience of Sasakawa Global 2000 programme. This programme involves thepromotion of a technology package consisting NP fertilizers, improved seeds and other culturalpractices on selected farmers’ fields with the involvement of the farmers in the actual operations.The other successful case chosen is the outcome of a package of farming system tested throughan NGO (World Vision) project in a given degraded and famine stricken locality. As a result ofthe intervention through the project, the degraded and low productivity area, comprising a largenumber of farmers, has been completely rehabilitated. Both cases are discussed below (Case Iand Case II).

Case I: National Extension Intervention Programme (NEIP)

The NEIP, which is considered a successful extension intervention programme, has beenlaunched by the government in 1994/95 through special programme which intensified the existingextension programme. The NEIP is mainly geared towards assisting small scale farmers toimprove the productivity of their landholdings through the dissemination of research generatedinformation and technologies for major food crops, including teff, maize, wheat, sorghum, as wellas potato and leguminous forage crops. The programme which was limited only to seven regionsand 35 000 farmers in the initial year (1994/95) has expanded to ten regions and 350 000 farmers


in the 1995/96 crop season. During the 1996/97 cropping season, the programme covered all theregions and the number of participating farmers reached 600 000. Considering the trickling effectof these Extension Management Training Plots (EMTP) in educating other farmers around eachdemonstration site, the numbers of benefiting farmers is expected to reach a couple of millions.The productivity improvement effects of the NEIP carried out on farmers’ fields in the differentregions during the crop season 1994/95 are shown on Table 12.

Case II: Lessons From Antsokia Valley : Natural Resources Management Project forSustainable Agriculture

The Antsokia project area is located 350 km northeast of Addis Ababa. The size of the projectarea is about 16 235 ha and is part of a big river basin, where the portion of the area is on steepslopes and uplands, lying at altitudes between 1 600 and 2 600 m a.s.l.. The 45 000 people livingin this area earn their living from mixed Agriculture, crop and livestock production on this land,where about 1% of the population are urban dwellers. The Antsokia area has been taken as aproject area by the World Vision during the 1984/85 famine period in the country, wherenumerous lives were also lost in this area. The emergency relief aid programme in this degradedvalley was gradually changed to a resource management project for sustainable agriculture andchanged the productivity of the valley and the life of the inhabitants successfully in ten yearstime. The situation of the area before the project, the interventions made and the impacts observedare briefly summarized below. Although the climatic condition at Antsokia is conducive andmoisture is adequate, due to deforestation and unwise land management, the area has beenexcessively degraded. The sloppy mountains and hills have lost their top soils and have becomebare rocks. The swamps and water-logged wet lands have become the deposition site of erodedsoil. The gentle slopes have lost their fertility as a result of repeated cultivation without fertilizeror rest. As a result of deforestation and increased runoff, springs dried up and rivers becameseasonal and flooding. Farmlands were reduced to the bottom of the hills where mountain tops areeroded to bed rock and the valley plains were water-logged. As a result of these phenomena, landcarrying capacity showed deficit for both humans and livestock.

The agricultural interventions made in Antsokia through the project are the following:swampland management, wet land management, crop land management, forest garden/ homesteadmanagement, and forest land management. The overall impact of the project is that totalproduction of cereal crops increased from 5 093 tonnes in 1990 to 8 372 tonnes in 1996, which isan increase of 56%. This is an equivalent to an average yield increase from 0.8 tons/ha to 1.2tons/ha. This increase in yield indicated a change in total productivity from deficit by 2 106tonnes to surplus by 372 tonnes, despite the increase in population and a little change in the areaof cultivated land. The production of vegetables, fruits and root crops, which was virtuallyunknown in the area, attained an level where it is exported to the surrounding areas. Similarly,surplus in livestock feed was also observed. As a result of the intervention through the projectwhich changed the overall productivity, there was also an increase in per caput productivity from141 kg/year to 186 kg/year. As a result of the intervention through afforestation, soil and waterconservation, agro-forestry, forest gardens, farm-foresting and inter cropping, the following arethe improved life support systems attained in the area: rehabilitated springs, plant growingseasons increased, erosion retarded, rains attracted, land carrying capacity increased, increasedfarm bio-diversity through the introduction of new crop species and varieties as well as additionallivestock that are new to the farm.

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The absence of a conducive national policy environment has probably been the single mostimportant factor which depressed agricultural performance in the last two decades. Theinappropriate agricultural policies include inter alia: (a) nationalization of privately ownedcommercial farms without compensation; (b) banning of private investment in commercial farms;(c) arbitrary redistribution of land: (d) insecurity of land tenure; (e) forced settlement andvillagization; and (f) rigidly controlled grain market and agricultural prices, etc. The policyenvironment is also not conducive for the implementation of resource conserving technologieswhich could encourage the use of indigenous and locally available resources for graduallysubstituting imported chemical fertilizers and develop self reliance for sustainable agriculturalproductivity.

The present extension policy gives too much emphasis to increased utilization of chemicalfertilizers that are less effective on degraded soils and lack sustainability, particularly with theever-increasing price of fertilizers and unreliability of rainfall. The absence of a conduciveagricultural policy has been cited as the probable single most important factor which depressedagricultural productivity and was the cause for excessive deforestation and land degradationduring the last three decades, particularly during the socialist Government era. Since the fall ofthe socialist Government, some policy environments have positively changed in many aspects,except the land tenure policy, which still maintains the ownership of land under the Government.The land tenure issue, which is believed to be very decisive in changing the farmers attitudes foraccepting and implementing improved land management technology packages still requires apolicy change, if increased and sustainable agricultural productivity are expected to be attained.

The current agricultural policy, with the weaknesses it has with respect to land tenureaspects, focuses on strategies for agricultural development led industrialization. The maincontents of the post 1991 agricultural policies are:

• Giving special emphasis to private small holder model to agrarian socialism,

• Promoting modern farming particularly in the low lands by encouraging national and foreigninvestors with the necessary capital and know how,

• Fostering conservation based development in order to restore ecological balance. Dueemphasis is given to solving the problem of soil degradation, deforestation and declining wildlife resources,

• Steps have already been taken to enhance normal or competitive functioning of agriculturalinput and output markets. Among the major actions worth noting are the National Fertilizerand Seed Policies that are put in place.

Prior to 1993, there was not also a national agricultural research policy and strategy to guideand support proper agricultural development. Since 1993, however, a new national researchpolicy and strategy has been formulated and proclaimed in order to shape up agricultural researchin the direction of the country's need. The recent Agricultural research policy clearly prioritize theneed for technology generation through research relevant to peasant agriculture for the purpose ofincreased agricultural productivity through conservation based and sustained utilization of landresources.



Bio-physical issues

Improved land and soil management. The soil is a non replenishable natural resource ifimproperly managed and once got lost. On the contrary and unlike the other natural resources, ifproperly managed and protected from degradation, it is inexhaustible resource which could beused to sustain life indefinitely. Therefore, in order to retard physical and chemical degradation ofsoils and ensure sustainable utilization of these vital resources, it is necessary to promote andencourage soil conservation based agricultural development.

Integrated nutrient management. As soil degradation, draught and excessive nutrient exhaustionare the major reasons for low yields in the majority of the Ethiopian peasant agriculture, it isevident that nutrients in the form of fertilizers have to be applied for increasing crop yields. Theexcessive degradation of soil organic matter as a result of repeated cropping and very little to noincorporation of residues to the soil have gradually lowered crop yields under the no externalinput system of the peasant farming. Although such conditions could be improved through the useof chemical fertilizers, it lacks sustainability because of the high price, low efficiency and logisticproblems for timely availability and distribution of these industrial products that are mainlyimported from abroad. A lasting solution to this problem could be popularization and promotionof integrated nutrient management (use of both organic and inorganic fertilizers) for wider use bythe farmers. Proper utilization of integrated nutrient management with increased utilization oflocally available organic resources along with soil and water conservation could be the means forattaining sustainable agricultural productivity with highly developed self reliance and littledependence on imported chemical fertilizers for improving soil fertility.

Policy and socio-economic issues

Reform in land tenure policy. The problem of land ownership on land resource management hasbeen very well known during the socialist government era where land ownership was communal.The commitment and devotion for sustainable management of land resources is directlyassociated with ownership right on the land. Farmers can not involve themselves confidently inany type of land rehabilitation and soil conservation programmes that are relatively costly andtime consuming, when they are not sure that the piece of land they are working on really belongsto them or could be shared and redistributed to other farmers at any time.

Changing the development approach. Since land and soil degradation are influenced at acatchment or watershed level the development approach should be through the direct interventionof conservation based development packages for a set of catchment or watershed involving acommunity farmers. If necessary, with sufficient investment to rehabilitate degraded and fragileenvironment with the direct participation of the whole community in an area in the form of aproject. The development approach through the present system which deals on management offarm plots with the supply of seeds and fertilizers will not have a sustainable effect and does nothelp to retard land degradation.

Policies to protect the farmers from low grain prices. The farmers are mostly reluctant to usesome better technologies like fertilizers and improved seeds on credit bases because of the fear ofnot being able to pay the loan, in case crops fail or if harvests are excess and prices of grain fall.If government protects farmers from unexpected price fall in localized areas by establishing floorprices, it may help farmers to take risks in accepting essential inputs even on credit basis.

Encouraging private investors to go into farming business. The low agricultural productivity inthe Ethiopian subsistence farming, where farmers work on small piece of land, is mainly because

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of the difficulty to come out of the vicious cycle of exhausted nutrient reserves in the soil and lowbio-mass productivity. Even where the problems are identified and solutions are available toincrease productivity, excessive poverty of the farmers prohibits them from adopting any kind ofimproved technology. Everything on the farm is consumed and no input of internal or externalsource goes to the soil. If policies permit farmers to rent their lands on individual basis or ingroups to private investors in terms of concession for a given period, high investment inputs couldtremendously change land productivity. The farmers would also be absorbed as labourers on thecommercial farms and at the same time getting the rent for their land without actually losing theirownership rights.

REFERENCES

Agricultural Research Task Force 1996. Review of the agricultural research system and recommendfuture directions. Eth. Agr. Res. and Training Project. Addis Ababa.

Bateno, K. 1997. Agricultural development aspects in soil fertility maintenance. a paper presented on aworkshop on IPNS, NFIA, Addis Ababa.

Belay, E. 1997. Agricultural extension aspects on soil fertility maintenance. Paper presented on aworkshop on IPNS, NFIA, Addis Ababa.

Berhe, W. A. 1993. Twenty years of soil conservation in Ethiopia. A personal overview. Regional SoilConservation Unit / SIDA / Nairobi.

FAO 1984. Assistance to Land Use Planning, (AG: DP/ETH/82/010). Field document 3.Geomorphology and Soils of Ethiopia. Ministry of Agriculture, Addis Ababa.

FAO 1986. Highland reclamation study, Ethiopia. Vol. 1 and 2. (AG:VTF/ETH/037). FAO, Rome.

Fikru A. 1990. The role of land use planning in the improvement of natural resources management: InNational Conservation Strategy Conference. vol. 3.

Janssen, M. and A. Willkens 1994. Interpretation of crop response data, Ethiopia. Consultancy Report,Project GCPF / ETH / 039/ITA, FAO, Rome.

Kelsa Kena, Tadesse Yohannes and Tesfa Bogale 1993. Influence of fertilizer and its relatedmanagement practices on maize grain yield. In Proceedings of the First National Maize Workshopof Ethiopia, 5 - 7 May, 1992. Addis Ababa.

Mesfin A. 1980. State of soil science development for agriculture in Ethiopia. EJAS 2(2). Addis Ababa.

Mohr, P.A. 1971. The geology of Ethiopia. SSI University Press, Addis Ababa.

Murphy, H. F. 1963. Fertility and other data on some Ethiopian soils. Expt. Stat. Bull. No. 11. EthiopianCollege of Agri. and Mech. Arts. Dire Dawa, Ethiopia. 511.pp.

Odenyo, V. A. O. 1984. Assistance to Land Use Planning, Ethiopia: Land use, Production Regions andFarming Systems Inventory. FAO. Rome.

SCRP 1985. Soil loss and runoff assessment findings. Soil Conservation Research Project, Addis Ababa.

Taye B. and W. Hofner 1993. Effect of different phosphate fertilizers on the yield of barley and rape seedon reddish-brown soils of Ethiopian Highlands. Fertilizer Research, 34: 243-250.

Tekalegn Mamo, et al. (edit.)1993. Improved management of Vertisols for sustainable crop-livestockproduction in the Ethiopian Highlands. Synthesis Report. Technical Committee of the JointVertisol Project. ILCA, Addis Ababa.

World Bank 1995. Staff Appraisal Report. National Fertilizer Project., Addis Ababa.

Yilma Getachew 1996. Lessons from Antsokia Valley. Natural resource management and sustainableagriculture. World Vision. Addis Ababa.


Kenya


Maize is the most important food crop in Kenya and constitutes the staple food for over 95% of thepeople with an average consumption rate of 128 kg/person/year according to the Workplan 1997,Ministry of Agriculture, Livestock Development and Marketing. It is grown in almost all agroecological zones of the country and predominantly on smallholder farms of less than 5 ha. About 80%of all land under cereal production are planted with maize. The crop is grown mainly for humanconsumption, livestock feed and industrial processing. In 1996, a total of 1.49 million hectares plantedunder maize produced 23 million bags giving a low national yield of 1.4 tonnes/ha. The 1995 crop wasmuch better producing about 30 million bags, probably due to more reliable rainfall. Among the foodcrops grown in Kenya, maize receives the bulk of the fertilizer used. It is estimated that about 25-30%fertilizer used in the country goes to maize production while a mere 2-3% goes to the other food crops.

Much agricultural research has also gone into maize especially in the area of breeding to producehigh yielding varieties suited to the various agro-ecological zones. This has yielded positive results asabout 60% of the maize planted is hybrid maize (MDB, 1995). The main constraints related to maizeproduction vary from rainfall unreliability, low use of farm inputs e.g. machinery for large scale farms,fertilizers and pesticides, unavailability of seeds and correct types of seeds; lack of credit facilities; poordissemination of improved technology; poor producer prices due to market restructuring in 1992; highcost of inputs and high post-harvest losses of up to 20%. Several interventions have been put in placeby the Kenya Government to assist the farmers e.g. setting up strategies of improving the provision ofmachinery and inputs; improve credit facilities at appropriate institutions, disseminate improvedtechnologies through extension workers as well as improved liaison with agricultural researchorganizations.


Agricultural production requires proper management of the inputs and outputs through proper planningand control. To do this a proper record or inventory of the various components is required. It isunfortunate that in Kenya, the inventory of agricultural land use has not been updated since 1979.However, this exercise has recently started through a new initiative of the Ministry of Agriculturewhere localized data in 7 random districts in the country has been collected and assessed. These datashow that numerous sub-divisions have occurred since 1979, new lands have been brought intocultivation while ownership status has frequently changed. These factors have impacted negatively onthe food production situation in the country as land fragmentation/subdivision automatically lead intoloss of agricultural land due to roads, footpaths fences, homesteads and public utility sites. Subdivisionalso leads to uneconomically viable parcels of agricultural land. Population pressure has led to a bigland pressure leading people into fragile lands with resultant negative environmental issues. Theconsequence of these circumstances is the deterioration of agricultural production efficiencies, declinein agricultural output, land degradation and land use conflicts.

S.M. Nandwa, P.T. Gicheru, J.N. Qureshi, C. Kibunja and S. MakokhaKenya Agricultural Research Institute and National Agricultural Research Laboratories, Nairobi

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Kenya is an agricultural country and depends almost entirely on land productivity for subsistence andsocio-economic development from one third of the country as two thirds of Kenya is semi-arid to arid.The pressure exerted on the fragile ecosystems that characterize the semi-arid and arid lands by thelarge and rapidly increasing human population is at the heart of the land degradation processes. It isnevertheless important to recognize that although land degradation is more of a problem of semi-aridand arid lands, it is also becoming a serious problem in the semi-humid and humid environments (alsoreferred to in Kenya as medium and high potential lands respectively), especially where cultivation hasbeen extended to steep hill slopes without adequate soil conservation measures. Chemical and physicalforms of soil degradation occurring in the country are reviewed in terms of their causes and resultanteffects.

CAUSES AND EFFECTS OF SOIL CHEMICAL DEGRADATION

Evolution of farming systems in Kenya shows a rapid shift from shifting cultivation or natural fallowsystems to continuous cultivation. The productivity and sustainability of fallowing systems aredependent on adequate restoration of fertility during the fallow phase to replace and build stocks lostduring the cropping phase (Padwick, 1983; Nye and Greenland 1960). This practice has becomeobsolete in parts of Kenya, as per caput arable land declines. In parts of the continent (includingKenya), abandonment of fallowing systems has been ascribed to pressures of population (Allen, 1965).In systems where fallowing is still practised, the arable phase is often extended beyond nutrientsrestored or accumulated during fallowing phase, which eventually renders the system unproductive dueto depletion of nutrients and carbon accumulated during fallowing. Jones (1972) found that 15 950 769and 85 kg/ha of carbon, nitrogen and phosphorus, respectively were accumulated in three years ofresting phase. However, when measurements were made after three years of cropping the elementswere found depleted to negative values of 19 700, 968 and 88 kg/ ha, respectively. High nutrientdepletion rates are commonly reported in farming systems in Kenya, where more nutrients are removedthan those replenished.

In many crop and livestock farming systems, major nutrient losses are via crop residues, runoffand erosion, denitrification, leaching and through removal in faeces deposited in deep pit latrines orsewage where it can no longer be recycled in agro-eco-systems. In assessing nutrient depletion in SSA,Stoorvogel and Smaling (1990) reported that of the total nutrients removed in harvested products andresidues, of cereal crops in the continent (wheat, rice, maize, barley, millet and sorghum), 43.1%,41.0% and 87.8% of N, P205 and K20 was removed in residues, respectively. This shows thesignificant negative contribution non-restitution of cereal residues can have on nutrient depletion. In along-term field trial investigating the effect of organic and inorganic inputs on yields of maize andbeans and nutrients removed, Qureshi (1987) reported substantial nutrient removal by maize and beansresidues (Table 1). Runoff and erosion occurrences in agro-eco-systems have also been reported tocontribute to nutrient depletion. From a study on a Nitisol at Kabete, Kenya, Tefera (1983) reportedannual soil losses of 35 and 18 t/ha from plots with 0.5 and 1.5 m wide grass strips, respectively; whilecumulative soil loss under bare conditions were reported by Gachene (1995b) to be 247 t/ha withbetween 247% to 936% richer in P than in the original soil (Gachene, 1995a). The author found thatchanges in soil pH, organic carbon and total N were significantly correlated with cumulative soil loss(r2 values of 0.59 0.35 and 0.50, respectively; n=20).

A number of studies have been conducted in Kenya on the subject of solute leaching (Smaling andBouma, 1992; Mochoge and Beese, 1986). In studying N leaching and by pass- flow in Vertisols inlake Victoria basin, Smaling and Bouma (1992) found that N leaching in tilled cropland was less than


5% of applied fertilizer (50 kg/ N/ha) compared to 40% fertilizer N leaching in grassland, unless thesoil was pre-wetted which reduced the losses to 12%. Mochoge and Beese (1986) found that leachingwas influenced by the amount and quality of applied cations and accompanying anions, which wereslightly higher when (NH4)2SO4 was applied than Ca(NO3)2. Hartemink et al. (1996) studied leachingin western Kenya, and estimated that some 100 kg/ N/ha/yr was leached as nitrates and gotaccumulated at 50-200 cm soil depths. It may be concluded from these studies that the observedleachable quantity of nitrogen could suffice a 4 t/ha maize grain crops if recycled or prevented fromleaching.

Nutrient balances are increasingly being recognized as important sustainability indicators of agro-eco-systems. Nutrients stocks are derived from inorganic and/or organic sources as well as fromweathering of minerals (feldspars, micas). They are subject to continuous changes as a result of naturaland man-induced processes, hence the static concept of nutrient stocks and dynamic concept of nutrientflows. At each spatial scale, the flows can be described in terms of the summation of inputs minusoutputs which may be higher or equal or lower than the value zero, hereby termed the nutrient balance.Based on nutrient balances, agro-eco-systems may be experiencing nutrient accumulation (S INPUTS>S OUTPUTS), or in equilibrium (S INPUTS = S OUTPUTS) or nutrient mining (S INPUTS <SOUTPUTS). Spatially, these calculations may be done at plot, farm, district, watershed and nationalspatial scales. The lowest level of measuring nutrient flows is at the soil solution level, whereby thevertical boundary may be the rhizosphere, where flows may be chemically or physically controlled e.g.by oxidation, fixation, leaching, weathering, denitrification, volatilization etc. The assessment of thevariations of plant nutrients from the onset of study (time t) to the end (time tn) of nutrient managementpractices may be accomplished by a formula proposed by Follet et al. (1987).

TABLE 1Nutrient removal by a harvested maize ad bean

Plant component N P K Ca Mg Cu Zn Mn FeMaize kg/ ha g/ha

Stover 40 4 130 19 10 73 30 675 2,712Grains 51 12 9 4 1 10 11 30 105Total 91 16 139 23 11 83 41 705 2,817

BeanGrains 35.5 5.6 20.3 1.7 2.9 10 52 24 78Hulled pods 9.9 1.1 17.1 4.8 2.8 6 25 76 260Leaves/stems 6.5 0.6 10.9 3.5 1.0 44 44 75 563Roots 0.68 0.06 0.76 0.70 0.18 1 3 7 55Total 52.6 7.4 49.1 10.7 7.0 61 124 182 956

Note : maize yield is 4t/ha, bean yield is 1.3 t/ha

Salinization results from natural cycles or from soil and water mismanagement, includingirrigation with low quality water. In Kenya it has often been observed that due to poor drainage, highground water tables develop and hence capillary salinization, leading to the abandonment of irrigationschemes. Excess exchangeable sodium and high pH also strongly influence the availability andtransformation of essential plant nutrients. The amounts of potassium in these soils are small comparedto sodium, calcium and magnesium, which indicates that there is a likelihood of interference in nutrientuptake and plant metabolism. Toxic levels of sodium in some of these soils may restrict penetration ofplant roots. Plant growth in saline soils is adversely affected by low soil-water availability because ofthe soil solution's high osmotic pressure. Toxic concentration of specific ions may also affect plantgrowth. Therefore, strongly saline soils have little vegetative cover and are subsequently susceptible towater erosion.

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Excess exchangeable sodium and high pH strongly influence the soil physical properties of saline-sodic soils. As the exchangeable sodium increases, soils become more dispersed and less permeable toair and water. Dispersion causes dense impermeable surface crusts that greatly reduce seedlingemergence and water penetration. The reduced infiltration of water enhances soil erosion. In those caseswhere sodicity occurs in the deeper subsoil, wetting of the soil may lead to structural collapse due todispersion and subsequent caving in. This may lead to the formation of tunnels which upon wideningform deep and wide gullies. Agricultural soils polluted with heavy metals especially cadmium, fromdifferent sources (sewage sludge, inorganic additions, mines etc.) is major concern in high externalinput agro-eco-systems as well as urban agriculture. Little research has been carried out to establish therelationship between soil available labile pools, sources and uptake in crops. This is a major researchgap for future research.

Causes and effects of physical land degradation

Soil erosion is by far the most important land degradation process in Kenya. The severity of soilerosion problems in the cultivated parts of the Highlands of Kenya was realized as early as in the late1920s. Maher (1937) described the causes of this soil erosion as due to wrong use of land. In anattempt to arrest land degradation, enforced soil conservation measures were introduced during theperiod 1930-1940. During this period an inventory of the state of soil erosion and land utilization in theAfrican reserves was carried out (Maher 1937 a, b, c, d). As a follow up, appropriate soil conservationmeasures were recommended. These included terracing, strip cropping, use of crop residues, plantcover etc. Major emphasis was however laid on terracing. Unfortunately, during the early 1960s therewas considerable laxity in soil conservation efforts; the soil conservation measures which were beingcarried out were not maintained and terracing started to disappear at a faster rate that they were beingconstructed. However, from 1972, a country-wide soil conservation programme was launched toincrease the awareness of the importance of protecting the soil resource from erosion and degradation.The one which are commonly practised are physical or biological, such as strip cropping, contourfarming, ridging, mulching and rotation. Physical structures include terracing, cut of drains etc.

At the national level, afforestation is now encouraged as a measure to control erosion. In 1980, thePermanent Presidential Commission on Soil Conservation and Afforestation was established to co-ordinate soil conservation and afforestation activities. In addition, the Soil and Water ConservationBranch of the Ministry of Agriculture, in collaboration with a large number of governmentdepartments, non-governmental organizations and community development groups, has been directly orindirectly involved in promoting activities related to soil conservation. It can be concluded thatconsiderable extension work has been done in the field of soil and water conservation. However, littleattention has been paid in researching on soil and water management and this is probably due to thelittle attention paid to this field. The degradation problem feared before the awareness of soilconservation has been reversed in some districts and the long history of conservation interventions insome regions of Kenya has created a favourable environment for attaining sustainable agriculture(Tiffen, 1992). There has been a long term political, social, economic and technical commitment to soiland water conservation. The results of this commitment include an impressive increase in conservedland according to several indicators. Some of them include increased awareness of soil and waterconservation techniques.

From previous experiences, wind erosion is expected to be a problem during the dry season andonly in the drylands receiving up to 600 mm of annual rainfall and with sparse vegetation. The areas ofthe country below 600 mm isohyet have been demarcated and eight climatological stations (Voi,Makindu, Garissa, Marsabit, Wajir, Moyale, Lodwar, and Mandera) with the longest and most reliabledata within these areas were selected to help determine land degradation indicators for these areas.


Synoptic wind measurements at 10 meter height were used to derive the mean wind speeds at 2 mabove the ground. Wind erosivity indices were then calculated using the Fournier equation. Aridityindices (Ratio of precipitation to potential evapotranspiration) were also calculated for the samestations. By combining wind erosivity indices, estimates of soil erodibility, aridity indices andvegetation cover, an assessment of the wind erosion hazard was made for the areas consideredsusceptible. A second and independent assessment was made by estimating the sand load in theatmosphere from observations of horizontal visibility made at the same sites (Wangati and Said, inpress).

The abundance, productivity, species composition and canopy structure of natural vegetation arevaluable indicators of land quality and hence the extent and severity of land degradation. Undesirablechemical changes in the soil (acidity, salinity or alkalinity) are often indicated by disappearance ofunadapted plant species and build up of species that are more tolerant to such conditions. Replacementof shallow rooted grasses and shrubs by deep rooted drought tolerant trees and shrubs would indicateloss of fertile top soil or serious loss of water holding capacity due to severe loss of soil depth as aresult of erosion. Overgrazing and charcoal burning may also result in predominance of unpalatable orotherwise undesirable plant species. The features just described are however often difficult to mapsince they usually affect relatively small patches of land and may look different in dry and wet seasons.Remote sensing either through aerial photography or high resolution satellite imageries has proveduseful but even such pictures require intensive ground truthing for accurate interpretation.

Indicators of land degradation

A continental assessment of the nutrient balances of 38 sub-Saharan African countries showed thatcountries of Eastern, Central and Southern Africa experience high negative nutrient balances, e.g. -42,-3 and -29 kg/ha/yr for N, P and K, respectively (Steervogel and Smaling, 1990). A district level studyof nutrient balances in Kisii, Kenya showed much higher nutrient depletion e.g. -112, -3 and -70 kg/ha/yr of N, P and K, respectively (Smaling, 1993; Smaling et al., 1993). These results are close tothose obtained from a NUTrient MONitoring (NUTMON) project in Kisii, Kakamega and Embudistricts of Kenya as shown in Table 2 (Bosch et al., 1998).

TABLE 2Average nutrient stocks, nutrient balance and relative gains and losses for 3 districts in Kenya

Kisii Kakamega EmbuStockkg/ ha

Balancekg/ ha/y

Change%

Stockkg/ ha

Balancekg/ ha/y

Change%

Stockkg/ ha

Balancekg/ ha/y

Change%

11 1163 59710 800

-102-2-34

-1.0-0.0-0.3

8 0212 5567 200

-72-418

-0.9-0.2+0.3

8 0563 32912 800

-559

-15

-0.2+0.3-0.1

The results indicate that all agricultural land uses in the mixed small-holder farming systems ofKisii District monitored cause high depletion of nitrogen (between -46 to 94 kg/ ha/ yr) followed bypotassium especially in tea and coffee farms (between -2 to 26 kg/ ha/ yr). Incorporation of thelivestock dairy enterprise was found to mitigate N and K depletion to some extent. These results thussuggested that land use and soil management practices adopted in Kisii, render the agro-ecosystemsnon-sustainable in the long-run. Results from Kakamega District showed a somewhat unique nutrientbalance trend to that observed in Kisii district. The most depleted nutrients were nitrogen (between -30to -80 kg/ ha/yr, except in livestock incorporated farms) and phosphorus (-kg/ ha/yr especially in non-contracted sugarcane and maize-based farms). The study also suggested that commercial enterprisestend to contribute more to gross margin at the detriment of soil fertility depletion, such that if currentmanagement practices are not changed with appropriate interventions, agro-eco-systems in Kakamega

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District will also be rendered non-sustainable fairly soon. Both studies from Kisii and KakamegaDistricts are in agreement with results obtained from a study in Vihiga District (part of old KakamegaDistrict e.g. at assessing the economic and ecological impacts of soil management options using adynamic simulation model (Shepherd and Soule, 1997). The authors reported higher negative balances(-44 kg/ /ha/ yr N and -3.6 kg/ ha/yr P) in low resource endowments farms (0.2 ha, lack of livestockand earning less than $ 455 per year) compared to -37 kg/ ha/ yr P and -1.5 kg/ ha/ yr P in mediumresource endowments farms (0.8 ha, with one or two heads of cattle and earning $ 1036) as shown inTable 3. The depletion was attributed to soil losses of 5.6 and 5.5 t ha/yr and N leaching of 21 and 30kg/ ha/ yr N in low and medium resource endowments farms respectively.

TABLE 3Simulated soil indicators for low, medium and high resource endowment farms, Vihiga District,Western Kenya

Indicator Units Farm resource endowmentSoil C balance Kg/ ha/yr -400 -318 190Soil N balance Kg/ ha/yr -44 -37 50Soil P balance Kg/ ha/yr - -1.5 32.7Mineral N net inflow Kg/ ha/yr 54 67 137-natural a) 10 10 10- fertilizer 0 0 47-active b) -8 5 47- slow 52 52 58Soil erosion Tons/ha/yr 5.6 5.5 2.1N leasing Kg/ ha/yr 21 30 5

Notes : Values for year 5 of the 20 years simulation.a) natural inputs from atmospheric deposition and asymbiotic N fixation, b) mineralization of active N

Nutrient balances reported above are based on subtraction of OUT 1-6 from IN 1-6 termed "fullbalance" and nearly all cases and elements they fall in the nutrient mining class e.g. SIN - SOUT <<0.Average "partial farm balances" SIN 1+2 - S OUT 1+2 were positive at levels of 34, 12 and 27 kg/ha/yr for N, P and K, respectively; suggesting that farmers used enough external inputs to offset thenutrient loss in harvestable products and residue removal. However, calculation of full balances OUT1-6 from IN 1-6 resulted in negative values of N (-71 kg/ ) and K (-9 kg/ ) per ha per year whileaverage P balance was still positive (3 kg/ ha/yr P). Negative balances in the NUTMON project werehigh which was attributed to estimates of leaching (50 kg/ ha/yr N) and gaseous losses (24 kg/ ha/yrN). Depending on the accuracy of the regression analysis data and assumptions, full balances can beeither under or over-calculated. This suggests that the application of the nutrient balance conceptshould be used in combination with soil total and/or available nutrients stocks.

A recent study of the past research on the maintenance and improvement of soil productivity inKenya identified five soil productivity indicators (besides nutrient balances). These were organic Ccontent; phosphorus stocks, availability and fixation; nitrogen (stocks, leaching potential gaseous); P/Npotential supply and soil acidity. At the onset of the long term fertility maintenance trial at NARL(Qureshi, 1987) experiment, the soil contained 36.5 t C/ha in the top 15 cm while after 18 years ofcontinuous maize bean rotation, soil organic carbon contents ranged between 32.6 t C/ha and 26.8 tC/ha in the best and worst conserved treatments (Kapkiyai et al., 1996) or an annual loss of 0.22 and0.50 t C/ha/yr, respectively.

Soil organic matter losses were intensified by fertilization and stover removal. The most soilcarbon was lost from the treatment where only N-P fertilizers were applied with stover removal and theleast soil carbon was lost from the treatment receiving the greatest external inputs while retaining stover(16%). In the long term trial one observation of concern is that all land management practices even


where there were large applications of organic matter resulted in a loss of soil organic matter over time.After 18 years of continuous maize bean rotation, soil organic carbon contents in a depth of 15 cmranged between 25.9 t/ha (stover removed, fertilizer applied) to 31.3 t/ha (chemical fertilizer andmanure applied and stover retained). This corresponds to losses of soil organic carbon at the rate of0.22 and 0.54 t/ha/yr, respectively.

Climatological influences on land degradation may be direct (as in the case of extended droughtswhich may result in destruction of ground cover and exposure of the soil to severe wind erosion) orindirect. Although the Kenya Meteorological Department has for many years established andmaintained a relatively large network of climatological observation stations, these stations are notevenly distributed and coverage of the arid and semi-arid lands is very sparse. The number ofobservation stations has also declined from over 1 000 to around 800 in 1995. The rainfall indicatorsconsidered fall roughly into two categories: those related to frequency and probability of drought, andthose related to rainfall erosivity. Climatological records show that in Kenya, recurrences of above andbelow normal rainfall anomalies and other extreme rainfall events are common in all rainfall timeseries. Some of the anomalies are relatively small while others are very severe, persistent and affectlarge areas. The mean maximum, minimum and range of air temperatures close to the ground influencethe rate of desiccation of the soil and vegetation. The same parameters are also influenced by theenergy balance of the land surface and will therefore respond to changes in land characteristics. Theseparameters have been investigated in Kenya as possible indicators of existing hazard of landdegradation (Wangati and Said, 1997).

Soil erosion resulting from surface water runoff is one of the important and easily recognizableindicators of land degradation. There are three major parameters that influence soil erosion: rainfallerosivity, soil erodibility, slope of the land and soil cover. Quantitative assessment of soil erosion ishowever problematic as soil erosion rarely takes place uniformly even on a small field. The mostwidely accepted method is the application of the Universal Soil Loss Equation (USLE) which expressesthe annual soil loss (tons per hectare) from a plot as a simple product of rainfall erosivity, soilerodibility, slope length, slope gradient, land cover and land management. The USLE model is howeverempirical and its application in a given environment requires determination of the relative weighting ofthe factors. This is done using standard replicated runoff plots on which most of the parameters and theactual soil loss from each plot can be measured. Very few runoff plot experiments have been conductedin Kenya and they do not even cover the major soil and land use types. The USLE model thereforeprovides at most an approximation to actual soil loss and has been adopted in this assessment as thebest means of comparing or ranking degrees of severity of soil erosion hazard. An initial assessment ofsoil erosion hazard based on the USLE has been done for the whole country at a scale of 1:1 million bythe Kenya Soil Survey. The manual integration of the many factors in the model is however a tediousprocess which does not provide for easy revision as the density of measurements improves with time.

From previous experiences, wind erosion is expected to be a problem during the dry season andonly in the drylands receiving up to 600 mm of annual rainfall and with sparse vegetation. The areas ofthe country below 600 mm isohyet have been demarcated and eight climatological stations ( Voi,Makindu, Garissa, Marsabit, Wajir, Moyale, Lodwar, and Mandera) with the longest and most reliabledata within these areas were selected to help determine land degradation indicators for these areas.Synoptic wind measurements at 10 metre height were used to derive the mean wind speeds at 2 mabove the ground. Wind erosivity indices were then calculated using the Fournier equation. Aridityindices (Ratio of precipitation to potential evapotranspiration) were also calculated for the samestations. By combining wind erosivity indices, estimates of soil erodibility, aridity indices andvegetation cover, an assessment of the wind erosion hazard was made for the areas considered

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susceptible. A second and independent assessment was made by estimating the sand load in theatmosphere from observations of horizontal visibility made at the same sites (Wangati and Said, 1997).

The abundance, productivity, species composition and canopy structure of natural vegetation arevaluable indicators of land quality and hence the extent and severity of land degradation. Undesirablechemical changes in the soil (acidity, salinity or alkalinity) are often indicated by disappearance ofunadapted plant species and build up of species that are more tolerant to such conditions. Replacementof shallow rooted grasses and shrubs by deep rooted drought tolerant trees and shrubs would indicateloss of fertile top soil or serious loss of water holding capacity due to severe loss of soil depth as aresult of erosion. Overgrazing and charcoal burning may also result in predominance of unpalatable orotherwise undesirable plant species. The features just described are however often difficult to mapsince they usually affect relatively small patches of land and may look different in dry and wet seasons.Remote sensing either through aerial photography or high resolution satellite imageries has proveduseful but even such pictures require intensive ground truthing for accurate interpretation.

It is estimated that the majority of the population ( over 70%) in Kenya live in the rural areas andare entirely dependent on fuelwood, mainly in form of wood fuel, as the source of energy for cookingand keeping their houses warm at night. At least one half of the urban population is also dependent onfuelwood, mainly in form of charcoal, as source of energy for cooking. Since supply of fuelwood fromdesignated forests is minimal, demand for fuelwood places tremendous pressure on the naturalvegetation especially close to human settlements. This is more so in the arid and semi-arid areas sincemost households in the high potential areas can meet their fuelwood requirements from on-farm wood-lots, hedges and multipurpose trees. The arid and semi-arid lands (ASALs) are also the main source ofthe large quantities of charcoal used in the urban areas. The impact of commercial charcoal burning onthe vegetation structure is already evident in the ASALs even hundreds of kilometres from the majorcities and townships. Since cooking fuel is a necessity in all households, fuelwood deficit (differencebetween supply and demand) is an important indicator of pressure on the vegetation and hence landdegradation hazard in Kenya. Assessment of this indicator has been made by compiling estimates ofdemand from previous surveys, projecting growth of that demand in terms of population growth anddistribution of human settlements, and transferring where appropriate, demand in cities and majorurban areas to the known and projected sources of supply. Fuelwood supply was estimated from anassessment of the structure and distribution of vegetation units considered accessible for fuelwoodharvesting.

The state of water resources is a valuable indicator of land quality. Thus, presence of largequantities of sediment in river water is usually the first visible indicator of soil erosion within awatershed while increase in frequency and height of flood peaks in stream flow is an indicator that thewater infiltration rate is decreasing as a result of soil compaction and/or loss of ground cover.Deposition of large quantities of silt on flood plains may also adversely affect land productivity throughdestruction of soil physical and chemical characteristics. In the absence of major and long term changesin rainfall pattern, variations in groundwater characteristics such as depth of water table may beattributed to either excessive water abstraction or land degradation resulting in reduced infiltration andhence groundwater recharge. Poor water and land management in irrigation schemes may also lead toimpeded drainage and rise in water table. Land then becomes degraded either through water logging orbuild up of salinity especially in the dry regions where the rate of evaporation is high. The use of theseindicators to identify extent and severity of land degradation has been investigated for each of the maindrainage basins, using the data already compiled under the Water Resources Assessment Project(WRAP) in the Water Development Department and the irrigation schemes have been mapped out aspotential areas of land degradation.


Socio-economic impacts of soil chemical degradation

A comparative study of 22 agricultural soils cultivated for 18-30 years in Western Kenya showed thataverage carbon stocks were 40 t C/ha while the average loss rate was 690 kg/C/ha/yr (Wissen, 1997).Existence of long-term field experiments provides opportunity to investigate the effects of different landmanagement practices on soil fertility and carbon stocks decline over time (Qureshi, 1987; Swift et al.,1994). For example in a long-term field trial at Kabete, Kenya, on maintenance of soil fertility withorganic and inorganic inputs, shows that in 21 years of maize production, yields of no-inputs and NPtreatment (120 kg/N and 52 kg/P per ha per yr) declined by 70% and 50%, respectively; which wasequivalent to loss in maize production yields of 3 and 2 t/ha/yr, respectively (Nandwa, 1997). Thenutrient balances after 21 years for the no-input treatment were -77 kg/N, -9 kg/P and -87 kg/K per haper yr; while that for NP treatment were -86 kg/N, +10 kg/P and -144 kg/K per ha per yr, respectively(Nandwa, 1997). Results from the experiment showed that there was decline in SOM over time in alltreatments with the greatest loss of 608 kg/ C per ha per yr (Kapkiyai et al., 1996). However, thelosses were lower by 49% when FYM was continually applied and maize stover restituted. The authorsinterpreted a loss of one tonne of carbon per hectare to be equivalent to a loss of 243 kg/ ha/yr of maizeand 50 kg/ ha/yr of beans.

A crude extrapolation from these changes in the Kabete long-term trial resulting from differentinputs suggests that it would require 35 t livestock manure/ha/year alone to maintain the SOM at itsinitial level or 17 t manure/ha/year with 16 t stover/ha/year to do so when mineral fertilizers areapplied. These high rates of manure and crop residues necessary to stabilize soil C in the soils of small-holder farmers are therefore, very high and fall beyond those which provide the most efficient cropreturns. Kipkiyai (1996) also compared SOM under various treatments against some soil parameters.Total N, Nitrogen mineralization, extractable K, and Ca, and CEC co-varied with SOM contentsresulting from different treatments. The covariance was greatest between N and SOM. Carbonbalances suggested that manuring restocks the particulate organic matter fraction more efficiently thando addition of maize stover and that fertilization without organic inputs hasten SOM loss.

A set of recently concluded fertilizer trials throughout Kenya provides additional information onsoil C changes during continuous cropping between 4 and 7 years with and without fertilizers. Theinitial stocks at the sites ranged between 30.2 and 44.1 t C/ha in the surface layer (FURP, 1994;Weemer et al., 1997). Across 24 fertilizer trial sites the overall annual loss from unamended cultivatedsoils was 0.69 t C/ha/yr. A small positive influence on SOM changes was observed with N fertilizationwhen compared to changes in soils receiving no fertilizers and SOM increases were most pronouncedin the soils that were most N-responsive. Besides decline in crop productivity decline, nutrient depletionhas other negative consequences for farm livelihoods such as less fodder for cattle and hence lessmanure, less crop and other plant residues to restitute and less fuelwood for cooking. Recent studiesindicate that 14% of the area covered by medium and high potential of Kenya has soils with less than0-10 kg/ of carbon which is interpreted to mean up 25% the area with less than one gram per kilogramof nitrogen stocks in the top soil (Braun et al, 1996). The study also indicates that over 24% of Kenya'smedium potential area has less that 0-15 kg/ of potentially suppliable phosphorus in the top soil (notwithstanding absence of data in 40% of the area). This may be attributed to long history of croppingand nutrient mining. To put back the agro-eco-systems to their original productivity potential requiresinvestment and replacement of the nutrients lost.

Nutrient balance studies in Kenya indicate that nitrogen and phosphorus is being depleted at a rateof 40-100 and 2-3 kg/ ha/yr, respectively. However, in spite of the negative balances, some agro-ecosystems are still productive. This is because soil fertility decline may not be noticed because of the

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soils high nutrient stocks and availability or unbalanced nutrient stocks and availability (N/P ratios).Soil fertility decline starts to be noticed in systems with low nutrient stocks and availability (crop yieldsgradually going down). These studies show that the unsustainability of agricultural production atnational level correspond with the observations at farm household level. Thus, from the full balancescalculations, the average N-balance at farm level is -71 kg/ ha/yr with large variations between farmsranging from -240 kg/ ha/yr to +135 kg/ ha/yr, while the average K-balance is slightly negative incontrast to the P-balance found to be slightly positive (Jager et al., in press). The authors concludedthat both N and K were mined, implying that 32% of the net farm income is based upon nutrientmining. The authors further reported that over 54% of the farms in the study sample realize incomelevels from farm activities which are below the estimated poverty line. From the foregoing it may beconcluded that a large portion of the farm households are producing in an economic unsustainablesituation and that off-farm income is essential for large groups of small scale farm households toachieve economic viability.


Productivity of major cereals (maize, wheat, rice, barley and sorghum) is primarily limited by nitrogenor phosphorus or both (FURP, 1987). It was found K to be adequate for most soils in the country andattributed it to parent materials which are high in feldspars and micas; although an early survey of K -deficient soils in East Africa and responses to different crops (bananas, potatoes, etc.) is still valid.Analysis by Esilaba and Ssali (1987) of 13 major agricultural soils in Kenya indicated that most of thesoils have a low C reserves (up to 406 mg kg/ -1). Chamberlain (1959) and Chamberlain and Searle(1963) studied trace elements in some East African soils, and found that Cu was deficient in mostwheat (Triticum aestivum) fields which resulted in the adoption of soil dressing of CuSO4 over andabove NPK fertilizer recommendations. Nevertheless, very few studies have been carried out in Kenyaon soil status of trace elements.

Soil fertility restoration and replenishment technologies

Fertilizer recommendations in Kenya for wheat, barley and rice are regularly adjusted to addresschanging soil biophysical conditions. This is possible because for a long time research on these cropshas been funded by the industry, e.g. Wheat Board, Kenya Breweries and National Irrigation Board,respectively. Blanket fertilizer recommendations for maize have remained in operation for a long time(KARI, 1992). In economic terms blanket fertilizer recommendations in the long run are considered awaste of resources to the state and to individual farmers. Recent studies suggest that fertilizerrecommendations based on limiting nutrients have much higher nutrient use efficiency than those ofblanket recommendations (FURP, 1994). To overcome the constraint of low nutrient recovery andoptimize fertilizer use there is need to replace such general and over-simplistic fertilizerrecommendations with types that are rationally differentiated according to agro-ecological zones (soilsand climate), crop types, nutrient uptake requirements and socio-economic circumstances of farmers(FURP, 1994; Jones and Wendt, 1995). Zone-specific and crop-specific fertilizer recommendations, ifadopted judiciously can mitigate nutrient depletion in four ways. First, substantial increase achieved inharvestable products is often in similar ratio to increases in crop residues and roots, both which helprecycle nutrients and build and increase soil organic matter (SOM). Secondly, targeted yields can beachieved over a relatively smaller proportion of land and thereby result in increased area of land left torecuperate in fertility through fallowing, improved fallows. Thirdly, relatively immobile nutrients suchas P, are built up to high levels in the soil, and can be made available for subsequent crops. Fourthly,application of fertilizer according to limiting nutrients, results in savings in fertilizer materials (avoiding


wastage) which can be used to combat depletion elsewhere in appropriate plots, fields, farms or sold toearn the much needed cash.

Long-term (more than three seasons) monitoring of the fertilizer use recommendations (FURP,1994) on three soil (Smaling et al., 1992) revealed that the same amount of fertilizer gave entirelydifferent yield response at the three sites due to very different climatic and soil conditions (Table 4). Ona Nitisol, Phaeozem and Arenosol or Alisol (FAO/UNESCO, 1990), maize grain yields were increasedby 133% (on Nitisol), 40% (on Vertisol) and 48% (on Alisol) through application of P only, of N only,and N+P together, respectively. This demonstrated the merits of zone specific and crop-specificfertilizer recommendations over blanket recommendations.

TABLE 4Yields and NPK uptake of maize on three Kenyan soils as a function of soil type and fertilizer treatment,1990

Nutrient uptakekg/ ha

Soil Treatment Yieldton/ha

N P KNitisol (red, clayey) N50 P0 2.1 42 5 30

N50 P0 2.3 50 6 36N0 P22 4.9 79 12 58N50 P22 5.1 82 14 65

Vertisol (black, clayey) N0 P0 4.5 63 24 95N50 P0

N0 P22

6.34.7

109 70

3523

126106

N50 P22 6.7 113 46 111Arenosol (brown, sandy) N0 P0

N50 P0

N0 P22

N50 P22

2.52.22.33.7

38 45 38 66

7 71116

42 47 68 77

A major limitation of zone-specific and crop specific fertilizer recommendations based on short-duration studies (less than three seasons), is that related to the development of soil degradation in formof nutrient imbalances. For example in FURP (1994), continuous application of P containing fertilizeron Nitisols increased N and K uptake by 88% and 93%, respectively, while application of N containingfertilizer on Vertisols increased P and K uptake by 46% and 33%, respectively. These findingsrendered the fertilizer use recommendations inappropriate after a short period and thus suggested thatthere was need to supplement the NP zone specific fertilizer recommendations with these additionallyuptake nutrients.

In FURP trials reviewed (FURP, 1994), continuous application of N and/or P also resulted inscenarios where Ca also started limiting production of maize, indicating that there was need tosupplement the recommended NP fertilizer recommendations with Ca containing materials. Jones etal.,(1960) showed that the supply of excess K from mulch was the primary cause of nutrient imbalancee.g. in form of Mg deficiency observed in coffee and that this problem was particularly observed withmulch from napier grass (Pennisetum purpureum), which is a known luxury consumer of K. Instudying the effect of fertilizer and crop rotation, Wapakala (1976) reported that continued use of(NH4)2SO4 as a source of N on a kaolinitic red clay soil in central Kenya depressed soil pH andavailable Ca, Mg and K; while a build up in Ca, a rise in pH and an increase in Ca-P in the inorganic Pfraction and a depression in occluded AI-P and Fe-P in the inorganic P fraction were observed whenCAN was the N source. Furthermore application of DSP was found to decrease available P (Mehlich)but raised the levels of AL-P, Fe-P and occluded Al-P in the organic fraction. After 3 years of

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continuous application of CAN, some soils of Fertilizer use trials also showed clear symptoms ofacidification (FURP, 1994; Smaling and Braun, 1996).

In parts of the country, prior to FURP trials, some farmers complained that yield increments as aresult of application of DAP were no longer economical (Kenya Times, 1989). An experiment set up toinvestigate DAP reaction with soil and consequences on yields showed decline in SOM and total N(probably attributed to removal and burning of crops residues). Compaction of subsoil (and inhibitionof water infiltration and root development) were major causes of uneconomical crop yields and notDAP per se. These results highlight the limitations of blanket as well as zone-specific and crop-specificrecommendations and thus mitigates for the need for balanced nutrition-based fertilizerrecommendations. The latter are also termed maintenance fertilizer recommendations. Only recentlywere the results of fertilizer use trial sites (FURP, 1987) based on the concept of agro-ecological units(Smaling and Van de Weg, 1990) published in district reports (FURP, 1994), journal papers (Smalinget al., 1993, 1992; Smaling and Janssen, 1993; Smaling and Braun, 1996), and doctoral theses(Smaling, 1993; Rotter, 1993; Wokabi, 1994; Nandwa, 1995). Available technologies that can bederived from the FURP district booklets (FURP, 1994) includes responses of maize and other 17annual crops to different combinations of N, P and K fertilizer, and FYM. Fertilizer response to annualcrops were earlier reported by Allan and Stroebel (1987), Okalebo (1977) and more recently byOkalebo and Nandwa (1997). A number of scientists are also preoccupied with studies aimed atextending the agro-ecological extrapolation of the above results, and hence add value to earlier researchfunding investment. Rotter (1993) investigated the use of a dynamic crop growth model, the WOFOSTmodel (WOrld FOod STudies), on maize growth using FURP data. Wokabi (1994) also used theAutomated Land Evaluation System (ALES) to predict maize yield gaps between different productionsystems. In most cases, these models gave good prediction indicators.

Full adoption of recommended fertilizers rates amongst smallholder is likely to be constrained bypoor return to fertilizer application because of (i) poor or low producer price to cereals; (ii) sub-optimaluptake attributed to low plant available water especially in the arid and semi-arid areas of the country.To solve the first problem, there is need for imaginative agriculturists fully involved in participatorytechnology development on the judicious use of mineral fertilizers, or other less costly inorganicmaterials such as rock phosphate, or application of the mineral fertilizers on high value crops.Phosphate rock-based technologies in Kenya include direct application, acidulation to producephosphoric acid of finished products, including partially acidulated phosphate rock (PAPR), and theproduction of thermally altered phosphates (e.g. fused Mg phosphate, Rhenania phosphate anddeflourinated phosphate).

The major challenge in the use of rock phosphates to combat nutrient depletion, is how to solvethe problem of ore types (low reactivity quality). This requires development of technology (which is notthere yet) adapted to varied ore characteristics (Mclellan and Notholt, 1986). Although Kenya’s rockphosphates (Rangwe carbonatite) have not been exploited (Gachiri, 1991), probably because of its lowquality e.g. 1.7-2.1% P (Idman, 1985; Van Kauwenbergh, 1986), nevertheless considerable depositsexist in Tanzania (Minjingu) and Uganda (Busumba and Suku) which could be accessed (Mclellanaand Notholt, 1986). In Kenya, several studies have been conducted on the effectiveness and efficiencyof rock phosphate in comparison to processed P fertilizers (Woomer and Muchena, 1996; Okelebo andNandwa, 1997).

The first overall conclusion derived from past studies is that amongst East African rocks,Minjingu deposits on average reaches 65% of the effectiveness of processed P fertilizers (TSP), butonly costs about 50 % of it on a P basis (Woomer et al., 1997). The second conclusion is that


application of rock phosphates with organic helps to hasten its solubilization. For example applicationof 400 kg/ ha-1 MRP (Minjingu Rock Phosphate) was shown to improve maize yield by 1-3 t/ha whenapplied in combination with organic sources of nitrogen. The third conclusion is that the benefits ofphosphate rock application are greater and much more likely only on low pH and P limiting soils(Okalebo and Nandwa, 1997). These encouraging results have provided an impetus and triggered theformulation of a number of projects and proposals in Kenya on large scale soil fertility recapitalizationor replenishment of phosphorus with rock phosphates (Okalebo et al., 1996; Weemer and Muchena,1996; Woomer et al., 1997). Lime and liming materials are often applied to reduce soil acidity, so as toenhance availability of nutrients. Soil acidity may also be ameliorated through better organic mattermanagement practices. The comparative advantages and disadvantages in the use of lime and dolomitesto correct soil acidity has been reported by several researchers (FURP, 1994). However, thewidespread adoption of liming technology is hampered by (i) its bulkiness (like phosphate rocks) andhence difficult to transport and apply, (ii) high leaching, especially under high rainfall conditions and insandy soils, and (iii) general unavailability to the resource-poor farmers. These constraints may beovercome by application of comparatively small dressings at a time, well mixed into the soil which hasbeen reported to be a more efficient way of lime application (FURP, 1994; Grant, 1970).

In Zimbabwe, liming-induced Zn deficiency has been reported, but this has been attributed toapplication of high rates of lime and P fertilizers (Tagwira and Mugwira, 1992, 1993). In generalliming technology tends to be adopted mostly by high-external input farmers rather than small-scalefarmers. A number of studies in Kenya have shown that liming contributed to higher pH values andbetter crop yields (up to pH 6), especially with wheat (Nyachiro and Briggs, 1987), tea (Wanyoko,1989), maize and beans (Nuwamannya, 1984) and beans (Ssali, 1981). The latter author found thatliming increased nodule weight and dry matter yield in soils with low organic C and substantialcontents of Al or Mn, but in soils with relatively high organic C contents, high lime rates depressed drymatter yields. In Kenya, the third problem (low soil available water) is being tackled through integratedfertilizer and water harvesting techniques field trials in the arid and semi-arid lands (KARI, 1997).

The use of termite soil in situ or through biomass transfer is commonly practised in parts ofKenya. Hesse (1958) studied termites and indicated that Cubitermers did not affect the pH of soil andthat termite mound soils contained more C and N than surrounding soil, probably due to highernumbers of cellulose decomposers, denitrifiers and nitrifiers (mainly Nitrobacter and Nitrosomonasspp.) found in termite modified soil than in surrounding topsoil (Mureira, 1980).

In many agro-eco-systems in Kenya organic inputs existing in farms are sometimes not fullyexploited as nutrient inputs due to complex trade-offs between costs (labour, land), and perceivedbenefits on a short and long-term basis. Nevertheless organic inputs may include biomass transfer,agro-industrial by-products and wastes and cropping systems based on nitrogen fixation.

Sustainable agricultural production based on nutrient cycling operates only in systems whereenough nutrient biomass is generated on-farm. With declining per caput arable land in sub-SaharanAfrica, such systems are decreasing fast. Consequently, many smallholders try to increase their nutrientquantities through materials carried to the site as biomass transfer and count as actual addition ofnutrients to the system. This may be in form of manure, leaf litter, pruning, plant residues etc. Biomasstransfer-based technologies are not common in the region except where there is abundant animalmanure available. A recent survey carried out in central Kenya highlands on biomass transfer indicatedthat 10-100% of the farmers surveyed imported animal manure from outside the dairy production zone,within the district or from other districts; at prices of between $ 5-100 per tonne, which in some casesis much more costly than inorganic fertilizers (AHI, 1996). A parallel study to inventorize the

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composition, biomass production and transfer and nutrient cycling potentials existing in hedges onsmallholder farms in Western Kenya revealed that over 28 species of hedge plants were ubiquitouslydistributed in the area, which were currently under-utilized in terms of biomass transfer or plant residuerestitution for soil fertility improvement. In Zimbabwe, biomass transfer of miombo woodland leaflitter used as a source of plant nutrients, has been reported as a common practice amongst smallholders(Musa et al, 1997).

The use of urban and agro-industrial wastes could help reverse the flow nutrients from cropharvest back to the farm (in form of nutrients cycling if the flows went back to the same farms), butwide adoption may not be justified in economic terms. The by-products and wastes of processed cropse.g. coffee husks and filter mud/bagasse from coffee and sugarcane, respectively, are important sourceof nutrients. One tonne of these products may contain about 5-20 kg/ N, 7 kg/P and 25 kg/ of K.However, because of their bulkiness, the use of these products tends to be limited to areas in closeproximity to their source. Further more, a recent study in Kenya showed that 1 kg/ of N and P fromcity composts costs 0.5 and 1.2 US $, respectively, compared to 0.42 and 0.18 US $ of N and P inpurchased fertilizers e.g. 20:9:0 a elemental N, P, K (Palm et al., 1997). In Kenya, an organic fertilizerhumus made from coffee husks named "cofuna" was reported to enhance fertilizer utilization by maizecrop. Its application at 400 - 800 kg/ ha gave yields of maize comparable to farmyard manure appliedat 4.2 t/ha, but its cost could only be recovered on high value crops.

Nitrogen contribution of legumes and other N-fixing plants has been widely exploited inenhancing productivity of agro-ecosystems, in terms of species for intercropping, relay cropping,agroforestry, rotational species or as species for use in improved fallow technology. Recent studies inEast and central Africa highlands on screening of species for improved six months fallows (Calopogonium mucunoides, C. agatiflora and C. mucronata) and twelve months fallows (Tephrosiacandida, Desmodium viscosa and Macroptillium atropurpurem) indicate that in 6-12 months thespecies produced 6 - 11 t/ha dry matter, 150 - 300 kg/N/ha and 20 - 30 kg/P/ha (AHI 1997). But manypast experiments on legume intercropping, have shown that many legumes hardly fix any nitrogenunder low soil available P conditions unless inoculated. Moreover, competition for water, light andnutrients between food crops and perennial legumes, makes the intercrops of the latter for soil fertilityrestoration, as an inappropriate technology, except for soil conservation purposes (Place et al., 1995).Similar competition has been observed in systems where food legumes have been intercropped withmaize as a risk aversion or minimization strategy, in case of drought.

Nevertheless, deep rooted legumes species planted as improved fallows contribute to soil fertilityrestoration through biological nitrogen fixation (BNF) as well as from nutrient capture from subsoil. Ina recent study in Western Kenya, on screening soil improving legumes for low P conditions (P stress),results indicated that some species like Dolichos lablabbronga, M. atropurpurem and Canavaliaensiformis responded negatively to P application, an indication that they can do well in P deficient soilconditions. Elsewhere, studies have shown that two tonnes of leaves of some non-leguminous trees andshrubs (Tithonia divesiforlia, Chromoleana ordorata, etc.) produce enough N and K for a 2 t/hamaize grain crop but six times more biomass would be required to supply adequate P. In systems withlimited per caput arable land, legume species likely to be adopted are those that are grown for food(grain) or forage purposes, but also yield high above ground (leaf biomass) and below ground biomasse.g. Arachis, Cajanus etc or leguminous cover crops such as Crotalaria, Dolichos Mucuna etc.

Nutrient saving and conservation technologies

Recent rising costs of chemical fertilizers has focused researchers attention on recycling of crop andother plant residues (restitution) and weeds as a strategy to buffer the level of soil fertility and maintain


soil organic matter (SOM). Poulain (1980) reported that organic residues may contain appreciableamounts of nutrients, commonly under-utilized in African farming systems. For example a 2 t/ha maizegrain crop (4 t/ha stover), on average contains 25, 7.2 and 65 kg/ ha of N, P and K, respectively, in thestover, which is 4 - 5 times that applied from mineral fertilizers by most farmers in SSSA (Steervegeland Smaling 1990). The development of appropriate technologies for efficient nutrient utilization ofcrop residues requires an understanding of the merits and trade-offs of residues restitution (Prasad andPower, 1991), and factors regulating their decomposition and mineralization and nutrient releasepatterns (Whitmore and Handayante, 1997). The technologies so formulated need to identify optimumquality, rates, placement and time of restitution of the residue in the context of cropping systemstargeted. A number of studies are presently undertaken to determine the short-term and long-termeffects of crop residue restitution on crop response (TSBF, 1995). Most of the studies in the region areconducted within the framework of the Tropical Soil Biology and Fertility (TSBF) African Network(AfNet) which uses standard methodology (Anderson and Ingram, 1993), to gain insights of theprocesses which regulate the release of nutrients.

Emerging results from the AfNet work indicates that (i) about 5 - 10 tonnes dry matter per hectareof crop residues may supply enough nitrogen for a two tonne maize grain crop (80 kg/ N/ha) butcannot meet P requirements (18 kg/ P/ha) and hence P must be supplemented by inorganic P (Palm,1995), (ii) the availability and supply of 5 - 10 tonnes of crop residues directly as nutrient sources maybe a problem especially on resource poor farms where there are competing uses as livestock feed orsource of fuel; (iii) and even if availability and restitution of low quality crop residues was possible, inmost cases materials with <2% N, >15% lignin, and >3% polyphenol (Palm, 1995) and <0.25% P(Blair and Bennet, 1986), will initially immobilize N and P, respectively, and exacerbate nutrientdeficiency, unless this is offset by combination with inorganics or high quality organics. In Zimbabwe,one mango tree has been reported to supply 22 kg/ of leaf litter (on average each farm has 11 mangotrees) which when applied was reported to immobilize 10.9 kg/ N/ha (TSBF, 1995). The majorconstraint to the adoption of or sourcing nutrients from plant residues, is that no field trials have beenconducted in the region which allow establishment and recommendation of fertilizer equivalency valuesof the residues especially for circumstances where organics and inorganics have to be combined (Palmet al., 1997).

Nitrogen recovery in the tropical cropping systems is often reported to be in the range of 30 - 50%which is largely attributed to leaching (Nielsen et al.; 1982; Birch, 1960; Smaling, 1993). In shallowrooted annual crops nutrients leached below the rhizosphere is as good as lost. Split application ofnitrogen dressing is one strategy aimed at minimizing such losses. Another strategy is throughutilization of untapped subsoil nitrates (Farrel et al. 1996). Such nitrates (at 50 - 200 cm soil depth) areestimated to be in the order <100 kg/ N/ha/yr in Western Kenya. Research on soil and waterconservation practices in Kenya dates as far back as 40 years. However little information exists whichrelates biological methods of control to amounts of nutrients saved from loss (Braun et al, 1997). Mostof the work has been concentrated on tillage and tied ridges, minimum tillage versus conventionaltillage versus contour farming, mulching and crop residues and crop cover. Kilewe and Mbuvi (1988)reported that minimum tillage had a reduction of 70.8 and 39.2% in runoff, and 53.0 and 58.7% in soilloss in the long and short-rainy seasons, respectively. This is in contrast with conventional tillage whichreduced runoff by 25.1 and 20.1%, and soil loss by 8.1% and 39.5%, respectively. The authors foundapplication of maize residues to reduce runoff by 58.7 and 78.6% and soil loss by 94.4 and 64.4%respectively, during the same periods. Similarly, maize intercropped with beans (compared to purestand maize) reduced runoff by 29.2 and 42.0%, and soil loss by 22.3 and 47.5%, respectively, duringthe some period. Technologies based on these results have proved fruitful in saving nutrients liable tolosses.

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Malawi


Malawi has a total land area of 11.8 million hectares, of which over 20% is covered by LakeMalawi and other small lakes and rivers. Malawi exhibits great diversity in terms of relief units,soils and climate for a country of its size. There are four major relief units: (i) The High AltitudePlateaus (1,350 to 3,000 m a.s.l.) dominated by Lithosols and some weathered Latosols, (ii) TheMedium Altitude Plain (750 and 1,350 m a.s.l.) with deep, well drained Latosols on upland sitesand poorly drained hydromorphic soils in dambos, (ii) The Lakeshore Plain (450 and 600 ma.s.l.) characterized by calcimorphic alluvial soils, and (iv) The Lower Shire Valley (35 to 105 ma.s.l.) dominated by calcimorphic alluvial soils, Vertisols and hydromorphic soils in dambos. Theclimate is semi-arid in the Lower Shire Valley and some parts of the Lakeshore Plain, semi-aridto sub-humid on the Medium Altitude Plateau, and sub-humid to humid on the High AltitudePlateaus. Although most parts of Malawi receive adequate total rainfall for rain-fed agriculture inmost years, its distribution is often poor, uneven, and erratic leading to crop failure. Thedistinctive feature about the rainfall pattern in Malawi is its concentration in a single crop rainyseason starting in November/December and ending in April/May. The population of Malawi iscurrently estimated at 12 million people and growing at the rate of 3.3% per year. About 90% ofthe population are rural and derive its livelihood from small land holdings of between 1.0 and 2.0ha per farm family of five people. The population density is estimated at 85 persons per squarekilometre, a figure that is too high by African standards. The average population densityincreases from the north to the centre and then to the south as follows: 44, 113 and 162 personsper square kilometre, respectively.

Agriculture dominates economic activities in Malawi. It contributes well over 40% of the GrossDomestic Product (GDP) and accounts for about 90% of the foreign exchange earnings.Smallholder farmers contribute about 85% of total agricultural production and 30% of the exporttrade, with the balance coming from the estate sub-sector. The major food crops are maize,groundnuts, cassava, sorghum, millet, beans and other various pulses. The main cash crops aretobacco, tea, sugar, coffee, groundnuts, cotton, macadamia nuts and maize. Maize is the majorstaple food crop grown by all smallholder farmers on about 65% of the total cultivated land area(estimated at 1.8 million hectares). About 94% of this is grown in association with legumes,whereas 6% is planted in pure stands. The smallholder sub-sector consists of about 1.8 millionfarm families. Women comprise about 70% of the total full-time farmers and play a vital andindispensable role in agricultural production in Malawi (World Bank, 1995; UNICEF, 1993).

A.R. Saka, W.T. Bunderson, M.W. Lowole and J.D.T. KumwendaChitedze Agricultural Research Station, Lilongwe;Malawi Agroforestry Extension Project, Lilongwe;

Soil Survey Commodity Team, Lilongwe

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High population densities and growth rates limit available land for agricultural expansion. In1987/88 56% of all smallholders in Malawi cultivated less than one hectare of land, 31% had 1.0to 2.0 ha, whereas an estimated 13% had more than 2 ha. The average landholding size amongthese categories of landholders was 0.55, 1.40 and 2.91 ha, respectively. Most smallholderfarmers lack basic needs such as adequate food, water, energy, shelter, health and education. It isestimated that over 60% of the smallholders live below the poverty line, whereas in urban areas,average wage earnings are infrequently sufficient to purchase food and other basic necessities oflife. Chronic food shortage is manifested though malnutrition and high mortality, especiallyamong children. The future prospects in meeting basic food demands for a growing populationare bleak and worrisome. Most households lack resources and support to undertake soundagronomic and animal husbandry practices to properly manage the natural resource base. Familylabour is also decreasing as household members engage in off-farm employment (ganyu) in urbanareas at a time when they are supposed to be cultivating in their fields. This has led to increasingpoverty and chronic food shortages (Bunderson and Hayes, 1995).

With existing population pressure trends, Malawi is facing enormous problems of naturalresource degradation, deforestation and loss of biological diversity. Recurrent droughts, reducedexport earnings and declining terms of trade, have magnified the social, economic andenvironmental problems facing Malawi today. Increasing population pressures on a limited landresource base has direct impact on employment, marketing, food security, health and education(Bunderson and Hayes, 1995). As of now, land degradation is a serious problem in Malawi. TheWorld Bank (1992) estimates that 20 t/ha/year are lost through soil erosion in Malawi. Inslopping hilly areas, and where the soils are more erodible, soil erosion rates of up 50 t/ha/yearhave been reported; whereas in areas with flat terrain and where good crop husbandry practicesare followed, soil erosion is negligibly small. The main causes of soil erosion include: pooragronomic practices, poor soil management practices, deforestation resulting from agriculturalexpansion and increasing demands for firewood, and over-grazing. Malawi's high and growingpopulation has led to chronic land shortages, declining incomes, and stagnating levels of cropproduction leading to food insecurity at both household and national levels. An examination ofnational cereal food production in Malawi over the last 10 years (1985/86 - 1994/95) indicatethat the per caput cereal requirements have not been met in all years, except during the 1992/93season which had a notably good rainy season (Table 1).

TABLE 1Population, cereal production (tonnes) and requirements (kg/ per caput ) 1985/86-1994/95

1985-86 1988-89 1989-90 1991-92 1992-93 1994-95

Population (000) 7 733 8 524 8 806 9 397 9 707 10 358Production: Maize 1 424 1 660 1 477 723 901 1 568 Rice 37 46 43 24 65 48 Sorghum 21 20 15 4 22 23 Millet 10 11 10 3 15 11 Wheat 1 1 2 1 1 2 Total cereals (000) 1 493 1 739 1 548 754 2 341 1 651 per caput production kg/ 193 204 202 80 241 159per caput requirement kg/ 232 232 232 232 232 232Deficit/surplus kg/ -39 -28 -56 -152 9 -73

Sources: Bunderson and Hayes (1995), as extracted from the 1987 NSO Population Census; Cropproduction estimates from the Ministry of Agriculture (1988); Cereal requirements from UNICEF (1993)


Using 1980 as the base, total food requirements rose by 171% in 1993 and are projected torise to 249% in the year 2010. The national maize demand in 1996/97 was estimated at1 351 842 tonnes; whereas the national demand was estimated at 1 800 000 tonnes (Bodzalekani,personal communication). This indicates a shortfall of 448 158 tonnes that must be imported intoMalawi. This has serious implications on foreign exchange reserves for Malawi. The actualcereal production (1985/86-1994/95) is given in Table 1; whereas projected national cerealconsumption requirements are given in Table 2. The predicted outcomes, or model forecasts,indicate an urgent need to increase cereal production to meet the demands of an increasingpopulation, against a background of declining land holdings. The declining trend in smallholdercrop production (food and cash crops) over the last decade (1985/86-1994/95) in relation to landarea is depicted in Table 3.

TABLE 2Projected national cereal consumption requirements (tonnes) in Malawi, 1995/96-2014/15

Years 1995-96 1997-98 2001-02 2007-08 2011-12 2014-15Population ('000) 10 694 11 384 12 826 15 115 16 700 17 905Cereal requirements: Maize 2 363 2 516 2 834 3 340 3 691 3 957 Rice 72 76 86 101 112 120 Sorghum 28 30 33 39 43 47 Millet 16 17 19 23 25 27 Wheat 2 2 2 3 3 3 Total cereals (000) 2 481 2 641 2 976 5 507 3 874 4 154per caput production kg/ 232 232 232 232 232 232per caput requirement kg 232 232 232 232 232 232

Source: Bunderson and Hayes (1995) as extracted from the 1987 NSO Population Census; Cropproduction estimates from the Ministry of Agriculture (1988); Cereal requirements from UNICEF (1993)Notes:1. Estimated annual growth rate of 3.3% from 1986/87 until 1994/95, this rate is assumed to fall by

0.05% from 1995/96 until 2014/15 because of efforts to reduce population growth (e.g., birth control;declining fertility rates; and the possibility of a rising death rate due to diseases)

2. Based on Malawi's current demographic structure, an average intake of 2,200 calories per day isneeded to meet minimum calorific requirements. To provide 80% of this requirement, about 190 kg/of milled maize grain (mgaiwa) needs to be consumed per year. This is equivalent to maizeproduction of 232 kg/person/year assuming a wastage of 18%. Other cereals (rice, wheat, sorghumand millet) have been included for the purposes of this year analysis on the same nutritional basis

3. Assumed that the estate sub-sector produces an annual 10% increment to smallholder maizeproduction.

TABLE 3Smallholder crop hectarage (ha) and production (tonnes) in Malawi, 1985/86 - 1994/95

Years 1985-86 1991-92 1994-95Food crops Hectarage Production Hectarage Production Hectarage Production

Maize 1,193,275 1,294,564 1,368,093 657,000 1,222,147 1,425,176Rice 22,874 37,407 18,241 23,798 33,038 47,577Groundnuts 176,293 88,937 64,386 12,060 89,373 37,182Sorghum 32,059 20,761 27,668 3,957 61,551 22,574Millet 17,424 9,526 14,767 3,418 24,882 11,311Cassava 72,904 218,282 63,965 128,827 94,616 321,362Sweet potatoes 22,477 80,003 19,886 43,074 56,113 342,003Irish potatoes - - 5,855 49,194 7,752 70,025total food crops 1,537,306 1,582,861 1,589,472Cash crops 247,254 369,648 505,125

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As alluded to earlier, maize is the major staple food crop in Malawi that is grown on anestimated 1.2 million ha under smallholder farm conditions. Hence, maize production needs torise almost threefold from 1.4 million tonnes in 1994/95 to 3.9 million tonnes in the year 2014/15to meet the demands of a growing population estimated at 20 million people. This will requiresignificant advances in productivity per unit area, and a commitment from Government, non-Governmental Organizations (NGOs), the donor community and the smallholder farmerthemselves. There is an urgent need to increase the current national average yield of 1.1 t/ha to 4t/ha in the year 2014/15 if Malawi is to satisfy its food requirements at the national level.National food security does not necessarily mean food security at the household level. This isprimarily due to the fact that national food security requirements do not take into account theproblems of the location where the food is available and its distribution. An average family of 5persons require a minimum food requirement of 1,058 kg/ at 232 kg/ maize per ha (Ministry ofAgriculture, 1988). Hence, landholding size is an important factor in attaining food self-sufficiency. Among the smallest farms, yields must average 1,924 kg/ ha if the whole 0.55 ha isdevoted to maize production (Bunderson and Hayes, 1995). This is 65% higher than the meanyield of 1,166 kg/ ha in 1994/95. Under current trends, these households will experience regularfood deficits on a year round basis unless they procure food by other means other than throughproduction. These include ganyu labour or other off-farm activities. The challenge facing theMalawi Government today is to produce enough food to feed the rapidly increasing populationthat is exerting enormous pressures on land and the natural resource base, on the nation's foodself sufficiency and food security, the labour markets and the provision of social welfare servicessuch as health and education. In retrospect, concerted efforts are required by Government and thedonor community to harness Malawi's natural resources so that the rate of food productionshould outstrip the rate of population growth.


Land use and land tenure

It is currently estimated that 60% (5.7 million ha) of the total land area (9.4 million ha) isconsidered suitable for agriculture under improved traditional management practices. Undertraditional practices, only 32% (3 million ha) can be classified as suitable for cultivation. As aresult of increasing population pressures on limited land area (Tables 1, 2 and 3), cultivated land(including land under short fallow) has almost doubled to 4.6 million ha over the last threedecades. Of the remaining 1.1 million ha of suitable land, 600 000 ha comprise national parks,game and forest reserves. Land is a resource of pressing importance in Malawi since all the landthat is suitable for cultivation under traditional systems of management, and much which isunsuitable for cultivation, is already under rain-fed cultivation (Green and Nanthambwe, 1992).Cultivated land area in Malawi has been unequal among the three regions, a scenario that reflectsthe longer-term land-use and availability over a longer period of time. The greatest increases inland-use over the last two decades have occurred in the Central and Northern Regions (50 and57%, respectively), where land for agricultural expansion is still available. The least expansionhas taken place in the Southern Region (3%) where the limits of agricultural expansion werereached in the 1960s (Table 4).

There are three major categories of land tenure in Malawi: (i) public land, (ii) private land,and (iii) customary land. Land under customary tenure represents about 87% of the total landarea. Land in the Northern Region and some parts of the Southern Region, is under the patrilinealsystem of inheritance; whereas that in the Central Region and some parts of the Southern Region,follows the matrilineal system of inheritance. Despite these differences, in either system, land


which is in use can be held indefinitely and can be inherited. Land that is not under any form ofuse is considered to belong to the community rather than individuals. All unused customary landis under the jurisdiction of the chief or his headman. This customary land may be declared publicland, or a lease (of up to 99 years) maybe granted to a private party or individual.

TABLE 4Expansion of cultivated area (hectares and %) in Malawi, 1966/67 - 1990/91

Area under cultivation by RegionYearsNorthern Region Central Region Southern Region Total country

has has has Has1967 577 300 1 478 300 1 477 200 3 532 8001990 902 900 2 171 850 1 505 500 4 580 250

increase % 56.4 46.9 1.9 29.6Source: Green and Nanthambwe, 1992

Trends in cereal crop production

With increasing population pressure on a limited land resource base, and continuous cultivationwith little or no added external inputs, most of the intensively cultivated soils in Malawi areheavily depleted of essential nutrient elements. There has also been an increasing trend in thecutting down of trees (deforestation) as a result of increasing population, expansion of theagricultural sub-sector, and increasing demands for fuelwood and wood products. These haveinteracted over space and time to increase the soil erosion hazard, with catastrophic consequenceson soil fertility. Increasing soil erosion, soil nutrient depletion, increasing soil acidity, accelerateddeforestation, over-grazing and the depletion of groundwater resources are all signs of Malawi'sland degradation, and deterioration of the natural resource base. All these factors have combinedover space and time to tremendously reduce crop yields in Malawi (Tables 1 and 3), hence foodinsecurity, especially among smallholders, and female headed households. Despite the increaseduse of fertilizer in Malawi over the past few decades, crop yields have either declined or stagnated(Tables 5 and 6). The main reasons for poor crop performance, despite the use of improvedtechnologies, can be attributed to several factors including poor crop husbandry practices (e.g.,late planting, inappropriate plant population densities and untimely weeding), poor fertilizermanagement practices, low soil fertility.

TABLE 5Three year running average yields of maize and groundnuts (kg/ ha), 1985/86 - 1992/93

Crop season 1985-86 1986-87 1988-89 1989-90 1990-91 1991-92 1992-93All maize 1.17 1.15 1.13 1.12 1.11 0.87 1.05 Local 1.01 0.98 1.03 0.99 0.91 0.67 0.74 Hybrid 2.94 2.92 2.74 2.69 2.77 2.26 2.42Groundnuts 0.45 0.46 0.37 0.36 0.36 0.34 0.38

Source: World Bank, 1995

Results from continuous cultivation of maize and cotton have indicated reduced maize andcotton yields, and deteriorating soil chemical conditions at Chitala (Table 7), whereas continuouscultivation under tea in Mulanje clearly illustrate the declining trends in soil chemical fertility,hence crop yields (Table 8). All these are indicative of crop yield decline owing to landdegradation under continuous cultivation. The situation is even worse under smallholder farmconditions.

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TABLE 6Maize and cotton yields (kg/ ha) and soil chemical changes under continuous cultivation with andwithout fertilizer application, 1962/63

Cropping sequenceFertilizer treatment VariablesContinuous maize Continuous cotton

No fertilizer applied pH 5.9 5.8OM% 1.81 1.81

total N% 0.07 0.06P ppm trace traceK me% 0.26 0.18

yield kg/ ha 918 2245 t/ha FYM + 200 kg/ ha pH 6.5 5.8sulphate of ammonia OM% 1.76 1.40

total N% 0.07 0.05P ppm trace traceK me% 0.44 0.32

yield kg/ ha 3562 941Source: DAR, 1965

TABLE 7Soil changes under continuous tea cultivation over a 25-year period, Nsuwadzi, Mulanje

TreatmentSoil variableVirgin soil

N0P0K0 N1P1K1 N2P2K2

OM (t/ha) 140 82.5 (41%) 102.5(27%)

97.5 (30%)

N (t/ha) 8 5.0 (38%) 5.0 (38%) 4.5 (44%)P (t/ha) 2.2 2.1 (5%) 2.3 (-5%) 2.8 (-27%)pH (CaCl2) 5.4 4.6 4.3 4.1K (t/ha) 606 137 (77%) 186 (69%) 205 (66%)Mg (t/ha) 420 152 (64%) 152 (81%) 30 (73%)Ca (t/ha) 1668 175 (90%) 140 (92%) 120 (93%)

Source: Maida and Chilima, 1976Note: Figures in brackets indicate % increase or decrease% decrease = (V - Tp) /v 100, where V = virgin soil; p= cultivated plotN0 - 45 kg/ N ha-1; P0 - 0 kg/ P205ha-1; K0 - 0 kg/ K20 ha-1N1 - 135 kg/ N ha-1; P1 - 15 kg/ P205 ha-1; K1 - 28 kg/ K20 ha-1N2 - 225 kg/ N ha-1; P2 - 30 kg/ P205 ha-1; K2 - 56 kg/ K20 ha-1

Effect of liberalization

The advent of multiparty politics in the 1990s has brought with it the liberalization of the Malawieconomy. The selling and buying of crops, except maize, and farm inputs, including fertilizers,has been liberalized. Liberalization of the market has already shown both interesting anddisturbing trends. Estimates of areas grown to different crops indicate considerable changes inresponse to fluctuating prices. There is generally an increase in the area grown to legumes, littlechanges to the area grown to maize (although there is a decrease in the area grown to hybridmaize but an increase to the area grown to open pollinated varieties), an increase in the areagrown to tobacco (a high value cash crop), and a significant drop in the area grown to soybeans(in response to low farm gate prices for this legume). With the declining land area under foodcrops, and the low levels of food production under smallholder farm conditions, Malawi is notable to feed itself as a nation.

For Malawi to be self sufficient in food production, there is an urgent need to raise averagecrop yields per unit area. Blackie and Canroy (1994) have estimated maize growth productionlevels to increase to 4 t/ha from the present 1.1 t/ha if Malawi is to achieve food self-sufficiency


and security at household level. World Bank (1989) has indicated that for sub-Saharan Africa toachieve food self sufficiency and security at household level, improve nutrition, eliminate foodimports and register modest improvements in the living standards of its peoples, then theeconomics of these nations must expand by 4 to 5% per year between 1990 and the year 2020.This is the challenge that lies a head for Malawi.

TABLE 8Estimated land area (000 ha) grown to various crops by smallholder in Malawi, 1995/96 and1996/97

Year VarietiesCrop1996-97 1995-96

Total maize 1,230 1,243 -1% Hybrid 299 369 -19% OPV 20 17 18% Local 911 856 6%Sorghum 79 76 4%Total cereals 1,386 1,398 0%Soybeans 39 54 -28%Groundnuts 97 72 35%Pulses 395 359 10%Cassava 108 116 -0.7%Sweet potatoes 71 69 0.3%Tobacco 98 79 24%

Source: MOALD, 1997


Land degradation has become an acute problem in Malawi. This is mainly as a result ofincreasing human population pressures on limited land area and increasing deforestation causedby agricultural expansion and increasing demands for fuelwood. Soil erosion is currentlyestimated at 20 t/ha/year (World Bank, 1992), with rates more than 50 t/ha/year in some parts ofMalawi. However, Saka, Green and Ng'ong'ola (1995) using data from Zimbabwe estimated thatMalawi is losing an average of 35 t/ha/year. In terms of nutrient loss per year, this translates into74.0 kg/N/ha, 539.0 kg/Organic carbon (OC)/ha and 5.5 kg/P ha. Hence, based on the aboveassumptions, it can be estimated that the whole of Malawi is losing some 160 million tons of topsoil each year from cultivated land that contains approximately 339 000 tonnes of N, 2.5 milliontonnes of OC, and 25,000 tonnes of P. Thus, the cost of replacing the lost N, P and OC isenormous considering the fact that fertilizer is an expensive farm input in Malawi owing to hightransport costs. The cost of N and P is estimated at over US $ 300 million each year (Saka,Green and Ng'ong'ola, 1995).

Types of land degradation

Water erosion is the major form of land degradation in Malawi. Soil erosion by water is quitewidespread and manifests itself in the form of rill and sheet erosion, and gullies on cultivatedland. It is estimated that 4.5 million ha are annually cultivated or are in recent fallow (Green andNanthambwe, 1992). Other forms of land degradation include: (i) wind erosion, (ii) rapid massmovement, (iii) salinity, and (iv) chemical, physical and biological degradation. Wind erosion isnot much of a serious problem because the ground maintains some of its cover in the form ofweeds or crop residues during the dry season. Ridges, which form a rough ground surface, havethe effect of reducing wind erosion. However, where the land is bare, this could be a problem,especially in August or September when there is severe wind blow as most trees species shade off

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their leaves. Over-grazed areas, such as in the Shire Valley or along the Karonga LakeshorePlain, pose a special problem to wind erosion, and so too are some large estates which are notplanted with trees on their boundaries.

Heavy and continuous rains have been reported to induce large movements of soil. Forexample, in 1946, too much rain fell in Zomba which caused massive amounts of soil to creepdown the Zomba mountain. In 1992, when too much and continuous rains fell around Mulanjemountain, the flush floods at Phalombe transported large quantities of soil, debris, rocks and treebranches that caused death to many people, destruction to property and untold misery tothousands others.

Salinity is another factor that contribute to land degradation, especially where salineirrigation water is used. This could be a problem in some of our irrigation schemes along LakeMalawi, the Shire Valley and some big river valleys, such as the Limphasa dambo. So far, thereare no reported records of salinity. This is perhaps a reflection that the water in Lake Malawi,and other rivers, is not saline, except maybe for Lake Chilwa that does not have an outlet to thesea via the Shire River.

Land degradation is manifested in the depletion of nutrient elements in the soil, the physicalbreakdown of soil structure and reduction in micro-biological activity in the soil. Since mostMalawi soils are old, they are highly weathered and leached of all essential nutrient elements. Thesoils are deficient in the major nutrients N, P and K, the secondary nutrients Ca, Mg and S, andthe micronutrients B and Zn, along with reduced levels of soil organic matter, hence increasinglevels of acidity. Reduced soil organic matter content has serious implications on soil structuralstability and soil-water holding and transmission characteristics. All these factors have interactedsequentially and simultaneously over time and space to reduce the productive capacity ofMalawi's soils.

Main causes of land degradation

The main causes of land degradation include the following: (i) rainfall, (ii) soil, (iii) topography,and (iv) cultivation methods. These have been exacerbated by increasing human and livestockpopulation pressures, deforestation and over-grazing. The total seasonal rainfall pattern, whichvaries from 600 to over 3,000 mm, is generally of very high erositivity. High intensity storms area major characteristic, especially during the beginning of the rainy season, with intensities of upto 75 mm per hour for several minutes. The highest intensities have been recorded for the southand east of Mulanje mountain in the Southern Region, and along some parts of Lake Malawi. Athigher altitudes (>1,700 m a.s.l.), intensities are usually lower, but apart from these areas, over40% of the total rainfall in Malawi falls at intensities that are greater than 25 mm per hour (Pape,1971).

Soils of Malawi are very variable. Erodibility too, varies considerably, although it cangenerally be said that most of the cultivated soils are moderately resistant to erosion under goodland and crop husbandry management practices. In the High Altitude Hill Areas, where the soilsare deep, well structured and highly permeable, run-off is very low despite the steep slopes inthese areas. The length of the slope and its steepness have an important influence on the soilerosion process. There are extensive areas in Malawi that are flat to gently undulating (slopes ofless than 6%). These mostly occur in the Shire Valley, the Phalombe Plain, and a large part of theMiddle Altitude Plateau. The erosion hazard due to topography in these areas is slight tomoderate. The Rift Valley Scarp Zone and the High Altitude Hills areas have steep slopes and are


dissected, although some moderate slopes are found. From the point of view of topography, theseareas have an erosion hazard that is high. Poor cultivation and crop husbandry practices havesignificantly contributed to soil the erosion problem on cultivated land. The main method of landpreparation in Malawi involves the making of fresh ridges every year; except in the Shire Valleywhere farmers have consistently planted on flat land, and some areas along the Lakeshore Plainwhere cassava is the dominant staple food crop. More often than not, ridges have not been alignedon the contour, inducing a serious avenue for surface run-off; hence massive losses of thevaluable top soil. Over-all, when all the factors influencing soil erosion are combined, a situationof high erosion hazard for Malawi emerges (Paris, 1990).

Forms of land degradation

A physically degraded soil exhibits several soil problems that greatly limit crop growth andestablishment. Some of the major forms of physical degradation include: crusting, water logging,compaction, reduced infiltration rates and soil organic matter contents. These are all signs of soilstructural deterioration. Soils exhibiting these characteristics have low soil organic mattercontents which is the binding agent for all well aggregated soil types. As alluded to earlier, thesegenerally will come about due to poor soil management practices, and inappropriate crophusbandry practices that do not allow quick vegetative ground cover after the commencement ofthe rains. In Malawi, most soil types which have been heavily cultivated, or are course-textured,on the Middle Altitude Plateau are showing clear signs of soil physical degradation.

Most of the fertile Ferruginous Latosols on the fertile Lilongwe-Mchinji Plain, are nowexhausted and are showing signs of structural instability. So too are the over cultivated sandysoils characterizing the Kasungu and the south-west Mzimba Plains. Increasing acidity,salinization, nutrient depletion and/or excessive nutrient leaching, pollution from industrialwastes, and from the application of agrochemicals, are the major forms of land degradation.Some of these are at an advanced stages in Malawi. For example, the use of sulphate of ammoniais not recommended on upland soils where it has been reported to increase soil pH. On the otherhand, this type of fertilizer is perfectly suitable for saline calcimorphic alluvial soils occurringalong the Lakeshore Plain or in the Shire Valley. Most soil types in Malawi are heavily depletedin essential nutrient elements as a result of continuous cropping without added external inputs.On the Middle Altitude Plateau many farmers do not return crop residues to their farms toimprove soil fertility. This is because of unfavourable dry weather condition that is not conduciveto leaf biomass decomposition soon after harvest. However, farmers in the wetter agro-ecologies,e.g., Shire Highlands, have developed cultivation methods whereby crop residues are incorporatedinto the soil soon after crop harvest. Due to the generally wetter climatic conditions in thesubsequent months following crop harvest, crop residues are able to decompose and contribute tothe soil organic matter pool. The cation exchange capacity of the soil is increased as the majornutrients, including secondary nutrient elements Ca and Mg, are released from the soil organicmatter pool. What is equally significant is the improvement in soil structure. The soil becomeswell aggregated leading to improved soil-water holding and transmission characteristics.

Extent and severity of soil degradation

Land degradation, as measured though soil loss due to wind and water erosion, physical andchemical degradation is widely spread in Malawi. All cultivated land, apart from a few wellmanaged estates, is prone to land degradation. It is only forest land or bush land, covered withtrees and grasses, that is well protected. The economic losses resulting from land degradation areenormous although they are difficult to quantify in exact economic terms. This is because no

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studies have been conducted on coordinated systems of management for soil erosion thatquantifies soil loss under different farming conditions in Malawi. However, as alluded to earlier,studies conducted in Zimbabwe, and extrapolated to Malawi, indicate that Malawi maybe loosingin excess of US $300 million due to N and P losses through soil erosion. Concerted efforts arerequired to reverse the trend of soil degradation in Malawi. Improved land management and crophusbandry practices are urgently required if Malawi is to improve soil fertility and reduce soilerosion, hence attain food self sufficiency at both national and household levels. Strategies thatutilize organic fertilizers, augmented with modest levels of inorganic fertilizers, will ensuresustainable crop production and food security for Malawi’s growing population.


Low and/or declining soil fertility is one of the major problems constraining crop production inMalawi. Farmers in Malawi have for time immemorial recognized this problem and have,consequently, responded appropriately. There are currently many options for addressing soilfertility decline and rampant soil erosion hazards, with varying degrees of acceptability, successand adoption rates. What follows is a brief outline of the currently available technologiesdesigned to mitigate the undesirable effects of low soil fertility and soil erosion. The traditionalsoil fertility improving technologies include: i) shifting cultivation (or bush fallowing), ii) isolatedtrees on farm land, and iii) use of leaf litter, anthill soil and ashes. Shifting cultivation, which wasa stable form of land use system for many decades in Malawi, is now less common, except maybein a few isolated areas where finger millet is still commonly grown (e.g., Chitipa). The systemwas able to restore essential nutrient elements under conditions of low population pressures (<15persons/square km), and long fallow periods (>15 years). With increasing population pressureson limited land area, fallow periods have become shorter rendering the system ineffective torestore declining soil fertility. Along with shifting cultivation, farmers also learned that leaves ofsome tree species have the capacity to release nutrients and therefore improve soil fertility.Likewise, some farmers have utilized anthill soil and ashes to improve soil fertility.

With the continuing trends in soil fertility decline, against a background of increasingpopulation pressures and the depletion of the natural resource base, other soil fertility enhancingtechnologies have been developed. These include: i) crop rotations, ii) green manure, iii) tobaccoremains, iv) homestead refuse, v) cattle, goat, sheep, pig and chicken manure, and vi)agroforestry technologies. Of the agroforestry technologies, the following have shown potential toimprove soil fertility: (i) alley cropping, (ii) relay and strip cropping, (iii) interplanting cerealswith Faihderbia albida, (iv) intercropping cereals with legumes, (v) undersowing cereals withTephrosia vegelii, and (vi) the use of improved fallows using various leguminous tree species(e.g. Sesbania sesban, pigeon peas and Tephrosia vogelii).

These basically include the use of inorganic fertilizers and improved agroforestrytechnologies. Tremendous increases in crop yields have resulted from the use of inorganicfertilizers over the past few decades. However, despite increases in fertilizer use in Malawi, yieldsof various crops have declined or stagnated (Table 2), indicating that the fertilizer-hybrid seedtechnology is not sustainable in the long-term. In Malawi, the use of organic fertilizers has alsobeen recommended since the early 1960s. Similarly, agroforestry technologies too have beenrecommended to smallholder farmers since the mid 1980', although research results have onlybegan to appear within the last five years. The problem with these is that they have not been fullyadopted by many farmers, including resource-poor smallholders who are constrained by cash to


purchase inorganic fertilizers. It would appear that farmers are attracted to technologies thatproduce quick and dramatic responses, provided they are affordable and appropriate. Inorganicfertilizers offer this opportunity, but unfortunately, they are beyond the purchasing power ofsmallholder farmers. Smallholders lack adequate cash to purchase farm inputs and have limitedaccess to credit facilities. This leaves the option where organic fertilizers are applied inconjunction with low rates of inorganic fertilizer.

Strategies for managing soil erosion have essentially involved the use of i) the traditionalphysical soil conservation measures, and ii) the more recent use of biological soil conservationmeasures. What follows is a brief outline of each of these. Efforts to control soil erosion startedin the early 1930s when cultivation of annual crops changed from planting on flat land or circularmounds to planting on ridges that were aligned on the contour. Tied ridging was simultaneouslyadvocated for water conservation. The only exception was cassava cultivation along the lakeshoreareas and in the Shire Valley where up to now, farmers insist on planting on flat land. Othermeasures include: (i) contour bands, (ii) bench terraces (especially for coffee production), and(iii) graded bands. For water harvesting, earth dams have been used effectively to collect waterfor various uses including: (i) stock watering, (ii) irrigation, and (iii) fish production. Biologicalconservation measures use technologies that utilize grasses and woody perennials to control soilloss through erosion by water and wind. By and large, this involves planting grasses, e.g., vetiveron marker ridges, and some agroforestry tree species, e.g., Tephrosia vogelii in mixed croppingsystems. A combination of all of these are being used by many farmers with varying degrees ofsuccess.


The Malawi Agroforestry Extension Project (MAFE) is a pilot project on agroforestry within theLand Resources and Conservation Department (LRCD) in the Ministry of Agriculture andIrrigation (MOAI). This is a cooperative extension activity between Washington State University(WSU) and the Government of Malawi (GOM) and has been funded by the United States Agencyfor International Development (USAID) since 1992. The goal of the of the project is to test,evaluate, and adapt prototype agroforestry technologies and support services provided tosmallholder farmers in Malawi. The specific objectives are to improve soil fertility andconservation to increase crop and wood yields. The MAFE project is operating in 13 pilot areasin the districts of Chikwawa, Mangochi, Ntcheu, Dowa, and Mzimba. At these sites, resourceconserving technologies are being implemented.

Machecheta Agroforestry Site, Mzimba

The Machecheta Agroforestry Pilot Site is located to the east of Mzimba Boma in theneighbourhood of the area where the tarred Lilongwe-Mzuzu Road crosses the Mzimba River. Itis located in Kazomba Section of the Manyamula Extension Planning Area (EPA), CentralMzimba Rural Development Project (RDP) in the Mzuzu Agricultural Development Division(ADD). Detailed description of the study area, number of farm families and environmentalcharacteristics of the pilot study area can be found elsewhere (Bunderson et al., 1992). Theresource conserving and soil fertility improving technologies, and related activities, being testedand evaluated at the Machecheta Site include the following:

• Soil and water conservation : contour ridging, planting vetiver on marker ridges, aligningridges on the contour,

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• Soil fertility improvement and enhancement : alley cropping, systematic interplanting ofmaize with Faidherbia albida, improved fallow, green manure banks, undersowing maizewith Tephrosia vogelii, intercropping maize with grain legumes (e.g., soybeans),

• Energy : woodlots, homestead and boundary planting, living barns (for constructing tobaccocuring sheds),

• Other resource conserving technologies and activities : gully reclamation, vetiver nurseries.

Several farmers in the study area are testing a combination of the above technologies. Thestatus on land area under each technology/activity and the number of participating farmers testinga particular technology are given in Table 9.

TABLE 9Land area subjected to different technologies and the number of farmers implementing thetechnologies, Machecheta, Mzimba

Technologies/Interventions Unit Adoption Levels Number of farmersAlley cropping ha 93 162Systematic interplanting ha 140 135Improved fallows ha 8 31Green manures ha 2.3 12Homestead/Boundary planting ha 605 123Live fencing ha 1,400 16Undersowing ha 6.4 55Woodlots woodlots 110 110Intercropping maize with legumes Soybeans Groundnuts Common bean

hahaha

7.45.67.5

104127112

Tree nurseries Individual Communal

n.n.

711

7221

Vetiver nurseries n. 9 21Vetiver hedgerows ha 60 98Gullies reclaimed n. 30 18Contour re-alignment ha 321 230Organic manure ha 54 233

Source: Bunderson and Bodnar, 1997

Maize and legume crops are performing very well at the site, especially in farmers' fieldswhere the above soil conserving technologies are combined with some modest inputs of inorganicfertilizer nitrogen, phosphorus and sulphur. For example, maize performance under alleycropping with and without fertilizer has registered large increases due to hedge effects (combinedeffects of 3.5 and 4.5 year hedges), between local maize and hybrid maize, and between fertilizedand unfertilized plots (Table 10).

The large positive effects of alley hedges on maize grain yields, 3 years after hedgeestablishment, despite the fact that some hedge species are poorly managed, shows that alleycropping is a technology that needs a gestation period to register gains in yields. As expected,hybrid maize produced more grain yields compared with local maize under similar fertility andclimatic conditions. Thus, we can classify technologies into there categories: short-, medium-, andlong-term. Alley cropping falls in the second category, interplanting cereals with Faiedherbiaalbida falls in the third category; whereas undersowing and improved fallows fall under the short-term category. Hence, for sustainable agricultural production, we require a combination of all


three types of resource conserving technologies; and for food security, at both national andhousehold levels, these need to be augmented with modest levels of inorganic fertilizer inputs.

TABLE 10Maize yield (kg/ha) under alley cropping with and without fertilizer N and P application,Machecheta, Mzimba

Fertilizer application With hedges Without hedges increaseWithout fertilizer Local maize Hybrid maize

1 721 (1)2 300 (6)

-1 136 (5) 102%

With Fertilizer Local maize Hybrid maize

-4 855 (1)

-2 594 (4) 87%

Source: Bunderson and Bodnar, 1997


The overall government policy is to improve the well being of Malawians through PovertyAlleviation Programmes (PAP). The overall strategy of PAP is to promote increased participationof poor women, men and youths in economic, social and political affairs with emphasis oneconomic empowerment of the poor and in stilling the spirit of poverty consciousness in planners,administrators, politicians, extension workers and research workers and the general public; andalso provides the spirit of self-determination and self-reliance by encourage participatoryapproaches to development. As a nation dependent on agriculture, Malawi appreciates theurgently of developing adoptable, production-increasing technologies that preserve the integrity ofits natural resource base. However, under existing population and land pressures, smallholderfarmers continues to experience a multitude of problems. Given the present situation of foodinsecurity, malnutrition, chronic rural poverty and the deterioration of the natural resource base,there is an urgent need to develop and execute a strategic plan of action that improves soil fertilityand conserves the soil and water resources of Malawi.

Institutions

The Ministry of agriculture and Irrigation (MOAI) is responsible for all soil conservation workon all agricultural land grown to crops and livestock in Malawi. Within the MOAI, soil and waterconservation, and advice on conservation and correct land use, is the prime responsibility of theDepartment of Land Resources and Conservation (DLRC), whereas the Department of AnimalHealth and Industry (DAHI) is responsible for animal health and husbandry, and grazingmanagement. Conservation on land that is not under agricultural production falls under theresponsibility of the Departments of Forestry, and National Parks and Wildlife. The overallresponsibility for environmental protection in Malawi falls under the Department ofEnvironmental Affairs under the National Research Council of Malawi (NRCM). However, thereare a number of activities in soil and water conservation and soil fertility improvement that areconducted by other programmes/projects, and non-governmental organizations (NGOs). Theseinclude: (i) Promotion of Soil Conservation and Rural Production (PROSCARP), (ii) MalawiAgroforestry Extension Project (MAFE), (iii) IFAD Smallholder Food Security Project, (iv)Development of Conservation Measures and Messages Projects (DCMMP), (v) InternationalScheme for Conservation and Rehabilitation of African Lands (ISCRAL), and (vi) several NGOswhich include World Vision International (WVI), Action Aid (AA), Concern Universal (CU), andChristian Services Committee (CSC).

Malawi244

Socio-economic and policy issues

Malawi, being an agricultural country, depends on the soil. More than half of the population ofMalawi has less than 1 ha of land available for cultivation, and farm size is said to be declining at3% annually (UNDP, 1991), and yields are estimated to be dropping at the rate 2% annually(Twyford, 1988). The socio-economic issues that hamper the implementation of sound soil andwater conservation practices generally centre under land tenure and legislation of soil erosionissues. The lack of legal title to land has often been cited as one of the major constraints to propersoil conservation measures and good land husbandry in Malawi. While this maybe true in somecircumstances, it would appear that it is not an important constraint under customary land (Greenand Nanthambwe, 1992). This is because land security is assured through inheritance andcontinued use. This appears to be a good enough security to land ownership. There is presently alegislation in the form of covenants contained in the in the leases granted to tobacco estatefarmers. The only problem is that these are often ignored by the lease, because the regulationsunder this act are not enforced by law. Strong legislation is required to protect steep slopes fromimproper cultivation.

To effect the necessary legislation for soil erosion control, local communities should beinvolved and empowered. Low adoption rates of soil conservation practices is generally a resultof their medium to long-term benefits, but attitudes are slowly changing due to the visible effectsof degradation. As such, farmers today are more willing to undertake soil and water conservationefforts. There is need to put in place policy guidelines for controlling the environment in Malawi,and soil erosion in particular. These policies should include the planting of trees on farm land(already in existence), making it illegal to cultivate steep slopes and fragile areas, such as streambanks and catchment areas. In particular, catchment areas should be protected. Deforestation inand around catchment areas has been identified as one of the main causes of siltation in the rivers,Lake Malawi, and then finally the Shire River. The direct consequences of siltation, accumulatedover the past 3-4 years, is reduced water levels leading to low power for electricity generation.This is causing economic disruption and stagnation that is currently a common phenomenonduring the dry season.


The main constraints to smallholder agricultural production and sustainability are: i) soil fertilitydecline due to continuous cropping with little return of nutrients through fallows, green manure,crop residues, farm manure, intercropping or external inputs of inorganic fertilizers, and ii) soilerosion brought about by cultivating steep slopes without proper ground cover, with no markerridges or ridges that are not aligned on the contour, or poor cultivation methods on highly erodibleand fragile soil types. Programmes or projects are required to improve or maintain the soilfertility status of cultivated soils and arrest soil erosion to enhance crop productivity and reduceland degradation.

Appropriate, suitable and adoptable soil fertility improving technologies for smallholderfarmers will out of necessity be those that are low-cost and low-input. This is because although itis well-known that inorganic fertilizers have the greatest ability to tremendously increase yields inthe short-term, these are expensive to purchase. Nearly all smallholder farmers are resource-poorand have limited access to credit facilities, hence are unable to purchase mineral fertilizers. Thisjustifies the need to employ organic manure based technologies. Some of these include the


following: i) use of farm manure (this can either be cattle, goat, sheep or chicken manure), ii)intercropping maize with food legumes (e.g., soybeans, cowpeas, pigeonpeas or groundnuts) ornon-food legumes (e.g., Sesbania sesban or Tephrosia vogelii), iii) undersowing maize withlegumes (e.g., Tephrosia vogelii, iv) improved fallows (e.g., using Tephrosia vogelii, Sesbaniasesban or pigeonpeas), v) mixed intercropping or interplanting maize with nitrogen fixing treespecies (e.g. Faidherbia albida), and vi) alley cropping cereals with fast growing N fixing highbiomass yielding tree species (e.g. Sesbania sesban, Tephrosia vogelii, Leucaena diversifolia orGliricidia sepium).

Other possible technologies for enhancing or improving soil fertility include cropdiversification and intensification. This would essentially involve the introduction of livestock intothe farming system and intercropping cereals with legumes in rotations or between the hedgespecies in alley farming systems. The livestock for diversification include goats, pigs, sheep,chicken and/or rabbits. Smallholders should also diversify and intensify the growing of high valuecash crops such as burley tobacco, and the growing of vegetables, chillies, peppers, and otherhorticultural crops under both rain-fed and irrigated conditions. Of special emphasis should bethe growing of both exotic and indigenous fruit trees.

The soil and water conserving technologies include the following: i) use of marker ridgesusing the A-frame that are aligned on the contour, ii) making box and tried ridges, during years oflow, uncertain and poorly distributed rainfall pattern, and iii) planting of vetiver grass, and othergrasses, on the marker ridges, gullies, buffer strips and farm boundaries. Both the soil fertilityimproving technologies and the soil and water conserving technologies will also conserve thenatural resource base. However, for increased crop production to feed the expanding humanpopulation, and sustainable agricultural production, strategies that combine the abovetechnologies with modest levels of inorganic fertilizers are required and highly desirable. Thestrategy is to augment soil organic matter and other soil conserving technologies with low rates ofinorganic fertilizer N, P and S. Concerted efforts are required by Government to step upcampaigns to: i) promote country-wide use and adoption of low input, low-cost organic fertilizers(especially farm manure, the integration of legumes into the farming systems, and augmentingorganic fertilizers with low rates of inorganic fertilizers), ii) promotion of crop diversification andintensification under both rain-fed and irrigated conditions, iii) creating an enabling environmentthat makes inputs (seeds and fertilizers) readily available to the farmers at cheap and competitiveprices, iv) demonstrating commitment to conservation by supporting the efforts of the Ministry ofAgriculture and Irrigation, and v) insisting that public land should be properly conserved and thatregulations which apply to leasehold land are observed and enforced at all times.

REFERENCES

Blackie, M.J. and A. Conroy, 1994. Feeding the nation: breaking out of Malawi’s yield trap. In: D.C.Munthali, J.D.T. Kumwenda and F.W. Kisyombe, (eds.). Proceedings of a conference onagricultural research for development. University of Malawi, Zomba; and Ministry of Agriculture,Lilongwe, Malawi

Bunderson, W.T., G.S. Phiri, L.M. Nhlane and S.J. Nanthambwe, 1992. Project description and pre-implementation plan. Publication Series No.1, Malawi Agroforestry Extension Project, Lilongwe,Malawi

Bunderson, W.T., and F. Bodnar, 1997. Maize yield in three MAFE sites under four year old hedgerows.A paper presented at the Land Resources and Conservation Branch, Mzuzu, Malawi, June 1997

Malawi246

Bunderson, W.T. and I. Hayes, 1995. Agricultural and Environmental Sustainability in Malawi. A PaperPresented at the Conference on Sustainable Agriculture for Africa, Abidjan, Cote d'Ivoire, July1995

DAR, 1965. Annual Report of the Department of Agricultural Research. Government Printer, Zomba,Malawi

Green, R.I. and S.J. Nanthambwe, 1992. Land Resources Appraisal of the Agricultural developmentDivisions: Methods and Use of Results. Field Document No. 32; MAO/UNDP/FAO,DP/MLW/011, Lilongwe, Malawi

IFAD, 1993. Malawi: Smallholder Food Security Project. Main Report and Annexes. Africa Division,Project Management Division

Maida, J.H.A. and C.Z. Chilima, 1976. Changes in soil fertility under continuous cropping of tea.Technical Bulletin No. 1/Bv/76, Bvumbwe Research Station, Limbe, Malawi

Ministry of Agriculture, 1988. The Annual Survey of Agriculture for 1987/88, Lilongwe, Malawi.Mimeographed

Ministry of Agriculture, 1995. The Annual Survey of Agriculture for 1994/95, Lilongwe, Malawi.Mimeographed

Ministry of Agriculture and Livestock Development (MOALD), 1997. The Annual Survey ofAgriculture for 1996/97, Lilongwe, Malawi. Mimeographed

Paris, 1990. Erosion hazard model (modified SLEMSA). Land Resources Evaluation Project. FieldDocument No. 13; MOA/UNDP/FAO, DP/MLW/011, Lilongwe, Malawi

Pape, W.J., 1971. Rainfall intensity in Malawi. Bunda College of Agriculture, University of Malawi,Zomba, Malawi

Saka, A.R., R.I. Green, and D.A. Ng'ong'ola, 1995. Soil management in sub-Saharan Africa: proposedsoil management action plan for Malawi. Ministry of Agriculture and Livestock Development,Lilongwe, Malawi

Twyford, I.T., 1988. Development of fertilizer use in Malawi. A Paper for the FAO/FIAC meeting,Rome, 1988. Smallholder Fertilizer Revolving Fund. MOA, Lilongwe, Malawi.

UNDP, 1991. Human development: from poverty to self reliance. Advisory note to the Government ofMalawi-UNDP Fifth Country Programme (1992-1996), UNDP, Lilongwe, Malawi.

UNICEF, 1993. Situation analysis of poverty in Malawi, Lilongwe, Malawi.

World Bank, 1995. Malawi Agricultural Sector Memorandum, Malawi. Volumes I and II.

World Bank, 1992. Economic report on environmental policy, Malawi. Volumes I and II, Lilongwe,Malawi

World Bank, 1989. Sub-Saharan Africa: from crisis to sustainable growth. A long-term perspectivestudy. Washington DC, USA.


Namibia


More than two-thirds of the country is arid to semi-arid having the rainfall between 100 - 500mm per annum. The mean annual rainfall of the country is approximately 270 mm and typifiesthe country as being burdened by extremely dry conditions. The potential for dry land agricultureis consequently very limited (van der Merwe, 1983). Four ecological zones are recognized(MAWRD, 1995): the desert region, comprising 22 % of the land area, where mean annualrainfall is less than 100 mm, the arid region, comprising 33 % of the land area, where meanannual rainfall varies between 100 and 300 mm, the semi-arid region, comprising 37 % of theland area, where mean annual rainfall lies between 301 and 500 mm, and the semi-humid andsub-tropical region, comprising 8 % of the land area, where mean annual rainfall is between 501and 700 mm. Almost 50 % of the Namibian labour force is in agriculture of which only 45 % areunpaid family workers. One third are subsistence agricultural workers. The principal occupationof 60 % of adults in the northern communal regions (Oshana, Omusati, Ohangwena andOshikoto) is subsistence farming. Out of these only 20 % of household income is derived formagriculture. Karas and Hardap region average only 21 % of income from agriculture, whileOtjozondjupa and Omaheke average 44% (Isaacson, 1995). The rest of the country either havevery little income from agriculture (Khomas) or do not agriculture as an income-generating sectoras the result of their tradition and lack of suitable resource (Kunene and Erongo).

The history of agriculture in Namibia is very inadequately characterized by broad referencesto colonialism. Rather, as will be demonstrated in detail, three distinct phases can be made outwithin the period of colonial domination which ended only seven years ago (Lau and Reiner,1993): German colonial period, 1892 - 1915; Union/Commonwealth period, 1915 - 1961; RSAperiod, 1962 - 1990. One of these periods was beneficial to the development of the country'sagricultural resources, namely the German era; the other two were under developing the country.During the German era, effective planning documents were drawn up, informed by community-intensive ideas of settler autonomy, self-sufficiency, and what today has been rediscovered asappropriate technology. This was the progressive stand in an undertaking which by force tookboth the land, and the planning out of the hands of Namibia's indigenous peoples. These planningdocuments came to shape settlement policies; the emergence of smallholdings; the setting up ofgovernment plantations or forestry stations, and the planning for agricultural infrastructure,especially water development. The German colonial administration had ordinances related toenvironmental protection and sustainable utilization: a) protecting existing agricultural resource,b) establishing production and distribution centres to achieve self sufficient subsistence andidentify potential cash crops, c) forbidding and/or restricting the cutting of trees, the pulling ofout of grass by its roots, burning of the veld, and hunting of game.

Jorry ZebbyUjama Kauriya, Department of Agricultural Research, Ministry of Agriculture,

Water and Rural Development

Namibia248

Dryland cropping is dominant in all regions and irrigated cropping is only practised by somecommercial farmers who have the knowledge and can afford conventional irrigation schemes.Crop failure in Namibia is common as the result of mainly drought as well as other environmentalfactors, such as hailstorm, pest and disease, flood, etc. Two economic systems characterize inNamibian rural (agricultural) community, namely commercial and communal system.Commercial farming system is mainly self-sustainable and economically viable system.Communal farming system is characterized by poverty, exhausted natural resource, highpopulation density and economically dependent on government subsidies. From physical evidencewithin the rural boundaries, environmental degradation can easily be linked to poverty inNamibia. Namibia had, for centuries if not millennia, various populations of gatherers andhunters, of pastoral nomads breeding and managing small as well as large stock, of sedentarygroups supporting themselves largely on undomesticated fruits and vegetables, ocean or fishresources, and veldkos, as well as cultivators of tobacco, vegetables and grain. While thecultivation of grain and domesticated vegetables seems to be limited to northern Namibia,purposefully cattle and stock breeding as well as tobacco and pumpkin cultivation is on recordfor at least the last 150 years throughout Namibia. Several studies document socially regulatedand agriculturally diverse systems which led not only to food self-sufficiency for all, but also tosurpluses used for exchange and barter (Lau and Reiner, 1993).

The major cereal crops grown in Namibia are maize, pearl millet, sorghum and wheat. Milletand sorghum are grown extensively by the northern communal farmers (mainly by Oshiwambospeaking). These two crops, especially millet is the staple food for these communities and areconsumed internally within these communities. Small internal market are created to supply thosewho did not have a harvest at the end of the season, some to take to urban areas for homeconsumption. Millet and sorghum are also exchanged for goods across the border to Angola, orexchanged for other nutritious crops such as cowpea, beans, nuts and veld food in areas wheresuch commodities are rare. Maize is produced in the commercial land as well as in the Caprivimainly under rainfed conditions. Maize under irrigation is only an option to buffer the unreliableclimatic conditions. In the Okavango it is restricted to riverine farming community who haveexcess to free water from the Okavango River. Commercial farmers supplement their irrigationfrom earth dams and boreholes under restricted quotas. Wheat is mostly grown as off-season(winter) crop under irrigation. The crop has got a good market because it is the only cerealproduced in winter and competition is low. National cereal production, as reported in Table 1,has varied in recent years from low of 33 100 tonnes in the drought year of 1991/92 to 118 900tones in the 1993/94 season.

TABLE 1National cereal production (tonnes), 1990-95Crops Year 1990-91 1991-92 1992-93 1993-94 1994-95Millet/Sorghum 57 700 17 200 43 700 69 100 41 100Maize 52 000 12 800 26 100 43 500 15 300Wheat 5 800 3 100 5 700 6 300 3 200Total 115 500 33 100 75 500 118 900 59 600

Source: Isaacson, 1995

Official market throughout the rest of the country has not yet been created despite tirelessefforts from the Government. This is partly because the demand from the rest of the Namibiancommunity is low. Most opt for eating maize and try by all means to produce maize even in smallgardens around their homesteads. Millet and sorghum in the northern communities are processedinto several delicious food types, from, porridge bread and cake to various soft drinks andalcohol, which are all consumed at household level to a ready-to-consume commodity for the


local market. The tow crops are preferred by those who grow them because of their adaptabilityto the low water and nutrient requirement and their ability to establish a crop in a very shortperiod. Millet, sorghum, maize, and wheat are produced every year in Namibia, except the yearof drought. In addition, cow pea, ground nut, sun flower and sweet potato have been produced ona smaller scale, but increased their production as the result of the Government campaign for cropdiversification for sustainability and food security. The cereal production varies significantlyaccording to rainfall (NFSNC, 1995a). With an estimated national demand for cereal of 201,900tones per year, even in the best years, Namibia must import a significant amount of its cerealrequirements (Isaacson, 1995).


Desertification, drought, deforestation, flooding, bush encroachment are some of theenvironmental degradation processed which received the national attention in recent years andindirectly result in soil degradation. Soil erosion, salinity, alkalinity and acidification, loss ofplant nutrients are forms of soil degradation processed which receives little attention on a nationallevel. Having these direct and indirect degradation process it will not be essential to deal withthem in isolation due to their interactive nature. Population pressure is one factor contributing toenvironmental degradation. In the Cuvelai drainage basin where many rural families still dependon hand-dug wells, people have to dig deeper and deeper each year. Too often they find onlybrackish water because the fresh water aquifer, perched on top of a brine like, has shrunk(Ashley, 1997).

Soil degradation

Soil degradation is the loss of fertility in the soil over a period of time, whether it be physical,chemical or biological. The process of soil degradation is usually long and takes several years orsometimes decades or even centuries to be physically visible to a human eye or detected throughthe new technological instruments used to date. However, there are exceptionally short-termprocess which cause drastic changes in few minutes. A good example of these is soil erosion,whereby extensive amount of soil is removed from a site in few minutes following a hailstormover loose sand. A gully of 0.5 m depth has been observed in the eastern part of Namibia(Gobabis district) following a less than twenty minutes shower. Livestock production is dominantand the concentration of animals near the water points has resulted in a remarkable exposure ofbare soil surface which gets severely damaged by the first storm following a long and dry season.A second example is the oil and waste disposal that affect both surface vegetation and groundwater quality in or near urban area. This phenomenon is minor compared to the former in termsof spatial distribution and intensity.

In Namibia most of these processes have not and can hardly be categorized one way oranother. Some processes can be man induced and over time, even years after man has left the areanature takes its course and the condition gets worse. In contrast, there are soils which arenaturally sensitive and vulnerable to human activities. A good example is the soil with higherodibility factor, thus prone to erosion. As human population increases and more activities areimplemented to sustain the growth pressure, these sensitive areas are subjected to human use andget degraded in the process. We cannot live without the soil and it is in that sense that impactassessment need to be carried out and sound management practices should be designed to selectand apply the friendliest method. Some of the common soil degradation process are outlined inTable 2. The asterisks indicate the relative geographical distribution and intensity of each processas envisaged in Namibia, each asterisk indicate the relative area where the type of degradation

Namibia250

has been a concern as well as the people awareness toward such degradation process. The morethe stars the more the type of degradation has been recorded in literature, unofficial reports andoral conversations.

TABLE 2Types of soil degradation processes, causes and their effects on plant production and quality ofland

Type of soildegradation

Causes Effects

Biological * Imbalance in microbial activities in the topsoil Deterioration in soil structure,surface crusting, slow turn-over

Compaction** Use of heavy machines for tillage, incorrectmanagement, hard-setting properties

Increase bulk density, pooraeration and infiltration

Water logging** Excessive irrigation, high rainfall intensity,poor drainage, build up of salts and reductionin many nutrients, Fluctuation in groundwater table

Poor aeration, availability ofcertain nutrients (Fe, Al, N, etc.)

Salinization andSodification *****

Irrigation with salty or sodic water,Evaporation from deeper horizons, highwater table

Availability of certain nutrients,alteration of soil structure

Toxification andPollution*

Disposal of toxic waste, release of heavymetals from industries or mines, elementsfrom ground water or spring water, oil spills,oil disposal, dumps

Toxic soils to plant growth,pollution of soil and water

Soil erosion***** Hail storm (erosive), loose soil (erodible),topography, animals

Loss of top soil, burial of top soil,destabilization of top soil, poor soilcover

Loss of plantnutrients***

Monoculture, overgrazing, tillage systems,poor water management

Loss of productivity, depletion insoil physical properties,acidification, poor soil cover

Flooding andSiltation****

high rainfall intensity, steep slopes, loose andbarren soil surface

high runoff, compacted soilsurface, crusting, erosion, loss ofwetlands, reduced water flow inrivers

Deforestation***** Human removal of vegetation, overgrazing high runoff, soil structuraldeterioration, low soil organicmatter, leaching of nutrients

Bushencroachment***

Improper grazing systems low carrying capacity, nutrientimbalance in the soil

Acidification* Acid rains, incorrect management practices,exploitation of the land

Poor soil cover, deterioration ofsoil physical properties

Notes:* indicates that the degradation process does exist but has not caused any serious concern at all levels(biological degradation, pollution, toxification and acidification)** indicate a localized condition that is manageable under the current expertise within the country(compaction and water logging)*** is about the mean and indicate a condition that has caused considerable damage in some areas andnational research is underway to try and stop or reverse the situation, but in most parts of the country itis non-existent (loss of plant nutrients and bush encroachment)**** stars indicate a condition whereby localized areas can be abandoned because of high costs involvedin reclamation and intensive agriculture is not practised or cautious steps are taken not to worsen thesituation (flooding and siltation)***** is the worse Namibian condition; despite national concern, some land portions has been abandonedfor intensive agriculture and reclamation is beyond the national capacity of expertise and costs within ashort time. Long term efforts are underway but mostly left to nature to take its course (salinization andsodification, soil erosion and deforestation).


Biophysical impact

Desertification is the process whereby an area is turned from a resilient, sometimes wellvegetated, area into a wasteland no longer able to respond to rainfall in a normal manner (Seely,1991). In Namibia this process has taken place without notice. It is fortunate that the lowpopulation density country wide allowed for recovery after an intense grazing period, drought ordeforestation as first steps in the process of desertification, there is no a clear cut as to where oneprocess ends and the other takes over. Whether desertification, drought or deforestation, thedanger of soil surface crusting, soil erosion (wind and water), loss of nutrients and organic matteris sky high. Namibia is economically unfit to reclaim the lost land as the result of desertification.The only option left is to manage the resource wisely to prevent desertification from taking place.The increase in population together with the ever-increasing aridity the potential fordesertification is threatening. Desertification Convention focuses on the plight of Africa, and aimsespecially to address issues such as food security, environmental conservation and sustainabledevelopment. Indicators of desertification in Namibia include the lowering of ground water table;soil erosion; loss of woody vegetation (trees); loss of grasses and shrubs; i.e. bare soil surface;decrease in preferred grasses and shrubs; bush encroachment, increase soil salt content (salinity)and decrease soil fertility. Desertification need not be a problem in Namibia if natural resourcesare appropriately used and managed (Seely and Jacobson, 1997).

Deforestation here is used to describe the process whereby natural vegetation is randomlyand indiscriminately removed. This process disrupt the ecosystem and may either reduce theproductivity of the land or cause an imbalance whereby new plant species of little use to humanand grazing by animals are introduced. In the north central and parts of northwest Namibia themopane tree (Colophospermum mopane) has fallen victim to intensive use as building materialfor houses and agricultural fields. Traditional fences are erected from stacking poles of mopanetree trucks in a row. If one pole is approximately 20 cm in diameter on average, thenarithmetically up to 20 000 poles are needed per hectare for agricultural field. This figure caneasily go up to four times for the construction of a big traditional homestead. If one tree cansupply five poles, then up to 4 000 trees will be used to build one field. The life expectancy ofthese poles is not documented in the literature cited, but interviews with few farmers indicate togo beyond twenty years in areas where termites do not cause a serious threat. Despite the fact thatthese tree is naturally termite resistant, the poles do slowly degenerate and new poles constantlyreplace the old ones.

The demand for poles is far higher then the supply in several regions and more people areencouraged, if not forced by circumstances, to integrate the steel wires for fencing to allow thegrowing plant to reach maturity. The same appears to be the case with the silver teminalia(Terminalia sericea) and the camelthorn (Acacia erioloba) in the southeast and east of thecountry, but to a lesser extent. Terminalia grows well in sandy soils and bud before the raincomes to provide food for livestock before the new grass cover becomes edible. This tree isunfortunately regarded as pest in areas where it encroaches the grassland (Bester, 1997).Camelthorn provides nutritious pods during the dry season, succulent leaves and flowers tobrowsers early in the wet season. The two trees are deep rooted and obtain water from deepsubsurface soil layers where only few trees can reach. Mineral nutrients from deep are brought upand with process of shedding their leaves in winter they help recycle nutrients for shallow rootedspecies to utilize. Like the mopane, they are also major sources of wood and poles for fencing.They are therefore harvested in bulk for these products. Sustainable harvesting techniques need toencouraged.

Namibia252

Chemical degradation

Salinity and alkalinity

Namibian soils are generally sandy. Due to a the arid climate soil genesis is rather slow and verylittle horizonation can be observed. The parent rocks of most of these soils is the Kalaharisandstone and granite which are both acidic, except for the small patches of dolomitic limestoneoutcrops in the central north from the Grootfontein district in the east stretching west wardthough the Etosha National Park into the central Kunene region. The soil are well drained and haspoor cementation. Loose particles on the surface of the soil are easily picked up by wind andwater and transported to new sites, and the cycle of removal and re-deposition continues. Naturalvegetation are the most significant stabilizers of soil movement by physically holding andshielding the soil surface from wind and flood water with their roots as well as providing organicmaterial that helps to bind the soil and form aggregates. Removal of natural vegetation istherefore critical for soil erosion.

Soluble salts are found in all soils as well as in natural waters such as rivers, streams andboreholes. Salts accumulate in soils largely as a result of percolated water, run-off and irrigationwater with the resultant concentration of these waters through evapotranspiration (Trippner, inpreparation). The main processes causing salinization and alkalinization are as follows: eolianinput, salt accumulation by evaporation, capillary rise of ground water, precipitation fromepisodic heavy rains together with evaporation, desertification and drought, Management(deforestation, irrigation and overgrazing). Indirectly, human activity cause erosion whereby ofdegraded or saline topsoil is transported to fertile land surface and bury it, thus causingdegradation. Several studies of soil in and around the Etosha National Park led to theincorporation of salinity, alkalinity and sodicity in the mapping unit (Buch et al., 1993; Beugler-Bell et al., 1993). These studies also present the only detail soil survey mapping work done inNamibia on a reasonable scale in terms of area covered. The park is protected an man-induceddegradation processes are minimal.

The small scale (1:800 000) Soil Map of Namibia has been refined and presented by theAgro-ecological zone (AEZ) project from the original FAO map. The Solonetz and Solonchaksarea presented include the above mentioned study area of Buch et al., 1993; Beugler-Bell et al.,1993 and Trippner et al. (in preparation9. Although most of these effects may be viewed asdetrimental to most plants. Soil salinity/alkalinity can be used by naturally adapted vegetation tocombat the excessive water loss by transpiration. Salty vegetation (e.g. Salsola spp.) also reducestheir uptake by animals and therefore protect the soil from being barren in areas prone toovergrazing.

During previous surveys it was determined that the majority of the soils of the Oshanasvaried between strongly saline, amorphic, medium textured materials to severe solonetz forms.These soils have no irrigation potential due to the high salinity and very slow to extremely slowinternal drainage. Without adequate drainage reclamation through leaching of soluble salts andremoval via open drainage works is not feasible. Desalinization by means of flooding and surfacedrainage with the objective of promoting upward leaching of salts is contrary to both normalpractice and current scientific principles and as a desalinization procedure is therefore veryunlikely to accomplish any significant success (A.O.C. 1967).

The effects of irrigation on saline soils can be grouped into two categories:


• Irrigation as the way to amend soil salinity and alkalinity. This is the case where the soil is salineand sodic but the irrigation water quality is high. Such cases are only experienced near majordams and/or perennial rivers. In these areas irrigation has been proved to improve thecondition of topsoil more than the deep subsoil.

• Irrigation as the way to worsen salinity/alkalinity. When irrigation water is drawn fromgroundwater of low quality, salts are added by this water to the soil. The salts in the soil isgradually increased to a level not suitable for plant production and may lead to theabandonment of once an agricultural land.

Saline soils can be reclaimed by removing the salts from the soil solution as well as replacingthe sodium on the colloidal fraction by a divalent cation or the hydrogen cation. Drainage isconsequently the first requirement followed by leaching through over-irrigation (FSSA, 1989).This practice has been successfully applied to the Hardap irrigation scheme, but the productivitydoes not last long. Repetition is required after some period in order to keep the salt levels low andmaintain the yield. As far as saline soils are concerned, it is only necessary to drain the soil and toleach out excess salt, but the danger of turning it into a sodic soil is high. With alkali and/orsaline-alkali soils it is necessary to first bring the percentage exchangeable sodium to below 15percent with lime (FSSA, 1989). Then the free and replaced salts must be leached out. Thisprocedure assumes that a large quantity of sodium will be leached out as well. Sodium can bereplaced by applying calcium salts a gypsum (CaSO4.2H2O) or acidifying agents like sulphur (S),Sulphuric acid (H2SO4), iron sulphate (FeSO4.7H2O) or aluminium sulphate (Al2(SO4)3.18H2O)(FSSA, 1989). Soil salinity has been extensively reported around the Hardap irrigation scheme inthe Fish river and early researchers and soil surveyors classified salinity as high, and sodicity ashigh or potentially high. Destruction of soil due to drastic changes brought about by levellingoperations and consequent excessive movement of soil make the soil prone to erosive forces. Thisoperation brought about high productivity and to be sustainable over a long period these soilsneed to be monitored and extensive data collection campaign need to be lodged as to theinfiltration, compaction, salinity and sodicity, alkalinity/acidity, and drainage capacityaccompanying the production capacity of these soils.

Soil acidity

Acidification of soils along the perennial rivers has been recorded by the national Agro-Ecological zone project. Fortunately, low agricultural activities exist near the river becausewetland conservation techniques practised. Except along the banks of the rivers there is littlewater drawn from this rivers for inland irrigation use by farmers. The major rivers in the northare the Kunene, Okavango and Kwando and the Zambezi, Orange in the south. In addition, theHoanib river, Ugab, Omaruru, Omatako, Swakop, Fish and Auob river host most of the country'smost important dams and they are mainly used for small scale production of high quality cropand bulk water for urban usage. The soil pH (H2O) map of Namibia produced a veryphenomenal results of which the most remarkable is the projection of acid soils along the majorrivers and drainage systems except for few localized points (pH<6.79). Below 4.50 is rather rarein this arid climate. These are areas that has water most of the year and irrigation (use of highwater quality) can be practised. It should be nodded that this map originates from samples thatreached the Soil Laboratory over the years. Blank patches indicate areas where no samples werereceived for analysis at the time of producing the map. There are no rivers in the eastern part ofthe country and crop production is almost zero, if excluding small scale when the rainfall isenough to sustain the crop over the growing season (which is rare) of ground water irrigation ispractised. Namibian ground water is slightly alkaline and saline. Continuous irrigation usually

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results in salty and alkaline soils and abandonment of the fields for new fields is unavoidable.This process results in an artificial selection of vegetation which are tolerant to such conditions aswell as the extinction of sensitive species. In most of Namibia tolerant vegetation are less soilprotective from erosion.

Water quality and water harvesting techniques

In general, Namibian soils are sandy (95% has less then 5% clay), deep and low in organic mattercontent. Coupled with contrasting climate and geomorphology the possibility of harvestingsurface rainwater is low. heavy thundershowers cause extensive runoff for less than 24 hours inmost places. This causes transportation of silt into dams, leaching of soil nutrients down the soilprofile or to the catchment, drainage of salts into aquifers which decreases the quality of groundwater. High quality rainwater is mainly utilized directly for dryland agricultural production andlivestock watering in water pans as well as irrigation of small gardens to a limited extend. In theCuvelai delta where most of the people rely heavily on surface water during floods (efundja) thewater quality changes as the water dries out. Good quality rain water immediately after the floodturn into saline and toxic water few weeks later. Similarly, after the disappearance of surfacewater good quality water for livestock watering is harvested from hand dug wells. After a whilethe quality of this ground water goes down to a toxic level which render unsuitable for livestock.In the eastern and southern Namibia where the Kalahari sand dominates the land surface, rainwater harvesting is almost zero, except for the small amount caught and stored in drums fromcorrugated iron roofs for drinking over a short period. Since this is the major livestock productionarea in Namibia, people rely on deep boreholes averaging 180 meter in depth throughout the year.However, supplementary water during the wet season comes from seasonal dry riverbed thatforms pans.

Artificial earthdams are also constructed by individual farmers in the commercial area. Theduration of water in this pans is variable and dependent on the amount of rainfall, evaporationrate, the depth of the water table as well as the distribution and length of the rainy season. Thewater scarcity is a major concern to the Namibian Government. Feasibility studies are underwaywith the objective to construct earth dams in communal area as a means to enhance the supply ofwater to rural community. A handful of commercial farmers around the country have constructedtheir own and some dams are already interfering with the inflow into the larger municipal dams.The Government also embark on the program of charging a fee at an economic rate for warsupplied by the State (DWA, 1993) to rural community. Research work is needed to standardizethe type of irrigation suitable and economically viable to Namibia. Drip irrigation has gained anupper hand in recent years recommendations (Beyers, 1996; Gomide and Netto, 1996), but theeconomic viability is not yet assessed.

Economic impact

The National Declaration on Food and Nutrition include a clause that deals with the protection ofthe natural resource which states: We commit ourselves to ensuring that developmentprogrammed and policies lead to a sustainable improvement in human welfare; that they aremindful of the environment and are conducive to better nutrition and health for present and futuregeneration. The multi-functional roles of agriculture, especially with regard to food security,nutrition, sustainable agriculture and the conservation of natural resources, are of particularimportance in this context. (NFSNC, 1995b). With the exception of 1994, agricultural growth inthe commercial land has been negative since independence (Table 3). Subsistence farming, incontrast, indicates an overall positive growth. This is partly attributed to the political changes


that led to the new Government to concentrate on the low income generating population andreduced attention to the commercial farmers. The 1991-92 drought has also taken its toll in theoverall agricultural economy. Another point to take into consideration is the incredible fluctuationin the growth of subsistence farmers as compared to their commercial counterparts. The latterappear to be the more stable of the two.

TABLE 3Growth in agriculture by sub-sector 1988-95Type of agriculture 1988 1989 1990 1991 1992 1993 1994 1995Commercial 1.4 9.2 3.5 2.7 -4.5 -3.9 3.2 -0.6Subsistence 2.6 2.4 3.0 10.9 -45.7 19.7 60.0 -21.8

Source: UNDP, 1996


Soil degradation in Namibia has been going on for years without notice, or proper documentation.The size of the country, her aridity together with low human population has misdirected theattention of her inhabitants as well as the international community away from sustainableresource utilization. The low productivity has been and is still a major concern in agriculturerather then a search for some measures to balance the short-term bumper crops with long termsustainable harvest. Policies and legislation are in place, and other policies are added year by yearwhich take into account the conservation of our natural resource. Implementation of these policiesis hindered by the lack of funds, expertise, well-defined programmes and projects, experience andtechnical facilities. Direction toward conservation of the agricultural resource is also shielded byshort-term programmes and projects which are directed toward short-term food availability. TheConstitution of Namibia as well as various policies which are designed for the conservation andsustainable utilization of the natural resource are assumed to include soil degradation as part andparcel of the overall environmental degradation.

The new, seven-year-old Government is faced with the challenge to reform these ruralstructures in order to address the issue of poverty eradication and economical balance betweenthose who suffered and those who benefited in the hands of the apartheid regime.

Policy and Legislation

The Namibian Constitution. Namibia is one of the few countries that has a well-defined andinternationally recognized environmental protection policy enshrined in the constitution. Article95 (l) of the constitution states that the State shall actively promote and maintain the welfare ofthe people by adopting, inter alia, policies aimed at maintenance of ecosystem, essentialecological processes and biological diversity of Namibia and utilization of living naturalresources on a sustainable basis for the benefit of all Namibians, both present and future; inparticular, the Government shall provide measures against the dumping or recycling of foreignnuclear and toxic waste on Namibian territory. Schedule 5 (1) of the Constitution recognizescommunal land as a Government property, while commercial land is under private ownership. Inaddition, Article 16 (1) ensures Namibians the right to acquire, own or dispose of propertyanywhere in Namibia. In rural community the right to own land is presently applied out ofcommunal boundaries. However, land can be leased out for agricultural purposes with littlerestrictions in terms of limiting others from the resource. Traditional authority holds the right toallow/disallow tenure structure within communal boundaries. This present structure is noteffective in terms of conservation and protection of the resource within communal boundaries and

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the Government is hindered by the lack of personnel to monitor any deteriorating conditionswithin these boundaries. Management of the resource will always be ineffective when comparedto commercial land.

National Agricultural Policy

The National Agricultural Policy (NAP) is a draft document designed by the Ministry ofAgriculture, Water and Rural Development to address the difficult problems caused by manyyears of neglect under the colonial administration. One of its goals and objectives is to ensure thatthe majority of Namibians to enjoy improvements in their current standard and quality of livingand promote the sustainable utilization of the nations land and other natural resources (MAWRD,1995). In this document the Government makes it clear that agricultural growth will not pursuedat the expense of the environment The Government will address the serious problems ofdesertification and environmental degradation caused by destruction of forest cover, soil erosion,overgrazing and bush encroachment. Environmental impact assessment studies and relatedregulatory sanctions will be fully considered, particularly when opening up new agricultural areasor when new land use activities are being planned. The Government will promote agriculturalentrepreneurship and sustainable farming systems that are consistent with appropriate land useand soil conservation practices (MAWRD, 1995). The policy, however does not refer to the SoilConservation Act No. 76 of 1969 in terms of improvement and/or application to the independentNamibia.

Soil Conservation Act

The Soil Conservation Act no. 76 on 1969 was drafted by the Government of the Republic ofSouth Africa for both South Africa and Namibia during the colonial era. The definition of the actwas to consolidate and amend the law relating to the combating and prevention of soil erosion, theconservation, improvement and manner of use of the soil vegetation and the protection of thewater sources in the republic and territory of South-west Africa; and to provide for mattersincidental thereto. In this Act the Minister of Agriculture by virtue of the power vested in him bythe State declare a direction to the protection and amendment of the soil with respect to thecultivation of the land, destruction of vegetation, drainage of vleis, marches, natural watersources, runoff or drainage of rain water, grazing strategies, veld fires, pollution of soil andwater. This direction shall be binding upon every owner and occupier of the land with reference towhich it has been declared applicable. The specifics of the conservation strategies is not enshrinedin this document and the punishment related to the offence and/or ignorance of this act is to bedetermined in the court of law.

Though the act is in place, it does not address specific problems encountered in the countryand how one should go about in preserving the soil quality deterioration. This deteriorationresults in the lack of vegetative cover (erosion) or an upset in the ecosystem whereby the lesspalatable and sometimes thorn trees and shrubs invade the area and result in bush encroachment.The application of the act to an independent Namibia requires certain modifications in order to beeffective. These includes:

• Define the soil as an environmental component that need to be conserved and protected,

• Outline specific causes of different soil degradation processes and deal with each in detail,

• Asses the most probable reclamation procedure(s) and stipulate the guideline,


• Take the necessary precautionary measures as to prevent any of the processes in Table 1from initiation or speeding up,

• Pin-point the necessary recognizable symptoms as to alert all soil users on the danger ofcontinuing specific practices,

• Define the possible penalty for the culprit found guilty of intentionally degrading the soil orignoring to take precautionary measures,

• Form an environmental protection unit in each Ministry to look for various interactionsbetween man and the environment from the various disciplines,

• This can be coordinated into one national unit as the one existing in the Ministry ofEnvironment and Tourism (MET),

• Weigh the advantages and disadvantages of the existing agricultural practices and look foralternatives, with long-term vision. High productivity now should not be equated with long-term conservation for food security, however a reasonable balance between the two willensure sustainability.

National land policy

Successive colonial regimes dispossessed large numbers of pastoralists and settled them in so-called 'native reserves'. Native reserve policy structured access to land along racial lines. Justover 4,000 predominantly white farmers owned about 43% of agricultural land under freeholdtitle, white approximately 150,000 households engaged in communal agriculture utilize 42%.Given present production techniques and even increasing population in the commercial areas,agricultural land is gradually being over utilized The Commercial (Agricultural) Land ReformAct (1995), (cited by UNDP, 1996) prescribes the procedures, for land acquisition anddistribution. All farms offered sale on the market first have to be offered to government Althougha Land Reform Act has been passed, government still has not come up with a comprehensive landpolicy. No legislation exists as yet with regard to ownership of land in the communal areas. In theabsence of which, members of the new, block elite and wealthy communal farmers are rapidlyenclosing communal land for private use (UNDP, 1996). One of the effects of this process is thataccess to grazing for small farmers become more difficult, as seasonal pastures becomeincreasingly inaccessible.

Since independence, little more than 100,000 ha of commercial farmland have been boughtby government. Government intends to spend N$20 million annually over the benefit of small-scale farmers (UNDP, 1996). The land policy acknowledge the fact that poor people are the mostvulnerable part of the society who require protection. The policy secure and promote the interestsof the poor, ensuring that they are in practice able to enjoy the rights of which they are assured inprinciple. Special programmes to help the poor to acquire and develop land are considered(MLRR, 1997). The policy also advocates for full and equal security and protection to all legallyheld land right, regardless of the form of tenure, the income, gender or race of the right holder. Italso recognizes Article 95 (l) of the constitution that highlight the sustainable use of the naturalresource.

As with the South African colonial government with regard to settlers, financial and taxincentives together with the necessary new and reinforced legislation will be put in place topromote the use of renewable energy resource, and the protection, promotion and rehabilitation ofexisting natural environment for all Namibians. Survey and mapping form the backbone of land-

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use planning. The policy provides for the Land Use and Environmental Board to ensure that landuse planning, land administration, land development and environmental protection are promotedand coordinated on a national and regional basis to guarantee environmental, social and economicsustainability. Failure to maintain such sustainable use, or the infliction of any otherenvironmental damage, will be cause for Land Boards to cancel a title. New private landenclosure is prevented. This will discourage the private fencing in communal land. Land withinthe communal boundaries is State land and mobility within this boundaries is regarded as free,provided that traditional authorities give approval. Better-off communal farmers tend to fence offland around villages in order to preserve pasture for their animals during the dry season.Overgrazing occur in the open land and during the dry season this land is left barren and nothingto buffer even a slight drought for those who can not afford fencing. The first rain is alwaysdisastrous in terms of soil degradation.

Environmental policy

Soil degradation in Namibia is better defined under the Environmental policy. Althoughagriculture contributes a great deal to the degradation, there is no well-defined policy from theagricultural point of view that addresses to its full. Several policies are in place which are notspecifically designed for this country, but rather applied in the general sense. Namibia is guidedby the international environmental protection treaties designed and implemented under the UnitedNations (UN) supervision. Developing strategies to halt and reverse the effects of environmentaldegradation" was one of the 1992 Rio Earth summit. The Basel convention treaty addresses theissue of the transboundary movement and disposal of hazardous waste, and was adopted in Basel,Switzerland in 1989. The long-term objective of this Convention is to reduce waste generation toa minimum in terms of quantity and level of toxicity. It recognizes the right of any state to ban theimport of foreign hazardous waste (as Namibia has done), and stresses that waste should becorrectly disposed in its country of origin (Tarr, 1997).

The European Community (EC) has instituted strict regulations governing the permissiblelevels of chemical residues in meat. Some of these chemicals are anabolics, thyrostatics,sulphonamides, antibiotics, ectoparasiticides, endoparasiticides and heavy metals. The Namibianparliament has passes legislation aimed at controlling the use of these substances in the country(Brown, 1992). The control of tsetse fly with dieldrin and alphamethrin; malaria with DDT;scavengers with strychnine and compound 10 - 80 are also other sources of environmentaltoxification which need alternative.

Water conditions and water policy

Water supply to the Namibian society is undoubtedly the most determining factor in the socialbehaviour, human population density in rural community as well as the development. Wetlandsare the rarest ecosystem type in Namibia, making up only about four percent of our landscape.As an arid country, Namibia values its Wetlands and is committed to protect and manage themthrough rational and integrated land use planning in accordance with the philosophies of theRamsar Convention (Hines and Kolberg, 1997). The Namibian Constitution clearly provides forthe government to assume responsibility for the overall management of the water resource andrequest the Government to be clear about its objective and policies. Multidisciplinary committeewas elected by Cabinet to serve in the Water Supply and Sanitation Sector Policy (WASP) fromthe following Ministries (DWA, 1993):

• Ministry of Agriculture, Water and Rural Development• Ministry of Regional and Local Government and Housing


• Ministry of Works, Transport and Communication• Ministry of Lands, Resettlement and Rehabilitation• Ministry of Health and Social Services• National Planning Commission• Office of the Prime Minister

The sector policy include: Communities to have the right with due regard for environmentalneeds and the resource available to determine which solutions and service levels are acceptable tothem. Beneficiaries should contribute towards the cost of the service at increasing rates forstandards of living exceeding the levels required for providing basic needs. An environmentallysustainable development and utilization of the water resources of the country should be pursuedin addressing the various needs. About 60 % of Namibia 's total population lives in the north. Ofthese, 75% live alongside the perennial or ephemeral wetlands. About 44% live within theCuvelai drainage system, where a mixed economy is dependent on the flood regime to replenishthe water table. regenerate grazing and provide rich protein source of fish. Although severelydegraded by overgrazing and adversely affected by the construction of roads and canals, thesystem still supports a great diversity of biota. Dams which have been proposed in the OkavangoRiver and the uncontrolled extraction of water would severely alter the flood regimes. Waterquality in the Okavango and Caprivi has already decreased due to pollution; while erosion andincreased siltation has resulted from the clearing of riverine vegetation of agriculture (Hines andKolberg, 1997). In the high rainfall areas of Okavango and Caprivi development such asirrigation, aquaculture and plantation are water based. These schemes and veterinary and publichealth programmed can directly of indirectly affect the functioning of wetland systems. Ofparticular concern is the accumulative affects of water withdrawal, the use of chemical pollutantsuch as DDT in mosquito control programmed, endosulfan sprays to control tsetse fly, and siltfrom poor upland agricultural practices (Brown, 1992; Hines and Kolberg, 1997).

Bulk water storage dams in Namibia are only found on the intermittently flowing rivers risingin the central region Although there is concern that these impoundments have negatively affecteddownstream groundwater levels, they provide important sources of water for industrial anddomestic consumption in otherwise arid regions. Excessive abstraction of upper catchmentimpoundments negatively affect the vegetation along the ephemeral rivers through the lowering ofthe water table. General habitat degradation has severely denuded riparian forest along theperennial rivers (Hines and Kolberg, 1997).


Possible solutions and successful schemes

Namibia has made an attempt to assess soil erosion on small scale (1:1,000,000). This processhas been hampered by the lack of concrete data available countrywide. Progress has been made incalculating the soil erosivity index from the average annual rainfall data using the Soil LossEquation Model for Southern Africa (SLEMSA). Extrapolations to areas where no record isavailable hampered the projection to specific areas, however statistics made it possible to fill thegap. Despite the availability laws and policies that provides for monitoring and assessing theimpact of environmental pollution and toxification hazards no attempt has been made to mapthese impact at a national level. The reason being that these type of degradation has not yet

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caused a national out cry, except for occasional cases reported in the urban and peri-urbanenvironment. So far that has been left to the municipalities to handle.

Reported cases of sewerage water leaks into agricultural fields has gone with therecommendation to abandon the field for a new field, but the impact is only determined by thedecrease in yield and stunted crop stand rather than the chemistry in the soil and plant tissue. Thelack of proper facilities for determining the type and degree of toxification is largely to beblamed. Soil fertility and fertilizer use as are well as chemical pest and disease control are yet tobe assessed but again the national use of fertilizers are very low. Those who can afford are fewand the fertilize and soil amendment chemicals have a high price. It is these price that controlchemical degradation.

Lowering of fertility is evident in communal areas where chemical fertilization is literallyzero. Cutting and burning of vegetation for clearance of new agricultural land is a commonpractice in Okavango and Caprivi regions. In the Oshana Ohangwena, Otjikoto and Omusatiregions shifting cultivation is not common, but rather expansion of agricultural field is adominant practice. This is mainly the result of population pressure. The yield differences betweenthe expanded portion and the old portion is magnificent in favour of the expended portions. Therest of the country is either commercial or livestock dominated. Livestock in commercial area arethe major causes of deforestation, soil erosion and bush encroachment imbalance in vegetationremoval allows for clearance of the most palatable plant material closer to water points. The lesspalatable material spread to this area without control. Bush encroachment is from definition thespreading of unwanted species of woody vegetation into an area.

The Government of Namibia has formulated an Eco-Systems Conservation and Protectionprogram with the objective to improve conditions of food security and nutrition by ensuring thelong term sustainable use of the environment and natural resources and conservation of forest,wildlife and Namibia's fragile eco-system. Environmental protection and ecological conservationis imperative to achieve sustainable agricultural and rural development, particularly in achievingfood security and improving nutritional status (NFSNC, 1995a). This program is multi-disciplinary and comprised of representatives from the following agencies and organizations(NFSNC, 1995a):

• Ministry of Environment and Tourism, Directorate of Environmental Affairs (lead agency),• Ministry of Agriculture, Water and Rural Development, Extension and Engineering Services,• Ministry of Agriculture, Water and Rural Development, Directorate of Planning,• Rossing Foundation,• University of Namibia, Social Science Division,• Council of Churches in Namibia.

Areas of support from the international community

The role of soil science in agriculture and environmental sciences is partly misunderstood bymany sectors in Namibia. A broader view of soil science need to be presented to all Namibian,and taught at school to the youth. It is a general perception that most Namibians regard soilscience as the formulation of fertilizers and manure for increased productivity. New projects areunderway to address soil physics, especially soil moisture management. This component is aimedat addressing the issue of climatic aridity with respect to productivity. The first step is investigatethe different soil tillage practices (deep ripping, shallow plowing and zero tillage) with respect tosoil moisture storage using the gravimetric techniques combined with field moisture meters.


Depending on the funds available, the second step will be to look into the structural deterioration,computability, crusting and nutrient loss when these are continued over several seasons under thesame crop. Results from this project will help addressing the shifting cultivation and continuousexpansion of agricultural fields which are not used to capacity in the communal farming sector,as well as the selection of the management practice suitable for Namibian condition.

The international community (Food and Agriculture Organization, Southern AfricanDevelopment Community (SADC), Commonwealth, European Community and all first worldcountries which are providing aid to Namibia for various means are kindly requested to assess theenvironmental programmes already in place and direct their financial and technical supporttoward long term environmental programmes which addresses conservation and sustainability.The existing policies and legislation should be regarded as an incentive for a healthy atmosphereand guarantees commitment from the Namibian Government. International schools and technicalinstitutions should consider personnel and student exchange with the Namibian counterparts, aswell as making provisions for Namibian students to enrol at their institutions while doing theirpractical, theses and dissertations on Namibian environmental issues. This will not only raise thelevel of expertise in Namibia and her environment, but also document the existing environmentalconditions with concrete data.

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Seely, M and Montgomery, 1996. Managing water points and grazing areas in Namibia. DesertResearch Foundation of Namibia. P. O. Box 20232, Windhoek, Namibia.

Seely, M and K. Jackobson, 1997. Desertification in Namibia. in Tarr, P. Namibia Environment, vol 1.Ministry of Environment and Tourism P/ Bag 13306, Windhoek, Namibia.

Strobach, B.J., A.J. Calitz and M.E Coetzee 1996. Erosion Hazard Mapping. Agricola. No. 8 MAWRD53-59

Tarr, P. 1997. International Environmental Treaties, in Tarr, P. Namibia Environment, vol 1. Ministryof Environment and Tourism P/ Bag 13306, Windhoek, Namibia.

Trippner, Ch. in preparation. Salt content as an Eco-pedological limiting factor in soils of the EtoshaNational Park/N-Namibia: Draft version.

United Nations Development Programme (UNDP), 1996. Human Development Report. UNDP.Windhoek, Namibia.


South Africa


World dilemma

World food demand will double by 2025 due to population growth, urbanization, rising income indeveloping countries and westernization (Sielaff, 1997). In 1994 global food production wouldhave provided a diet with adequate calories for about 800 million more than the actual worldpopulation, had it been evenly distributed (Borlaug, 1997). According to the FAO, the 50countries of the Africa continent could feed three times the present population (Spurling et al.,1992) but in 1990, the continent produced 27 percent less food than in 1967 for each African(Lean, Hinrichsen & Markhan, 1990). SADC’s domestic availability of major staple foods in the1990/91 marketing season was reported to be 8 percent in excess of requirements. Despiteproduction statistics, 30 million people in Africa are threatened by famine and require emergencyfood aid, much of which is imported (Rwomire, 1992). These statistics point to two key problemsof feeding the world’s people namely producing sufficient quantities of food of desired qualityand kind in environmentally and economically sustainable ways and secondly of distributing foodequitably (Borlaug, 1997). Both these problems are daunting as a healthy natural resource base isat stake to ensure sustainable food production and as the poor lack purchasing power. The latterexplains why 1 thousand million people in the world are starving. An aggravating factor to foodsecurity is that on a worldwide basis, only 11 percent of the soils are deemed to be free oflimitations (Scotney & McPhee, 1990).

Food production and agricultural potential

In South Africa, the diversity, nature and distribution of the natural resources soil, terrain,climate, water and natural vegetation, enable the country to produce a wide variety of food andfibre products which take full command of the people’s nutritional needs. In terms of value andquality the country not only meets its own food requirements, but is a major exporter of certainagricultural products (Van der Merwe, 1995). Land utilization data reflect (Table 1) that out ofthe 122 million ha of South Africa almost 86 percent is used for agriculture. This excludessubsistence farming, smallholdings and almost 5 percent under forestry. Agricultural landcomprises almost 74 percent natural veld and 12 percent arable land of which approximately 1.2million ha is under irrigation. Irrigation is a stabilizing factor in South Africa’s agriculturecharacterized by water scarcity, variable and erratic rainfall. Irrigated agricultural productionaccounts for almost 30 percent of total crop production and four percent of GDP (Scotney & Vander Merwe, 1995; Goodland, 1995) but this may not increase if water is put on a full cost-pricingbasis. Modern technology constantly enhances production.

A.J. van der Merwe and M.C. de VilliersInstitute of Soil, Climate and Water, Pretoria

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TABLE 1 Present and additional area land (ha) according to potential class (excluding former homelands)

Classes High Medium Low Notcultivable

Unclassified Total

Present area perpotential class

5 898 586 5 391 826 3 402 412 452 235 74 353 619 89 498 678

Additional area perpotential class

1 061 423 888 575 235 594 -452 235 -3 849 357 0

Total 6 960 009 6 280 401 5 754 006 0 70 052 027 89 046 443

A mere 3 percent of the 13.5 million ha arable land currently utilized by agriculture is ofhigh agricultural potential and presently 0.5 million ha non-arable land is used for agronomicproduction. Theoretically speaking, only 1.3 million ha is available for horizontal agriculturalexpansion (Van der Merwe, 1992; 1994), but it is envisaged that this area could be expandedsignificantly as land, mainly in the former homelands (almost 10 million ha), presently usedmostly for subsistence, is brought into production. The Corporation for Economic Development,other agents and commercial farmers in these areas agree that most of the 10 million ha has ahigh production potential (Van Marle, 1981; Smith et al., 1990). According to Van Marle(1981), the agricultural potential of 100 ha of land in former homelands is roughly the same asthat of 147 ha in the former white areas. Grobler, quoted by Van Marle (1981), tasked sevendifferent areas from the former KwaZulu, Northern Black States and Bophuthatswana andclassified the sample areas according to production potential and grazing capacity. He concludedthat with the rough estimates of agricultural potential and capacity for food production as basis,25.6 million people could be self-supporting on the 9 618 000 ha.

Van Marle (1981) reported that annual maize production in the former Bophuthatswanarocketed by more than 1 000 percent over four years. This increase in production led toemployment opportunities, wealth creation and the creation of silo complexes. The reason forprevailing low yields is not low production potential but a lack of agricultural inputs, the attitudeby traditional leaders and farmers’ management, technology, personal motivation and the landtenure system. The area should be able to feed a total population of 30 million but presentproduction is sufficient for only 2 million (Van Marle, 1981). This gap is likely to widen unlesswell-planned and directed corrective action is taken urgently.

The ARC-Institute for Soil, Climate and Water initiated a land type survey in 1971 aimed atproviding an inventory of soils, terrain forms and macroclimate. The data from this and detailedsoil and climate surveys, integrated by a geographic information system, allow reliableassessments of agricultural potential and land suitability. The former Ciskei and Transkei areexcluded but ISCW and its partners, the National Department of Agriculture, the Eastern CapeDepartment of Agriculture and Land Affairs and the University of the Transkei negotiated fundsto survey these areas and to develop a natural resources information system for the Eastern CapeProvince. Considering area extension possibilities, South Africa can probably feed its populationfor many years to come (Van der Merwe, 1995) provided the current major problems of pooragricultural land management, land degradation, competition for arable land, population growthand equitable food distribution are addressed in a sustainable manner. Equally important,provided sufficient funds are available to implement effective monitoring, auditing and precisionfarming systems and to continue critical research and technology development.

Most agricultural production extension should come from the former homelands which areless developed and mainly used for subsistence. Affluence needs a stock component as well asgross national product per caput which is an economic flow component (Goodland, 1995). SouthAfrica, where 74 percent natural vegetation occupies the agricultural land area, has a major niche


for cattle. In the former homelands, 80.3 percent of the agricultural land area is utilized asgrazing (Van Marle, 1981). According to Goodland (1995) cattle, with a social value to mosttribes, are responsible for major land degradation which will become irreversible throughoutmuch of South Africa’s dry and fragile soils, unless cattle are scrupulously managed. It isestimated that 60 percent of the natural veld is in poor condition. Measured against the grossvalue of individual agricultural products, maize, sugar cane, and wheat are South Africa’s mostimportant field crops, followed closely by hay. Deciduous and other fruit, vegetables and potatoesare the horticultural crops with the highest growth value while poultry and cattle products top thelist in 1994/95 of animal products. Table 2 projects the increase in production required to feedSouth Africa’s nation until the year 2010. In compiling Table 2, cognizance was taken of thecountry’s mosaic of socio-cultural habits and massive urbanization resulting in new lifestyles.Considering an annual population growth rate of 2.5 percent, crop production will have to beincreased by 3 percent per annum (Schulze, Kiker & Kunz, 1993). An even more daunting taskthan an increase in food production is that of ensuring affordable food and sustainable farmingsystems as South Africa’s soil mantle is most vulnerable and as the country is largely semi-aridto arid.

TABLE 2 Projection of increase in production required to accommodate population growth

Commodity Production estimate (%) 2000 2010

Estimated annual growthrate in production (%)

Maize Wheat Beef Chicken Deciduous fruit Subtropical fruit Sugar Vegetables

117.2 117.2 116.1 152.4 126.8 128.0 129.3 134.4

137.4 137.4 134.7 232.1 160.7 163.9 167.1 180.6

1.6 1.6 1.5 4.3 2.4 2.5 2.6 3.0

Cereal production

Table 3 portrays the extent planted to maize, wheat, barley, oats and grain sorghum from1975/76 to 1994/95 and production yield. Subsistence production is obviously excluded. Thisinformation unfortunately, tells nothing of the ecological implications of crop production, thestandards of agronomic practices, soil selection or climate influences. Maize, occupying 56.5percent on average of the land used to cultivate field crops, represents 49 percent of thecarbohydrate consumed by South Africa and 59 percent of the energy sector of livestock foods.By the year 2000, white maize consumption could rise from the 3.6 million tons to between 4.3and 7 million tons, and yellow maize consumption from the present 3.1 million tons to between4.5 and 5.2 million tons (Van der Merwe, 1994). Table 4 illustrates how maize production can beconservatively increased from the average 2.4 t ha-1 under dryland conditions to 3.5 t ha-1 andfrom 6 to 8.2 t ha-1 under irrigation to take command of projected requirements.

Schoeman & Scotney (1986), ignoring individual farm viability, calculated that if maize inthe main production areas was planted according to soil potential a total crop exceeding the1984/85 level of 8.3 million tons could be reaped from a area one third smaller than the areaplanted that season. Such general assessments are of little value at the farm level where far moreresource information is needed, where management is a critical factor (Scotney, 1987), and wherethe farmer’s financial position is unknown. Soil productivity is an intrinsic value of soil and longterm soil productivity an indicator of soil sustainability. Agriculture involves the rearranging ofnature to bring it more in line with human desires. It does not imply exploiting, mining or

South Africa266

destroying the natural world. Plant nutrient applications (NPK only) for the period 1992/96(Table 5) illustrate a significant increase in domestic fertilizer consumption in 1996 after adecline since 1985. Skeen (1997) ascribes this to favourable climatic conditions in most parts ofthe country during the 1995/96 production year and higher than normal farm income. It issignificant that the average plant food concentration marginally increased from 28.8 in 1992 to29.7 in 1996 (Skeen, 1997). Figures in Table 5 reflect domestic fertilizer application only and isnot an indication of nutrient balance which takes cognizance of atmospheric and irrigation waterdeposits besides natural nitrogen provision processes. A NPK balance sheet (Table 6) compiledfrom 1971-81 data, indicate N and K depletion annually. Annual nutrient loss (42 774 N tannual; 34 219 P t annual; 470 514 K t annual) due to erosion is particularly alarming. K lossesdue to erosion exceed fertilizer K application 4x while N losses account for 14 percent of thatapplied and P for 21 percent. Erosion is a serious threat in terms of both sustainability andeconomic production.

TABLE 3 Average area planted to maize, wheat, barley, sorghum and oats and average yield (1975/76-1994/95)

Crop Area planted Production (000 ha) Arable crop area (%) Total production (000 ton) Yield (t ha-1)

Maize Wheat Barley Sorghum Oats

4 369.25 1 694.05

95.60 232.90 548.10

56.47 21.89 1.23 3.01 7.08

8 328.80 2 073.00 172.80 445.80 68.40

1.9 1.2 1.8 1.9 0.1

Total 6 940 89.68 11 088.80 All other* 797 10.32 18 382** Total 7 737 100.00 29 470.80

* Dry beans, sugar cane, tobacco, cotton, groundnuts, sunflowers and soybeans ** Sugar cane production represents 95.5% of all other crops total production TABLE 4 Maize yield according to level of management

Management level Dryland yield (t ha-1) Irrigation yield (t ha-1) Average farmer Top farmer Experimental

2.4 3 3.5

6.1 7.7 8.2

TABLE 5 Domestic fertilizer use in South Africa and related statistics 1992-1996 (000 tonnes)

Plant nutrient 1992 1993 1994 1995 1996 Change1996/95 (%)

N 348 408 375 371 415 +117 P 96 106 108 106 112 +5.2 K 99 103 108 112 119 +7.1 Total 543 617 591 588 646 +9.7 Plantfood concentration 28.8 29.1 29.5 29.4 29.7 +1.0

Source: after Skeen, 1997

Considering an annual population growth rate of 2.5 percent in South Africa and the country’sagricultural potential, South Africa is committed to improving and increasing agriculturalproduction to meet the food demands of the people despite the decline since 1960 in agriculturaland forestry land by almost 20 percent in favour of urbanization and nature reserves (Dept.Agric., 1994). South Africa’s major task is to ensure that the natural resource base is carefullymanaged to sustain future generations. This vision can be realized, provided that:


TABLE 6 NPK Balance sheet for 14 million ha cultivated land (1971-1981 average per annum)

Application/removal

N ton/annum

P ton/annum

K ton/annum

NPK application/deposit Fertilizer Atmosphere Irrigation water

310 940 142 580 2 608

165 579 11 406

544

106 629 114 064 2 934

Total 313 548 (1) 177 529 223 627 N P K removal Crop & residues Maize Sorghum Wheat Oats Barley

145447

6 552 36 573 1 778 1 674

(a)

75.7 3.4 19.0 0.9 0.9

(b)

44.1 2.0 11.1 0.5 0.5

26 446 1 917 7 165 413 302

(a)

73.0 5.3 19.8 1.1 0.8

(b)

48.7 3.5 13.2 0.8 0.5

64 223 2 369 9 154 585 558

(a)

83.5 3.1 11.9 0.8 0.7

(b)

28.9 1.1 4.1 0.3 0.2

Total for cereals 192 024 36 243 76 889 Total otheragronomic/horticultural crops

137 946

17 997

145 430

Total all crops 329 970 54 240 222 319 Erosion 42 774 34 219 470 514 Total: crops,residue, erosion

372 744 88 459 692 833

Balance -59 196 89 070 -469 206 Source: after Biesenbach, 1984 Notes: (a) % of cereals; (b) % of all agronomic/horticultural crops; (1) Fertilizer and irrigation water only.N from atmosphere assumed to compensate for N losses due to leaching, denitrification andvolatilization

• under- or undeveloped high to medium potential land in the former homelands is developedsustainably,

• soil quality is improved,

• agricultural management, cultivation practices and precision farming systems are improvedsignificantly,

• land use and land management are dictated by the intricate interactions between soil, climateand terrain,

• land degradation is reversed,

• impact assessments are undertaken prior to South Africa’s development programmes like theredistribution of land,

• input cost is reduced.


The cutting edge of Africa’s crisis, says Harrison (1987), is the steady decline in agriculturalproduction per person, especially of food. Between 1965 and 1982 Africa’s food production perperson fell by 12 percent in 33 of the SSA countries despite the significant increase in foodproduction at a rate of 2.1 percent per year through the 1970s. In the same period, SouthernAfrica’s per caput food production fell by an average of 19 percent. Decline in food production

South Africa268

can be attributed to many factors but the factual causes are the rate of population growth inAfrica which was 3 percent per year in the 1970s (Harrison, 1987) and the continent’s longhistory of continued bad land use and resultant low agricultural productivity (Okigbo, 1990).This endorses the formidable challenge described by SDC (1994) namely to produce enough foodfor an increasing population while preserving the natural resource base and in particular the soilsas key resource for agricultural activities.

In South Africa, the expected annual population growth rate is 2.5 percent. This implies thatthe population will double in 40 years which is alarming when compared to major parts ofEurope where the population doubles every 71 years or more (Luiz, 1994; Goodland 1995; Vander Merwe, 1995). Person-to-land ratios are worsening fast and it is estimated that the area ofarable land per caput will drop well below the accepted minimum of 0.4 ha before the year 2010(Van der Merwe, 1995). Inadequate consumption per caput, poverty and rapid population growthundermines future consumption per caput.

At present, food production per caput in South Africa is sufficient but agricultural outputwill have to be expanded from more intensive cultivation mainly in areas already used foragricultural production (Greenland et al., 1994) or we will become dependent on food importswhich will be conducive to the downward spiral of the poverty trap. If South Africa can succeedin conserving its natural resource base in the face of continued pressure on land, a win-winsituation is possible (Van der Merwe, 1995). In most regions of the world, increasing food supplyover the past two decades were gained mainly by increasing yields. The major exception to theworld was SSA where most of the growth in production has occurred due to expansion ofcultivated areas (Borlaug, 1997). South Africa, due to population pressure, scarcity of land,endemic technology and a history of food export, more or less maintained agricultural productionover the last two decades.

Fluctuations in areas planted to arable crops and yield per annum can be directly related toclimate conditions, and in particular to rainfall and rainfall pattern. Climate conditions and thesubsequent financial position of the farmer dictate plant nutrient applications. A comparisonbetween the 1991/92 and 1993/94 maize production seasons shows that the 1993/94 season, withaverage annual rainfall, yielded an above average 2.8 t ha-1 while the 1991/92 season with a wellbelow rainfall (340 mm in 1992) yielded a disappointing 0.78 t ha-1. Plant nutrient (NPK)application in 1993/94 was 22 percent higher than in 1991/92. Area planted to maize was 10percent less in 1991/92. As a result of these interactions, 91 percent more maize and maizeproducts were exported in 1994 while the import of maize and maize products was 85 percenthigher in 1993 than in 1994. The average area grown to the cereals maize, wheat, barley,sorghum and oats over the past two decades was 89.68% (6.9 million ha) of the total area grownto arable crops (Table 3). Maize, planted to 56.47 percent of the total area planted, stayed SouthAfrica’s major arable crop, followed by wheat planted to 21.89 percent of the total arable area.Table 3 excludes subsistence and non-marketable data. Such partial productivity measures relateoutput of a single input factor (Thirtle & Van Zyl, 1993) and address indicators of the economicgroup and to a certain extent, indicators of the physical group, but not those of the social orbiological groups. Both social and biological indicators are of critical importance, and inparticular biological indicators including aspects like cropping systems, length of and changes infallow, soil biota and other indicators fundamental to sustainable soil productivity (IBSRAM,1995). Soil is regarded as more than a production factor by most commercial farmers and theyusually try to maintain soil productivity even when it is economically unjustified. This is a majoradvantage even when the pressure on natural resources is high. However, contrary to intention,


farmers are often forced to neglect soil care when economic returns from agriculture are too lowto justify investments in soil maintenance. Liming to ameliorate soil acidity falls in this category.Naturally occurring acid soils affect more than 15 percent of South Africa’s land area but theexact extent of man-induced topsoil acidity is unknown. According to Beukes (1995; 1997),trends in soil analysis indicate increasing soil acidification and Farina (1997) states that almost15 percent of South Africa’s arable land is likely to be affected by some degree of subsurfaceacidity. On acid soils, with a low nutritional status, maize yield loss could be as high as 60percent and in the worse scenario for wheat, yield loss of 71-87 percent could occur (Beukes,1997). In view of food production, soil acidity is undoubtedly South Africa’s worst enemy as itresults in poor vegetative crop growth, impedes root development and subsequent water andnutrient uptake, causes Al, Mn and other toxicities and as it causes poor nodulation inleguminous crops (Beukes, 1997).

The influence that land tenure will have on per caput cultivated land and food security inSouth Africa is not quite clear. The communal system of land tenure within the tribal context,mostly in the former homelands, is practised on an estimated 13 percent of South Africa’s arableland. Land tenure is often blamed as the cause of agricultural failure as the system, according toBeuster (1981), incorporates a number of inherent weaknesses including :

• the absence of sense of value regarding land. Traditionally tribal communities regard theacquisition of the agricultural use of land a right and subsequently land is seldom seen as aneconomic production factor which has to be used optimally in order to ensure success,

• non-differentiation between farmers and non-farmers as land units are relatively small and inmost cases the farmer has the option of selling his labour to nearby industrial or miningareas. This leads to neglect and the under-utilization of valuable agricultural resources,

• tribal tradition regarding agricultural practices with a retarding influence on the acceptanceof modern agricultural practices,

• a negative attitude towards agriculture, especially in the eyes of the younger generations.Agriculture is associated with poverty, hardship, subsistence economy, dirty work and ofvery little scope for real progress. Small farms house large numbers of people who have fewalternative sources of employment and income (Van Marle, 1981). In the former Qwaqwa, avery sensitive ecological area due to topography, for example, population density in 1990was estimated at 163 persons per kilometre compared to the 28 for the whole South Africa(Scotney, Volschenk & Van Heerden, 1990).

Soil management and development programmes should be undertaken with adequate

participation of the soil users and mainly small farmers, with emphasis on women. Women havethe principal responsibility for over 20 percent of all small farms in developing countries (SDC,1994). Furthermore, international market policies and practices tend to work against the interestof poorer developing countries. Industrialized countries, through export developing, importrestrictions and subsidies to improve the productivity of domestic agriculture, have reduced returnon land in developing countries by lowering world market prices. Poorer, less advanced countriesare net losers (SDC, 1994) and the poor have little incentive to care for soil productivity in asustainable way. To change from subsistence farming to a cash economy, money, inputs such assoil nutrients, good seed, appropriate machinery, technology and management are vital. Farmersmust be willing and able to accept training, new technology and sustainable soil managementpractices, and rural infrastructure must be in existence or created (Van Marle, 1981). TheSheila/Verdwaal project in the former Bophuthatswana bears evidence that a communal land

South Africa270

tenure system can be successful. This community consists of 197 farmers cultivating 3,426 ha ofland. With the assistance of and training in modern technology by an economic developmentagency and an agricultural cooperative, the community reaped 3.25 t ha-1 maize. The same groupof farmers yielded 1.68 t ha-1 with the initiation of the project 3 years earlier (Beuster, 1981).

Land reform programmes require long-term perspective, strong political consensus andfunctional legal institutions, with well-defined property rights as farmers’ investments and theirability to receive normal credit depend on clearly defined ownership of land (SDC, 1994). Landreform, according to Goodland (1995) however widely implemented, will not be sufficient toalleviate rural poverty or food security as the available supply of land is simply not sufficient togrant a useful quantity of land to even the majority. To ensure food security and wealth creation,effort will need to be devoted to generating non-farm employment opportunities in rural, urbanand peri-urban areas to meet the needs of future population growth. Most effort needs to befocused on reducing population pressures if all investments are not to be rapidly overwhelmed(Goodland, 1995). The South African Department of Land Affairs is promoting a farm equityscheme. This scheme is a partnership arrangement between a commercial farming enterprise orprivate sector investor and the beneficiaries namely the landless, farm workers, labour tenantsand residents who want to secure an agreement of ownership of land, the sharing of profits andthe risks of the venture. Part of this programme is the empowerment of women (Dept. LandAffairs, 1997). South Africa will hopefully avoid mistakes of unsustainable agriculturaldevelopment in the past. In the 1970s, sub-economic land allocations were made to virtuallyevery tribal family in a section of the former Bophuthatswana. As a result of the sub-economicsize of plots, most of the land was unused and neglected while poverty and urbanization thrived.Afterwards, traditional rights to cultivate land were withdrawn and tribal members, willing tobecome full-time farmers, were allocated economic land units of 100 ha (Beuster, 1981). Thiswas the beginning of moving from survival economics to emerging economics.


According to Sielaff (1997) one quarter of global land is degraded and 4 percent is so badlydegraded that it is beyond repair. There has been a 17 percent cumulative productivity loss due todegradation, which has been more than offset by the doubling of world food production duringthat time. Land degradation or the loss of productive capacity of land to sustain life, is the majorsource of insufficient food and the poverty trap. The two main components of land degradationare soil degradation and the impoverishment of the vegetative cover. Soil limitations presented ona world-wide basis show that droughtiness (28%), mineral stress (23%), shallow depth (22%),waterlogging (10%) and permafrost (6%) are all important as only 11 percent of the world’s soilsare deemed to be free of limitations (Scotney & McPhee, 1990).

The major forms of soil degradations in South Africa threatening a sustainable naturalresource base and food security, are soil acidification, organic matter depletion and pollutioncausing salinization and alkalinization, compaction/crusting, runoff and erosion, infertility anddesertification. In the rural subsistence environment, fuelwood collection, concentrated populationdensities, inappropriate land use and overgrazing are major causes while unsustainable farmingsystems, incorrect and/or poor planning and catastrophic natural disasters are the majoragricultural production causes of soil degradation (Van der Merwe, 1995; Goodland, 1995).International programmes, protocols, treaties and conventions place much emphasis on soildegradation forms like erosion and desertification. These and other are most important to addressand reverse in view of a sustainable natural resource base and food security. At the bottom of


virtually all kinds of soil degradation, lies soil acidification, organic matter depletion andpollution. Once these have been addressed effectively, much of the other threats won’t be asimminent. The different forms of soil degradation are briefly discussed with emphasis on soilacidity, organic matter depletion and pollution.

Soil acidification

The aspirations of economic growth and the reduction of poverty are imbedded in sustainableproduction (Schaffert, 1997). Acid soils limit production throughout the world and is a majorconstraint to crop production in many countries. Soil acidity is of particular importance in areaswith low-input agriculture where there are few opportunities to counteract yield depressingfactors such as subsoil acidity with or without surface soil acidity, moisture stress and otherlimiting crop performance factors, specifically P deficiency (Eswaran, Reich & Beinroth, 1997).Acid soils occupy between 26 - 30 percent of the world’s ice free land area. Globally 67 percentof acid soils support forests and woodlands, approximately 18 percent are covered by savannas,prairie and steppe vegetation, 4.5 percent is used for arable crops while a further 33 million ha isutilized for perennial tropical crops. The poor fertility of acid soils is due usually to acombination of Al, Mn and Fe (reduced soil conditions only) toxicity, P, Ca, Mg and Kdeficiencies while many acid soils are affected by physical factors including low water holdingcapacity and susceptibility to crusting, erosion and compaction (Von Uexküll & Mutert, 1995;Eswaran, Reich & Beinroth, 1997).

Lack of moisture is rarely a major constraint to plant growth on acid soils in the humidtropics (Farina, 1997; Von Uexküll & Mutert, 1995) where population growth and thesubsequent increase in food demand is greatest. The humid tropics have the advantage of fewrainfall and temperature constraints to high yield, provided primary nutritional constraints (e.g. P,Ca, Mg, K deficiencies) are removed and the soil is managed expertly. Poorly crystallizedweathering products formed as a consequence of extreme acidification and weathering in forestsoils revealed an intense destruction of clay minerals and other silicates leading to anaccumulation of poorly crystallized to amorphous compounds. Besides Si, the weatheringproducts contain small amounts of Al and Fe (Veerhoff & Brümmer, 1993). which can clog soilpores on penetration causing runoff and erosion. In arid areas like South Africa, P, S, Mo and Bdeficiencies further complicate nutrition constraints as well as Mo and P fixation due to the use ofammonium fertilizers and the oxidation of organic material when soils are cultivated. Soilmanagement must allow rotation periods between regeneration and cultivation. There areexamples of highly successful development on acid savanna in Brazil and according to VonUexküll & Mutert (1995), the Potash and Phosphate Institute makes use of a fast growing legumecover crop in combination with heavy applications of lime and P to enhance soil fertility ondegraded anthropic savanna. Provided that good soil conservation is practised and nutrientsreplenished, sustained annual yields of 6.10 t/ha maize, upland rice, ground nuts and soybeans in2 to 3 crops per annum are possible. Unfortunately there is no example of a low-input systemworking over the long term.

An estimated 659 million ha of Africa’s total area is occupied by acid soils. This is the thirdlargest area on a continental basis and almost 16.7 percent of all acid soils. Eleven million ha(1.7%) is arable or planted to permanent crops (Von Uexküll & Mutert, 1995). Unlike the humidtropics, large parts of the Africa continent is characterized by dry climates. Soil acidification is,without question, the most dominant soil productivity problem. Naturally acidic subsoils occurover a wide spectrum of climate conditions varying from arid (± 500 mm per annum) to humid

South Africa272

(750 mm per annum). In total, more than 14 percent of South Africa’s land area is affected bynaturally occurring acid soils and 15 percent of the arable land is likely to be affected to somedegree by subsurface acidity (Beukes, 1995; Farina, 1997).

The exact extent of human-induced surface and subsurface acidity is difficult to establish,and the management of acidity in South Africa is particularly demanding in terms of bothquantification and identification (Farina, 1997). According to South African Agricultural Co-operatives (Fourie, 1997), approximately 60 percent of the country’s cropland area is moderatelyto severely acid (pH(KCl) < 5.1). Should the ideal pH (6.5) for crop production be used asindicator, close to 100 percent of cropland is acid. The human economy with its cultivation,tillage and fertilizer practices, plays a major role in the process of soil acidification. Fertilizerpractices are often injudicious, particularly N fertilization, directly affecting the C/N ratio. DuPreez & Burger (1985) for instance, using USA norms on residual inorganic N contents prior toplanting, determined that N application should have been one third less on 50 percent of the 82localities investigated and at least two thirds less on 25 percent of the localities.

A large percentage of N fertilizers in South Africa are ammonium based. Due tonitrification, ammonium transforms into nitrate in the soil, releasing hydrogen ions that promotesoil acidification. Cultivation increases oxidation of organic matter and therefore nitrification ofreduced nitrogen in organic matter that promotes soil acidification. To optimize the organicmatter contents, the C/N ratio, critical in view of a sustainable soil mantle, present cultivation,tillage and fertilizer practices will have to be seriously reconsidered and soils users in SouthAfrica will have to buy into the concept of sustainable farming systems. The first step willobviously be to ameliorate soil acidity. This will be an expensive exercise as 100 percent of thecropland could be acid to varying degrees.

On average, 2 t ha-1 lime will be required in the initial phase to correct soil acidity. Theinitial phase to ameliorate soil acidity (Von Euxküll & Mutert, 1995; Beukes 1992; Du Toit etal., 1994) will also be marked by correcting other plant nutrient deficiencies with emphasis on Pand by establishing leguminous cover crops. As pointed out by Von Euxküll & Mutert (1995),this is, financially wise, an expensive and unproductive phase. It is also the only way to correctthe C/N ratio and to ensure sustainability. The three step development cycle (Von Euxküll &Mutert, 1995), from South African experience, will take four years (Beukes, 1992). It should beborne in mind that both natural and human-induced soil acidity should be addressed to preventother forms of soil degradation and to develop medium to high crop potential land. Soilacidification is further intensified by acid rain. Commercial farmers’ liming programmes largelydepend on cash flow. Their often unjustified soil sustainability decisions are dictated by financialmeans. Since 1981 liming material sales dropped by more than 1 million ton. This decline isdespite concerted awareness campaigns, research and extension dedication, and demonstrationtrials.

As discussed in area extension possibilities for food production, the 10 million ha of thecommunal agricultural surface area (former homelands) should be developed. Large parts ofthese areas lie within both the warm and high rainfall areas of southern Africa and 76 percent ofthe total area receives more than 500 mm rainfall per annum. These areas have at their disposalthe necessary natural resources, entrepreneurs and labour. What they do need, says Van Marle(1981), is training skills and enthusiasm to become entrepreneurs, modern technology anddevelopment finance. Soils of lower potential in relatively high rainfall and high soil acidity areashave much potential for expanding production provided the soil acidity is ameliorated and high


yielding pasture legumes are introduced into livestock systems. Strydom & Wassermann (1984)computed the area in South Africa suitable for the introduction of legume based pastures at 17million ha, injecting approximately an extra 400 000 tons of nitrogen into the system annually,through the agency of nitrogen fixation by Rhizobium bacteria. This can lead to the trebling andquadrupling of livestock production per ha. The liming of acid soils will not only optimize pastureproduction under the favourable rainfall conditions along the East Coast in South Africa but willalleviate the endemic problems of micro-element shortages. Soils limed to pH 6.5 are moreresistant to erosion while improved pastures and sustainable crop production systems madepossible by liming will prevent further degradation of an important natural resource. Theamelioration of natural acidity of soils in Africa can be a major catalyst to economicdevelopment.

Approximately 3 million of the 10 million ha in former homelands is potentially arable land.The major portion of medium to high agricultural potential land is found in the former Ciskei,KwaZulu and Transkei areas. These three areas with roughly 1.2 million ha high potential landare blessed with a mean annual rainfall exceeding 700 mm. Van Marle (1981) postulated that iffarmers are to be settled on 100 000 ha of land suited for wheat production, 160 000 ha for maizeproduction and 2.6 million ha of grazing in Bophathatswana, then a total of 6 439 farmers can besettled on maize and wheat farms, 625 on irrigation units of 9.7 ha each, and 2 541 cattle farmerson units to carry 169 mature livestock. A total of 9 605 farmers could thus be settled in thetransformation from subsistence to cash economy. Van Marle (1981) also pointed out that thetotal production of maize and wheat would be so substantial that it would provide for export.Grobler, quoted by Van Marle (1981) notes that KwaZulu could successfully accommodate aminimum of 7.5 million self-supporting people instead of the 4.9 million in 1990, the northernareas 10.9 million and the western areas 7.2 million. However, agricultural production potentialis seriously jeopardized by excessive soil acidity at a pH of 4.5 on even lower; 100 times moreacid than the ideal. In the former Ciskei, KwaZulu and Transkei with the highest agriculturalpotential, subsistence dominates within tribal and communal land tenure systems. There is anurgent need to develop these areas sustainably and economically. These areas should be used asframework to develop the other former homelands.

Technology and norms, suitable for South Africa with its complex and vulnerable soilmantle and diversity, exist to facilitate the amelioration of soil acidity to levels conducive tooptimum crop and pasture yields. Ameliorating soil pH for instance from the present 4.5 andlower to 6.5, will increase maize yields from 0.5 to 8 ton ha-1 on high potential soils. Potentialincome could escalate over 1 000 percent. Pasture production could be upgraded significantly byintroducing legumes which would contribute substantially to sustainable agro-ecosystems asalready proofed by the Potash and Phosphorus Institute in Brazil (Von Uexküll & Mutert, 1995).Von Uexküll & Mutert (1995) suggest a three step development approach :

• an initial phase that establishes leguminous cover crops supported by liming and Papplications to enrich the biological and nutrient cycle of topsoil and prevent erosion,crusting and compaction. This is an expensive and unproductive phase in the sense that littleincome is generated from harvested materials,

• concentrate on deepening and enriching the rooting zone for marketable crops to generatefarm income. This phase still requires investment,

• balanced nutrition and efficient management to establish an ecologically and economicallysustainable and viable system.

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Borlaug & Dowswell (1997) warned that “world peace will not be built on empty stomachsand human misery. Deny the small-scale farmers” (like those in South Africa’s formerhomelands) “of the developing world access to modern factors of production and much neededagricultural expansion in the acid soil areas to help feed future generations and humankind will bedoomed, not from poisoning and environmental melt-down, but from starvation, social andpolitical chaos”. Only where sufficient funds and assistance are provided during the first twophases of ameliorating soil acidity will wealth be introduced to landscapes where poverty wouldotherwise reign says Von Uexküll & Mutert (1995). This statement is the foundation forsustainable development in South Africa.

Soil organic matter depletion

In South Africa, the organic C contents of soil is steadily declining, signalling unsustainability(Du Toit et al., 1994). Factors like South Africa’s isolation over many years and restricted landarea, largely necessitated monoculture cereal production, short fallow, the absence of croprotation systems, as well as intensive tillage. The authors are of opinion that the sustainableutilization of the natural resources for cereal crop production in South Africa can be achievedonly if:

• the organic matter contents in soils can be sustained and increased,• input costs are reduced,• soil acidification and pollution/sterilization are prevented.

To increase and sustain the organic matter contents of South African soils, the oxidation oforganic matter will have to be minimized and the C/N ratio be manipulated by minimum tillagepractices, grass ley legume systems, crop residue conservation and nitrogen fertilization practicesthat will promote the uptake of reduced forms of nitrogen and minimize the oxidation of reducedforms of nitrogen. It is well documented in literature that organic matter in soils is correlated withaggregation of soil particles, a favourable structure, water holding capacity, nutrient supplypower and soil biota contents minimizing crusting, compaction, runoff, erosion and leaching ofnutrients. Due to microbial and earthworm activity it is possible to reduce cultivation, fertilizationand liming costs.

Runoff and erosion

The irreversible loss of good quality soil not only influences the capacity of the farmer to producesufficient food, but also the loss of the capacity of dams. Approximately 159 tons of sediment aretransferred annually by South African rivers. The balance between ratios of soil formation andsoil loss determines biotic activity. As an estimated 20 percent of the country’s total area ispotentially highly erodible, erosion is a serious agricultural and environmental threat (Van derMerwe, 1995). Natural erosion shapes the landscape under natural vegetation and, apart fromepisodic floods, does not pose a threat as it approximates the rate of soil formation. Accentuatederosion results from human activities and takes place at rates far in excess of those for naturalerosion (Scotney & McPhee, 1990). Both water and wind erosion are serious problems in SouthAfrica (Table 7). Wind erosion affects some 1.3 million ha and water erosion almost 1.7 millionha. The estimated annual soil loss of 2.5 ton per hectare far exceeds tolerance levels as theestimated rate of soil formation is 0.31 ton per hectare per annum (Van der Merwe, 1995). Soilloss tolerances (T value) vary considerably for different soil conditions and for arable and non-arable situations. In South Africa, suggested tolerance levels for cultivated land are between 3 tha-1 a-1 (shallow soils) and 9 t ha-1a-1 (deep clay and organic soils) according to Scotney &McPhee (1990). Even the 3 t ha-1a-1 however exceeds soil formation of an estimated 0.31 t ha-1a-


1. Accurate soil loss quantification is evasive despite reliable soil loss prediction equations andrunoff trials. Equations like the USLE and RUSLE are used successfully to predict soil lossunder different management practices. Sustainable farming practices and erosion preventionmeasures can fortunately prevent soil erosion. Scant attention has been given to soil losses fromnon-agricultural land. High losses result from activities such as road building, quarrying, sandwinning, mining and site preparation. Quantitative estimates for South Africa have not beenattempted according to the authors’ knowledge.

TABLE 7 Extent of wind and water erosion

Type of erosion and land use Seriousness of erosion and area affected Total (ha) Serious

(ha) Moderate

(ha) Non-significant

(ha)

Wind - Cultivated land - Pastures

415 001 569 524

1 325 749 1 700 436

1 427 088 7 932 671

13 370 469 Water - Cultivated land - Pastures

930 735 801 288

2 258 193 3 128 613

2 886 727 6 973 149

16 978 705 Total 2 716 548 8 412 991 19 219 635 30 349 174

Soil compaction

Cultivation and depletion of organic matter has led to several important soil physical problems.Compaction is prevalent in fine sandy (<10% clay) soils which is an estimated 80 percent of thesoils cultivated for maize production. Maize yields may be reduced by as much as 30-40 percenton such affected soils (Van der Merwe, 1995).

Soil crusting

Soil crusting as a result of organic matter depletion, soil acidification and alkalinization increasesrunoff from a wide range of cultivated and non-cultivated soils, hampering crop production andpromoting erosion. The extent of crusting is unknown but a joint project by ISCW and theWestern Cape Province showed an increased wheat yield of 60 percent after soil crusting wasalleviated (Van der Merwe, 1995).

Soil infertility

The synthesis of chemical, physical and biological soil degradation, influenced by climate andmanagement practices causes soil infertility (Scotney & Dijkhuis, 1989). Physical structure, adesirable pH level, organic matter contents, proper aeration, adequate moisture and an optimalnutrient status must be maintained if sustainable food security is to be maintained. In SouthAfrica, most fields in cultivation consist of different soils with different crop productionpotentials and soils rather than fields should be fertilized to reduce input cost and to ensurefertilization profitability (Van der Merwe, 1995). Some arid, semi-arid and even sub-humidecosystems are impoverished by the combined effects of human activities and adverse climateconditions. The financial position of the farmer dictates if the nutritional status of the farm ismined or not.

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Desertification

More than half of the surface area of South Africa is threatened by desertification and theresultant decline in biological productivity. Desert encroachment is seldom progressive. Fragile,dryland ecosystems are allowed to degenerate through mis-applied technology, poor land selectionand bad management (Van der Merwe, 1995).

Soil pollution/alkalinization/salinization

Soil alkalinization and salinization often goes hand in hand with waterlogging and pollution.Alkaline/saline and waterlogged soils can be reclaimed but at great expense and meticulous soilmanagement afterwards. An estimated 10 million ha of irrigated land over the world is abandonedeach year as a result of waterlogging, alkalinization and salinization (Van der Merwe, 1995). Asurvey by the Department of Agriculture (1990) pointed out that 54 000 ha of cultivated land inSouth Africa is seriously alkaline and waterlogged with 128 000 ha moderately affected. Thisexcludes the former homelands. The management of reclaimed soils in South Africa is negativelyaffected by deteriorating water quality used for irrigation (Scotney & Van der Merwe, 1995) aswell as poorly designed and operated irrigation systems. Unsustainability occurs when the flow ofhuman economy exceeds environmental economy (mainly soil resources and sinks) in the flow ofmaterials and energy from natural resources, used by the human, and then returned to soil sinksas waste (Goodland, 1995). In South Africa, solid waste, effluents, agriculture and acid rain arethe major causes of soil pollution. Acid rain is a particular threat to some parts of the highestagricultural production area, responsible for almost 9 percent of the country’s total farmingincome (Van der Merwe, 1995). As South Africa depends on coal for 80 percent of its primaryenergy, any transition is unlikely (Goodland, 1995) but the problem of acid rain receives ampleattention by Mining Houses (Tanner, 1997). Population pressure and land transformationactivities like urbanization, agricultural practices, deforestation and biological invasion aredecided threats to the ecosystem and biodiversity. Invasive biota are a major threat to naturalbiotic communities. AVAILABLE TECHNOLOGICAL OPTIONS FOR CONTROLLING SOIL DEGRADATION ANDENHANCING PRODUCTIVITY

The performance of concerted research and extension has had little success in enhancingsustainable soil management in developing countries. This is attributed by SDC (1995) Pinstrup-Andersen (1982) and Harrison (1987) to :

• the lack of understanding or neglect of relations between soil management, economic andpolitical factors at local, national and international level. This includes inadequate foreign aidand aid provided which was irrelevant to core problems,

• the lack of dialogue between policy development and research entities involved in decisionmaking with relevance for the sustainable management of agricultural soils,

• the priority given to crop improvement programmes,

• the viability of research and development to integrate the dimensions of time and space intoprogrammes,

• inadequate participation of the majority of soil users, the small farmers and in particularwomen, in defining policies relevant to soil management,


• the complex task for researchers to identify core soil management requirements by farmers asmany factors influence soil management. The lack of farmer involvement in the developmentof soil management systems, often results in textbooks as origin of promoted innovations,

• a short planning horizon in decision making with emphasis on immediate increase in foodavailability with little concern for possible deterioration of the resource base which is neededfor future production.

The truth of these arguments is indisputable but there is also little doubt that the developmentand use of high-yielding crop varieties, increased use of fertilizers, better production systems andother yield-increasing factors have been of great importance in increasing food availability and inlimiting land degradation. The significant effect of modern technology is frequently overlooked(Pinstrup-Andersen, 1982). Goodland (1995) quotes Ehrlich who notes that there is littlejustification for counting on technological miracles and that technology also damages. It is truethat inappropriate irrigation and drainage caused waterlogging and salinization and thatagricultural practices can cause soil pollution but soil institutions with a global mandate likeISRIC, IBSRAM, WASWC and ISCO succeeded significantly in increasing yield and inconserving soils in danger of degradation by developing improved soil and management systems.The human factor is probably the most uncontrollable and unpredictable in research andextension application efforts. Düvel (1997) stated that neither soils nor farms have problems.People have problems. Düvel (1997) suggests approaches aimed at behaviour intervention and ona sound understanding of human behaviour which emphasizes the land user participationapproach essential to all soil research and management programmes if the integrated cycle ofprocess research, management research, development/economic evaluation, extension, farmingsystems and feedback described by Robertson (1987) is to be successful.

The major forms of soil degradation in South Africa are organic matter depletion, acidificationand pollution. To facilitate improved soil management technologies, ARC-Institute for Soil,Climate and Water (ISCW) developed and maintains national natural resources databanksincluding those for soil profiles, land types, soil surveys at different scales, agro-climate andNOAA satellite images. These databanks contain results of extensive ongoing reconnaissance anddetail surveys, soil and climate classification, characterization, quantification and monitoring.ISCW focuses on the characterization and quantification of the natural resources soil, climate andwater, natural resources monitoring and auditing and on the sustainable management of thenatural resource base. Research and technology development are aimed at the followingprogrammes to control soil degradation and to enhance agricultural production and food security:Soil inventories, geographic information systems, nutrient management, soil acidity, soil andwater management, reclamation of physically disturbed land, remote sensing technology, small-scale farming technology, analytical services (soil, water, plant, ameliorants, fertilizer andgrowing media), climate monitoring, agroclimate research, soil and environmental protection, soiland water quality, and soil quality indicators. Multi-disciplinary, cross-sectoral programmes areland use planning; precision farming; small-scale farming, food security, job creation andtraining; risk and disaster management; spatial development initiatives; and monitoring andauditing of the natural resources. The overall objectives of these programmes are :

• National welfare and economic objectives namely i) sustainable land use, land use planningalso in view of appropriate alternative uses, land reform, and farming systems, ii) themaintenance and increase of physical and monetary agricultural production, iii) theenhancement of values which embody a sustainable perspective in rural communities andsocieties and iv) early warning of food security, natural disasters and climate change.

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• Sustainable natural resources utilization and ecological objectives to conserve the soil andwater resources and to ensure long term soil productivity: i) the prevention of chemical,physical and biological soil degradation, including the maintenance and increase of bioticactivity, the maintenance and enhancement of soil organic matter, water quality and quantityas well as the availability of plant nutrients, the maintenance and improvement of physicalsoil structure and properties, the absence of toxic levels of hazardous micro-nutrients andelements, land husbandry and monitoring, ii) water conservation priorities are aimed at themaintenance of acceptable water quality by investigating and promoting bufferzones/wetlands, catchment, runoff, monitoring systems and integrated catchmentmanagement, the maintenance and enhancement of water availability by watershedmanagement, water wise food production and water harvesting.

• To empower people, training as an integral part of particularly provincial projects isintensified to supplement present projects which focus mainly on communities in view ofhousehold food security, mentorship and hands-on training. The empowering of people inSADC countries will remain a high priority.

Selected ISCW projects over the past five years in view of improved soil management to

enhance productivity and to control soil degradation are summarized. Most of the projects aremulti-dimensional and therefore applicable to both soil management and soil degradation.

Soil management

Natural soil fertility in South Africa is comparatively low because of natural acidity, low organicmatter content and a low P and other nutrients status. Supplementary nutrition accounts for onethird of input cost for crop production. Both soil factors and management practices areresponsible for the sub-optimal utilization of applied fertilizer by crops. Only 33 percent offertilizer applied annually are utilized by crops, affecting the farmer’s rate of return negatively.Furthermore, chemical fertilizers are often too expensive for subsistence and small farmers.Unutilized fertilizer could cause soil and water pollution as well as soil degradation. Thefollowing technology and research were aimed at improving the utilization of both macro andmicro-nutrients, at low input food production and at food security:

• Stable isotope 15N techniques to quantify nitrogen fixation in soybeans by rhizobium and todetermine the effect of nitrogenous fertilizer on rhizobium N fixation.

• Organic C and total N in virgin ecotopes prediction, organic matter decomposition rate,organic matter loss due to cultivation and the influence of climatic factors on organic matterloss.

• Nitrogen transformation in soil and N fertilizer evaluation to establish N utilization, ammoniavolatilization, denitrification, urea hydrolysis, organic C, N and S mineralization, nitrificationinhibitors and the utilization of fertilizer ammonium and nitrate uptake from soil. Most ofthese ISCW projects were in partnership with the National Chung Hsing University in theRepublic of China and the South African University of the Free State.

• Methodology development to determine low P contents in soil extracts.

• Evaluation of fertilizers e.g. zinckated fertilizers utilization/residue to prevent toxic levels insoils.

• Heavy metal contents in dam water sediment, benthic organisms and soils irrigated.

• Cu, Zn, Mn and Ni leaching.


• The effect of deteriorating water quality on soil.

• Irrigability characteristics of different soils to ensure irrigation effectiveness, to preventcrusting, compaction and erosion and to ensure optimal water utilization.

• Aerobically produced sewage sludge compost utilization, composting of household waste,also using fungi as reactor and the utilization of household waste and household waste waterin low-cost food production. The latter is a multinational project funded by the EuropeanUnion.

• Evaluation of manufactured byproducts as alternative fertilizers.

• Soil biota’s role in the soil nutrient cycle. These include studies and recommendations to theDepartment of Water Affairs and Forestry on the safe utilization of industrial effluents forirrigation and on the dehydrogenase activities and nitrification properties of such effluents.

• Soil fertility monitoring.

• The contribution of P and K to the protein contents of soybeans.

• Evaluation of the effectiveness of agricultural lime sources and methodology development todetermine the lime requirements of acid soils.

• Feasibility and suitability studies in view of viable and sustainable food production as well asarea, regional and national development. Natural resources information systems andalgorithm development to determine aspects like soil potential are fundamental to thesestudies. ISCW also uses a digital terrain model in view of the country’s topography, tosupply information for crop growth (including forests) and climate models. Land use mapsare produced to indicate agricultural classes, open-cast mining, urban areas and surfacewater resources in view of development programmes and monitoring.

• Precision farming systems and farm input.

• Facilitation of workshops with emphasis on problem analyses.

• Project management.

• Rehabilitation of physically disturbed soil (e.g. open-cast mining) and water balance studieson mine dump rehabilitation sites, also in view of the stabilization of slime dam slopes, andthe characterization and production potential of such land.

• Water use efficiency studies including crop water use optimization, water quality - soil-croprelationships, water balance on agricultural and forestry land, irrigation scheduling and low-cost irrigation systems for household food security.

• Training of extensionists, subsistence and community farmers as well as the practical trainingof selected technical students. Selected high technology training e.g. on GIS and land useplanning which was presented to SADC delegates.

• Food security by spatially establishing the extent of cultivated fields and by predicting yield,by ameliorating climate conditions, by changing micro-climate and by modelling.

Soil degradation

Soil organic matter depletion/nitrogen fixation/nitrification inhibitors. Projects are noted undersoil management.

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Soil acidity

• Methodology development and evaluation in view of determining the lime requirements ofsoils.

• Liming materials effectiveness determinations.

• Soil acidity determination, monitoring and training to ameliorate.

• High value research and technology by e.g. the ARC-Grain Crops Institute, Agricultural Co-operatives, tertiary institutions, fertilizer manufacturers and lime producers are not recordedin this report. These can be cited in the 1997 Proceedings of the Soil Acidity Initiative (venueMpumalanga) which can be obtained from either ISCW or the National Department ofAgriculture.

Soil erosion

• Models are evaluated, adapted and used to predict soil loss under different managementpractices and to predict the siltation rate of dams. The latest study, with the University ofPretoria as partner, determined the siltation rate of the Lesotho Highland Water Scheme. Themajor advantage of modelling is that the potential irrigability of an area under specificmanagement practices is assessed which enables the prevention of erosion,

• A spatial (remote sensing) Bare Soil Index was developed to inventory eroded and overgrazedareas as well as rural settlements,

• Remote sensing inventory and monitoring studies including rainfall probabilities; the impactof drought, biomass burning, floods and bush encroachment on agriculture and on theenvironment; land cover which forms part of a southern Africa initiative to establish andmonitor vegetation impoverishment and denudation to supplement land degradation data andto monitor progressive desertification. Indices like the normalized difference vegetation index(NDVI) enables the deduction of the severity and extent of drought,

• Characterization of the irrigability of different soils. Soil pollution/alkalinity/salinity

• Historical, analytical and other data are integrated to monitor salinity on irrigation schemeswhile multi-spectral videography (low level remote sensing) establishes salinity status. Thistechnique is developed in cooperation with the University of the North.

• Irrigation scheduling and the effect of different water qualities on soils.

• Soil reclamation programmes

• Agriculture is both an efficient utilizer and contributor to pollution as listed under soilmanagement projects. Large volumes of organic composted products are being utilized byparticularly vegetable producers. Many composted products contain undesirable bio-available trace elements and micro-nutrients which could accumulate in the soil. Mostsignificant results are that: i) lettuce accumulated the most Co, Cd and Zn, wheat the mostCu, and bean pods the most Ni, ii) higher soil pH, with a few exceptions, decreases theconcentration of trace elements in plants, iii) existing methods like the EPA 3050 does notpredict soil loading. Plant bio-availability of trace elements therefore needs to be re-established and iv) Hg levels in the Loskop Dam catchment are relatively high.


• Background values for health-related elements in South African soils need to be establishedas micro-nutrients and other health-related threshold values determined for other continentsare not suitable for South Africa’s very distinct geology. Values for I and Se were recentlydetermined for the Department of Health to monitor deficient or toxic levels. Initialinvestigations and methodology development were in cooperation with the University of Bonnin Germany and much of the latest work is in cooperation with the Universities of Pretoria inSouth Africa and Ghent in Belgium.

The last paragraph of the Heidelberg Appeal presented to the Heads of State at the

conclusion of the UN Conference on the Environment in Rio de Janeiro, 1992 is quoted: “Thegreatest evils which stalk our Earth are ignorance and oppression and not Science,Technology, and Industry, whose instrument, when adequately managed, are indispensabletools of a future shaped by Humanity, by itself and for itself, in overcoming major problemslike overpopulation, starvation, and worldwide diseases”. SUCCESSFUL CASES OF IMPROVED SOIL MANAGEMENT

Conservation tillage systems have been researched by several institutions over many years inSouth Africa but research application over the long term is limited. The transformation ofconventional to conservation cultivation necessitates a complete change in mind frame,perseverance and goal-directed planning, observation, study and adaption. Such a transformationis not a flash solution. Beukes (1992), selected an experimental site previously under ley grass toestablish a cultivation trial with grain sorghum. Cultivation practices were no-till and tine till withand without stubble removed and a conventional mouldboard/disc tillage system with stubbleretained. The study, over a period of six years, indicated that the no-till and tine systems retainingmost of the stubble on the soil surface resulted in an increase in aggregate stability as well as soilC and N. The conventional mouldboard/disc system, despite stubble retainment, did no betterthan the no-till and tine systems with stubble removed. Statistical analyses showed that apartfrom cation exchange capacity (CEC), aggregate stability is determined primarily by the C/Nvalue of the soil. The following example of a long-term conservation tillage system in practice,substantiates Beukes’ (1992) findings and those of other researchers. Mr A Muirhead, farming inthe Drakensberg area near Winterton in the northern KwaZulu-Natal Province, adopted aconservation tillage system 20 years ago. This system comprises minimum till, stubble mulchingand crop rotation with an animal factor. Maize yield over the past two seasons was 5 t ha-1 fordryland and 9 t ha-1under irrigation. Major success factors, according to Mr Muirhead (Pretorius,1997) are meticulous optimal and betimes weed control programmes, crop rotation (maize andsoybeans in Mr Muirhead’s case) to control disease cycles and most important, that all cropresidue must stay on the land. The following major advantages culminated from Mr Muirhead’slong term sustainable soil management and cultivation practices:

• Soil related. The cycle creates a soil top-layer rich in soil biota and humus. Soil biotaincrease the decay of stubble and maize residue. Humus increases water penetration and thefarmer had no runoff the last couple of years while moisture is conserved for planting. Thestubble furthermore ameliorates the impact of raindrops and retains water. Soils inclined tobecome waterlogged, recover very soon.

• Financial. This system has the lowest cultivation energy requirement of all cultivationpractices and the highest saving in capital investment for farming machinery. Furthermore, as

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less weed grows in a well managed conservation cultivation system, less weedicide is usedover the long term.

Provisa for a successful conservation cultivation are:

• a very high level of soil management,

• continuous and goal-directed planning, observation, study and adaptations. Time planning,particularly in view of weeding programmes is critical. Fields should be free of weeds,

• fertilization programmes in strict accordance with soil analysis and plant food requirements.Soils and not fields are fertilized,

• annual liming (2 t ha-1 in Mr Muirhead’s case) as soil acidity must be prevented,

• rectifying subsoil acidity in the initial phase of the cycle,

• that all crop residue must stay on the land. Fine materials are utilized by farm animals onlyuntil the first rain. Thereafter animals are withdrawn to prevent soil compaction. For thesame reason, vehicle traffic is restricted and the tyres of cultivation machinery are kept flat.Stubble must cover at least 30 percent of the soil if conservation cultivation is to be effective.

In the 1997 season, this farmer is bringing a further area under vegetation into conservation

tillage production. Although data such as organic matter content is unknown, it is obvious that thisconservation tillage system followed for two decades is an example of improved soil managementconducive to the sustainable utilization of soil, increased soil productivity and the prevention ofmany different forms of soil degradation. INSTITUTIONAL FRAMEWORK AND POLICIES FOR LAND RESOURCES MANAGEMENT

South Africa has been confronted by significant political, economic and social changes over thepast four years. Policy changes in 1994 with emphasis on the adoption of the Reconstruction andDevelopment Programme (RDP) by the Government of National Unity (GNU), meant thatdifferent government departments had to redefine their roles and objectives in line with the RDPframework (Molope, 1997). The RDP framework is cohesive and ensures focus by governmentdepartments on GNU goals. The process of policy formulation in the post-election years wascharacterized by the release of a number of documents setting out the vision and strategies of thenew government. Building on the RDP, the National Growth and Development Strategy (NGDS)was released early in 1996 and later in the year, the framework for Growth, Employment andRedistribution (GEAR) was adopted. The NGDS and GEAR strategies are aimed at building theeconomy to higher levels of growth, development, employment and equity (Molope, 1997).Government custodianship for the natural resources rests primary with the National Departmentof Agriculture (NDA), the Department of Land Affairs, the Department of Environmental Affairsand Tourism, and the Department of Water Affairs and Forestry. The Department of Arts,Culture, Science and Technology is also concerned as the eight parastatal Research Councils areunder its jurisdiction. The Agricultural Research Council (ARC) established in 1992 is one ofthese Councils. ISCW is one of the 15 ARC Institutes. ARC staff, prior to 1992, were theresearchers of the Department of Agriculture. The role of national government departmentsdirectly concerned with agriculture are discussed briefly:


National Department of Agriculture (NDA). Prior to 1993, agricultural institutions in theRepublic of South Africa were separated according to race. Following the election of the GNU,the former 10 self-governing and TBVC areas were incorporated in South Africa’s land area andall government institutions amalgamated under the authority of NDA. Nine Provinces weredelineated and nine Provincial Departments of Agriculture were established as per constitution.Against the background of the RDP, NDA’s aims are to “ensure equitable access to agricultureand to promote the contribution of agriculture to the development of all communities, society atlarge and the national economy to enhance income, food security, employment and the quality oflife in a sustainable manner”. Department of Land Affairs (DLA). In South Africa, as in many countries in the world, land hasalways been a sensitive issue and the former dispensation has left a complex and difficult legacy.The mandate of DLA within the RDP is to address the legacy of apartheid in relation to landdistribution and to create security of tenure and certainty in relation to rights in land for all SouthAfricans. The three parts of government’s land reform programme constitute land restitution,land distribution and land tenure reform including farm equity schemes, also redressing currentimbalances against women (Dept. Land Affairs, 1996). These two national departments and the other directly concerned with the natural resource base,work closely together. Socio-economics issues

South Africa faces a future of divergent possibilities. Population pressure on land is the majorcomponent in the cycle of unsustainability but if the country can succeed in conserving thenatural resource base in the face of continued land pressure, a win-win situation is possible.South Africa is characterized by a mosaic of people with different cultures, lifestyles and eatinghabits. Furthermore, there is a dualism of Third World and First World, particularly inagriculture with tribal and communal forces on the one and well-established commercial farmerson the other hand. In tribal and communal societies, women are the major farmers. The socialenvironment is characterized by urbanization and demographic changes due to, inter alia,population growth, economical conditions and persistent drought. Social changes are indisputablya major threat to our limited natural resources soil, particularly high potential agricultural soil,and water. Poorer people constitute the vast majority of the population and there is a decided needfor development assistance to promote the six NGDS core pillars namely investing in people,creating employment, investing in household and economic infrastructure, crime prevention,poverty alleviation and the creation of safety nets, and transforming institutions of governance.Poverty alleviation should reduce pressure on the environment in meeting short-run subsistenceneeds. The main causes of rural environmental degradation are fuelwood collection, artificiallyconcentrated population densities especially in the former homelands, which exacerbates povertyand denied access to resources, inappropriate land use and much deforestation. Soil losses stemfrom the conversion to inappropriate land use and overgrazing (Goodland, 1995). Direct interventions to reduce inequality, to alleviate poverty directly, and to accelerateenvironmental sustainability are essential. South Africa’s income inequality is probably the worstin the world (Goodland, 1995) where a full half falls below the generally accepted poverty lineand a conservative 20-40 percent of South Africans are unemployed. These selected factorsexplain why stability in general is so important for South Africa. Stability will secure prudentresource balance and equity as well as security for an investment climate (Goodland, 1995).

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South Africa’s economic growth and development does not rate it a world top. Population growthrate is higher than that of GDP and the standard of living is declining. With structural changesfavouring health, housing and education, there is a decline in capital available for research andtechnology development which could jeopardize critical development projects to create wealth.“Sustainable soil management in agriculture is the use of soils for the production of agriculturalgoods - to meet changing human needs - while assuring long-term socio-economic and ecologicalsoil functions” (SDC, 1994). SDC (1994) established the following socio-economic indicators forthe maintenance and enhancement of soil functions which developing countries should take noteof :

• maintenance or enhancement of values which embody a sustainability perspective in ruralsocieties who see the role of soil as an essential part of heritage,

• complementarity with land use patterns,

• maintenance or increase of physical or monetary agricultural production. As discussed earlier, land tenure and tribal community farmers, have little incentive to crossthe subsistence bridge and extensionists have little success as behavioural change is only possibleonce basic human needs are fulfilled. Furthermore, as these people lack financial security, they donot have easy access to loans. Soil improvement plans and the reclamation of degraded land istherefore largely without reach should the necessary assistance not be provided and shoulddemonstration plots not be established to convince people of benefits to be reaped. ISCW wassuccessful with such a project within a squatter camp (Stanza Bopape) near Pretoria.Demonstration trials and training of selected community leaders made household food security areality without degrading the soil. This multi-institutional project has the full participation of thecommunity and is managed by the community. The Stanza Bopape project is regarded as rolemodel. Policy issues

Legislative responsibility for the natural resource base is not well-defined between thegovernment departments of Environmental Affairs and Agriculture in South Africa, despitedifferent mandates. This seriously jeopardizes much needed natural resources monitoring andauditing to ensure sustainability and to a certain extent, sustainable development in less developedareas as priorities differ and as government finances are restricted. The objective of mostdeveloping countries has been rapid industrialization to create employment and wealth. This hasled, according to SDC (1994) to a macro-economic mix and agricultural policies of taxes onexport products which lower real income of farmers and hence their capacity to invest in soilmaintenance. This, to a large extent is also true for South Africa but with an aggravating factorin view of soil maintenance, namely droughts which are detrimental to cash flow. In the newdemocratic South Africa, transparency, consultation and participation are on the forefront when itcomes to policy development. The 1995 White Paper for Agriculture sets out a broad new vision for agricultural policyframework that is roughly consistent with the spirit of the new dispensation and the RDP.Agricultural policy formulation is complex because of the proliferation of institutions involved.Following the election of the GNU, former agricultural institutions amalgamated under theauspices of NDA and there are nine Provincial Departments of Agriculture as per constitution.Amalgamation also included the agricultural institutions in former homelands. Policy formulation


also involves the broader sector as much as possible. Agricultural policy themes presentlyconsidered by various working groups are:

• sustainable resources utilization with emphasis on incentives e.g. soil conservation worksversus incentives for farmers to utilize land more effectively and sustainable. The FAOdefinition of sustainable development and criteria for sustainable agriculture and ruraldevelopment (SARD) are used as basis (Molope, 1997),

• food security focusing on household security,

• trade, to consider the advantages and disadvantages of different trade regimes for variousagricultural sub-sectors within the context of GATT, SACU and SADC,

• drought and disaster management focusing on guidelines for distinguishing natural disasterfrom normal risk situations. In the past, interventions on drought and disaster were reactiveand poorly rationalized,

• cooperatives, to determine how to support the establishment of new cooperatives to meet theneeds of emerging and disadvantaged farmers,

• credit and finance, to carry forth the terms of reference of the Commission of Enquiry into theProvision of Rural Financial Services,

• farmer support services, which can be divided into human resource development, researchand extension,

• rural tenure system. The Interim Protection Act lapses by the end of 1997 by which time farreaching and long term measures should be in place, including a tenure security law.

Environmental, political, social and economic issues are inextricably connected and fullcognizance is taken of these interaction in framing agricultural policy. NDA correctly believesthat the responsibility for achieving sustainable natural resource utilization should be underpinnedby the ethic of caring and must be shared by all sectors of South African Society (Molope, 1997).These include central and national governments, local authorities, organized labour, commerceand industry, community groups, civic associations, families and individuals. PROPOSALS OF PROGRAMMES FOR IMPROVED SOIL MANAGEMENT AND PRODUCTIVITYENHANCING

Two programmes are proposed by South Africa within the framework Integrated SoilManagement for Sustainable Agriculture and Food Security in Southern and East Africa. Thefirst programme, on organic matter depletion, is aimed at realizing the soil potential in formerSouth African homelands in view of sustainable rural development, job and wealth creation, foodsecurity and sustainable soil productivity. The second programme, also aimed at developing ruralareas, concerns the development of a land information system with soil fertility and erosion asmain criteria. Such a system is a basic requirement for sustainable land use planning and rapidbut non-destructive agricultural development. Both programmes are multidisciplinary and cross-sectoral.

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Project 1. Realization of Soil Potential: a Recipe for Rural Development in the FormerHomelands

Soil acidity is a major factor limiting agricultural production in South Africa. Naturally acidsoils, normally associated with areas of high rainfall, occur over a diverse spectrum of climaticconditions and have been identified in the Northern Province with an average annual rainfall fromas low as 500 mm, as well as in the Mpumalanga, KwaZulu- Natal, Eastern and Western CapeProvinces where average annual rainfall is over 750mm. In the communal agricultural areas ofSouth Africa (former homelands), with a surface area of approximately 10 million ha, rainfalland rainfall pattern should favour crop, horticultural and livestock production and development,as well as pasture production. Pasture production could furthermore be upgraded significantly byintroducing legumes which would contribute substantially to sustainable agro-ecosystems. Approximately 3 million of the 10 million ha is potentially arable land. The major portion ofmedium to high agricultural potential land is found in the former Ciskei, KwaZulu and Transkeiareas. These three areas with roughly 1.2 million ha high potential land are blessed with a meanannual rainfall exceeding 700 mm. However agricultural production potential is seriouslyjeopardized by excessive soil acidity. Soil pH favourable for agricultural production shouldideally be 6.5 while this area is characterized by a pH of 4.5 and even lower (100 times more acidthan ideal). In 1990, population density was estimated as 153 persons per square kilometre inKwaZulu, 69 in the Transkei and 97 in the Ciskei compared to an average of 25 in the formerRepublic of South Africa. This emphasizes the urgent need for economic development in theformer homeland areas, in which agriculture could provide the driving force for development.Extreme rural poverty in these areas has prevented such development being initiated locally.Strong government support for such development is essential. In terms of the Constitution theNational Department of Agriculture is the custodian of these yet undeveloped natural resources.In view of the agricultural potential, surface area and population density in the former Ciskei,KwaZulu and Transkei, this document focuses on these areas without disregarding theimportance of the other former homelands. Technology and norms exist to facilitate the amelioration of soil acidity to pH levelsfavourable to optimum crop and pasture yields. A pH of 6.5 is optimal for macro and micro-nutrient uptake, nitrogen fixation, soil microbial activity and the like, all essential for sustainableproduction, optimal yields, and vegetation cover. For example, changing the pH from 4.5 to 6.5will increase maize yields from ½ to 8 tons per ha on high potential soils. In the areas of highpotential (60%) of the former Ciskei and Transkei, potential income from maize production couldescalate from R300 to R4 800 per ha. Acid soils are extremely susceptible to water erosion as aresult of crust formation. This partially explains the high levels of land degradation in formerhomeland areas. Soil acidity and unsustainable land use practices are the major causes ofdesertification. Proposal

The amelioration of yield-limiting soil acidity in former homeland areas by the large scale limingof soils with agricultural potential is proposed. The introduction of legumes as nitrogen suppliersas well as practices to sustain and increase the soils organic matter contents, are fundamental tothe success of this project. This will make it possible for the agricultural production potential ofsuch areas to be realized which will subsequently stimulate agricultural development, theestablishment of small, medium and micro-enterprises, wealth creation and employment by meansof the following:


• the emergence of productive, commercially viable and sustainable smaller scale farmenterprises,

• the exploitation of existing lime deposits in the affected areas by local black entrepreneurs,with concomitant job creation. This would substantially reduce the cost of lime in such areaswhile retaining money in the local economy,

• the creation of transport enterprises to move lime to the areas where it is required,

• the creation of enterprises to spread and incorporate lime on arable soils,

• the distribution of lime on high potential arable land as well as lower potential rangeland soilssuitable for the introduction of pasture legumes,

• seed supply and eventually production to upgrade rangeland,

• the development of storage and marketing infrastructure for increased crop, horticulture andlivestock production (and eventually exports),

• agri-business development (value adding).

In order to optimally utilize the increase in production potential due to liming the followingservices will have to be put into place by resuscitating Provincial laboratories (e.g. Umtata) aswell as the provision of targeted training services to empower people:

• soil analytical services to establish liming and other nutritional requirements on a locality/soilspecific basis,

• extension services to provide the knowledge/expertise base to enable communal and tribalfarmers to optimally utilize the newly created opportunities,

• small business training for the newly established entrepreneurs,

• planning of programmed infrastructure improvement,

• creation of local fertilizer and micro-nutrient distribution enterprises. Among the many advantages to be derived from this project will be:

• rapid and visible economic development within all affected areas,

• a highly significant increase in entrepreneurial and employment opportunities andestablishment of agri-business (SMMEs),

• significant improvement in community health through improved nutrition and elimination ofthe endemic animal and human health problems associated with soil acidity e.g. micro-nutrient deficiencies and toxicities and the association thereof with aspects such as highincidence of oesophageal cancer in humans and general debilitation of livestock,

• improved rural infrastructure and the effective usage of presently under-utilized assets suchas the existing rail system for lime, fertilizer and product distribution and irrigation systemsat present in disuse,

• a sound basis for an agriculture based regional development programme in which theOutreach Programmes of Resource Centres can be optimally deployed.

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Synopsis of Project

The Realization of Soil Potential programme will have a radical and sustainable beneficial effecton agricultural production in presently depressed areas. This radical effect will cascade down intoall those peripheral areas involved in supplying inputs, processing and marketing outputs andcreating and maintaining appropriate infrastructure. The effect on job creation, economicdevelopment, food insecurity, environmental sustainability etc. will be greater than that of anyexisting development project, including the very successful “Working for Water” programme. Anestimate of the area of high and medium potential arable soil in the former Ciskei, KwaZulu andTranskei to be brought into effective production is 1.2 million ha. A 16 fold increased maizeproduction will introduce R5 760 million into the rural economy, utilizing maize as aconservative criterion of increased production. Higher value crops will gradually be introduced,thus increasing the agriculture derived benefits. This area is especially suitable for citrus,vegetables, grapes and other temperate crops with export potential. The introduction of appropriate pasture legumes on more marginal areas would alsosignificantly improve carrying capacity and animal production and will confer similar benefits onthose communities largely dependent on outputs from such areas. Export orientated productionwill serve as a catalyst for port and transport infrastructure development. The lime required forthe amelioration of soil acidity in the Ciskei, KwaZulu and Transkei areas will be approximately2.4 million tons (2 tons per hectare) per year, spread over 5 years. Maintenance requirementsafter that period will be 0.6 million tons per annum. The cost of the liming exercise, based onpresent commercial costing (R150 per ton, including transport, spreading and incorporation) willbe R360 million for five years or R72 million per annum, and thereafter R90 million per annum.The development of local lime sources will stimulate local developments and job creation. Shouldmedium potential land (40%) be excluded from the liming programme, the cost of liming, spreadover 5 years would be R216 million for the 720 000 ha high potential land followed by R54million per annum for maintenance applications. In ensuring that the benefits of liming are effectively utilized, the provincial departments ofagriculture together with the NDA, the ARC and other relevant organizations, will have to ensurethat :

• financial support services are available to small farmers for fertilizer, seed and implementrequirements,

• service infrastructures such as processing, storage and marketing are brought into place,

• technology transfer mechanisms to extensionists and from them to farmers and others areeffectively put into place,

• support to SMME entrepreneurs in terms of finance and training are available,

• local and provincial development plans are developed in concert with the deployment of theRealization of Soil Potential programme,

• problems related to the apportionment of land use are timeously addressed. The successful implementation of the programme will require the following, amongst others:

• the development of an integrated project proposal by the NDA and ARC, in concert withPDAs, locally based universities and other possible stakeholders, for submission tointernational donor agencies and national sources of development funding,


• detailed soil mapping,

• Mapping of lime deposits and computation of reserves,

• computation of lime and nutrient requirements per soil type per locality and mapping thereof

• delineation of areas to be limed and prioritization thereof

• planning of liming and fertilization operations, annual programmes, dumping points, jobcreation requirements, etc.,

• determination of optimal crop production and pasture improvement options and mappingthereof

• appointment of area project managers to co-ordinate distribution and incorporation of limeand the integration thereof with existing and improved production systems,

• establishment of centres where recommended options can be demonstrated on an ongoingbasis. Such centres can be bases from which training and other technology transfer exercisescan be launched.

Recommendation

In order to present a project or programme proposal capable of drawing international andnational funding the following is proposed:

• That NDA commissions the ARC to draft a detailed proposal in which the benefits in termsof development, poverty alleviation, job creation, long term sustainability, etc., the steps to befollowed and the financial and human resources to be employed are clearly set out. The ARC,with the support of the NDA, will liaise with PDAs and others in order to ensure that thefinal proposal is acceptable to stakeholders.

• The NDA will endorse the final proposal when it is satisfied with it and facilitate theaccessing of the necessary funding.

• When funds enabling the initiation of the programme have been committed, a Project SteeringCommittee (PSC) on which the NDA, ARC and PDAs are represented, together with otherswho can make a significant contribution, will be appointed.

• The PSC will appoint a National Project Manager who will be supported by Area ProjectManagers and Area Project Committees.

• The project will be implemented by starting with any necessary refinement of resourceinformation, detailed integrated planning per reasonably homogeneous area, initiation of limeproduction and finally, leading into the introduction of improved crop production systems andpastures.

Project 2. The Development of a Land Information System for Developing Areas withErosion Risk and Soil Fertility as Main Criteria

The 10 former homelands of South Africa are characterized by high population growth, poverty,accelerated soil degradation, increasing pressure on land, an attitude not conducive to sustainablesoil management, and the lack of incentives and means to practice sustainable soil managementwithin tribal, communal or land tenure systems. Most of the former homeland areas have mediumto high agricultural potential which needs to be developed in view of food security and wealthcreation. To facilitate sustainable land use planning and rapid agricultural development in

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harmony with soil potential and to enable the improvement and maintenance of soil productivity,the development of a land information system is a basic requirement. Much and various types ofdata and statistics are available but is to no avail if not manifested in sustainable soil productivityand the subsequent prevention of soil degradation. The human factor is critical in the manifestation process, particularly in the formerhomelands, where tribal culture differs vastly for that of the western world. South Africa’s highlycomplex mantle is most vulnerable to the loss of productivity and soil degradation of all forms.Soil erosion is a particular threat to soil productivity and the organic carbon contents is rapidlydeclining throughout most of the country. A pilot study in the Nsikazi development area (8,000ha) of the former KaNgawane to establish areas suitable for crop production, revealed that theorganic matter contents has declined seriously, that P is seriously deficient and that the area ishighly susceptible to gully erosion and moderately to sheet and rill erosion. The fairly deep sandysoils have a low clay contents on granite bedded material, and the annual rainfall is 680 mmwhich implicates at least medium to high agricultural potential. The area is characterized bycommunal farming, mainly with cattle while the major crop cultivated is maize. Maize productionis sub-optimal. Remote sensing techniques (satellite imagery), supplemented by field work, wasused to determine the status of this pilot area. Existing natural resources data was used as themajor source of ground truth. The pilot study re-emphasized the desperate need for a landinformation system (LIS) which will enable rapid but sustainable development and optimalagricultural production.

Proposal

Rapid but sustainable agricultural development in the former homelands is essential to halt thedownward spiral of the poverty trap and to ensure sustainable socio-economic growth in SouthAfrica. The primary objective of this programme is to develop a digital LIS for developing areasin view of land suitability and soil productivity assessments to facilitate sustainable development.Immediate aims are to:

• determine the current status of natural resources (degradation, soil-water and nutrient status)by means of remote sensing data and field verification,

• determine the social and economical factors influencing land use planning in the district,

• determine the use of digital terrain data (DTD) in soil mapping (refining of land type data)and soil loss modelling,

• use GIS based erosion models (adapted for developing areas) in predicting erosion risk,

• determine and quantify soil nutrient status and balances,

• use land evaluation models and techniques e.g. CYSLAMB and ALES for land suitabilityratings (development of settlements, crop production and grazing),

• develop and implement an integrated GIS based Land Information System at a 1:50 000scale.

Research activities

• A pilot study area of approximately 30 000 ha will be selected in the developing areas ofSouth Africa.


• The study will be initiated by Provincial contact with those involved in land use planning,GIS and extension. Contact will then be expanded to communities concerned. This will bepreceded by contact with the National Department of Agriculture and the Department ofLand Affairs.

• The initial phase will also be used to determine what relevant information/data is available, toevaluate the data/information, and to investigate compatibility with ISCW’s national naturalresources systems.

• The current status of the natural resources soil and vegetation will be determined by means ofLandsat TM and SPOT satellite data. This type of data proved to be a valuable source ofland use information for GIS. On-screen digitizing methods will be used to extract theinformation from the satellite data. Verification of results will include ground and aerialsurveillance.

• Close collaboration with agricultural extension and headmen will be necessary to determinethe social and economical factors that must be taken into account in developing practical andfeasible land use strategies. This information will be integrated into the GIS.

• Digital terrain data (DTD) at various resolutions will be used to create digital terrain models(DTM). The DTMs will then be used to produce digital terrain unit maps (DTUM).Integration of DTUM and available land type information to produce soil maps, that can beused in soil loss and land evaluation models, will be investigated. This is a very importantpart of the project since land use planning strategies are not viable without reliable soilinformation and semi-detailed soil maps are not always available for developing areas.

• Erosion risk areas will be determined by means of a GIS based erosion model adapted toconditions in developing areas. The following information will be integrated into the model: i)soil erodibility (land type, geology, DTM and field trails), ii) slope angle (DTM), iii) slopelength (DTM), iv) rainfall erosivity (ISCW AgroMet database) and various other terrainmorphological parameters.

Integration of erosion risk data with current land use and land management information(remote sensing data) will give an indication of actual erosion or soil loss. The most challengingpart of this phase will be the production of a soil erodibility map. This will include rainfallsimulation trials on different soils (ecotopes) under different land use practices:

• determine soil-water balances for different ecotopes as a function of land use (crop andforage production) practices,

• determine and quantify soil nutrient status and balances of the area. Soil and plant sampleswill be collected and analysed (physical and chemical). This information will also be used inthe production of a soil suitability map with the risk of soil degradation, soil fertility and soil-water status as main criteria. Inputs and removal of nutrients from the area will be quantified,

• the following step in the project will be to integrate relevant information into a landevaluation model. Different land use scenarios will be evaluated. During this stage experts incrop production and grazing will be consulted,

• the final step will be to develop and implement an operational GIS based Land InformationSystem. This system will have to be user friendly and easily accessible for updatingpurposes. Training of Provincial land use planning and extension staff will form an importantpart of this stage.

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Products planned

• Recommendations on the required data inputs (soils, terrain, climate, social and economicalindices) for land use planning at a 1:50 000 scale,

• Practical, scientifically based and verified: i) status of the natural resources, ii) soildegradation management,, iii) soil-water and nutrient resources and iv) crop production,

• A user friendly GIS based Land Use Planning Decision Support System,

• Although the system will be developed for decision makers at district level, small scalefarmers will benefit from this project in the sense that the restrictions they have to deal withwill be revealed. Improved farming systems can then be introduced by extensionists throughactive involvement of the community.

Duration of pilot project

18 months

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Sielaff, C., 1997. World food demand and supply by 2025. Paper presented at Value-added AgricultureCongr. Oct. 1997, Pretoria.

Skeen, J.B., 1997. President’s Report. Fert. Soc. S.Afr. J. 3-10.

Smith, D.J.C., Van Rooyen, G.I., Geldenhuyis, I.S., Vosloo, W.A. & Le Roux, P.A.L., 1990. Verslagvan die komitee vir die ontwikkeling van ‘n voedsel- en voedingstrategie vir suidelike Afrika.Sentrale Owerh.

Spurling, A., Poe, T.Y., Mkamango, G. & Nkwanyama, C., 1992. Executive Summary. Agriculturalresearch in Southern Africa. A framework for action. World Bank Discussion Papers. Afr. Tech.Dept. Series No. 184. The World Bank.

Strydom, B.W. & Wassermann, V.D., 1984. Huidige en potensiële bydraes deur biologiesestikstofbindingsisteme tot die Suid-Afrikaanse landbou. Proc. Nitrogen Symp., Tech. Commun. No.187, 80-86. Govern. Printer Pretoria.

Tanner, P.D., 1997. Soil acidity and the mining industry. Proc. Soil Acidity Initiative (venueMpumalanga). Ermelo. In Press.

Thirtle, C., & Van Zyl, J., 1993. Explaining total factor productivity growth and returns to research andextension in South African commercial agriculture, 1947-91. Research project report, Univ.Pretoria.

Van der Merwe, A.J., 1992. Die vermoë van ons grondhulpbronne om aan toekomstigevoedselvoorsieningsbehoeftes te voldoen. Paper presented at South African Agricultural UnionAGRICON Congress, Pretoria.

Van der Merwe, A.J., 1994. Agricultural productivity and the challenge of food security. Paperpresented at SAFFOT Conf., Cape Town.

Van der Merwe, A.J., 1995. Wise land use: the basis for sustainable growth and development in SouthAfrica. Proc. ARC-ISCW Wise Land Use Symp. 2-8. ARC-ISCW.

Van Marle, J., 1981. Resources for agricultural development in Southern Africa. Fert. Soc. S.Afr. J. 2,17-22.

Von Uexkull, H.R. & Mutert, E., 1995. Global extent, development and impact of acid soils. In R.A.Date, N.J. Gudon, G.E. Rayment & M.E. Probert (eds). Plant-soil interactions at low pH: principlesand management 5 - 19. Kluwer Academic Publishers, The Netherlands.

Veerhoff, M. & Brummer, G.W., 1993. Formation of poorly crystalized weathering products in stronglyto extremely acid forest soils. Z. Pflanzenernähr. Bodenk. 156, 11-17.


Tanzania


The population of Tanzania is expected to reach 100 million in the second half of the twenty-firstcentury. In 1982, the population was 19.1 million; in 1989 the population was 23.0 million and islikely to reach 39.1 million in the year 2000 and 83.8 million in the year 2025. In the year 1980,the rural population in Tanzania represented 87% of the total population, in 1989 it was 80% andin 2010 it is expected to be 65% and by the year 2025 it is expected to decrease to 55%. The totaldemand for food and non-food commodities in Tanzania and in the region is expected to haveincreased by more than three and half times by the year 2025. Although the proportion of therural population is likely to decrease to 55% by that time, the absolute size of the rural populationis expected to increase from 10.5 million in 1989 to 46.1 million which is more than four-foldincrease (Table 1). Available information on land use patterns in Tanzania shows that Tanzaniais diverse and each region has its own unique mix of crops and animals. Many of the crops grownhave a national spread while others are confined to certain regions (Tables 2, 3, 4 and 5).

TABLE 1Potential rainfed population supporting capacity at different input level and populationprojections of 20 regions

Regions Landarea

(000 ha)

Cultivablearea

(000 ha)

Potential populationsupporting capacity

Population(million)

Low Interm. High 1989 2000 2025 plateauArushaCoastDar es SalaamDodomaIringaKageraKigomaKilimanjaroLindiMaraMbeyaMorogoroMtwaraMwanzaRukwaRuvumaShinyangaSingidaTaboraTangaTotal

8 2313 241139

4 1315 6862 8393 7041 3316 6051 9576 0357 0801 6711 9596 8646 3505 0784 9347 6152 681

88 129

1 1041 049

32410

3 0301 5091 878233

2 820346

2 6784 713892973

4 3215 2181 3626 0052426851

36 600

1.051.000.030.392.881.431.780.222.680.332.544.470.850.924.104.951.290.572.300.8134.60

4.354.140.131.62

11.945.957.400.92

11.181.36

10.5618.583.523.84

17.0320.575.372.389.573.35

143.70

15.1614.400.445.63

41.5920.7125.783.20

38.714.75

36.7664.7012.2527.8659.3271.6318.708.30

33.3111.68500.4

1.390.661.401.271.241.360.881.140.661.001.521.260.911.900.710.801.820.811.061.31

23.13

2.351.122.372.152.102.301.491.931.121.692.572.131.543.211.201.353.081.371.792.22

39.13

5.032.405.084.604.504.923.194.132.403.625.504.563.306.872.572.896.602.933.834.75

83.80

6.002.866.065.495.375.883.814.932.864.326.575.443.938.203.073.457.873.504.575.67

100.0Source: Planning and Marketing Division

S. Nyaki, Senior Scientific Officer, National Soil Service, TangaA.L. Mawenya, Project Manager, Scapa

Tanzania296

TABLE 2Area (000 ha) under food crops in 1988/89

Regions Maize Millet Paddy Bean Bananas Cassava Sw/Pots TotalArushaCoastDar Es SalaamDodomaIringaKageraKigomaKilimanjaroLindiMaraMbeyaMorogoroMtwaraMwanzaRukwaRuvumaShinyangaSingidaTaboraTangaTotal

155.213.91.8

60.2266.966.949.747.319.225.0

168.1125.445.5

122.086.8

138.7298.252.6

146.090.4

1,980

47.18.60.1

194.023.87.71.76.6

26.239.724.830.954.957.248.87.3

124.394.542.20.6

841.2

1.320.73.00.40.83.46.93.8

10.51.5

32.564.027.561.515.224.679.51.4

37.26.7

402.4

53.53.20.26.8

53.870.725.922.613.13.2

46.213.714.347.644.722.386.76.0

31.17.3

572.9

11.22.62.00.5

127.65.7

47.5

5.326.94.9

1.70.60.4

12.9249.8

1.636.55.50.90.5

85.014.75.6

29.942.913.932.389.9

144.836.853.254.336.326.436.7

746.9

1.20.51.23.04.4

11.20.80.6

12.415.40.50.2

55.38.00.6

66.76.6

17.40.2

206.1

311.186.013.8

265.9357.7372.5105.4134.198.9

129.2328.0271.7232.2490.1241.0709.7197.4300.3155.0

5,047.0Source: National Food Security Unit

TABLE 3Estimated production (000 tones maize equivalent) of food crops in 1988/89

Regions Maize Millet Paddy Beans Wheat Pineapple CassavaArushaCoastDar Es SalaamDodomaIringaKageraKigomaKilimanjaroLindiMaraMbeyaMorogoroMtwaraMwanzaRukwaRuvumaShinyangaSingidaTaboraTangaTotal Food

304.719.10.972.0

444.793.771.785.924.228.5

267.4185.561.5

143.1160.1264.5444.166.2

246.0141.6

3 125.5

53.17.80.0

150.919.96.91.19.927.126.827.133.057.137.658.36.9

111.0112.446.20.7

803.8

2.91.91.90.30.83.11.39.26.91.439.461.026.885.320.520.1

112.10.530.18.0

833.4

52.42.70.03.846.362.425.520.610.91.840.38.214.538.345.819.388.74.727.09.2

522.5

73.50.00.00.08.30.00.00.00.00.00.20.00.00.00.10.00.00.00.00.082.1

30.87.20.00.20.0

351.615.8130.90.0

14.574.213.50.04.81.51.00.00.00.0

35.5682.6

3.376.716.32.01.1

178.530.911.962.988.429.267.9

188.8304.977.2

111.7113.976.355.577.0

1 573.5Source: National Food Security Unit

Therefore, the vast agro-ecological resource base is well reflected in the current land use patterns(Table 6). Sixty-four agro-ecological zones have been identified for the whole country based on ascale of 1:2 000 000. The main criterion used in the zoning is the temperature and moistureregime during the growing period. The dependable growing period varies from less than 2 monthsto 8 - 10 months. The main agro-ecological zones along with the associated farming systems inthe northern zone of Tanzania are shown in Table 6.


TABLE 4National aggregate food production (000 tonnes)

Year Maize Paddy Wheat SorghumMillets

Pulse Cassava Potatoes Bananas

1980/81 1 939 200 90 705 310 1 458 n.a. n.a.*1982/83 1 651 350 58 793 297 1 967 n.a. n.a.1984/85 2 093 427 83 1 024 510 2 052 n.a. 7741986/87 2 359 644 72 954 251 1 709 336 7921988/89 3 125 720 97 804 385 1 948 337 7431990/91 2 332 624 84 750 425 1 566 291 7501992/93 2 282 641 59 929 406 1 708 260 8001994/95 2 567 723 73 1 250 378 1 492 451 6511996/97 1 831 550 78 845 374 1 528 372 411

Source : MAC-FSD * Data not available

TABLE 5Total land suitability for grazing, land used for grazing, area infested with tsetse and distributionof animal population in 1984

Animal populationRegion Land fit forgrazing

Land used forgrazing

Land infestedwith tsetse Cattle Sheep Goats

ArushaCoastDar es SalaamDodomaIringaKageraKigomaKilimanjaroLindiMaraMbeyaMorogoroMtwaraMwanzaRukwaRuvumaShinyangaSingidaTaboraTangaTotal

12 225567nil

3 1343 689628

1 510418

2 3228 6362 0951 644398413

2 6221 8003 9912 327

281 579

50 036

11 000144nil

1 9222 45932430537782

3 4551 271303370380152246

1 3861 416

3489

26 084

1 803302nil

934

17760365

1 00932

8892 305175108337187

1 0541 776278

1 18412 864

1 855886

1 00048036562

4086

97090133315

1 35739239

9401 882926473

12 500

75851

170925436

2219

2161015315

2502120

487280174117

3 080

1 2311910

54019734416743813

39417114085

57075

138477472310258

6 450 Source : Planning and Marketing Division, MALD

Important food crops grown are maize, millet, rice, sorghum, wheat, beans sweet potato,cassava banana and plantain. In 1988/89, the total cultivated area for these crops was just over 5million ha and the total production (in maize equivalent) was 7.5 million tons. The total estimatedconsumption of food (in maize equivalent) was 5.9 million tons that represented a surplus ofapproximately 1.6 million tons. Other important crops are oil seed crops and nuts (groundnuts,sesame, soybean sunflower, and coconuts) cotton, tobacco, coffee, tea, cashew, sugarcane,pyrethrum and sisal. The total area under these crops in 1988/89 was 1.3 million ha. There areapproximately 50 million ha suitable for grazing of which 26 million ha are currently beenutilized and 12.9 million ha are infested with tsetse (Table 5). In qualitative terms one cananticipate that agricultural production will become more intensive on favorable soils in order tomeet market demand. It is also anticipated that as the yield of staple food crops increase the areaneeded for their cultivation will decrease. The remaining areas are likely going to be used for theproduction of vegetables and fruits.

Tanzania298

TABLE 6Farming systems zoning for the Northern Zone of Tanzania and Kondoa District

Farming system Crops grownFs

ZoneName

Agro-ecological

ZoneMajor Minor

N-2B Intermediate dry lowlands;maize legumes

E2 Maize, Beans pigeonpeas and sunflower

Sorghum, finger millet andcassava

N-2C1 Intermediate lowlands;maize beans tree crops

E1 Maize, beans rice, andsome banana

Spices, coffee cassava,sorghum, coconut, cottonmango

N-4C1 Intermediate highlands;maize beans systems

N4, N5,E12, N1

Coffee, banana, maizeand beans

Cassava, sugarcane, clovescardamom sorghum pastures

N-4C2 Intermediate lowlands;maize legumes

N1 Maize beans andpigeon peas

Coffee, banana, cassava,sorghum finger millet and fruittrees

N-4C3 Large scale wheat N1 Wheat and barleyN-4D Highlands ; coffee banana E12, N4,

N5Coffee banana andintensive dairy

Horticultural crops, maize,finger millet, beans yamsround potatoes and sweetpotatoes

N-2A,N-3AN-3B

Arid to semiarid lowlands E12, N3,N6, N7,N8, P1,and P2

Pastoralist, bushlandsand gameparks

N-2C2 Large scale sisal E1 Sisal

Tanzania has approximately 36.6 million ha of rainfed cultivable land Table 1)and 5 millionha of potential irrigable land. Tanzania has a future (year 2000 and beyond) surplus supportcapacity of 48 to 105 million persons at the intermediate level of inputs (approximately 10 to 20million tons of food grain) and 400 to 461 million persons at the high level of inputs(approximately 100 million tons of food grain). According to estimates made by the Ministry ofAgriculture and Livestock Development (MALD) in 1988/89 by the National Food Security Unit,by the year 2000, 13 regions will not be able to meet their food needs from regional rainfedproduction at low levels of inputs and by the year 2025 17 out of the 20 regions will belong tothis deficit category.


Food crop production contributes 34% of total GDP while export production contributes 5%,livestock 18%, fishing and hunting 4%, and forestry 1%. The whole of the agricultural sectoraccounts for 61% of the country production. An example of land area and production trends fortwo regions in Tanzania (Arusha and Shinyanga ) is presented in Table 7. Although there aresome considerable variations from one year to another for both regions, which could be attributedto seasonal variations in weather conditions as well as differences in production potential betweenthe two regions, it should be noted that the contribution of subsistence farming is only estimatedusing indirect methods while the informal sector is dominated by agricultural production which isnot recorded.

The quality of the production data has also deteriorated further because of the declining roleof state owned marketing companies. A large amount of food crops and export crops is smuggledout of the country. The production trends for the food crop sector has been very responsive tochanging policies which may have direct or indirect effects on soil degradation. An indication ofthe responsiveness of the agricultural sector to changing policy environment is the GDP. growthin the sector which increased from about 2% per year in 1981/82 to around 5% in 1986 - 1982.


The agricultural sector has grown more rapidly than the other sectors of the economy after thestructural adjustment program which was launched in 1986 and now represents more than 60%of the GDP. compared to about 40% in the mid-seventies. Unfortunately, the share of thegovernment resources spent on the agricultural sector is only 6% of the total expenditure and hasshrunk from about 10% in the early 1980s to less than 3% today. Private capital must constitutethe largest share of new capital investments in Tanzania, Currently, there are many positive signsof increased interest from the private sector including funding of research activities in general aswell as extension. Therefore, activities related to development of improved technologies for soiland water management will likely benefit from such a support.

TABLE 7Cropping pattern and production in Arusha and Shinyanga regions 1986/87 to 1993/94 (000 ha,000 tonnes)

1986/87 1988/89 1990/91 1993/94Season cropArea Prod. Area Prod. Area Prod. Area Prod.

86/94

Arusha regionMaizeSorghumWheatBean localSunflower

143.0301.524.034.639.1

30.960.746.4

169.7244.228.532.642.2

36.165.528.2

154.838.033.931.83.3

227.237.960.350.82.4

163.128.639.756.3

222.632.263.752.5

1.41.21.70.8

Shinyanga regionMaizeSorghumBR milletRiceSunflower

239.2138.117.158.410.2

188.4131.412.3

106.76.1

314.191.218.476.10.8

220.377.114.9

142.70.5

275.2129.526.675.20.0

251.5206.320.9`98.0.0

218.1151.330.156.75.7

178.3118.216.450.44.0

0.81.10.82.01.5

Source : Ministry of Agriculture Arusha and Shinyanga

The state, supported by donors has a role to play with respect to investment in theagricultural sector which is also closely related to soil degradation either directly or indirectly.Besides the government policy to liberalize and to deregulate the agricultural sector, thegovernment priority areas are agriculture and livestock research, expansion of small-scaleirrigation, provision of basic infrastructure as feeder roads in rural areas as well as storage andprocessing facilities. The government has also accepted the role of making sure that harvesting ofnatural resources is done in an environmentally sustainable way which has also a strongimplication on soil degradation.

About half of the Tanzanian population have incomes under the poverty line. Poverty inTanzania is by large a rural phenomenon. It is estimated that 83% of all the poor people live inhouseholds where the main occupation is farming. Poverty does not seem to be related to accessto land but rather access to education, health, off-farm employment, and distance from efficientmarkets. Therefore, poverty alleviation in Tanzania should have a rural agricultural profileparticularly with respect to increasing the returns to labor in the agricultural sector. Therefore,restructuring should support systems that give smallholder access to inputs such as fertilizersploughs transport, roads and credits and advice farmers to use environmentally sustainablemethods of farming and forestry management.

A major obstacle to private business and investment in the agricultural sector in Tanzaniawhich according to (Semu et al., 1992) contributes significantly to soil degradation is the poorlegal environment. Property rights and land entitlement by pre-nationalization landowners,cooperatives, villages and individuals is still unclear. Therefore, laws governing land tenure

Tanzania300

systems should be revised to give way to further investments and provision of credits to smallscale farmers which will also have a bearing on soil conservation strategies.

EXTENT OF SOIL DEGRADATION AND ITS BIO-PHYSICAL AND SOCIO-ECONOMIC IMPACT

Causes of land degradation in Tanzania

Land degradation in most parts of Tanzania is triggered by human intervention on the naturalsetting. Thus, the present status and rates of land degradation can be attributed to naturalprocesses inherent in the physical setting of an area and the influence of human action in suchareas. Land degradation begins where human and animal activity disturbs the geological andbiological balance between landscape setting climate and vegetation cover.

Inadequate Extension Services. Even though the extension officers have to attend to largegeographical coverage, they are often without means of transport. Poor linkage between theextension staff and research is another factor which contributes to delayed or poor transfer oftechnology from research to farmers. This problem is magnified by the fact that the majority ofthe people involved in agricultural land use are as a whole resource poor peasants with very lowlevel of formal education. Their access to extension messages and the media is limited. Thefamily labor has to be divided between food and cash crop production, provision of water for thefamily and livestock and activities related to the provision of shelter and fuel. Land which ispoorly managed deteriorates rapidly thereby becoming less productive.

Inappropriate cultivation practices. In many parts of the country flat cultivation is practicedwhere animal drought or tractor power is used and cultivation is commonly done down slope.Both these methods are in effective against soil erosion and may even accelerate the process.Protection measures such as contours terraces etc are employed to a very limited extent andusually not done correctly. In areas where commercial agriculture is practiced e.g. (NorthernMbulu) the continuous use of heavy machinery has led to destruction of topsoil structure andformation of a plough pan. Poor policies have resulted in high pressure on arable land, rangeland,forests and water resources. The contribution of stock routes to erosion is significant. Mayspectacular forms of erosion are linked to the movement of livestock along specific routes.Grazing and trampling destroy the vegetation cover along these routes. Initially, narrow pathsgradually merge to form broad bare strips which readily develop into gullies because in mostcases they run along slopes. In addition, woodcutting for fuelwood, for construction and timberhas lead to substantial land degradation. Construction of roads down slope has also caused manyroadsides to develop into deep gullies. Policies on tenure, as well as appropriate use andmanagement of land resources have been absent or not enforced. Major parts of land in Tanzaniacontinues to be freely accessible and changes in policies such as removal of subsidies onagricultural inputs such as fertilizers have had a negative effect on agricultural production andland conservation.

Types of soil degradation

The intensity and types of erosion are related to vegetation cover, slope gradient and types ofsoils. The main agents of soil erosion are wind, runoff water and seepage of rainwater. Winderosion is very important during the dry season. Soil survey studies in Mbulu district (Magoggoet al., 1994) showed that 8.5% of the district was severely eroded 20.1% moderately eroded55.2% was slightly eroded and 16.2% was not affected by erosion. Gullies develop readily in thered and black soils of the volcanic area in the north even on gentle slopes.


Physical degradation. The common form of physical soil degradation is destruction of soilstructure. This is common in areas where there is continuous cultivation particularly where tillageis done using tractors or cases of excessive trampling by animals. Structure deterioration is alsomanifested by plough pan formation and surface capping. Surface crusts are also observed inareas where physical degradation is common e.g. Mbulu Kondoa and Dodoma. They areparticularly common in cultivated and over grazed areas which have sparse vegetationparticularly when the soils are low in organic matter.

Chemical Degradation. Chemical soil degradation refers to the change in chemicalcharacteristics of the soil in terms of decreases in plant nutrients and/or increased adverse effectof chemical elements and salts. Tanzania's arable soils lost nutrients at an average rate of 27, 9,and 21 kg N, P205 per ha per annum in and the rate of loss was projected to increase to 32, 12,and 15 kg N, P205 and K20 per ha per annum by the year 2000 if current trends are not reversed.The ability of the soil to supply nutrients differs significantly from one place to another as well asfrom time to time. Physical properties of the soil such as depth texture and structure alsocontribute to their productivity. Each soil has its inherently productive potential (Tables 8 and 9).Acidic soils have a high potential to fix P in forms that are not easily available to plants leadingto phosphorus deficiency symptoms in such crops.

TABLE 8Soil characteristics for selected sites in Arusha and Kilimanjaro regions - Northern Zone

District Altitude* PH (H20) Tot. N(%)

O.C.(%)

Avail. P(ppm)

Arusha SitesSARI-FarmKikatitiHimitiEndamarariekEyalabeKilimatemboMbuyuniMguu/ZuberiKibayaDosidosi

ArushaArumeruHanangMbuluMbulu-KaratuMbulu-KaratuMonduliMonduliKitetoKiteto

MediumHighHighHighHighHighhighHighLowLow

7.56.17.06.56.86.97.27.35.75.8

0.090.440.130.100.150.140.230.180.070.17

2.05.71.01.22.42.51.32.30.61.0

2216

Trace284421814817

Average 6.7 0.17 2.0 25Kilimanjaro Sites

KindiLyamunguUroriKiraeniMkuuUsseriMiwaleniSanya juuKIALambo

Moshi ruralMoshi ruralMoshi ruralRomboRomboRomboMoshiHaiHaiHai

HighHighHighMediumHighHighMediumMediumMediumMedium

5.75.56.46.25.86.77.77.37.46.6

0.240.220.270.090.210.160.090.240.130.14

3.62.63.51.52.12.01.13.31.52.3

473480102182318

Trace68

Average 6.5 0.18 2.4 33Notes: *Low altitude: - <800 m above sea level; Medium altitude: - 800-1300 m above sea level; Highaltitude:- >1300 m above sea level

Heavy application of fertilizers can be profitable on soils that have high productive potentialbut which are low in fertility. Declining soil fertility is very severe in most parts of the countryparticularly on sandy soils. In all cropping patterns the total nutrient removals is usually greaterthan corresponding amounts removed by various processes. Most of the losses occur throughcrop harvests and crop residue removal. Certain crops need larger amounts of particular nutrients

Tanzania302

than others. Legumes for instance require large amounts of phosphorus whereas cereals requireproportionately more nitrogen. Improved varieties are more responsive to higher doses offertilizer. Therefore, nutrient mining is mainly responsible for the decline in soil fertility andproductivity in many ago-ecosystems. In areas with low rainfall soils lose very limited amount ofnutrients through leaching. However such soils are very susceptible to salinity problems. It isestimated that 3.6 million ha of salt affected soils are in Tanzania and of these 2.9 million ha aresaline while the remaining are sodic. (Mkeni 1996). Most of the salt affected soils in Kilimanjaroregion are found in the lowland areas surrounding the Kilimanjaro and Pare Mountains. Lack ofproper drainage in the layout of irrigation schemes was identified as one of the main causes of thebuild up of salts.

Salt-affected soils fall into two main categories i.e. saline soils containing excess of neutralsalts which are dominated by chlorides and sulfates whereas sodic or alkali soils have a highcontent of sodium salts

TABLE 9Soil characteristics for selected sites in Shinyanga Region - Lake Zone

Location District pH(H20)

OC(%)

N(%)

AvailableP (ppm)

CEC

Mwanhuzi Meatu 7.6 1.28 0.30 1.6 39.0Isagehe Kahama 4.9 0.50 0.02 1.6 7.9Ngulyati Bariadi 5.9 0.69 0.07 4.0 10.3Mwambegwa Meatu 8.0 1.41 0.16 1.6 69.0Nyalikungu Maswa 7.6 0.62 0.09 2.0 10.7Gula Maswa 6.5 1.55 0.13 2.0 15.0Nyakabimbi Bariadi 6.6 1.04 0.10 8.0 10.6Nyashimbi Kahama 6.6 0.32 0.03 2.0 4.3

Irrigation poses special problems in the use of fertilizers and also provides some uniqueways to supply nutrients not encountered in non-irrigated agriculture. Crop yields must be highfor irrigation to be profitable and this is usually associated with greater nutrient uptake by crop.In order to maximize irrigation efficiency nutrient needs of irrigated crops must be met by anadequate fertilizer program. It is also well recognized that anions such as NO3

-, Cl- and SO2- aremobile in the soil especially under neutral and alkaline irrigated environments. The three broadirrigation methods furrow, flood and sprinkler irrigation have implications for fertilizer useefficiency. Furrow irrigation leads to marked redistribution of most mobile nutrients. In floodirrigation movement and eventually losses of mobile ions is more effective.

Biological Degradation. Biological degradation is a decrease in soil biological activities whichare essential for maintaining the physical structure of soils and their ability to supply chemicalelements to plants which is usually controlled by the organic matter content of the soil. Theproduction and deposition of organic materials provides substrates for microbiological processesand accumulation of soil organic matter. Mineralization of the OM is a major source of plantnutrients in soils with low inherent fertility. Organic matter improves the water holding capacityof soils, improves nutrient retention and storage.

Evidence of chemical/fertility decline

The main evidence of soil fertility degradation in Tanzania can be obtained from the wideresponses of various plant nutrients in form of mineral as well as organic forms of fertilizers.(Nyaki 1997 and Kamasho 1997). Mineral fertilizers were first introduced in Tanzania in 1956for use in cash crops particularly tobacco, cotton and coffee. In 1976 the National maizeprogramme was launched and the use of mineral fertilizers in food crops, particularly maize was


spread in most parts of the northern zone as well as other zones in Tanzania. (Urassa and Isaac,1997, and Nyaki 1997). Responses to mineral fertilizers were quite evident in some parts of thenorthern zone (Table 10). During the 1980s other projects such as Kilimo/ FAO FertilizerProgramme followed by SG2000 were initiated and these demonstrated the importance of mineralfertilizers in increasing food production throughout the country. The maize improvementProgramme funded by USAID through CIMMYT also created awareness in the use of mineralfertilizers by small holder farmers in the southern highlands of Tanzania. Fertilizer trialsconducted in the southern highlands showed strong responses to N as well as phosphorus and insome instances responses in micronutrients such as Cu in crops such as wheat, which also clearlyindicates that these nutrients are highly deficient in such soils.

Nitrogen is the most limiting nutrient forcrop production in Tanzania. Unfortunately,the use of most nitrogen fertilizers forimprovement of soil fertility in most parts ofTanzania has also declined substantially inrecent years largely due to the high costs ofinputs in relation to crop prices, particularlymaize. The most common types of mineralfertilizers normally used in Tanzania includeSA, urea CAN and NPK. (Urassa and Isaac,1997). Due to removal of subsidies in mostagricultural inputs including mineral fertilizersthe economic optimum rates of N for theproduction of most crops in Tanzania hasdropped to rates between 40 and 60 kg N perha when compared to rates as high as 112 kgN per ha when fertilizers were fully subsidized(Table 10). In fact, at the moment very fewfarmers in the northern zone of Tanzania areapplying mineral fertilizers in their maizefields. It is estimated that until recently 70% ofthe amount of fertilizers consumed in thecountry went into maize while small amountsare applied to paddy potatoes and wheat.

Fertilizer use in tobacco is increasing dueto the role of the tobacco buyers are applyingand the low profitability on maize of NPK.95% of 6:20:18 goes into tobacco while 95%of the 25:5:5 is applied to tea. Based on theagronomic data available so far and theprevailing economic environment (high fertilizer prices and relatively low crop prices ) it appearsthat the most fruitful contribution to alleviate chemical soil degradation is to assess the effect offactors which can significantly decrease the amount of mineral fertilizers applied whilemaintaining significant increases in yield since complete removal of subsidies in fertilizers hasresulted in a sharp decline in the consumption of fertilizers except for a few profitable crops suchas potato, tobacco and cotton.

TABLE 10Some-up-to-date fertilizer advice to agro-ecological zoning economic optimum ratecalculation

Agro-ecological

Zone

N(kg. ha-1) P205 (kg. ha-1)

MaizeH5/H6/H7 60 0S2 40 0H2 (1) 40 0H2 (2) 30 20E7 60 0R1 30 20E2 60 0N2 50 0N4 50 0

WheatH7 70 0H2 (1) 60 0H2 (2) 50 30E7 40 20N4 40 0

BeansAll 30 20

PotatoH7 60 50H2 80 40E7 80 50N4 60 40

PaddyE9/E10 60 0P4/P8 40 0S2/E7 50 0

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It should be noted that the decline in the use of mineral fertilizers in most parts of Tanzaniawill likely result in very rapid decline in the fertility of the soils unless other alternative forms ofplant nutrition are established. Integrated Plant Nutrition Studies (IPNS) conducted in Tanzaniaso far clearly show that organic forms of fertilizers such as FYM can be used as a source of plantnutrients, particularly N. However, its utilization is labor intensive and demand facilities totransport it from the homestead to distant fields. In some areas of Tanzania FYM availability isalso very limited and the amount required can not be met to satisfy the needs of crops. Somestudies have also shown that it is possible to increase crop yields without using fertilizers byusing improved farming practices such as ridging cultivation for maize, improved watermanagement for paddy fields, improved tillage for different crops, crop rotations andintercropping practices.


Due to agro-ecological diversity within the country, different soil management systems haveevolved over time to produce husbandry practices which conserve the soil and ensures effectiveuse of available water. Most of the systems developed involve small holder production systemsand very limited cases of large scale farming (Antapa and Angen 1990)

The case of the Soil Conservation and Agroforestry Program in Arusha Region (SCAPA) inNorthern Tanzania

The Soil Conservation and Agroforestry Program SCAPA is a community based land husbandryand agroforestry program. It is funded by the Swedish International Development Agency (SIDA)and employs integrated land husbandry strategies to increase agricultural productivity in mediumand high potential areas of Arumeru and Arusha district in Arusha region. The low cost easilydisseminated and adaptable techniques have convinced the farming community in the programarea that appropriate land husbandry practices are among the possible strategies to increase andsustain agricultural production in the area. Along with the planning activities aimed at assistingthe farming community SCAPA also creates awareness on the techniques and processes involvedin promoting improved land husbandry strategies. Major components of the program includetraining, soil and water conservation techniques through water harvesting /conservation,agroforestry, livestock husbandry and crop management. Field activities at the village level areimplemented by the Village Soil Conservation Committee (VSCC) under the guidance of thevillage extension officers (VEOs).

Soil erosion is one of the major constraints to increased agricultural production in Arumerudistrict. Arumeru has a total area of 2 900 km2. According to Semu et al. (1992), 70% of the areain the district is affected by soil degradation mainly through soil erosion. Large gullies of up to 10m wide can be found in areas such as Oloitushula and Oldonyosambu area in Muklat Division.Rill erosion is also evident in cultivated fields in Sakila destroying large tracts of land. Severesiltation of water reservoirs in some parts of the district is additional evidence of the extent ofland degradation in the district.

The major causes of land degradation in Arumeru district are the following:

• High population density in high potential areas resulting in lack of arable land which temptsfarmers to open up fragile land for crop production. The population density for Arumeru district isthe highest in all the districts of Arusha region. Arumeru district has an annual population growthrate of 3.8% which is among the highest in Tanzania. The population density of 108 persons per


square km in the district is also considered as very high. In fact, in some areas around mount Meruthe population density can be as high as 200 people per km2. The average family land holding isless than 0.8ha. About 98% of the population is engaged in agricultural production.

• Deforestation and poor forestry management resulting from lack of adequate supplies offuelwood and timber also contributes to soil degradation there is a strong evidence supportedby the inhabitants of the area that at one time a large part of the district such as the Sakillaand Oloitushulla area were covered with heavy forests. Gradually, these forests were clearedto provide land for farming and grazing as well as fuelwood and building materials.

• Overstocking, and consequently overgrazing in low potential areas is also one of the maincauses of land degradation in the district. On the lowland areas the pressure on land mainlyoriginates from large livestock populations. According to the 1984 livestock census the wholeof Arusha region had 2.4 m livestock units. (L.U.). (1 L.U.= 1 cow averaging 250 kg). Theland available for grazing in the district is about 5.6 m ha. Therefore, there is 2.5 ha of landfor every L.U. However, the optimum carrying capacity of the land is 4 ha per L.U.Therefore, the land in the district is overstocked by a factor of 40% which contributessubstantially to soil degradation in the lowland areas of the district.

• Poor farm management practices.

• Low level of awareness regarding land and environmental degradation within the farmingcommunity and among government and political leaders.

• Inadequate facilities and skills within the extension system to solve soil degradationproblems.

Implementation strategies of soil conservation measures by SCAPA

The objectives of the SCAPA Program are the following:

• To improve and increase agricultural production on a sustainable basis through soil andwater conservation with emphasis on small holder farmers in the medium and high potentialareas in Arumeru and Arusha districts.

• Formulate a suitable extension package for integrated soil conservation in relation to ruraldevelopment

• Provide sites for training and demonstrations for soil conservation practices.

The target groups in the program were mainly small scale farmers in Arumeru and Arushadistrict in Arusha region. There are more than 160,000 small scale farmers in Arumeru districtand more than 78,000 small scale farmers in Arusha district. These farmers are characterized bythe use of poor farming tools and very limited use of improved agricultural inputs. Averagehousehold /family size of small scale farmers in the program area ranges between 6 - 8 peoplewho depends entirely on land to satisfy their basic needs. The majority of the farmers in theprogram practice mixed farming, raising agricultural crops and rearing livestock for both foodand cash. Pastoralists mainly occupy the low potential and marginal areas in the region whereaverage land holding is relatively high. Except for a few plots of farmland grazing land iscommunally owned with free range grazing system.

The basic soil conservation structure promoted by SCAPA is the contour band or ridge.Farmers in the district are trained by the PCT on the procedures of laying out such ridges usingsuch simple equipment as line levels. A line level assembly consists of two poles or sticks of

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equal length (about 1.5 m). The upper ends of the poles are connected by a string (usually 10 mlong). On the middle part of the string a small (pocket size) spirit level is fixed so that it ishorizontal when the string is tightly stretched between the two poles, when held in a verticalposition. Three people are needed to layout a contour. Two of them hold the poles vertically withthe string tightly stretched in the direction of the contour line The third person monitors the spiritlevel and advises the person holding the front pole to move either up slope or downslope until thespirit level indicates that the string is now level. Pegs are then placed in the positions occupied bythe poles. The rear pole is then moved ahead and the process starts again.

For effective soil conservation ridges the spacing between the contour ridges depends on theslope. A general consensus was that for slopes below 25% vertical intervals of 2 meters weresatisfactory. But for slopes above 25% vertical intervals should not exceed 1.5 meters. Once thecontour lines were established furrows were dug on the up slope side of the contour line and theexcavated soil was hipped on the established contour to form a ridge. The procedure is firstdemonstrated by the PCT and the extension staff and then farmers continue on their own. Mostfarmers were initially concerned about decreases in cropping areas in incidences where theintervals were too short. However, they latter realized that in the process of stabilizing the ridges,new opportunities for increased fodder and fuelwood as well as building materials were openedup. Napier grass (Pennisetum purpureum ) is then planted using cuttings on the entire length ofthe contour ridge. The grass establishes quite well within the first year and contributessignificantly to the stabilization of the ridge due to its extensive root system.

In some fields agroforestry tree species are planted either along the slopes or downslope.These include species such as Sesbania sesban, Grevillea robusta and Leucaena leucocephala.All the tree species were strongly believed to contribute further to the stability of the ridges inaddition to providing the community with fodder (grass spp.) Sesbania spp. and Leucaena spp)as well as fuelwood and eventually building materials (Grevillea spp). Initially, the grass and treespecies seedlings were provided free by the SCAPA Project, but it was later learned that theexercise was very expensive. Therefore efforts were initiated to promote village based, privategroups and individual based nurseries in the villages involved in the Project. Soil degradation inthe drier areas of Arumeru district is closely linked to livestock production. In the highland areasimproved dairy cows are very common. Zero grazing is widespread since livestock in such areasis not allowed to graze freely in order to protect the soil cover.

Farmyard manure from livestock is usually collected and spread in the fields to improve soilfertility. In the rangeland, the number of livestock is very high and has resulted in seriousovergrazing. Unlike the highland areas the grazing lands are usually communally rather thanindividually owned Therefore no individual takes the responsibility to take care of the grazingland by limiting the number of animals to the carrying capacity of the land. Livestock keeping is adeep rooted tradition for the tribes living in the dryland areas of the district. A large number ofcattle to them provides economic security as well as spreading the risk. It is also important tonote that improved breeds are very susceptible to diseases and are also more demanding when itcomes to feeding and water requirements during the dry season, Therefore the issue of destockingin such areas has to be handled with care, and in most cases it should involve the farmersthemselves. Inadequate moisture is one of the major limitations to optimum crop production insome villages of Arumeru and Arusha districts. In such areas soil conservation measurespracticed are also complemented with other water harvesting techniques SCAPA in collaborationwith Sida RSCU is implementing a pilot intensive watershed management in selected programareas. The SCAPA creates awareness on land husbandry and environmental conservation amongthe farming communities, government and political leaders through training. It is also through


training that soil and water conservation issues are incorporated into the agricultural and relatedextension systems.

Institutional aspects

The SCAPA program usually follows the set up of the government administration. However, tosome extent, the program is more or less semi-autonomous. The program manager is the overallsupervisor while the program coordinator is the team leader of the Program Coordinating Team(PCT).The program administrator is responsible for monitoring and evaluation of the programimplementation. There are three soil and water conservation committees, one at the regional leveland two at the district level. These committees ensure that SCAPA activities are incorporated inthe district annual development plans and that the integrated approach is adhered to by all partiesinvolved. At the program area level SCAPA activities are organized and implemented by thePCT. The PCT is a multi disciplinary team comprising of technical staff from the forestry,agriculture, community development, livestock and water development.

The SCAPA is a program operating through the normal government extension system.Therefore, it is the task of the PCT and district functional managers to ensure maximumcooperation with extension staff in the mechanism of the implementation of the program. ThePCT also assists extension staff in the planning and implementation of program activities in theirareas of jurisdiction. In many respects there are the equivalent of a catchment or subcatchmentsoil conservation committees depending on the size and nature of the area confined in the villageadministrative boundaries. The major reason of including these subcommittees in the program isto ensure active participation of farmers in the planning and implementation, and therefore,sustainability of the program achievements. The SCAPA has initiated collaborative activities withother government and non- governmental organizations located in Arusha and Arumeru districtsworking for rural development.

Since its inception SCAPA has extended good and effective co-operation with Heifer ProjectInternational (HPI)I. Through this cooperation SCAPA has trained and assisted farmers toconserve and manage their land with the main focus of increasing productivity. Promotion offodder production necessitate zero grazing systems as well as optimization of time and laborresources. At community level the SCAPA proposes to HPI a list of potential farmers whoqualify for in calf heifers. The Mbulu District Rural Development Program (MDRDP) is anintegrated rural development program. The implementation of a program in this project in regardto soil conservation started in 1989. The Land Management Program in Babati (LAMP) is anintegrated rural development program supporting sustainable development in agriculture forestryand livestock. Other areas include water resources wildlife and fisheries communication andcommunity development. It is a district based program operating through the district council andis partly funded by Sida and partly by the Tanzanian Government.

The Monduli development Program SNV is funded by the Netherlands DevelopmentOrganization and Monduli district council and focuses on integrated rural development programs.Farm Africa is an agricultural development program based and operating in Babati district. Itstarted in the United Kingdom in 1985 and is currently operating in four African countries(Kenya, Ethiopia, Tanzania and South Africa). The project is intended to boost the economies ofthe poorest farmers through appropriate agricultural, livestock and forestry activities. Includingrearing of dairy goats, agroforestry, primary school activities. Involvement of women indevelopment activities in rural areas has been of great concern to the program at all time. In fact,women stand for a large part of the farm production activities. SCAPA is assisting in the

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formation of women working groups in the program area The program is providing technical andmaterial support to the group to enable them attain their development aspirations.

Summary of SCAPA achievements for the period 1989 -1996

• More than 10 079 farmers have been covered in soil conservation and agroforestry activities.

• More than 1 900 km of contour bunds have been laid out of which 95% have been plantedwith grass or multipurpose tree species.

• 1 113 900 multipurpose tree seedlings have been distributed and planted on the farmland andfarm boundaries The survival rate of the seedlings is estimated at 75%.

• 374 tons of grass material for planting on the contours were distributed to farmers. Thesurvival rate is estimated at 90%.

• 117 extension staff have been included in study tours involved in promoting appropriate landhusbandry practices and water harvesting.

• More than 10 878 farmers have been provided with basic training on soil and waterconservation as well as appropriate land management practices.

• The program has assisted establishment of 87 on-farm tree nurseries in various programareas.

The impact of SCAPA activities in Arumeru and Arusha districts has been estimated asfollows:

• Increased awareness on importance of soil conservation: There is a rapid build up ofawareness of the importance of soil conservation among the farming community as indicatedby increased number of people requesting for conservation services through the VSCCs,which has received a considerable amount of training on such activities. As a result, the PCCteam has reduced the number of visits to many of the initial programme sites because most ofthe activities are now been implemented by the VSCCs (Annual report 1997). Theintroduction of improved breeds of cattle in the program area has significantly reduced theincidence of free grazing in many villages. Very effective by laws are in place and closelymonitored by the VSCCs to ensure that free grazing in conserved areas is non existent even inones own field. The conservation technology promoted by SCAPA has been adopted by over75% of farmers in the Programme areas. It was also reported that most of the farmers whowere not initially interested in the installation of contour bands in their fields are now askingfor such services because the benefits of such practices have become more and more obviousto them. There are also several requests for fruits trees, and assistance to establish treesnurseries. Unfortunately, such efforts are being constrained by water shortage particularlyduring the dry season as well as the high costs of the respective inputs.

• Increased crop yields due to soil conservation: The yields of crops in areas such as Kingorivillage particularly maize were quite low (6-8 bags per acre) before intervention of SCAPAand other NGOs particularly SG2000 because most farmers used to grow local varieties ofmaize without any consideration for improved agronomic practices. Today, about 75-80percent of farmers in the village use improved maize seed, and about 80 percent applymineral fertilizers in their maize fields and plant in rows to attain optimum plant populations.Average maize yields in the conserved areas now range between 20 and 25 bags/acre in goodyears. It is very likely that the higher yields may largely be attributed to both the soil andwater conservation aspect of the SCAPA Programme as well as adoption of some of the


improved technologies promoted by SG2000. Some of the farmers who did not practice thesoil conservation technology have already noted the significant increases in grain yields andare rapidly changing their minds in favour of adopting soil conservation measures in theirfields.

• Increased livestock productivity: The farmers contacted clearly acknowledge the fact thatestablishment of grass strips (Napier grass) and establishment of fodder tree species such asLeucaena, Calliandra and Sesbania on the contour bands, has led to increased supply offodder from the contour bands, for zero grazed animals, particularly at times of adequateprecipitation. Excess fodder has also become an attractive business to some farmers in thevillage. Some farmers are now selling fodder to other farmers in the programme areaparticularly those who did not adopt the conservation technology. Most farmers have nowshifted from free grazing to zero grazing practices thereby eliminating the overstockingproblem in the area which contributed substantially to accelerated soil erosion. Improveddairy cows produces between 10 to 14 litres of fresh milk a day when compared to 4 litres orless per day which was usually produced by local breeds.

• Reduced Nutrient Mining from lowland areas: Increased availability of fodder fromconserved structures coupled with high costs of transportation of crop residues from lowlandto upland sites, has also significantly reduced the incidence of transferring crop residues fromthe lowland areas to the upland areas. This practice used to contribute substantially tonutrient mining in the lowland areas through grain harvests as well as crop residues.Currently, arrangement are made such that some farmers who have settled in the lowlandarea utilize the crop residues generated by farmers residing in the uplands with theunderstanding that in return they will till their fields during the following season. Most ofthese arrangements are working quite well because often times the farmers who settled in thelowlands are related to farmers who reside in the upland areas.

• Reduced soil erosion: construction of contour bands and planting of grasses as well asvarious trees species has reduced both water and wind erosion in most farmers fields in thearea. Incidences of water erosion that was seriously causing damage to the agricultural landthrough large gullies as well as sheet erosion has been reduced to less harmful levels. Thelarge gullies that used to be quite evident in the area that have more or less disappeared andevidence of sheet erosion (rills and sediments/siltation) is also non existent even at times whenthe amount and characteristics of rainfall received was adequate to cause some erosionproblems.

• Improved environmental conditions due to afforestation: several multipurpose tree speciessuch as fodder trees have been introduced in the Programme area. There has also been anincreased emphasis to plant and maintain most of the indigenous trees species in the areawhich include Grevillea, Miruka, Mijohoro, Mringaringa, Mfurufuru, and Msesewe, as asource of timber, building polls, fuelwood and stakes. Therefore, the vegetation cover hasincreased significantly as a result of the SCAPAs efforts. It is currently estimated that about40% of the surface is planted with permanent trees. Increased vegetation cover has a bearingon the extent of soil erosion and moisture conservation as well as nutrient cycling. Trees alsoact as windbreaks in the area which contributes to reduction of wind erosion and conservationof soil moisture. The presence of a large number of trees in the area has also created a coolmicroclimate when compared to the hot environment which used to persist when the area wasrelatively bare. By laws afforestation are in place and are closely monitored by the VSCCs toensure that they are adopted by the respective farmers. According to the farmers contacted

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implementation of the by laws in the area has been very successful in promoting afforestationin King’ori village.

• Improved standards of living: the standards of living of people in the rural areas hasimproved considerably due to adoption of the SCAPA technology of soil conservation.Higher crop yields have earned them more income and improved their food security. Theirfeeding habits have also changed in favour of a more balanced diet containing enoughcarbohydrates, proteins and vegetables. Most farmers are also getting more income from milksales and using some of the milk as part of their meals to improve their health standards. Afew farmers have also started building some improved houses as result of increased incomefrom farming activities. More children are also being enrolled for primary schools, secondaryschools and technical colleges. Therefore, the number of youths migrating to towns seekingfor employment has been reduced. In previous years most of the young people were largelyinvolved in grazing of animals. Higher incomes has also enabled some farmers to hireequipment for land preparation as well as increased their ability to purchase limited amountsof inputs (improved seed pesticides and fertilizer to improve their productivity).

• Improved gender relations: some of the activities which were not originally shared betweenmen and women including fetching water for animals, milking, cleaning of cowshed, cuttingand carrying fodder to livestock in the homestead are now equally shared by both men andwomen. Due to greater involvement of women in the SCAPA activities the freedom ofexpression by women has also improved considerably. Both men and women now hold jointmeetings to discuss issues that affects their lives. Women today have more freedom to worktogether through women groups involved in activities such as raising vegetables gardens andtree seedlings. Zero grazing and increased availability of fodder closer to the homestead hasreduced the workload on the woman in that they don’t have to wait for the animals to comeback for milking Therefore they are more free to do other things including more time tosocialize.

• Increased interaction with local regional and international visitors: because most villages havesuccessfully adopted the soil conservation technology promoted by the SCAPA many visitorshave shown keen interest in the technology and have forwarded applications to the SCAPAmanagement to visit the programme areas to get an experience of the achievements. Some ofthe visitors received so far originate from other parts of Arusha region East Africa as well asthe international community.

Traditional cultivation practices and their linkages to environmental /soil conservation - Thecase of the Ngoro cultivation system in Mbinga district - Southern highlands of Tanzania

Rapid population growth in Mbinga district has forced people to clear more land on steep slopesfor growing crops. Therefore, land degradation is becoming a serious problem in the area ifappropriate soil conservation measures are not observed. Land degradation processes takingplace in the area include loss of fertile top soil and water through runoff. Such losses leads tolosses in productivity as well as environmental degradation. Currently, in the matengo highlandswater from streams is being polluted by soil sediments and silt particles from cropped land usingthe ridge system of cultivation as well as poorly designed ngoro systems. The Matengo pits(Ngoro) cultivation system is an indigenous method of land preparation which has been practicedby the Matengo small scale farmers for a long time. The system was developed before 1890 forthe control of run-off erosion on steep slopes (Allan 1965).

The Ngoro system of cultivation is estimated to be currently practised on approximately18 000 ha of land in Mbinga district (Martin et al 1996). The system consists of a series of pits


surrounded by ridges on which crops are grown. Its construction involves an in situ compostingof the grasses in the ridges. The grass rows are arranged down slope and across slopes, thusforming ridges around the pit. The Ngoro system of cultivation is a common feature of steepslopes (10 - 60%) of the Matengo highlands. The activity involves three main steps namelycutting of the grass (kukyesa), arranging the grass in rows (kubonga) and construction of the pits(kujali) i.e. piling the grass in squares 2 m x 2 m and then using a hand hoe to cover the grasswith soil from all sides. During the process of constructing the pits there is a distinct genderdivision of labor. The first two steps are done by men while the third stage is mostly done bywomen. The construction of the structures is done when the soil is wet but the rains are about totail off (March/April).The pit system has also been linked with crop rotation and fallowingpractices (ICCRA 1991).

The main rotation system associated with the Ngoro system in the Matengo highlandsinvolves fallow-beans-fallow-maize-fallow-beans. Maize is sown by making planting holes on theNgoro ridges in December following a July to November fallow following the harvesting of themidseason bean crop. Beans are usually sown by broadcasting on newly half formed Ngororidges in March after fallow following the harvesting of maize in August. The Ngoro system hasalso sustained soil productivity in highly sloping lands of the Litembo area in Mbinga District forover 100 years without the use of mineral fertilizers. In the past fallow periods were much longer(up to 10 years) to sustain productivity, depending on the population. According to ICCRA(1991) fallow periods are now as low as one year on the hills and are much shorter on theplateaus due to increasing population pressure. Due to increasing labor constraints, the Ngorosystem is slowly been replaced by the less labor intensive ridge cultivation system and modifiedforms of the original ngoro system although crop yields are usually less than yields from theoriginal ngoro system.(Ellis Jones et al. 1996). The Ngoro pits currently been practiced are nolonger square in shape as they used to be but rectangular in shape and are also much shallower.The ridge system was found to be less effective in controlling runoff and soil erosion whencompared to the ngoro system Thadei (1995) demonstrated that soil losses of up to 7.3 t/ha wererecorded in a slope of 8.9 and 14.3t/ha in a slope of 20.9 o in the ridge cultivation practice. Forsimilar plots soil losses were 2.4 t/ha and 5.8 t/ha when the ngoro system was practiced.

Some of the most important features of the Ngoro system can be summarized as :

• in situ conservation of runoff water into the soil for use by crops,

• prevention of both physical and chemical soil degradation,

• improved soil fertility management through decomposition and mineralization of plantresidues during the pit construction process,

• promotion of crop rotation and fallowing practices.

The case of large-scale mechanized wheat farming in northern Tanzania - Evolution of large-scale soil conservation practices

Land clearing practices in relation to soil conservation. Due to the serious soil eosin problemsthat were experienced on the farms during the 1980s soil conservation structures were surveyedand installed on such farms. These included grass strips, absorption and graded channel terracesIn general, the structures were moderately effective but the main disadvantages were highincidences of weed infestation and poor movement of farm machinery between strips, reduction oftotal cultivable land and sometimes structural failures. Farms that were opened later involvedleaving of a 5-8 m wide strip of natural vegetation on contours and natural waterways untouched.

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This approach proved to be very effective in controlling soil erosion. Current efforts to controlerosion on originally opened land also include construction of broad base terraces andconservation tillage practices which have also been shown to be very effective.

Soil erosion control structures. Extensive surveying at the HWC enable the farms to install soilconservation structures on 7,585 ha of land from 1988-1991. The exercise is still in progresstoday. Studies conducted at HWC have shown that absorption channel terraces were quiteeffective in controlling erosion on 2-4% slopes particularly on medium to course textured soils.On the other hand absorption channel terraces were very ineffective. (Antapa and Sayulla, 1991).Graded channel terraces are similar to absorption channel terraces except that they are gentlysloped to discharge water into grassed waterways. They are commonly used in areas with slopesin the range of 4-6 percent. Broad based terraces have also been found to be very popular sincethey do not take any land out of production. Unfortunately, like absorption channel terracesBroad based terraces are not very effective in controlling soil erosion on heavy textured soilsbecause water collects on the upper channels, which delays field operations and causes waterlogging problems.

Tillage practices. During the early stages of the establishment of the wheat farms the dominanttillage implements were disc ploughs and harrows. Generally, the disc ploughs tended to pulverizethe soil and incorporated most of the trash, thus increasing the erosivity of the soil surface. In thelater years of the Wheat project cultivators attached with sweeps were introduced and are now themajor tillage implements being used. These tillage implements are designed in such a way that upto 70% of the crop residues is retained on the soil surface after the tillage operation. Substantialamounts of soil can be lost through runoff water if the soil is left bare after tillage operations orcontains very limited vegetation due to overgrazing. Excessive tillage is sometimes practiced in aneffort to control weeds, but in many instances it has been shown to promote accelerated erosion.In recent years herbicides such as roundup have been introduced to substitute for some of thetillage operations to minimize excessive tillage. Air seeders have also been introduced and areincreasingly been used by the wheat farms to promote minimum tillage. The equipment is capableof eliminating some tillage operations since it can perform the tillage and seeding operation in thesame path.

Implications of current tillage practices on moisture conservation and nutrient availability tocrops:

• The duration of weeds in the field has a direct effect on the extent of moisture depletion onthe wheat fields. Therefore, weed control practiced close to the planting time will likely resultin less available moisture to the crop when compare to tillage practices which ensure weedfree fields for a significant part of the season.

• The effect of substituting tillage operations by using herbicides may also have some negativeimplications on the quality of organic matter as well as soil microbiological aspects.

• Decomposition of wheat straw to release nutrients to the wheat crop after the tillage operationwill likely be influenced by the timing of the tillage operation. Wheat straw is known to havea wide C:N ratio and therefore requires more time for decomposition to release nutrients tocrops. Control of weeds using herbicides also leaves most of the residue on the surface.Therefore, it is only through the second tillage operation using the air seeder that microbialdecomposition of the residue is initiated.

• Continuous tillage operations using heavy duty equipment may also result in considerablecompaction of the soil which may limit the infiltration capacity of the soil and encourage


runoff. Tillage operations by most small scale farmers is done either using the handhoe,oxplough or small tractors. Therefore, the problem of compaction is almost non existent.

Management of Vertisols in relation to their physical and chemical characteristics. Vertisolsoccupy about 50% of the total area under wheat production in large scale wheat production farmsin northern Tanzania usually refereed to as the Hanang Wheat Complex (HWC). Vertisolsusually occupy the depressions as well as lower slope positions. Other soils include Mollisols,Inceptisols, Alfisols, and Ultisols which occupy the upper slopes and mid slope positions.Although the Vertisols of the Hanang wheat complex area are high in natural fertility and have ahigh water holding capacity the high content of montmorillonite type of clay which is also acharacteristic of such soils promotes water logging under wet conditions and very hard andcracking surfaces when dry. These effects have several implications in the management of suchsoils:

• Post harvest tillage operations need to be conducted at the appropriate moisture content toavoid equipment damage which can be expected when tillage is done when the soil is too dry,

• Appropriate choice of tillage equipment as well as appropriate adjustments is also essential(Antapa and Angen 1990),

• Seeding operation- Usually, due to the large acreage involved in mechanized wheatproduction the lighter textured soils are tilled and seeded first while the heavy clay soils areseeded late because of their higher moisture holding capacity,

• High pHs of Vertisols on depressions in this area shows that investigations into thepossibility of application of P fertilizers should be explored. In fact, soil analysis data the Plevels on such soils are relatively low.


The improvement of government capacity has now emerged as the most important issue in theongoing structural adjustment effort. Reforms required now involve efforts to increase theeffectiveness of various research activities including soil management activities. Future strategiesinclude:

• a shift from central to district and even levels below,

• capacity building and sustainability shall have top priority,

• gender equality reflection will be observed,

• land tenure and land policy issues and their effect on the projects under preparation should beconsidered and analyzed during the identification and preparation of support programs,

• district projects shall build on priorities made by the land users,

• Tanzania shall monitor and evaluate not only technical subject matter areas but also socio-economic effects of the donor supported projects,

• support to district projects shall aim at increased productivity among smallholder throughsustainable use of natural resources including support for land tenure and land management,

• in addition to high and medium potential areas support shall also take low potential areas intoconsideration.

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Currently, there is a significant shortfall in the policies on soil and land resourcesmanagement, conservation and rehabilitation. Where these policies exist, they do not adequatelyaddress problems of soil degradation because they lack legal framework and concrete action plansto tackle the problem. Nevertheless, the government has some positive steps in combating landdegradation such as the establishment of the National environment Council (NEMC) and theNational Land Use Planning Commission (NLUPC). The NEMC has already formulated aNational conservation strategy for Sustainable Development and the National EnvironmentAction Plans which have established a framework for integrating environmental issues in thenations overall economic and social development. However, the absence of a comprehensiveenvironmental policy clearly indicating goals objectives mandates and responsibilities of differentinstitutions casts doubts to the successful implementation of the action plans. Besides, there wasvery little input from the grass roots.

The National Land Use Planning Commission (NLUPC) has produced a draft on nationalland policy which addresses mainly the issue of land tenure which as indicated earlier plays asignificant role in soil degradation. Unfortunately, most of the plans in the draft consist of rigidland use zoning which is not suitable for proper management of rural land resources. Therefore,there is a need to formulate a policy that takes into account the different environments and ascientific criteria for land use planning. A national policy on soil will contribute towards attainingnational development policy by protecting and conserving the environment which is likely toreduce poverty and increasing food security through sustainable use of soils. Although laws onsoil conservation exist most of them have not been applied for decades now. These need to berevived, revised and if possible enact new ones to conform with new soil policies. The separationof environment, natural resources, land and soils into different line ministries and organizations isa hindrance towards attaining intersectoral and multi disciplinary approach to environmentalmanagement and conservation. Lack of infrastructure and well trained personnel in soilcharacterization classification evaluation correlation management conservation and rehabilitationcompounds the problem even further.


Based on the experiences learned from the SCAPA and other sources of available informationnew strategies to combat soil degradation will have to take the following aspects intoconsideration:

• Institutional Framework: Although there are many institutions engaged in soil and waterconservation they lack coordination cooperation and linkages. They are sectoral and employdifferent approaches and methodologies and have different formats. Therefore, they should beharmonized. Most national institutions are inadequately funded ill equipped and poorlymanaged due to inadequate human resources. Donor funded projects are sometimes notsustainable.

• Policy and Legislation. The country needs a comprehensive land use and tenure policies aswell as straggles and program of action in order to adequately address issues of sustainablesoil and water management. Such policies will optimize the use of land as well as minimizeconflicts between different land users and stakeholders.

• Land Use Planning. Lack of scientifically based, flexible land use plans at national, regionaldistrict and village level often results in soil degradation. Land use planning will also guiderational and judicious use of land at different levels.


• Research and Extension services. These are institutions charged with the development andpropagation of land use technologies. As such they need to direct their efforts to on farm,problem oriented research which addresses farmers problems and provide them with practicalsolutions that are within their socio-economic circumstances. Critical is the research -extension - farmers should participate fully in the planning and implementation process ofresearch projects. Therefore, their local knowledge, skills and technologies should berespected. Emphasis should be concentrated on resource - poor small scale farmers who arethe majority.

• Mass awareness and Mobilization. Local communities need to be abdicated to raise theirawareness on soil degradation, conservation, and rehabilitation. Past experiences have shownthat adoption of new technologies was very limited without involving farmers and theirwillingness to cooperate.

• Information. is an important tool in facilitating planning processes of soil and waterconservation. It is essential for creating awareness and mobilization, training and policyformulation. Information must be easily accessible in a timely manner. It must be collected,processed stored and disseminated.

• Training. Rural populations are characterized by low levels of literacy. This limits theircapability to assimilate packages and technologies on land husbandry practices andconservation. Farmers must therefore, be literate in terms of the basics of soil and watermanagement conservation and rehabilitation. Extension staff also need training in bothtechnical aspects as well as approaches necessary to encourage motivate and mobilizefarmers to actively participate in soil conservation and rehabilitation.

• Poverty. The rural communities are generally poor and spend a lot of time and energy insearch of fuel, food and water and have very little time left to consider environmental issues.

• Sometimes environmental issues are in conflict with their activities. Socio-economicenvironment involving aspects such as schools health care facilities, and services, water etcare either lacking or very limited. Credits and markets for increased agricultural productionare often lacking. These problems often result in poor soil management practices leading todegradation of the soil.

• Gender issues. The bulk of agricultural activities in rural areas are carried out by women. Inaddition to field activities women are responsible for the supply of fuelwood fetching water,cooking and taking care of the family. Unfortunately women have very limited participationin decision making issues when rural development programs are started. Therefore, oftentimes the role of women in soil management issues is often overlooked.

Integrated soil management approaches can be considered as the most logical strategy toadopt in most parts of the country due to rising costs of inputs such as fertilizers and theincreasing concern for environmental degradation. Such an approach should be developed toinclude aspects such as tillage, soil conservation crop rotations agroforestry and contributions oflegumes through BNF, crop residues, FYM. The IPNS should adopt a holistic approach to alsotake into consideration all the socio-economic aspects of the clients being addressed.Collaboration between various Institutions and NGOs should be promoted to maximize the use oflimited resources such as manpower transport and equipment.

Institutions such as SCAPA could be adopted elsewhere. Collection of adequate backgroundinformation through surveys and PRAs should be emphasized for easy identification of priorityareas of intervention and potential solutions. Such information should include characteristics of

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natural resource base as well as socio-economic and environmental data and should include thedevelopment of a data base which could be updated regularly for improvement purposes. Most ofthe key actors in agricultural production require frequent training at different levels in aspects ofsoil management and related inputs (seeds, fertilizers and pesticide).

The coordination between the various partners should also be strengthened. Extensionservices directed to farmers or farmer groups should be targeted to improved productivity andproduction. Farmers at the village level should be assisted to form farmer organizations in orderto strengthen their bargaining power with respect to marketing of their crops as well as access tocredit facilities required to improve productivity. Some of the recommendations developed suchas those with soil and water conservation technologies developed by the SCAPA should beimplemented on a community based action plan in order to promote their adoption. Such aspectsas management of forests, communal grazing land and wildlife areas should be addressed on acommunity basis, hence participatory land use planning.

To improve land security aspects surveys, border demarcation and mapping of village landsshould be supported. Land rights should be clearly known to including processing of titles ofownership. Village and District capacity building should be considered to address the problemsand constraints of intermediate target group. Improved revenue collection efficient and costeffective delivery of services are the main issues organizational development and in servicetraining of District Council Administration (DCA) and village level government is essential.Local populations and their local governments representatives are increasingly been viewed as thecustodians of natural resources. Therefore, issues of land tenure are key components of this.Therefore, studies on indigenous knowledge systems in land use as well as evaluation of landtenure aspects are essential in order to develop straggles to empower communities to manage theirresources.

REFERENCES

Allan W. 1965. The African Husbandman Oliver and Boyd, London pp. 505.

Antapa P. L. 1991. Soil conservation measures on the Vertisols of the Hanang Wheat Complex,Tanzania. Paper presented in the annual review meeting on Africaland Management of Vertisols inAfrica held in Nairobi Kenya 4-6 March 1991.

Antapa P. L. and T.V. Angen 1990. Tillage Practices and Residue Management in Tanzania. State ofthe Art. Paper presented to the 3rd Regional Workshop on Tillage and Organic mattermanagement in Humid and subhumid Africa Antananarivo, Madagascar 9-15 January, 1990.

Enwezor W.O., E.J. Udo and N.J. Usoroh 1989. Fertilizer use and management practices for crops inNigeria. Series # 2.

Ensar Rennes 1992. New challenges for soil research in developing countries. A holistic Approach ECWorkshop held in March 1992 in France.

Gosta Ericsson and A. Berger 1995. Agricultural Research in Tanzania. Desk study requested by SIDAto explore possible options for Swedish support to Agricultural Research in Tanzania.

Haki J.M, S.D. Limo and R. Ngatoluwa 1997. An overview of Research Capacity and Activities atSelian Agricultural Research Institute (SARI) in the Northern zone of Tanzania. Paper presented toa workshop on Research support to LAMP in the Tanzania-Sweden Local Management of NaturalResources Program held in Morogoro 16-18 September 1997.

ICCRA. 1991. Analysis of the coffee based Farming systems in Matengo highlands; Mbinga districtTanzania. Working Document series 15 ICRA. Wageningen, The Netherlands. pp. 20.


Ellis Jones, J.Kayombo B. Martin H.L. and H. Dihenga. 1996. What future for the Ngoro soil and waterconservation system. An interim evaluation.

Ministry of Agriculture and the Program office in Arusha. Soil Conservation and Agroforestry Programin Arusha (SCAPA), 1996.

Kirway T.N., S.D. Lyimo, B.W. Rwenyagira, L. Chalamila I. Mshare, and E.J. Mbise, 1997. Research-Extension-Farmer Linkages in Tanzania and the Impact and Future direction of the DRT/ISNERProject on Linkages. Paper Presented to the Regional Workshop on Sharing experiences anddrawing lessons from the DRT/ISNER Project on Linkages held at the White Sands Hotel DSM.27-29 August 1997.

Martin H.L., T.J. Willcocks and B. Kayombo 1996. Technical aspects of the Ngoro/Matengo pit systemof cultivation from the soil and water conservation viewpoint. Proceedings of EnvironmentResearch Project Regional Workshop (ERPRW) Nyeri and Embu Kenya 26-29 May 1996. SRIReport No IDG/96/15.

Mkeni P.N.S. 1996. Salt affected soils their origin, identification reclamation and management. Acompendium of graduate course notes on salt affected soils, Sokoine University of Agriculture,Department of soil Science, Morogoro.

Ngazi H. 1993. Women and soil conservation in Rural Shinyanga. Paper presented to the 18th AnnualGeneral Meeting of the Soil Science Society of East Africa held in Mwanza Tanzania Nov.29 toDec.1993.

Nyaki A.S. 1996. Review of Status of Wheat research and Production in Tanzania. Paper presented tothe Maize and Wheat Prioritization Workshop held in Nairobi Kenya June 10-13, 1996.

Nyaki A.S. 1995. A review of Research Activities in Plant Nutrition in the Northern zone and Proposalsfor future collaboration between SARI and Kilimo/FAO Plant Nutrition Program. Paper Presentedto the Kilimo/FAO Plant Nutrition Program Regional Coordination meeting held in Arusha,September 22, 1995.

Nyaki A.S. 1991. Management of Vertisols in Northern Tanzania in relation to their physical andchemical properties. Paper presented in the annual review meeting on Africaland Management ofVertisols in Africa held in Nairobi Kenya 4-6 March 1991.

Nyaki A.S. 1997. Review and assessment of Kilimo/FAO Plant Nutrition Data in the Northern and Lakezones of Tanzania. Consultant Report for Project GCF/ART/106/NET.

Nyaki A.S., C.J. Lyamchai and H. Mansoor 1997. Status of the current activities in Agroforestry/naturalresource management Research in Northern Tanzania. Paper presented to the Research Planningmeeting of AFRENA-ECA held in Embu Kenya 10-14 February 1997.

Scaglia J.A. 1997. Synthesis of Project Prominent. Findings and Recommendations Consultancy reportfor Project GCPF/URT/106/NET. Kilimo/FAO Plant Nutrition Program in Tanzania.

Semu E. Goran Bergman and E. Skoglund, 1992. A report on Evaluation of the Soil Conservation andAgroforestry Program - Arusha (SCAPA) in Tanzania.

Ugen M.A., P.K. Jjemba and M. Fischler 1992. Farmer Participation in Soil Management Research inMatugga Village (Mpigi district) of Uganda. An Alternative Approach.

Urasa S.J. and F. Isaac, 1997. A survey on fertilizer use survey conducted in Iringa, Mbeya, Ruvuma,Tabora and Arusha Regions of Tanzania mainland. Field Document for Project GCF/ART/106.

Thadei S.Y. 1995. Evaluation of Erosion by Modeling. A progress report Miombo woodland project.Sokoine University of Agriculture.

VSCC. 19997 Annual report.

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Uganda


Uganda has a total area of 236 000 square kilometres out of which 194 400 square kilometres of dryland, 339 226 square kilometres open water and 7 674 square kilometres of permanent swamps. Muchof the country lies on the African plateau at an altitude of 900-1 500 m above sea level (ASL).Towards the South, the characteristic scenery consists of flat-topped mesa like hills and broadintervening valleys frequently containing swamps; towards the north, the landscape is more subduedconsisting of gently rolling open plains interrupted by occasional hills, mountains and inselbergs. Tothe South-west, broken hill country characteristically encircling lowland embayment forms thetransition to the deeply incised plateau that reaches its greatest hill height levels of over 2 000 m ASLin Kabale district. The Rift Valley, which runs near the western border, is represented by two troughs,that of Lakes Edward and George and that of Lake Albert. Between these depressions lies the glaciatedhorst mountains of the Rwenzori Range, rising to the highest peak in the country at 5 100 m.

Uganda's food production has changed very little over the years, especially when compared withpopulation increases of about 3%. Most of the increase has been attributed to increase in area ofproduction by moving in virgin land including forest and swamps. The three major sources of food arecereal crops, root crops and bananas. Table 1 and Figure 1 show the evolution of food crop productionfrom 1987 to 1997: cereal and banana production increased by 48% and by 30.9% respectively, whileroot crops production decreased by 6%. Consequently, total food crop production increased by 18.8%,from 13 219 000 tonnes to 15 703 000 tonnes. In the period 1981-1995 population increased from13.68 millions to 19.57 millions, or 42.9%. Population is increasing much faster than the foodproduction. Since the population growth rate increased from 2.8% (1981-90) to 3.1% (1995-97) thefood situation in the country is likely to become very alarming.

TABLE 1Food crop production 1987-97 (000 tonnes.)Year Cereals Root crops Banana Total1987 1,220 4,960 7,039 13,2191989 1,637 5,474 7,469 14,5801991 1,576 5,268 8,080 14,9241993 1,880 5,417 8,222 15,5191995 2,030 4,849 9,012 15,8911997 1,805 4,682 9,216 15,703

Note: cereals are: finger millet, maize, sorghum, rice, wheat. Root crops are: sweet potatoes, Irish potatoes andcassava

Julius Y.K. Zake, Charles Nkwijn and M.K. MagundaMakerere University, Department of Soil Science, National and Agricultural

Research Organisation KARI

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Bananas occupy the largest cultivated area of all staple food crops and are produced by over 75%of the farmers in Central, Southern and South Western regions of the country. Uganda produces about7.0 million tonnes of bananas annually which makes her the world's largest producer (third monitoringsurvey, 1995-96) and consumer, representing nearly 20% of the total world production (Rubaihayo,1991). Over the last 2-3 decades, however, banana production has stagnated with serious decline in theoutputs and yields. Any increases that have been registered have been largely due to the opening up ofnew land. Thus, banana production has been shifting from its traditional homelands of Mpigi andMukono districts (Central Region) to further west. Because of the dwindling yield of bananas, thepeople in the Central region are now the greatest producers and consumers of cassava and sweetpotatoes, while the Western region is the greatest producer of bananas (Matooke).

There was a sharp drop in the area under cultivation in 1979 and 1980 from which the countryhas still not recuperated. The total area cropped fell from an all-time peak of 5.5 million ha in 1978 to3.5 million ha in 1980. This may be due, in part, to statistical problems associated with thedeterioration of Government statistics collection during the Amin regime. The sharp drop may alsoreflect a one-time adjustment for the gradual decline in area cultivated from 1970 (0.5 ha per caput) to1980 (0.3 ha per caput). Since 1980 the data gathering effort appears to have been more consistent.The area under food crops expanded from 1970 to 1978, and dropped sharply during the war years of1979 and 1980. In spite of rapid growth during the 1980s, areas under cultivation for food have stillnot reached the level of 1976 - 78, and less food is produced per caput, now than in the early 1970s.Despite internal dislocations and economic uncertainty, or perhaps because of them, the area underbananas has increased continuously since 1970 to 1.4 million ha in 1990 at a trend-growth rate of1.8% per year.


A large proportion of Uganda's area can be cultivated. After lakes, swamps and forest reserves areexcluded, more than 75% of the country's 18 million hectares is available for cultivation, pasture orboth. It is not clear what share of this is unsuitable for cultivation. Much further work is needed todetermine what protective measures are justified to ensure that production systems are sustainable. Outof the 17 million hectares classified as arable on a preliminary basis by Langlands (1974), only 4-5

FIGURE 1Food crop production 1987-97 (million Mt)


million hectares are under cultivation. Comparing the 1974 Langlands data on cultivable area andcensus information, rural population density on cultivable land has increased from 53 people per km² in1969 to 88 in 1991. Eleven of the thirty-two districts analysed had a rural population density exceedingtwice the national average in 1969 and 1991. The distribution of these densely occupied areas has notshifted. In Eastern, Southern and Western Uganda, more than half of the districts have a ruralpopulation density of 180 persons per km² of cultivable land. A rough calculation of the share ofcultivable land actually cultivated in each district, based on the cultivation capacity of the rural family,shows that only 30% of total cultivable area are being used. Of the thirty districts reviewed, nineteendid not cultivate 50% or more of the available arable area. These assessments indicate that manydistricts appear to have substantial land of moderate to good potential available land for crop-basedproduction.

With the return of security and stability, and the migration of small farmers from the denselypopulated southwest and northwest into under-utilized zones in the west, the cultivated area willcontinue to be expanded as it has in the past.

An estimated 4.6 million ha were under cultivation in 1990. However, it is likely that the actualarea is somewhat smaller, since there is no registration available indicting percentages of doublecropping and intercropping. Of the total area under cultivation in 1990, 36% was under perennialcrops. Of the 1.7 million ha under perennials about 1.4 million ha was under bananas, and 0.25 millionha was under coffee. Sugar was grown in about 50,000 ha and tea covered about 50,000 ha. Exceptfor about 70,000 ha of cotton and 4000 ha of tobacco, annual crops were all food crops. Of the 2.9million ha in annual food crops, 1 million ha were in pulses and 0.4 million ha in oil seeds. Annualcrops like maize and cassava remove a lot of nutrients and if they are grown yearly withoutreplenishment, the soil would get exhausted. If maize is interplanted with cassava, soil nutrientdepletion would be faster, and yet this is a common practice in Uganda where population density ishigh. Table 4 indicates the amount of major nutrients removed by the major food crops in 1989. In theannual crop zone with a more severe dry season, finger millet has been the staple food but has recentlybeen replaced significantly by maize, cassava and sweet potatoes. These food crops are cultivated inrotation with cotton and groundnuts. Uganda has been a significant oil seed producer, groundnuts andsimsim (sesame) being two major crops. Within the zone, groundnuts have predominated in the east inTeso, Busoga and Bukedi Districts, while sesame is mainly grown in Luwero and Bunyoro Districts.Increase in population growth has accelerated soil degradation, land fragmentation, deforestation andleaching. Sanchez (ICRAF) has shown significant losses of nutrients when the land is cultivated (Table2).

Since Uganda's population has been growing at the rate of about 3% soil productivity should havealso increased at a similar pace. However, agriculture has been growing at the rate of only 1.5% byincrease in the area rather than in productivity per unit area. The highland areas which carry over 50%of the population are therefore threatened by soil degradation due to soil erosion and intensive croppingwithout rotation or addition of manure and fertilizers. According to Bagoora (1988) the areas of higherosion risk lie between 1.500 and 2,500 m. In the Southern and Western crop zone, the main crop,bananas or plantain, is grown mixed with Robusta Coffee on a smallholder family farm. Bananas arethe staple food in this zone. Favourable natural conditions have fostered the development of this systemfor cultivation of these two major perennial crops.

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TABLE 2Comparison of nutrient balances between an undisturbed tropical rainforest and a small farm agro-ecosystem

Nutrient Balance Amazon Rainforest* Kenya Farms **N P K N P K

InputsAtmospheric deposition 6.1 0.2 10.6 6 1 4Nitrogen fixation 16.2 - - 8 - -Organic manure - - - 24 5 25Mineral fertilizers - - - 17 12 2Total 22.3 02 10.6 55 18 31

OutputsCrop harvest removal - 0 0 55 10 43Crop residue removal 0 0 0 6 1 13Runoff and erosion - - - 37 10 36Leaching 14.1 0 4.6 41 0 9Denitrification 2.9 - - 28 0 0Total 17.0 0 4.6 167 21 101

Balance +5.3 0 +6.0 -112 -3 -70Notes: * Oxisol in Venezuela (Jordan 1989), ** Kisii District (Smaling 1993), - Not determined or negligible

TABLE 3Production of cereals and bananas, 1987 to 1997

Year Area underCereals (has)

Total cultivatedland

(000 ha)

Area underBananas

(ha)

Per caputcultivated land

(ha)1987 855 36241988 972 39341989 1079 41481990 1055 4277 15 720 0.271991 1099 4385 16 700 0.261992 1139 4498 17 522 0.261993 1220 4673 18 102 0.261994 1295 4769 18 682 0.261995 1292 4862 19 263 0.25

1996 (Estimated) 1318 4960 19 484 0.251997 (Projection) 1335 5033 20 438 0.25

Increases 56% 39% 30%Source: Republic of Uganda Statistical Abstract 1997

Cultivation of bananas in a well established farm will provide a family with their basic starchrequirements for a lifetime and helps to free the family labour for the cultivation of Robusta Coffee as acash crop. According to Tumuhairwe (1996) most of Uganda's bananas soils are currently of low soilfertility status especially in terms of K, P, N and organic matter. The plateau in the Southern andCentral region which used to be the traditional major banana growing area has now poorer soil fertilitystatus than the highlands in South-western, Western and extreme Eastern regions. Data presented inTable 3 indicates that the area under cereal production increased by 56% over a ten year period 1987to 1997 and the total cultivated land increased by 39%. Since the rate of food production has not copedup with population increase as seen above, it is the increase in area that has mostly catered for theincrease in food production. Accordingly the per caput cultivated land has decreased slightly form 1990to 1997 indicating the trend in land pressure. What is making the situation worse is the tremendousincrease in the cultivated land under cereals which (as seen above, Table 1) tends to lose tremendousamounts of nutrients



Background information

Land is by far the most important natural resource in the country. About 90% of the country'spopulation live in rural areas and directly depend on the land for cultivation and grazing. Most of thesefarmers are engaged in small scale arable and livestock farming. The national average farm holding isabout 2.5 ha and about 8.4 million hectares are farmed annually under small scale agriculture(National Biomass study, 1995; Magunda, 1993). Consequently Uganda's economic, social welfareand its environmental quality depend on effective and efficient empowerment of the resource-poorsmall-scale farmer. Low and insecure incomes at the grass root level leads to inability to promote andapply new technologies (equipment, seeds, soil and water conservation measure etc.). The low incomelevels prohibit the resource poor farmers from hiring additional labour. Consequently most of thelabour is provided by the family with women and children providing the largest proportion. Lowownership of production assets (ploughs, sprayers, shellers etc.) is an additional limiting factor.

The numerous production constraints lead to subsistence farming (low acreage, simple hand toolsetc.) and consumptive spending. Consequently production per unit area is low and the farmers haveremained poor. The current pattern of land management and utilization as well as the increasingdemand for land present numerous environmental problems. Inappropriate farming practices/systemsare ranked second in the underlying causes of land degradation in Uganda; poverty and landfragmentation leading to over exploitation with inadequate soil and water conservation is ranked first.Land degradation is the loss of utility or potential utility, or the reduction, loss or change of features ororganisms which cannot be replaced (Barrows, 1991). Soil degradation is the partial or total loss of theproductivity of soil in quantitative or qualitative attributes. Vegetation degradation is the reduction invigour and/or species diversity or a decline in regeneration which may spread over decades.

Types of soil degradation

Soil erosion is the most important form of soil degradation and a large part of the country has beenaffected to one extent or another (NEAP, 1995). Some of the most seriously affected areas include thesteep slopes of Kabale, Kisoro, Bundibugyo, Mbale and Kapchorwa districts. Even in the relatively flatareas such as Iganga, Kamuli, Tororo and Kumi, soil erosion has occurred at an alarming rate largelythrough rill and sheet erosion and thus leading to gradual but steadily increasing losses in soilproductivity (NEAP, 1995). Soil erosion is very severe in the semi-arid areas of Uganda where fragilevegetation cover has been degraded by over stocking under nomadic grazing. The seriously affectedsemi-arid areas include Karamoja, Soroti, Katakwi, Mbarara, Rakai and North Luwero. These areassuffer from both water and wind erosion. There is extensive wind erosion in Kumi, Soroti, Katakwi,Kotido and Moroto during the dry season because soils remain exposed during prolonged dry monthsafter the cultural practice of uncontrolled bush burning. Apart from the rapid decline in fertility andproductivity of the original land, soil erosion has also led to the siltation of rivers and lakes. In additionto the physical obstruction, the sediment is also rich in nutrients and thus encourages eutrophication.This, in turn, deprives the fish population in these waters of oxygen when the excessive vegetativegrowth decays as a result of bacterial action. This phenomenon is observable in most of the rivers andlakes but more particularly in the Manafa, Kafu, Nyamwamba and the Nile river (NEAP, 1995).Rainfall can be singled out as the most important climatic factor contributing to erosion in Uganda.Several workers (Bagoora, 1990; Tukahirwa, 1996; Magunda et al., 1997) have investigated variousaspects of the causes of soil erosion and made recommendations on remedial measures. These studieshave shown that the soils in the Kabale highland areas (>1500 m a.s.l.) are very stable and exhibit highinfiltration rates (>100 mm hr-1). They have shown that in the highland areas the main causes of soilerosion are a combination of the slope and rainfall factors. Soil fertility decline or nutrient depletion is

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basically due to inappropriate or poor farming practices as explained before. Fertilizer use is restrictedto large estates because the majority small scale subsistence farmers cannot afford fertilizers. Availabledata show that fertilizer consumption in Uganda declined 10 fold between 1962 - 1980, reducing theinput of phosphates (P) and nitrates (N) to virtually zero except in large estates. Quantities of fertilizersimported into the country between 1990 - 1995 averaged 6,000 tonnes per year while quantities ofpesticides and herbicides imported averaged 435,000 litres/year and 105,000 litres/year respectively(Magunda, 1995). These quantities, though increasing, compared to those used between 1962 - 1980,are very low considering that approximately 90% of the population in Uganda is engaged in farming.Besides nutrients depletion through crop harvest, leaching and erosion, nutrients are also lost fast whenhigh yielding improved seeds are introduced without at the same time, introducing appropriate soilmanagement packages. Soil degradation in Iganga District is partly attributed to the growing of heavyfeeder soybean during the Amini era (1971 - 1979) without any fertilizer input or use of rhizobiainoculant. Crops following soybean yielded poorly.

Soil compaction is serious in those districts of Uganda which are over stocked and overgrazed.These are the rangelands or the "Cattle Corridor" districts of Moroto, Kotido, Mbarara. Luwero, andMasaka. These rangelands cover an area approximately 84 000 square kilometres. These areas areseriously degraded because of the high animal population in most areas. The immediate impacts of thehigh numbers are de-vegetation and compaction which subsequently leads to serious erosion. Soilcompaction occurs in most areas where large-scale mechanized farming is practised. It is particularlynotable on large estates where heavy machinery is used for bush clearing and other field operations.This is common in parts of Mukono and Jinja districts, where large - scale commercial sugar canegrowing takes place. Kigumba in Masindi district where large scale mechanized farming has beenintroduced in recent years is also beginning to show symptoms of soil compaction (bulk densities >1.5gm cc-3). The districts of Kumi, Soroti, Katakwi and Lira which were heavily stocked and ox ploughingwas practised also had problems of soil compaction, until the recent rustling that deprived them of theircattle.

Surface crusting is extensive but "salient" in Uganda because many farmers are not aware of itsexistence and effects. Structural and depositional crusts are very prevalent in Uganda although they arenot well documented. Their formation is mainly attributed to poor soil structure (particularly on soilsthat are under continuous cultivation), low organic matter content leading to unstable structure, heavyrainfall providing the required kinetic energy to shatter the soil aggregates or particles, soil managementwith heavy machinery, heavy silt loads in running water (Magunda, 1981). The consequence ofcrusting, is quite severe sometimes and replanting must be done due to the failure of seedlings toemerge through the surface crust. Experience at Namulonge Agricultural Research Institute showedthat cotton had to be replanted on several occasions due to severe crusting (Magunda, 1981). Theultimate consequence of replanting is not only the costs of repeating seedbed preparation in order tobreak the crust, but also the fact that the most optimal planting period is lost.

Waterlogging or the excessive saturation of soil by water is common and severe in most rivervalleys, swamps and areas adjoining lake Victoria and Lake Kyoga, where hydromorphic soils aremost affected. After the peak flood period the soils become excessively dry, compact and crack intolarge lumps especially during the dry season. These areas require ox ploughing or use of tractor drawnimplements because of the heavy nature of these soils i.e. in most cases small-scale farmers, thatdepend on hoes, cannot effectively till these areas because of their high tillage power requirements. Inareas where tillage power is limited these areas are not utilized.


Causes of soil degradation

The causes of soil degradation are complex and involve interaction between several factors. Landtenure and the related socio-economic factors are among the important causes of soil degradation.Close to 40% of agricultural holdings in Uganda are comprised of two or more non-contiguous smallholdings. Furthermore, 85% of the rural households produce both food and cash crops and raiselivestock on holdings of 2.5 hectares. Land fragmentation is most serious in the heavily populateddistricts of Kisoro, Kabale, Mbale, Kapchorwa and Bushenyi. The most notable consequence of landfragmentation is continuous cultivation often without adequate soil conservation or regenerationmeasures. This situation has led to the two major forms of soil degradation - massive loss of soilthrough erosion and rapid decline in soil productivity or nutrients mining. There are nine farmingsystems in the country each with its degradation problems. The magnitude of the degradation in eachsystem is largely driven by population pressure, land pressure and other bio-physical factors. Themajority of farmers have inadequate knowledge of or few opportunities to learn about improvedfarming methods. The lack of exposure to better practices has been blamed on the inadequate/poorextension system.

Overgrazing is extensive in the cattle corridor extending from Moroto and Kotido in the northeast through the flat areas of Lake Kyoga down to the Masaka and Mbarara regions. These areas areseriously degraded because of the high animal population. Close to 70% of the livestock in the countryis in the hands of traditional keepers while the rest is commercial ranching. In these areas overgrazing isa serious problem. Particular areas affected are the counties of Ruhama, Nyabushozi, Kazo, Buruliand the whole of Karamoja region (NEAP, 1995). The resulting effects of overgrazing include soilcompaction, erosion (particularly gully erosion) and the emergence of xerophytic species withsubsequent decline in carrying capacity and therefore low productivity. Although purchased physicalinputs (agro-chemicals, seeds and tools) represent less than 30% of the total cost of crop production inUganda, the current trend indicates that the use of pesticides is becoming widespread.

The recent developments in the cut flower industry, in the last three years, have shown atremendous increase in the use of agro-chemicals on large estate. It is however important to note thatthe small holders have had little, if any, training or skills in pesticide application/ use, storage ordisposal. Overall use of agro-chemicals is still very small and limited to large estates. Acaricides arecommonly used for the control of ticks, especially in the rangelands, however their degradation effectsare localized. While there are several causes of deforestation, the conversion of forested lands intoagricultural areas has been the principle contributing factor to loss of forest cover. Deforestation foragricultural purposes has occurred in gazetted forest areas through encroachment or official de-gazetting, as well as on unprotected public areas. It is estimated that between 1973 and 1986 Ugandalost a net acreage of 256 Km-2 of natural vegetation to agriculture, thus exposing the land to agents ofsoil degradation (FAO/UNEP, 1993). The seasonal burning of grass and bushes occurs widely inUganda and carried out as part of land preparation for cultivation or for rejuvenation of pastures or tofacilitate hunting of game. The exposed land, after burning, is subjected to wind erosion during the dryseason and water erosion on the on-set of rains. This cultural practice is widespread in Uganda but isparticularly intensive in eastern Uganda in the districts of Kumi, Soroti, Katakwi, Moroto and Kotido.

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Severity of soil erosion in Kabale Area

Kabale area is taken for the assessment of the extent and severity of one form of degradation - soilerosion. Erosivity of the rainfall, steepness and length of slope, vegetation cover and land managementinfluenced by anthropogenic factors are the most important factors that influence the amount of run offand soil erosion in Kabale. Several workers (Bagoora, 1990; Bagoora, 1993; Tukahirwa, 1996) havecarried out assessment of causes and effects of soil erosion, in Kabale district, with the aim ofproviding information for the design of more accurate conservation policies and strategies. Bagoora(1993) obtained very high erosion values of 106.08 g per M-2 soil loss in a single rainstorm on arecently opened plot on a valley side slope (14.3o). Tukahirwa (1996) on a different site found low runoff and soil loss (run off was 6.25, 14.83 and 13.76 mm per ha per year and soil loss was 1.4, 38.29,and 19.40 tons per hectare per year) on 10%, 25% and 45% slopes respectively. Under green houseconditions with simulated rainfall Magunda et al. (1987) obtained 0.19 kg/ M-2 soil loss on 5% slope ina storm of 63 mm hr-1 of a duration of one hour; this was on a Palehumult soil from Kachwekano. It isimportant to note that none of these workers addresses the economic impacts of this mode ofdegradation.

Soil erosion estimates extrapolated from the run off plot studies have over estimated the actualmicro-catchment soil loss. Data on the different forms of degradation are very scanty in Uganda.Consequently there is hardly any data on economic analyses of degradation. Yields have beenquantified on plots under different management practices in soil erosion studies but detailed economicimpact assessments have not been carried out. Accessing data in Uganda is further complicated by thelack of databases in the relevant line institutions handling natural resources management research.Information dissemination is still very poor in Uganda.

Socio-economic constraints for the control of soil degradation

In situations where farmers have no permanent title to land, there is a reluctance to adopt improvedland management and conservation practices. The less secure the land ownership the greater thetendency for the farmers to exploit it using non-sustainable practices. Credit is often unavailable totenant farmers and consequently they are unable to invest in new seed varieties, agrochemicals and newtechnologies. In the Central Region the majority of land operators are tenants since also womentraditionally were not supposed to possess land titles, gender has something to do with poor landmanagement and soil conservation.

Increasing population. Population growth increases the pressure on the land. In the absence of soundsoil management practices and adequate amounts of inputs, the soil is "mined" of its nutrient contentand eventually becomes unproductive. The Eastern and Western Regions are very highly populated andsoil degradation is quite extensive in these areas as well as in the Central Region. The Northern regionwhich is not so densely populated is less degraded.

Poverty in rural areas. Most small-scale farmers produce at the subsistence level using very lowinputs of external resources. Yields are often poor and farm incomes are too low to sustain the family,let alone to maintain the resource options for maintaining soil fertility using crop residues which areseverely constrained by competing uses for a scarce resource. Presently poverty has deepened in thecountryside as agricultural productivity dwindles.

Awareness. Farmers may be aware of declining soil productivity as indicated by reduced yields butthey may have no knowledge of improved methods of soil management. They would have used some ofthe locally available inputs to rehabilitate the degraded soils.

Technology transfer. Effective research and development in agriculture involves vertical and horizontaltransfers of information. Vertical transfers involve the flow of information from the farmers to


researchers and back to the farmers through extension services. Often research priorities have not beenset with a clear appreciation of farmers' needs and constraints. The horizontal transfers involveexchange of information between the farmers and between African states of experiences and solutionsto common problems. This can be achieved through conferences, workshops, scientific exchanges andinformation media. Transfers of new technologies from advanced research institutions outside theAfrican sub-region must also involve assessment of their applicability to local agro-ecologicalconditions.


There are a number of technologies existing in the country, which can be used to combat soildegradation. What is required is awareness through various media and demonstrations.

Use of chemical fertilizers. Data shown in Table 4 indicate that Uganda uses very small amount ofchemical fertilizers despite the fact that allot of nutrients are lost through crop harvest. This is sobecause fertilizers are expensive (on average shs 600/= per kg) and there is a very strong campaign bypoliticians and NGOs against the use of chemical fertilizers in preference for organic farming. As aresult, some farmers even fear to touch fertilizers. Presently it is only commercial farmers who usechemical fertilizers, yet these fertilizers give very good responses when used properly. For instanceZake et al (1996a) reported an increase of 125% for the yield of bananas by using only 25 kg K/ha ofmuriate of potash.

TABLE 4National consumption of N1, P2, O5 and K2O in selected years from 1962 to 1988

Year N P2O5 K2O Total1962 1200 1100 300 26001964 1500 1200 500 32001966 1864 1500 1000 43641968 1709 1327 740 37761970 2220 1150 1200 45701972 4400 2500 1200 81001974 4000 2400 787 71871976 872 660 157 16891978 300 500 300 11001980 0 0 0 01982 500 100 0 6001984 0 0 0 01986 200 0 0 2001988 500 0 0 500

Organic-inorganic fertilizer combinations. This is one of the most important options in controlling soildegradation and also in enhancing productivity. It may be used in different soils. The Levels ofcombinations may vary according to soil type, crop and nature of organic matter. Zake et al (1996)obtained different combination results in different places using coffee as a test crop. Treatmentsconsisted of four levels of coffee husks, 0, 5, 10, and 15 t/h a represented as OM1 OM2, OM3 andOM4. N, P, and K were applied in the form of N:P2O5: K2O fertilizer, at rates 0:0:0, 14:100:30,80:200:60 and 120:300:90. These were symbolized as NPK1, NPK2, NPK3 and NPK4. It is especially,convenient with organic matter of high C/N ratio and also moderates the unfavourable properties ofchemical fertilizers. Ashes normally lack nitrogen, whereas cow dung is deficient in phosphorus. Acombination has been found effective in the production of bananas. This technology is common where

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bricks for building are fired, using a lot of firewood. Phosphorus rock with composts manure - usedaround the source of the rocks; it has been found effective in increasing the availability of phosphorus.

Since Uganda mostly use fresh food e.g. bananas, potatoes, cassava, fresh maize, vegetables andfruit, there is a lot of urban garbage which tend to cause health hazards. Composting the urban wasteshas contributed to the food productivity in some of these areas. In the city of Kampala alone over 1 000tonnes of garbage are produced every-day.

Appropriate placement of organic material Depending on the texture of the soil, different crop yieldshave been obtained according to whether the organic material was applied on the surface, completelyincorporated or half incorporated and half surface applied (Zake et al., 1996a). In heavier soils, thereare advantages of incorporating some organic materials into the soil, especially around Lake Victoriaarea (Figure 14, Zake et al.,1996a). Use of organic mulching materials Different mulches have beenfound to give significantly higher yields of bananas compared with the control, but live mulches whenpermanent in perennial crops may depress yields (Zake et al., 1996a). Mulches are used widely inbanana growing areas.

Integrated Pest Management-IPM Rubaihayo (1992), indicated that some of the reasons for thedisappearance of bananas from around Lake Victoria to Western Uganda were because of extensiveinfestation of weevils and nematodes as well as soil nutrient depletion. Many farmers are now usingconcoctions of various herbs, animal urine, wood ashes and hot paper. This has a dual action of killingthe diseases and pests as well as providing the major nutrients especially N and K. This technology wasdeveloped and it is being extended by farmers themselves.

Crop Residue Management. The objective of this technology is to harvest the minimum and leave inthe field all the rest. This is in response to burning the crop residue or putting it at the boundaries aspart of clean weeding. Before this technology is recommended the problems caused by diseases andpests should be watched.

Green Manuring. Inoculated legumes are turned into the soil before flowering. This protects the soilwhen the major crop is harvested and increases the level of nitrogen. Zake (1988) and Wortmann et al.(1994) have demonstrated the use of this technology in Uganda.

Inoculated legumes together with phosphorus Rock Since the application rate of phosphorus rock ishigh, this technology is convenient for use in areas near the source of the rock, such as Tororo nearSukulu rock and Mbale near Busumbu rock. Zake (1988) obtained promising results using thistechnology which would avail both nitrogen and phosphorus to crops.

Biological Nitrogen Fixation as a low-input technique. The Department of Soil Science, MakerereUniversity, produces rhizobia inoculants for various legumes. It also exports some to Rwanda.Locally, this technology is slowly picking up for use in producing soybean, beans, groundnuts and treecrops. The major concern is that the technology does not work well for beans which are the mostwidely grown legume in the country. However, this technique provides feasible crop management thatincreases legume crop yield and crop residue. The cost of rhizobium packets required to inoculateseeds enough to plant a hectare of land is U.Sh 4800/= compared with the cost of a 50 kg bag of Ureaof U. Sh 28,000/=. Nkwiine et al. (1993) have obtained good results in BNF technology.

Appropriate tillage and surface management For lighter soils there is minimum or zero tillage whilefor heavy soils such as Vertisols there is deeper regular tillage requirement (Zake 1993). In heavy soilsmany farmers are aware of higher yields after tractor ploughing.

Water harvesting. Various methods of water harvesting have been used, especially in places whichexperience drought or in places with heavy surface soils such as Vertisols.


Improved fallow. The traditional fallow period takes many years for the soil to recover the depletednutrients and organic matter. With improved fallow there is an inclusion of inoculated leguminous treeswhich help to increase the level of nitrogen in a short period. The fallow period in this case may be onlythree years. This technology is becoming popular in the Western highlands of high population.

Animal - Crop (Cereal) - Forestry farming system. The forestry trees are normally leguminous shrubswhich can be fed to animals (cattle, goats) and the manure from the animals is put into the crop field. Inthe peri-urban area where zero grazing is practised, this system is becoming popular.

Agroforestry. A combined stand of plants of different growth habits and phenotype. Mechanical soilconservation measures such as contour bunding, contour trenching and bench terraces have not beenwidely adopted by small-scale farmers in tropics because of high installation and maintenance costsand lack of short-term benefits. Yet some agroforestry techniques have great potential for soilconservation and the scope of their adoption is also high because they combine production with soilprotection. The relevant technologies for sub-humid to humid tropics are: Contour (or barrier)hedgerows on sloping lands, trees on conservation structures, and multi-strata systems (Rao 1994). InUganda a number of these techniques are used in the Western region.

Appropriate intercropping. This provides balanced nutrient uptake from different soils horizons and amore continuous ground cover, protecting the soil against erosion.

Alley cropping. Farmers' acceptance of this technology is limited because of the loss of income fromthe space taken by the hedgerows and lack of returns from the efforts required to maintain thehedgerows.SUCCESSFUL CASES OF IMPROVED SOIL MANAGEMENT

The Nangabo Farmers Association is an association which was set up by the local farmers inNangabo Sub-County, Mpigi district. The county is situated around 15.5 kilometres north east ofKampala. The members of the association practice all types of occupation including someprofessionals. The majority of the Nangabo people (60.8%) get their income from agriculture.About 70% of farmers have less than 2.5 hectares of land per household. Very few farmers(9.9%) have 5 or more hectares of land. However there is a ready and near market foragricultural products in Kampala City. The majority of the farmers (98%) grow root crops,followed by legumes (88.2%) and third was bananas (86.3%). Many farmers kept poultry(64.7%) followed by those who kept cattle (49%) and third animal type kept are pigs (41.2%).Many farmers are knowledgeable of the soil management practices like mulching, crop rotation,land fallowing, construction of soil bunds and furrows, and use of inorganic and organicfertilizers. It is indicated that farmers who practice the soil management practices range between40% to 83%. The least practised soil management practice being the use of inorganic fertilizers(41.2%); very small percentage of farmers did not practice and did not know the practices.

In order to benefit to develop agriculture in their area, farmers of the sub-county set up theirassociation with three objectives: to be self sufficient in food especially to be able to once againgrow the liked staple foods for example bananas, to alleviate poverty through agriculture and tosustain production without damaging the environment. The strategy laid by Nangabo farmers todevelop agriculture in their area : mainly persistent in farming business, effective cooperation,proper leadership of their association, accessibility to practical agricultural information andpractising good farming systems according to agricultural information obtained from differentsources. Agricultural Programmes of Nangabo Farmers Association have been successful mainlybecause of efficient association of farmers with active farmer participation in the diagnoses andimplementation. Exemplary leadership (i.e. leading people in what you are also practically doing)or farmer to farmer extension has contributed much to the success. Raising awareness of farmers

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in seeking for agricultural information is also identified as a requirement for development ofagriculture. Radio programmes as source of agricultural information in this case is very effective.In fact when we discussed this Mrs. Ruth Nsubuga Nalongo, 55 years old of Katta village,Nangabo, praised the agricultural radio programmes put on Radio Uganda. She could notimagine missing any of them. Her problem was to get constant availability of dry cells for herradio. The members of the association have benefited from agricultural radio programmes to theextent that the association now has a weekly radio programme to inform the members and otherpeople from other districts.


Institutions

The ministries and institutions having something to do with conserving soil degradation are thefollowing:

• Ministry of Agriculture Animal Industry and Fisheries which is the ministry responsible for policyformulation regarding crop production, strategic planning, management systems reform andinformation strengthening. The Ministry also supervises the National Agricultural ResearchOrganisation (NARO), responsible for national agricultural research.

• Ministry of Natural Resources. The role of the environmental protection department in relation toagriculture is, among other tasks, to co-ordinate inter-disciplinary activities with the responsibilityto monitor the use of chemicals and fertilizers, to advise on their effects and to assess theenvironment impact of all projects.

• Ministry of local Government. The 21 000 kilometres of rural feeder roads, essential fortransportation of agricultural products to domestic and export markets are responsibilities of thisministry through its objective administration..

• Ministry of Trade and Industry, responsible for developing marketing policies for various crops.Movement permits to traders and internal marketing are controlled by the various authoritieswithin the ministry.

• Ministry of planning and economic Development. Since Agriculture is the main foreign exchangeearner; this ministry is central in overseeing agricultural productivity together with the Ministry ofFinance. The Uganda National Council For Science and Technology is under the Ministry ofPlanning.

• Uganda Commercial Bank. In addition to banking, the bank undertook agricultural lending throughRural Farmers Scheme. This scheme however, has not produced the desired effects.

• Makerere University - Faculty of Agriculture and Forestry - also carried out agricultural researchand extension. It should be noted, however, that the University is under the Ministry of Educationand Sports.

In the East Africa region the soil Science Society of East Africa was set up over twenty years agoand scientists have been meeting yearly rotating in the East African Countries of Kenya, Uganda andTanzania. A lot of soil information in the region is contained in the proceedings which are compiledafter each conference.

The African soil science society was also started in 1988 and so far two conferences have takenplace. A number of local journals also exist in different countries, regions and continentally. All these,however, are spoiled by the acronym "Publish or perish". The researchers' only objective is to publish


at any cost, without regard to the impact of the end-users of new technologies, the farmers. Over 99%of the farmers are usually not aware of the published information. Moreover, it is not clear whether thisinformation is applicable to the farmers' situations.

Land Reform Law. The Parliament of Uganda is currently debating the Land Reform law with theobjective of giving peasant farmers Land security. This is supposed to limit the subdivision ofagricultural land in unprofitable units. It will also ensure commitments of the farmers to the issues ofsoil conservation and rehabilitation. However, this issue is very delicate and it may take several years toreach a consensus. Since the poor tenants may have to pay the land lords to obtain the land titles.

Policies

Before Independence in 1962, Uganda had very effective soils policy and both soil conservation andsoil productivity were very high. There were strong decentralized systems of political administrationand there were bye-laws in each district pertaining to soil conservation and crop productivity. Chiefswere responsible for enforcing the bye-laws. When the bye-laws were broken, the offenders receivedstandard punishments just like for civil offences, since the same chiefs were also responsible forenforcing other social obligations such as collecting taxes, maintaining roads and ensuring properhealth. Therefore both soil conservation and crop productivity were considered as civil obligations bythe people; that is why the public responded positively. It is true force was used. After Independence,however, the political system changed towards very strong central governance. There was anemergence of agricultural extension officers replacing the chiefs in enforcing the bye-laws, but not inpunishing the culprits. These officers drew their authority from the centre in Kampala. Consequentlyboth soil conservation and crop productivity collapsed. With the emergence of concern over theenvironment regarding natural resources and concern over local administration, there are differentorgans of Government responsible for these areas. There is therefore often, general lack of co-ordination of activities between various departments of the ministries and between land-use relatedinstitutions, NGOs and agencies. This adversely affects the development of effective land-use policieswithin the country. Consequently there is often duplication of research efforts and the development anddissemination of different technological packages on similar topics to the same target group of farmers.The latter group often gets confused and the desired goal of improved management practices isdefeated.

The Agricultural Development strategy of the Government are:

• Increase agricultural productivity, especially in food production, raising incomes and preventingexpansion into marginal agricultural lands,

• Diversify the production base and reduce the heavy dependence on coffee for exports andgovernment revenue.

• Raise yields by the adoption of appropriate technology through strengthened agricultural researchand extension institutions,

• To promote self sufficiency in food.

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Inventory of resources

A semi-detailed survey should be conducted at national, and if possible, at finer scales in order toquantify the magnitude of resource degradation, and to assist the extrapolation and improvement ofmanagement practices. Rapid reconnaissance surveys are needed to collect data on the circumstancesof farmers and resource utilization within their farming systems, as well as external sources ofinorganic fertilizers, pesticides and organic matter. After the initial inventory is obtained, there shouldbe periodical monitoring of soil degradation through crop yield, soil analysis and vegetative cover data.

Stream lining research and extension system in the country and in the region

Agricultural research is the responsibility of NARO, Parallel to this, there is a strong research systemby the University. These two bodies are linked loosely. Above these bodies there is the NationalCouncil for Science and Technology. The Ministry of Agriculture Animal Industry and Fisheries,however, does not house the National council for Science and Technology. There should be a clearNational Vision, Mission, Strategy and objectives for agricultural research at any one time. This shouldbe set from the top and the bodies below should realign towards the national strategy. In order to avoidduplication of research and conserve scientists, the University agricultural research system should bemore strongly linked with the national research system. Extension should be integrated in the varioussections of research just like the Land Grant colleges of the United States which incorporate nationalresearch, extension and training. Dissemination of research findings has always been the responsibilityof extension staff. There should be a stronger linkage between the researcher, the extensionist, theadministrator and the farmer, in every section of research envisioned by Cecilio R. Arboleda (Figure18). The role of opinion leaders should be emphasized in research formulation and extensiondissemination of results. That is why pre-independence extension by chiefs was very effective sincethey were respected by society. International organizations should be asked to facilitate networkingamong African Scientists and between African and non-African Scientists in the provision of facilitiesfor publication and bilingual translations in the compilation of electronic data bases on relevantinformation and provision of exchange opportunities among African Scientists. They should alsosupport the regional and continental scientific conferences. In fact Networking is the most cost-effectivemeans of collaborative research. It helps cooperators to identify their priority targets and it is the mostcost effective way of tackling research problems (Plucknett et al. 1984 and Greenland et al. 1987).

Training for improved soil management and sustainable agricultural productivity

Many institutions of higher learning have abolished the Departments of Soil Science. They are nolonger effective in combating soil degradation. Suggestions. Institutions should be created toencompass soil science. Such studies as agronomy, animal science and forestry should be attached tothe studies of soils. The naked expansion of the subject of soil science is making the students of soilscience redundant. In this respect the University of Philippines, Los Banos, has proposed the cluster ofthe Institute of Agricultural Resource Management to include soil science, farming systems andmeteorology. To isolate soil science as a separate study eliminates its attention to the public. It shouldtherefore be initiated in all sectors of study pertaining to the public. Another reason why soilconservation and food productivity succeeded before independence is that these areas were regarded asamong other social aspects of society. A new area of study “social soil science" should be emphasizedin the curriculum just like social forestry is succeeding in maintaining forests.


Introduction of new technologies to the farmer

When introducing new technologies, there should be several of these technologies including the use oflocally available materials. It is not necessarily the technology that gives the best results that should beforwarded. The new technologies should start with the use of the ones which are partly familiar tofarmers. This makes innovations more acceptable than would be the introduction of completely newones at a go.

Liaison between National Research System and IARCs

It is cost-effective for Uganda to have appropriate updated information from IARCs tested andtransferred to the farmer as soon as possible. It has been observed that many technologies developed bythe IARCs have as yet had very little impact in Uganda in contrast to some other countries in Africa.Therefore, it is recommended that a post be created in NARO to be responsible for contact with IARCsin order to be constantly aware of the latest available technologies for possible adoption trials andeventual use in Uganda (Hartmans 1989).

Soil science

Soil Science is increasingly becoming a theoretical discipline rather than a field one. Every year thereare volumes of books and articles written on such subjects as nitrogen, phosphorus, potassiumequilibrium, CEC, synchrony etc. without any additional field impact. Although there are no availabledata, it is right to estimate that only about 1% of what is written and discussed in conferences yearlyactually pertain in the field, in developing countries. In fact many soil scientists have acquired theirexpertise only by writing about rather than by influencing the management of the soil. it is high time thepractice of soil science also acquired as much recognition. Some professional soil scientists should beencouraged to partake field experiences on a commercial basis and more funds be devoted to observingand understanding success stories especially of small scale farmers.

There should be establishment of Soils Laboratories in the different ecological zones as a basis forresearch work in soil structure, soil biology and fertility problems. This will also help in appropriaterecommendations to the farmers.

Research

Long-term fertilizer usage for perennial and annual crops. There are currently only relatively long-termprojects on banana and coffee management at Makerere University Agricultural Research InstituteKabanyolo (MUARIK). The Banana research started in 1992 and it is testing different mulches,fertilizers and different application practices of coffee husks. The Coffee research is testing sevendifferent soils inputs including locally available low-input ones. This will avail several soil inputoptions to the farmer. One new research for annual crops should be started to rotate maize in the longrain season with beans in the short rain season. This will give information on the rate and level of soildegradation under annual crops management. Research to test the interaction of inorganic fertilizers-organic matter and lime in different soils of Uganda. This is to respond to the current soil nutrientdepletion, soil acidification making P unavailable as seen earlier, organic matter depletion and soilcompaction. The output of this research will be appropriate soil management and use of locallyavailable material in the case of organic matter. The degraded soil will be rehabilitated.

Study on Soil Rehabilitation and soil fertility Management under Intensive cropping in Uganda: Asthe population increases, the traditional method of rejuvenating soil fertility through shifting cultivationcan no longer sustain crop productivity. On the other hand the popular low input -agriculture cannotsustain intensive soil productivity especially with high yielding crops. However, chemical fertilizers

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alone may acidify the soil, cause soil physical problems and pollute the environment resulting intobiodiversity imbalance. Therefore a long-term solution in necessary which increases soil productivitywithout damaging the environment.

The proposed Study has the following objectives :

• to provide balanced soil inputs that are based on locally available materials which wouldameliorate soil fertility on a long-term basis without damaging the environment,

• to avail to the farmer several soil ameliorating options.

The scope of the Study is to provide fertilizer recommendations that shall be location specific. Thequestion should be not what the optimum application rate is but rather how little fertilizer is enough.The research should involve the farmer in deciding on the different option combinations in aparticipatory manner after both the researcher and the farmer have agreed on the nature of the soilproblem. The methodology would be as follows:

• Recognize the nine Farming Systems identified in Uganda.

• In each zone detailed soil and social economic surveys will be carried out to give: a) soil statusaccording to the researcher and according to the farmer, b) dominant crop residue or organicmatter resources e.g. green manuring materials, Coffee husks, water hyacinth, rice husks etc., c)identification of other soil resources available in the area e.g. phosphate rock, peat, wood ashesetc., d) identification of major cropping systems, e) identification of gender biases in farmoperations;

• Treatments will involve interacting organic materials in the area with non-organic materials basedon those locally available, but usually to include low rates of NPK.

• There will not be more than four treatments for each farmer including the control; but farmers willbe able to opt for the suitable combinations deemed necessary by the farmers themselves;

• Awareness sessions will be carried out for the existence of a number of options at the disposal ofthe farmers including the existence of new technologies such as biological nitrogen fixation,composting, green manuring and mycorrhiza. New practices such as planting in raw, properspacing and water harvesting will also be pointed to the farmers;

• Monitoring of the effects of the new approach will be made every year.

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Bagoora, D.F.K., 1990. Soil erosion and mass wasting risk in the highland area of Uganda. Africa Mountainsand Highlands, Problems and Perspectives. Messerhirwa, B. and H. Hurni (ed.). African MountainsAssociation, Walsmorth Press. USA. pp 133 - 135.

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Sanchez P.A. Tropical Soil Fertility Research: Towards the second Paradigm. ICRAF. P.O. Box 30677,Nairobi, Kenya. Ovational Paper.

Third Monitoring Survey, 1995-96. Ministry of Planning and Economic Development Statistics Department.Draft third Monitoring Survey, 1995-1996 (Crops)

Tukahirwa, J.M., 1996. Measurement, Prediction and Socio Ecology of Accelerated Soil Erosion in KabaleDistrict. Ph.D. Thesis, Makerere University.

Tumuhairwe J.Y. 1996 Soil Fertility Status of Banana growing Areas of Uganda. Paper presented at the firstInternational Conference on Banana and Plantain for Africa, 14-18th October 1996, Kampala, Uganda.

Wortmann, C.S. Isabirye, M., Musa, M, 1994. Crotalaria Ochroleus as a green manure crop in Uganda.African Crop Science Journal, Vol. 2 No. 1 pp. 55-61.

Zake, J.Y.K. 1988. Research an application of Tororo rock phosphate as a fertilizer in Ugandan soils. UnitedNations commission for Africa. A paper presented during regional conference on development andutilization of mineral resources in Africa, Kampala, Uganda June 6-15 1988.

Zake J.Y.K 1993 Tillage systems and Soil Properties in East Africa. Soil and Tillage Research (1993) ElsevierScience Publishers B.V. Amsterdam.

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Zake Y.K., D.P Bwamiki and C. Nkwiine 1996a Soil Management Requirements for Banana Production onthe Heavy soils Around Lake Victoria in Uganda Paper presented at the First International Conference onbanana and Plantain for Africa, 14-18th October 1996, Kampala, Uganda.

Zake J.Y.K; D.P. Bwamiki and C. Nkwiine 1996 b Potential for organic and Inorganic Fertilization forsustainable Coffee production in Uganda. In Improving Coffee Management Systems in Africa.Proceedings of IACO workshop, Kampala, Uganda. 4-6 Sept. 1995.


Zambia


Zambia covers about 752 600 square kilometres. A large part of Zambia is on the central Africanplateau between 1 000 and 1 600 metres above sea level. Although Zambia is tropical, temperaturesare modified by altitude. Zambia is subdivided into 36 agro-ecological zones; these have been groupedup into three agro-ecological regions mainly on the basis of rainfall. Region I covers the semi-arid, rifttrough areas of Zambia, largely the Luangwa, Lunsenfwa and Zambezi valleys, the low altitudeplateau areas in the south and south-west, that is Sesheke and the Senanga west. The region ischaracterized by high temperatures, high evaporative losses and a short growing season due to low andpoorly distributed rainfall of less than 800 mm. Region II includes the entire plateau stretching fromEastern through Central and Lusaka Provinces to the Western and also covering Southern Provinces.This region has an annual rainfall ranging from 800 - 1,000 mm. Region IIb consists of the Kalaharisands area. Region III is popularly known as the high rainfall area. This covers the Northern, Luapula,Copperbelt, North-Western and part of Central Provinces. Annual rainfall ranges from 1 000 – 1 400mm.

Zambia has a rapidly-growing population. In 1990, the population was 7.8 million and the annualgrowth rate was about 3.2 percent (Population Census 1990). At that growth rate, the population in1995 is estimated to be 9 million. By 2010, it could be 14.6 million, unless there is a reduction in thegrowth rate. About 43% of the country’s population were classified as urban in 1990, and theproportion is projected to increase to between 50 and 60 percent by 2006 (Ndiyoi and Tembo, 1995).The growth rate of Zambia’s agricultural production has not kept pace with population growth inrecent years. Accordingly, the country faces serious and chronic food deficits in the coming yearsunless measures are taken to reverse the adverse trends. The country has faced food deficits in thepast, mainly as a result of droughts. Equally, low food production especially cereals, havedropped in response to unfavourable agricultural policies. These drops in food production havenot been matched with the country’ population growth. In the period 1992-94, the total value offood imports was 47.1 million US dollars. In the same period, the country received 795 077metric tons of food aid in 1993.

The 1992 drought highlighted the vulnerability of the country’s food supply to rainfall whilethe 1993 bumper harvest equally underlined the role of policy and institutions on agriculture.Assuming that the population continues to grow at the current rate of 3.2%, Zambia wasexpected to produce 1.5 million tons of cereals in 1996, rising to 2.0 million tons in 2006. Thismeans that by 2006, the country’s cereal demand is projected to increase by 41% from thecurrent level (Ndiyoi and Tembo, 1995).

Nawa Mukanda and Douglas MoonoMt. Makulu Research Station, Chilanga

and Golden Valley Agricultural Research Trust, Chisamba

Zambia338

In contrast, the projections of current trends indicate a cereal production increase of only3%. In particular, using similar assumptions, national maize demand is projected to rise by 37%between 1996 and 2006, whereas total maize production is projected to decline by 2% in the sameperiod. Cassava is the third most important food crop in Zambia after maize and sorghum. Likefor maize, the demand for cassava is projected to rise by 37% from 247 000 Mt. in 1996 to 339000 Mt. in 2006 while production in this period is projected to increase by only 2%.

The projections suggest that unless prompt measures are taken to increase food productionrapidly, the periodic food deficits observed could become chronic during the next decade andwould need to be offset by food aid or commercial food imports on a large scale. Maizeproduction figures and demand trends are presented in Table 1 and in Figure 1. Much ofZambia’s land is grossly under-utilized. Of the country’s total area of 753,000 sq. km, almostone-quarter (about 18 000 000 ha) is considered arable, but only 11 percent of this is croppedannually. Unfortunately, the population increase over the years has depended on this 11 percentcausing land pressure. From 1990 to 1993, the agricultural sector’s contribution to GDP atconstant 1977 prices was estimated at 15%, 16%, 11% and 16% respectively. The estimatedGDP for the same period at current prices was 15%, 16%, 18% and 23% respectively.

TABLE 1Maize production and demand trends in Zambia (tonnes)

Year Estimatedpopulation

Maizeproduction

Maize trendwithout NAP

Maizedemand

Improvementrate

Maizeproductiontrend with

NAP1984 6 456 786 871 740 1 246 186 891 0371986 6 876 632 1 230 594 1 228 592 948 9751988 7 323 779 1 943 219 1 210 997 1 010 6811990 7 800 000 1 092 671 1 193 403 1 076 4001992 8 307 187 483 492 1 175 809 1 146 3921994 8 847 354 1 020 749 1 158 215 1 220 9351996 9 422 644 1 409 485 1 140 620 1 300 325 0.000 1 140 620.461998 10 035 342 1 123 026 1 384 877 0.054 1 186 740.292000 10 687 880 1 105 432 1 474 927 0.147 295 329.392002 11 382 849 1 087 838 1 570 833 0.245 1 440 728.772004 12 123 007 1 070 243 1 672 975 0.332 1 602 085.822006 12 911 294 1 052 649 1 781 759 0.409 1 781 095.78


Maize, rice, wheat, other cereals (sorghum, bulrush millet, finger millet) and cassava areZambia’s staple food crops. Maize generally accounts for 60 – 70% of the total cropped area andfor over 90% of total cereal production. National area and production figures for important cropsare shown in Tables 2 and 3. The tables given below show that production of staple food cropshas varied greatly over the past decade. Contributory factors have been variations in annualrainfall and its seasonal distribution, and changes in economic policy. The production of cerealsfell below potential demand in half the years of the past decade, but there was a surplus of morethan 70% in 1988, a year with good rainfall and favourable prices. On the other hand, in 1992,severe drought caused a deficit of more than 50%. The food production and consumptionprojections shown in Figure 1 are based on historical trends. However, their relevance for future


planning has been thrown into question by the effects of market deregulation since 1992. The1995 trend appears to indicate that the production of maize, wheat and rice are to decline and forthose of sorghum, millets, soybeans(plus other legumes), and possibly cassava to increase.

TABLE 2Crop production (hectares and tonnes) in 1987/88 and 1993/94

Crop Maize Sorghum MilletSeason Area Production Area Production Area Production1987/88 753 244 15 526 831 33 964.5 214 534 35 462 279 9511993/94 679 356 55 245 82 302

TABLE 3Maize production and fertilizer application, 1996/97

Fertilizer application (kg)Province Area planted (has) Production(90 kg bags) Basal Top

CentralCopperbeltEasternLuapulaLusakaNorthernN-WesternSouthernWestern

93 45539 266

198 99617 36626 98045 70325 216

158 75743 330

1 703 611590 023

2 756 589375 628493 924

1 080 54425 094

2 799 285444 037

3 805 551934 340

1 970 979962 932873 425

3 183 157307 711

4 531 688704 938

3 9831 442 6

2 306 786994 082

1 196 5202 999 560

397 3844 356 179

764 116

Tables 2 and 3 show very serious inconsistencies particularly for maize production. Twoareas of interest can be compared here. These are Regions II and III. Region II has been the grainbasket of Zambia, mainly represented by central, eastern and southern provinces.

FIGURE 1Maize production and demand trends in Zambia

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After independence in 1964, the Zambian government popularized maize production to thepoint where monocropping in Central, Eastern and Southern Provinces became the norm. Thisresulted in serious soil degradation. Over the years, southern province slowly lost its number oneposition in maize production mainly due to soil mismanagement as we have already seen underanother chapter of this report. Over just an eight or nine year period from 1987 to 1996/97 botharea planted and production have slowly but steadily been declining in Region II. For example,area planted under maize in central, eastern and southern provinces in the 1987/88 season were119,047, 344,986 and 155,757 ha respectively; in the 1993/94 season the figures were 161,208174,816 and 130, 745 ha respectively.

In a summary form, Table 4 below gives areas planted under maize for 1987/88, 1993/94and 1996/97. It is clear that things are happening in both central and southern provinces. Thedeclines per caput cultivated land and maize yields are mainly due to two main factors: reactionto unfavourable agricultural policies and general land degradation. The main causes to the declineper caput cultivated land and cereal yields in Central, Eastern and Southern provinces are thehigh population growth rates; poor cultural practices such as low plant density, late planting,untimely weeding, poor crop cover, inappropriate tillage practices and tillage equipment; declinein soil fertility, soil erosion; frequent droughts, deforestation and inadequate financial services tosmallholders. These have brought about a general decline in cropping land area per farm familyand decline in crop yields and general land degradation. The major effect of these problems inZambia has been widespread household food insecurity and poverty.

The trends observed in Region II are supposed to be the opposite of those in Region III.Region III is characterized by high rainfall, and historically the region has not been a major maizegrowing area. But over the years, especially following the popularization of maize, there has beena steady increase in both area planted and production. Table 5 below give a summarized pictureof maize production in the four provinces of Region III.

TABLE 4Maize production areas (ha) and production figures (tonnes) in Central, Eastern and Southernprovinces, 1987/88, 1993/94 and 1996/97

Years/area planted and productionProvince 1987/88 1993/94 1996/97

Area planted Production Area planted Production Area planted ProductionCentralEasternSouthern

119 047344 986155 757

3 44 5153 306 2045 300 484

161 208174 816130 745

---

93 455198 996158 757

1 703 6112 756 5892 799 285

TABLE 5Maize production areas (ha) and production (tones.) in Region III, for 1987/88, 1993/94 and1996/97

Years/area planted and production1987/88 1993/94 1996/97

Province

Area planted Production Area planted Production Area planted ProductionCopper beltLuapulaNorthernN/W

24 94710 41555 581

-

842 886317 747

1 262 996-

29 78516 89870 81824 595

----

39 26617 36645 70325 216

590 023375 628

1 080 570425 094

The drop in area planted in the 1996/97 season is the general reaction to the liberalizedmaize marketing policy. Since 1992, farmers producing maize are required to find market fortheir produce. This has disadvantaged rural provinces as transport costs have discouraged buyerswho need to haul maize to the line of rail where the market is large. In the same period, there hasbeen a very serious drop in the availability of financial services to smallholders resulting in the


abandoning of commercial maize production, and reverting to traditional crops such as beans,cassava, finger millet and sorghum.


The causes of land degradation in Zambia relate to both bio-physical as well as socio-economic factors.The bio-physical and socio-economic causes and effects of environmental degradation are also inter-related. For example, deforestation will lead to environmental degradation. But the causes ofdeforestation are usually economic, social and cultural. This relationship tells us that when we aredealing with land degradation, we should approach it from a holistic point of view, thus, policyinstruments must offer benefits as well as deterring options.

Deforestation

Deforestation for agriculture is at a wider scale in Zambia. In the slash and burn (Chitemene) shiftingcultivation systems, the distances to the chitemene fields are getting longer. The depletion of forestswill reduce shifting cultivation. Thirty years ago, it was common to find chitemene fields under fallowof 15 years or older. But today, trees are rarely allowed to regenerate for about 10 years. In large urbancentres, the demand for charcoal and wood fuel is increasing all the time. This demand is contributingto the fast depletion of forests and to desertification for example, in Mapangazya area of MazabukaDistrict and Monze East both in Southern Province, Mansa and Samfya districts in Luapula Provinceand the Kagoro area of Chipata District in Eastern Province. The role of forests in controlling naturalsoil erosion, nutrient recycling and water catchments has been negatively affected. This has resulted inincreasing degradation of arable land and water supply.


One of the main reasons for shifting cultivation in Region III of Zambia is the inherent low soil fertilityand inherent soil acidity and its associated aluminium toxicity. The majority of subsistence farmers inZambia apply little or no fertilizers to crops. Since most of the soils of the country are already infertile,continuous cultivation is only possible for a few years after which people have to move to new land.This practice can no longer continue under increased population pressures. The direct consequences ofsoil infertility in rural Zambia is the perpetuation of poverty. The majority of farmers are resourcepoor. They cannot afford fertilizers, therefore, rely heavily on the slash and burn cultivation system,whose lifeline, the forest resources, are diminishing. Without fertilizers with less trees to cut forChitemene; this translates into reduced yields. With increasing population, there will be less food to goaround, thus leaving a weak and malnourished population with less energy to conserve theenvironment. Again the excessively long distances that have to be covered to well wooded areas forChitemene fields, have resulted in reduced cropped land and indeed in the production of inadequateamounts of food. Elsewhere in the country, particularly in Southern, Eastern and some parts of CentralProvinces, soil infertility has come about mainly due to over-use resulting in both chemical as well asphysical soil degradation. Chemical soil degradation includes loss of soil fertility through leaching ofbases or nutrients beyond the plant roots and the acidification and toxification of soils by theapplication of fertilizers.

Leaching of nutrients beyond the plant root zone occurs in all soil types and is more prevalent inRegion III where the rainfall is high (1 000-1 400 mm) and the soils are generally sandy. Over theyears the soils have become acid due to the washing down of the bases such as magnesium, potassiumand calcium by heavy rains. The result has been the build-up of elements such as aluminium, which istoxic to plant growth. The loss of soil fertility through leaching may be prevented by maintaining

Zambia342

adequate soil vegetation cover, as this helps in recycling plant nutrients. Once the vegetation isremoved, as in the slash and burn shifting system of the high rainfall areas of Zambia or when thestover is grazed as in the maize-cattle cultures of Eastern and Southern Provinces; or when otherimproper cropping systems are followed such as burning of crop residues, the nutrients in the soil arewashed down very rapidly. Costly ameliorative measures such as liming and the application offertilizers, which unfortunately cannot be met by the majority of small scale farmers have to be made toretain soil fertility. The application of mineral fertilizers to increase crop yields is not always beneficialto the soil. Particularly in Southern; Eastern and Central Provinces, experience has shown that oncommercial as well as on medium scale farms where fertilizers have been intensively used over manyyears crop yields have been declined. This is partly due to increased soil acidity. All the fertilizercompounds presently in use make the soil acid after years of application. Some fertilizer materials,such as sulphur compounds, acidify the soil more quickly than others thus lowering the productivity ofthe soil after only a few years of use. Therefore, occasional liming of the soil is essential to maintain itsfertility.

Sodicity or salinity is more prevalent in Region I which has high evaporation rates and lowrainfall. The Gwembe and Luangwa Valleys have a considerable occurrence of highly sodic soils.Exchangeable sodium percentages (ESP) usually exceed 15% in subsoils. Calcium carbonate levels arealso generally high. The generally weakly developed soil structure and highly compacted layers in thesevalley soils may be attributed to high sodium levels. This is a serious threat to crop production mainlybecause these conditions promote low infiltration and permeability rates and secondly reclamation byuse of gypsum would seem to be ineffective due to the already high calcium carbonate levels. On theother hand, saline soils inhibit plant growth by stopping plant uptake of nutrients and water.Application of sulphuric acid or sulphur on highly sodic soils with high calcium carbonate levels andadequate drainage to prevent the build-up of salts are alternative measures to improve these soils.

In the Gwembe valley sodicity/alkalinity is a natural phenomenon due to the nature of the soils.Elsewhere, such as at Nakambala Sugar Plantation in Mazabuka, southern province and MpongweFarms on the Copperbelt severe sodicity/alkalinity has affected crop production as a result ofcontinuous irrigation. Heavy operations to reclaim some parts of these schemes are taking place. Inaddition to high maize grain yields, the Sesbania sesban improved fallows resulted in productionof 10, 15 and 20t/ha of oven dry wood following 1, 2, and 3 years respectively. This wood thoughof lower calorific value than the Bracystegia spp of the miombo, is substantial. It can relievewomen and children the burden of firewood collection. At a land use system level, fuelwoodproduced on the farm could reduce miombo deforestation and conserve its biodiversity. In RegionII this problem is highly prevalent on commercial farms where irrigation takes place. Thisproblem is wide spread, but appears to be concentrated in the Lusaka and parts of CentralProvinces, perhaps an indication of the kind of bed rock found in these places. This isexacerbated by improper or non-availability of, and/or poor drainage structures in place andpossibly by the poor quality of water. Analysis of irrigation water for various elements, especiallyfrom the Lusaka and Chisamba areas have shown exceedingly high levels of calcium abovethreshold levels.

Physical soil degradation manifests itself mainly in the reduction of soil porosity or through theloss of topsoil due to water or wind erosion. Most Zambian soils have coarse textured topsoils and arethus susceptible to erosion and compacting, mainly due to the destruction of the soil structure. Once theland is cleared of natural vegetation, the soil is exposed to high rainfall intensity and solar radiation.The result is rapid decomposition of organic matter by micro organisms and consequently a decline insoil aggregate stability and in water holding capacity. The decline in soil structure increases the risk oferosion. Soil compaction may also be caused by heavy tillage implements. In Southern, Central andEastern Provinces of Zambia, soil structure and organic matter content deterioration is a serious


problem on cultivated land. It is a major contributing factor to the decline in crop yields. In the field, thedestruction in soil structure is often observed by the formation of crusts on soil surfaces and hardpansor compacted layers below the topsoil. Soil surface crusts reduce water infiltration rates, hinderemergence and increase water run-off. Compacted soil layers reduce water storage and restrict watermovement and hinder root penetration into the subsoil. This results in localized soil droughts leading tostunted growth and the eventual death of plants. To maintain good soil structure, crop residueincorporation, crop rotations, use of green manure, mulches and proper tillage practices must beemployed. It is clear that most farmers who have over-used or misused their land have no financialresources, no labour or no enough land to practice any of the known ameliorative measures. Thisfailure to practice some minimum conservation measures perpetuates low yields, poverty and hunger.

Soil erosion by water is the most important in Zambia, though significant amounts of erosion bywind may occur on unprotected lands especially during and after ploughing time. The intensities ofrainfall in Zambia are high, and this is the major factor influencing erosion rather than the total rainfall.Soil erosion is a major threat to crop production, more so in Central, Eastern and Southern Provinces.In Eastern and Southern Provinces, the physical causes of soil erosion are due to deforestation, densehuman populations, overgrazing and poor crop cover and land management practices. In most of theseareas, crowded cattle kraals are built around villages and both human and animal tracks create rillswhich eventually develop into deep gullies. Where gullies are common, they are reducing the area ofarable land at a fast rate. In Central Province, the major factors causing soil erosion are the unsuitablesoils and poor crop and land management methods such as ploughing down slope rather than across theslope. Most of the soils have sandy topsoils overlying heavier-textured subsoils, which, if not wellprotected, easily erode. Reduced soil fertility is the first consequence of soil erosion, especially inthe Mkushi Farm Block where the soils are generally sandy.

Burning as practised in chitemene kills most soil flora and fauna which are responsible formaintaining good soil physical properties. The destruction of organic matter denies the microbesthe feed on which they depend during mineralization; thus reducing their numbers and making thesoil inert. During mineralization, the breakdown of organic matter releases nutrients which aredirectly used by plants. Continuous cultivation without ploughing back crop residues into the soilenhances soil biological degradation. The ploughing of plant residue back into the soil, and alsoleaving land under fallow are, therefore, measures that can help maintain yields. The removal ofvegetation cover or cultivation increases soil temperatures and reduces microbial activity. Whenall the organic matter is broken down the number of living organisms in the soil drops drasticallyrendering the soil inert. The slash and burn cultivation systems of Region III, the continuouscultivation and overgrazing problems in many parts of Region II contribute to biological soildegradation.

A compacted soil due to various factors usually does contain very low levels of microbes and insuch cases biological fertility of the soil is very low to the extent that crop production is hampered. Theconditions which support the growth of these organisms in the soil are the available moisture, amountand type of nutrients, degree of aeration, temperature, etc. The ecology of soil microbes which isconsidered biologically fertile should contain a minimum 105 – 108 numbers per gram of soil withseasonal fluctuations. Soil microbes prefer moist soils for maximum microbial activity of decomposingorganic matter. A study which was conducted in the Eastern Province of Zambia at Kagoro found thatthe bacterial plate count, a technique used in determining the total microbial counts per unit soil, wascorrelated with the soil chemical data for Mzime which recorded a higher nutrient level and organicmatter (Tables 6 and 7).

Zambia344

TABLE 6Correlation of organic carbon (%) and microbial counts in the Kagoro Area, depth 0-15 cm

Parameter Cultivated Fallow land 76 years

O.C.% 0.57 1.62Microbial count cells/g soil. 4.6 x 106 7.6 x 106

Source: After Bunyolo, et al 1995

TABLE 7Yield of maize (kg/ha grown continuously without the return of stover)

Treatment 1964-65 1965-66 1966-67 1967-68 1968-69 1969-70

No stoverSingle stoverDouble stover

7 8408 0148 120

7 5728 3987 596

7 8098 4758 113

3 1945 5185 306

3 3794 0115 599

2 7604 9004 780

After Bunyolo, et al 1995

Food insecurity

Rural Zambia is generally food insecure. The major deficits are in staples, vegetables, and concentratedenergy sources. The causes of food insecurity in most rural households of Zambia are many. Theremoval of fertilizer subsidies by Government has caused a decline in land productivity. Farmers haveresorted to extensive use of the land with serious consequences on the environment. Other causes havebeen attributed to decreased household food production due to the infertile soils and the diminishingtrees for chitemene. Poor on-farm food storage facilities result in less food stored for hunger periods.Staples such as cassava and maize are always in short supply between January to March every year.Vegetables are always in short supply during the cold dry season between June and the beginning of therains in November. The long distances to fields has caused reductions in the size of chitemene fields,because more time is spent on walking to and from the fields. This translates into lesser yields andlesser available food.

Lack of education on food preservation and lack of credit for non-cash-based crops such as beans,groundnuts and cowpeas have contributed to food insecurity in the country. Poor feeder roads in thecountry have amplified the problem of accessibility to support services such as credit, markets,agricultural supplies and health services. Lack of seed and other planting material are a majorbottleneck for improving crop production as well as encouraging crop diversification. The shortage ofboth groundnuts and oil (no cash) means that the diet of most people is low in fat. The incidence ofmalnutrition among children in Zambia is recorded as 15%. However, some parts of Zambia such asLuapula Province have recorded up to 34% which is too high. In adults, protein energy malnutritionleads to weak bodies, easy attack of diseases and less productivity. There is urgent need to promotegroundnuts and beans as these are some of the important sources of vegetable protein. The lowavailability of fats and oils is likely to affect the transport and utilization of vitamin A in the body. Thisscarcity of energy supplements is the principle weakness in the food security-situation in Zambia.

Population increase, land scarcity and land tenure

In 1990, the total population of Zambia was estimated at 7.8 million while the cultivated land area isestimated at 2.5 million hectares thus giving a ratio of rural population to arable land for the wholecountry of 3 persons per hectare. In some parts of Zambia such as Eastern and Luapula provinces,population density is reported to be quite high. For example, in Luapula Province, population densityfor the valley area is reported to be about 200 persons per square kilometre. Such densities are farmuch higher for a purely chitemene based system to be sustainable. The increase in population hasexerted tremendous pressure on agricultural land resulting in reduced fallow periods from 15 years to 8


years and thus leading to low productivity. People are crowded where amenities such as good roads,schools, clinics, marketing facilities, etc. are available. Since well placed and accessible agriculturalland is not adequate for all the people, its intensified use has led to serious degradation.

The private ownership of land has been increasing since 1985. This has aggravated the pressureon land resources in some provinces. As the total land area under title deeds increase, gaining access tonew land becomes more difficult, and the pressure on the land already under cultivation increases. Thisis likely to affect soil fertility as farmers will have to shorten the period of bush fallowing to maintainproduction levels on old fields. The traditional land tenure is very strong in Zambia. The rights overfallows or surrounding forest areas are very strongly developed and these rights are getting stronger asthe population pressure is increasing. This breakdown of traditional distributive mechanisms of landhave had and will continue to have a negative impact on the household food security and the livingstandards of the disadvantaged and vulnerable households.

Labour constraints

Labour constraints have direct consequences on sustainability or on production that goes withconservation. Most rural households in Zambia are dependent on outside labour hired foragricultural work, like cultivating, or for food production preparation such as harvesting,pounding maize, etc. Recent studies further show that labour shortage was on land clearing, landpreparation, planting, weeding, harvesting and transportation of produce from the fields to thehomesteads. Despite other findings that show that labour shortage was mainly due to thedisproportionate division of labour between males and females, the fact stands thatimplementation of environmental considerations into farming activities using hired labour willremain an issue of list priority. It is clear that as the environment gets more degraded, and foodavailability is reduced, the health of the people will decline; malnutrition will be on the increaseleading to high infant mortality and reduced life expectancy, thereby reducing the population,especially the rural family sizes. This in turn will reduce the labour available; labour-demandingtechnologies might only lead to a worsening of the food availability or shortage in the country.

Poor infrastructure development

The infrastructure development in the rural areas of Zambia are generally very poor. There are fewgood roads, clinics, schools, shops and marketing facilities. This has forced people to crowd in areaswhere these amenities are available. As a result there is tremendous land pressure for agriculturalactivities which leads to serious land degradation. If these amenities are not improved upon, feederroads in particular, with the liberalized marketing arrangements now in place, private traders will shuninaccessible areas. Thus the delivering of inputs and the buying of farm produce will be determined bywell maintained feeder roads. A deliberate attempt should be made to construct or maintain improvedfeeder roads in areas where agricultural production is of great potential on one hand, and areas wherenutrition variables are critical on the other.


The extension of soil and water conservation practices to small holders in Zambia has in the pastbeen the responsibility of the Department of Agriculture, MAFF. Efforts have concentrated ontraining extension staff in conservation practices and the production of pamphlets and handbookson soil and water conservation measures. Recommendations have focused primarily onformalized conservation and agroforestry activities, such as contour bunding and ridging, storm

Zambia346

drains, gully protection, vetiver strip planting, etc. The adoption of these recommendations bysmallholders has been negligible, primarily due to the high labour requirements, the failure tointegrate conservation measures with crop husbandry practices and the lack of immediate benefitsto farmers.

Recent initiatives by the Department of Agriculture

It was in 1985, when the Department of Agriculture with the support of the Swedish InternationalDevelopment Authority (SIDA) and the assistance of its Regional Soil Conservation Unit inNairobi, launched a programme in Eastern Province to take soil conservation to the people. Thisproved successful such that it was included in SIDA’s country frame in 1988 to become what isnow known as the ‘Soil Conservation and Agroforestry Extension (SCAFE) Programme. Theprogramme concentrates at present on the most threatened Provinces: Eastern, Southern andCentral Provinces; limited activities have also been started in Lusaka and Luapula Provinces. Theprogramme works fully through the extension system of the Government, involving officers fromthe Department of Agriculture, the Department of Forestry, the National Agricultural InformationService, and Department of Natural Resources on a Provincial and District Team basis.

The SCAFE programme had been following (after an ad hoc approach in previous years)since 1991 a participatory, holistic village/catchment approach, which has helped to increase itsachievements substantially. Significantly increasing figures for the 1991/92 and the 1992/93seasons in all activities clearly indicate, that the programme is finally taking off. The followinglist gives the figures for the agricultural season of 1992/93:

• physical soil conservation measures have been adopted by more than 5 000 farmers (doublethe amount of the previous year),

• soil fertility improvement measures were adopted by more than 4 000 farmers in the reportingseason,

• about 1 000 000 trees were planted by 5 000 farmers,

• almost 400 tree nurseries were established by farmers, women groups and field days,

• almost 6 000 farmers attended training courses and field days,

• almost 6 000 farmers watched dramas, slide and film shows,

• the staff training was beneficial to more than 800 officers (almost double that of the previousyear).

It should be emphasized, that three reasons are responsible for this success:

• the consequent training of staff and more and more of the farmers themselves,• the participatory village/catchment approach,• the investment in facilitating transport.

Other organizations have also been trying to tackle some of the land degradation issues:

• Lusume Services of the family farms in Mazabuka had started a project in Southern Provincewhere some agroforestry methods were being introduced and encouraged.

• The Forestry Department through FAO funding, started two projects dealing with treeplanting in Mapangazya area (Southern Province) and Mbala Island (Luapula Province).


• The Animal Draught Power Development Programme supported by the NetherlandsGovernment has developed a range of equipment including the Magoye Ripper and Subsoilerdesigned to provide farmers with draught equipment more suited to MT/CF.

• Detailed assessment of these equipment in conjunction with local farmers is being undertakenat Magoye Technical Assessment Site in Southern Province. Trials to compare the yields ofconventional and CT Ox-draught and hand hoe systems are also being undertaken at Magoye.

• The Research Branch of the Department of Agriculture have long realized that the majorreason for shifting cultivation, is the rapid decline in soil fertility and deterioration in the soilphysical conditions usually after one or two years of cultivation. This is worsened by reducedfallow due to population pressure and higher demand for land.

• The Agricultural Research Division of the Department of Agriculture has been carrying outun-systematic soil fertility and soil conservation research since the early 1940s. Mostprogrammes kept suffering from discontinuities due to staff movements.

• A soil and water management research activity worth reporting is the experiment on tieridging. Tie ridging may be a very useful soil water conservation measure in regions prone todrought. Work done at Lusitu Research Sub-Station, Zambezi Valley, in Region I, forexample, gave consistently highest crop yields with tie ridges made before the start of therains (Honisch, 1974). Mean yields of maize, sorghum and bulrush millet were higher on theridges than on conventionally prepared land by 168, 159 and 17 percent in the 1968-69 to1970-71 seasons respectively. In these experiments, tie ridging before planting createdimproved soil moisture conditions. Despite these good results, tie-ridging is not beingpractised in Region I, and the area continues to suffer from crop failures every year. Some ofthe reasons given by the farmers for their failure to adopt the tie ridging system are highlabour requirements for construction, practical difficult in planting, ridge maintenance andweeding.

Since the advantages of some of the soil and water conservation measures were notimmediate, their adoption by traditional farmers required better Organisation and effectiveextension services. Enforcement of these practices created resentment as was the case in the pre-independence times. It is necessary to identify the socio-economic factors of the communitybefore the practices are introduced. In 1981, the Research Division created the Soil ProductivityResearch Programme under the sponsorship of the NORAD. The team’s approach is to developenvironmentally sound, sustainable, easily adaptable, and economically viable cropping andfarming techniques. Some of their research activities include (a) the use of cheaper sources ofnutrients to enhance soil fertility (these include organic and green manure, legumes in rotationsand crop residues recycling); (b) encourage management practices that will increase soil organicmatter content to neutralize soil acidity and improve the soil physical conditions; (c) the use ofmanaged fallows to regenerate the fertility of abandoned lands; (d) evaluation of the use of greenmanure in the mound (fundikila) system to increase land productivity; the selection of effectiveand adapted Rhizobia strains for optimum nitrogen fixation for small-scale farmers; and to tacklealuminium toxicity and other problems related to managing acid soils.

The NORAD programme has an agroforestry component. This component is being tackledat two levels - that of the cultivation system level, and that of the farming system level. Researchat the cultivation system level focuses on ways in which the main cultivation systems could beimproved by agroforestry techniques, and is carried out mainly at the research station. Researchto understand how the cultivation systems fit together with each other to form the differentfarming systems, and to integrate agroforestry interventions into the whole system, and such takes

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place mainly in selected farmers’ fields. This programme is expected to assist the small holders inachieving sustainable yields. It is also expected to develop a more stable system of agriculturewhich will produce semi-permanent or permanent farming systems in the high rainfall areas forfarmers at different levels of technology. In region II, the Zambia/ICRAF Agroforestry researchprogramme has made headway in producing very useful agroforestry technologies. The use ofSesbania sesban in improved fallows to overcome land depletion and low soil fertility has provedsuccessful. The use of Sesbania sesban improved fallows for one year results in increased maizeyields (from 1.5 to 3 tons/ha), two years fallow yields up to 5t/ha and 3 years fallow can give upto 6t/ha of maize. These results have proved that the use of expensive inorganic fertilizers can besubstantially reduced. This is and will be a relief to the majority of the small scale farmers whocannot afford inorganic fertilizers after the Government removed subsidy on the commodityfollowing the structural adjustment programmes.

Initiatives by the Zambia National Farmers’ Union

In the late 1980s Mr. R. Landless pioneered commercial minimum and zero tillage productionsystems based on maize, soybeans and wheat on his farm at Landless Corner, Chisamba, incollaboration with ART Zimbabwe for a number of years. As a result of this initiative, in mid1995 discussions between Donors, the Ministry of Agriculture, the National Farmers’ Union andthe Golden Valley Agricultural Research Trust (GART) centred on the need to establish a costeffective and productive unit to coordinate and promote the adoption of Conservation FarmingSystems (CF) among smallholders initially in the more drought prone regions of Zambia, andthereafter throughout the Agro ecological Regions I & II (low to medium rainfall). In November1995 with interim support from the World Bank and the EU, a Conservation Farming Unit andConservation Farming Liaison Committee was established under the Zambia National FarmersUnion (ZNFU). The Committee has representatives from all organizations and agencies interestedin promoting sustainable agricultural systems in Zambia, including ZNFU, Palabana ADP,MAFF, SCAFE, GART, and LONRHO. The Committee meets every two months and has thefollowing responsibilities:

• ensure standardization of technical messages, methods and approach,• act as a forum for exchange of ideas and experiences,• recommend priorities for research and seasonal demonstration CF in the field.

During the 1996/97 season Golden Valley Agricultural Research Trust (GART) on behalf ofthe Conservation Farming Unit (CFU) started conducting long term CF trials and demonstrationsfor small holder farmers. These replicated trials are investigating:

• Tillage practices. Three tillage practices of Minimum tillage (MT), conservation tillage (CT)and Residue tillage (RT) are compared with full (or conventional) tillage (FT) for theireffectiveness to capture rainfall (water harvesting) during years of drought, hence reducingrisks of total crop failure, increase crop productivity and Food Security to the farmer.

• Intercropping practices. Among other practices conservation farming requires rotations withlegumes. During the 1995/96 cropping season, 60,000 small scale farmers grew cotton forLONRHO in Central Province as a monocrop. The cotton has to be sprayed to control pests.Cowpea is a suitable legume for small holders to grow in rotation with cotton. However fieldpests can severely reduce the cowpea grain yields. Therefore the purpose of the trial is toassess the effects on cowpea yields from cotton spray drift and direct row spray when cowpeais grown as cotton/cowpea inter-rayed with cowpea monocrop as control. If the cotton


insecticide can be able to control cowpea pests in these cropping configurations, then thefarmer has managed to kill two birds with one stone.

• Herbicide weed control. One of the main agronomic problems facing the small scale farmer,who is practising conservation tillage (No till + water harvesting techniques) is control of theearly flush of weeds which occur at the onset of rains. These early rains which may notnecessary be planting rains are received at the end of October or first week of November. Atthis time the farmer would have prepared his planting holes (hoe) or planting lines(ceemattine) during the dry season (August - October). By the time planting rains arereceived, mainly after the second week of November, this flush of weeds would have grownup. Instead of starting with planting the farmer has to scratch out or clean their planting lineswhich have been invaded by the fresh weeds.

In this situation an application of a post weed emergence, pre-crop emergence herbicide isnecessary, such as Roundup (glyphosate). This can assist the farmer plant early without worryingabout the weeds in the next 30 to 40 days. The purpose of the trial is to assess the efficacy ofRoundup herbicide at three rates of 0.7 litres, 1.0 litre and 1.5 litres per hectare when comparedwith conventional hand weeding. The GART/CF trials initiated during the 1996/97 season aredesigned as a backup to the series of demonstrations carried out by CFU with various Non-Governmental Organizations (NGO) in Southern, Central and Eastern Provinces. The purpose ofthese series of CF demonstrations by CFU is to show and make farmers aware that conservationfarming (CF) systems provide the benefit opportunity for farmers to reduce their costs, increasetheir productivity, ameliorate the effects of drought, improve their food security, and protect theagricultural resource base from further degradation.

Key CT/CF practices presently recommended

One of the most important requisites being propelled in conservation farming is the retention ofcrop residues. Crop residues are retained on the land and not burned. If residues are scarce theyare raked into ‘trash lines’ across the slope to capture rainfall and reduce run off. Ideally aminimum ground cover of 30% residue is recommended. Residues reduce soil temperatures,protect the soil, minimize run off and in time improve fertility. Secondly, land preparation isrecommended to commence in August or even earlier. The labour requirement can be spread overa period of 3 to 4 months. In this way the farmer is ready to plant his/her crop as soon as the firstplanting rain falls. Planting is finished in a day and early weeding can commence as soon asweeds emerge.

Farmers are encouraged through on farm demonstrations which they themselves carryout.Planting basins of 30 cm x 15 cm x 15 cm are dug with the hoe (these may be smaller in higherrainfall areas). These basins are permanent and are never moved. Successive crops are planted inthe same basins each season. Carefully measured applications of basal dressing and/or manureand apart from weeding operations the inter-row soil is not disturbed. This approach has manyadvantages. The basins remain concave after planting and concentrate the early rain around theseed and help to reduce run off. Fertilizer and manure are placed where needed and wastage isminimized. Successive crops can take advantage of the root channels and residual fertilizerapplied the previous season. Because the inter-row is not ploughed and weeds are not allowed toseed, the weed bank diminishes in time. Basins are spaced so inter-row weeding can be done byhand or oxen.

Ox farmers have been encouraged to use the new low draught CEEMAT tine rip in the dryseason and then establish their basins over the rip lines using the hoe. Alternatively they can use

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the Palabana Furrower to open planting furrows over the rip lines as soon as the first plantingrains have fallen. Ripping reduces compacting, breaks plough pans and reduces the crop'ssusceptibility to poor rain distribution. In the drier areas of Zambia demonstrations are carriedout to encourage farmers to use the hoe to make pot holes in the inter-row during the firstweeding. This technique captures (harvests) rainfall, improves infiltration, and reduces cropstress during dry periods.

CF combines sound husbandry and management practices which enable farmers to spreadout labour demand and get their work done on time. The technology can be applied to a widerange of farming groups from resource poor to commercial with good results. The adoption of CFpractices produce immediate, medium and long term benefits and the technologies involved areeasy to understand and implement. A Conservation Farming Handbook for small holders inRegion I and II was produced in July 1997 by Conservation Farming Unit (CFU), with thesupport of FAO Integrated Crop Management Food Legume Project. The agricultural sector hasa major impact on the environment and the promotion of CF is in harmony with the wider goal ofintroducing more environmental friendly methods of agricultural production in Zambia.


he history of soil conservation in Zambia spurns from the 1940s. Prior to 1950, soil conservationwas limited to the construction of dams and weirs. Such works in European farming areasqualified for a 50-60% Government Subsidy. In the African farming areas the soil conservationprogramme promoted improved farming methods which aimed at minimizing nutrient andstructural deterioration of the soil through the use of cattle and green manure, crop rotation andconstruction of contour ridges and grass strips. These soil conservation works on Africanfarmlands (in the tribal areas) were financed from a native fund growers. Between 1939 and1944, over 1,600 km of contour ridges and 180 km of grass strips were laid down in SouthernProvince while 24,000 km of ridges were surveyed and pegged in Eastern Province during 1946-50 (Chiti, et al, 1989). In 1950, the Natural resources Board (NRB) was established under theNatural Resources Ordinance to exercise supervision over natural resources, including soilconservation. In European farming areas, farmers were encouraged to form intensiveconservation area (ICA) committees. This programme failed. In the African farming sector, themaize levy was replaced by the payment of a graduated bonus on a hectarage basis in the 1950s.The bonus payment was based on the area of land that was green/or cattle manured (Chiti et al.,1989) but for a farmer to qualify he had to practice certain laid down farming methods and goodland husbandry which included soil erosion control.

In 1953, the Government through the Department of Agriculture started to promote soilconservation through the implementation of regional conservation plans. This programmeemphasized on soil and water conservation works and alignment and construction of farm andfeeder roads. By 1964, fifty-four regional plans covering over 1.4 million has in the Europeanfarming areas were formulated. However, contrary to the belief that farm planning wouldnaturally follow once a regional conservation plan was implemented, farmers were reluctant tocarry out farm soil conservation measures, and the programme failed to secure the protection offarmlands from erosion. In 1970, the Natural Resources Board (NRB) was dissolved and a newlaw - The Natural Resources Conservation Act - was enacted. This act brought about the NaturalResources Advisory Board (NRAB) which replaced the Natural Resources Board. The new boardwas responsible for ensuring the wise exploitation of natural resources and their conservation,including soil conservation. The NRAB operated through committees without a competenttechnical staff. The NRAB and its committees failed.


In 1972, the Department of Natural Resources was established to serve the NRAB. Thedepartment has continued to suffer from inadequate competent technical staff since its inception.Consequently, the Department concentrated on the propagation of theoretical natural resourcesconservation education while the Land Use Section of the Department of Agriculture continued tocarry out the practical aspects of soil conservation on farmlands. In the meantime, the ExtensionBranch of the Department of Agriculture has over the years paid more attention to cropproduction at the expense of soil conservation. The legacy that was inherited after independencewas carried over even during the period between 1970 to the mid 1980s. During this time thesame organizations that tackled conservation problems were still doing so. The Land Use Branchof the Department of Agriculture for example continued to carry out measures on cropland only.In most cases this was on commercial farms. The Natural Resources Department addressed theproblems in a rather general way, and its main activities were directed at curing gullies andreforestation programmes. What was seriously amiss with both programmes was to take soilconservation to the small scale farmers.

It is clear from the historical perspective that soil conservation was well articulated toaddress the various effects of environmental degradation. However, the approach by the colonialmasters provoked resentment instead of creating a sense of economic gain into the people.Independence meant being free from the labours of soil conservation. Thus where soilconservation structures existed, these were either slowly being destroyed or not maintained at all.Most of these structures have since disappeared. Using the holistic approach, we can link severalsocial, political, economic and environmental factors to causes of land degradation. In Zambia thepolitical economy of the first Republic which emphasized on consumption instead of productionkilled the agricultural sector. Farmers concentrated on increasing production instead ofsustainability. As the economy of the country got worse and worse, the rural - urban migrationincreased. This denied the rural areas of the much needed labour, not only for essential foodproduction activities but for soil conservation works as well. This migration left the aged and thechildren to man very labour demanding activities. When the Rhodesia declared UDI thegovernment’s reaction cost Zambia all its foreign reserves. The consequence was devaluation ofthe Kwacha and expensive imports. Fewer farmers could afford most inputs. This led to rapidsoil fertility decline, which also led to less food in most households. A survival strategy croppedinto the lives of people. The slash and burn shifting cultivation increased. Soil fertility had tocome from the available natural resources by depending on the ash. No farmer was legally boundto control overgrazing, over-stocking, indeed even the discriminate cutting down of trees as longas it was outside a protected forest area.

Government institutions such as Extension and Research continued to get less and lessfunding. This naturally meant lack of transport, lack of motivation and lack of resources. Thefarmer, who was already faced with severe financial problems for inputs and labour shortagessaw less and less of the extension worker. Even where the extension worker appeared, the shortterm economic benefits of soil conservation is difficult to sell in the absence of soil erosionresearch data which we still lack up today. This vicious cycle has far reaching consequences onour society. The economic and social consequences of environmental degradation are both shortand long term. Deforestation and overgrazing brings about immediate economic and socialproblems. Women have to walk long distances to look for fuel wood. Those who depend oncharcoal burning have to cover long distances to find good tress as well as to ferry the charcoalback to the markets. The long term effects of destroying vegetation on catchment areas areincreased surface run-off, thus causing soil erosion and eventually silting of streams and dams.

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There are already a number of organizations in Zambia addressing the issues of soil management andproductivity enhancement. Some of the organizations include:

• The soil conservation and agroforestry extension project (SCAFE). This project is funded bySIDA and covers three out of the nine provinces of Zambia. It addresses physical structures onsmallholder farms. Recently, however, the programme has included soil fertility amelioration in itsactivities. These mainly concern organic matter management and general conservation farmingapproaches such as minimum tillage (MT).

• The International Centre for research in agroforestry (ICRAF) project operating in the Eastern andLusaka provinces of Zambia have concentrated on nodulating and high biomass producing treeand shrubs mainly for soil improvement.

In Region III there are efforts to introduce low input sustainable technologies to overcome lowsoil fertility (high acidity) and improve yield of traditional crops, and also to develop alternativesto traditional shifting cultivation for eventual evolution to semi-permanent/permanent agriculture.This is proposed to be achieved through the introduction of agroforestry technologies, e.g., use ofmultipurpose trees and their advantages in biological N-fixation, mycorrhizae association andefficient nutrient recycling mechanisms into the traditional farming practices, e.g. improvedfallows and alley cropping:

• The soil productivity research programme based in Northern Province is funded by NORAD. Thisprogramme endeavours to find answers to acidity and aluminium toxicity which inhibit propercrop growth, and also addresses the issues of the slash and burn type of cultivation.

• The Conservation Farming Unit which is a wing of the Zambia National Farmers Union haveconcentrated on conservation farming, mainly working with small scale farmers in minimum tillageas well as organic matter management. Over 800 farmers are participating.

• The Golden Valley Agricultural Research Trust (GART) in collaboration with the Conservationfarming Unit (CFU) of the Zambia national farmers union have in the last 2 years been involved inconservation farming research promising results from the first season have already been recorded.

• The European Union (EU) have so far funded a proposed regional conservation farming network,to incorporate Botswana, Lesotho, Malawi, Zimbabwe and Zambia. If approved, Zambia hopes tobring all key players within the country and collectively address, through research and extension,land degradation. Three major problems identified by the five participating countries includedeclining crop yields, declining cropping land area per family farm and land degradation.

There seem to be very strong programmes either already in place or being proposed forimplementation. But for a long time to come Zambia is going to continue experiencing seriouslegal issues and institutional constraints contributing to land degradation. The regulation andrights on land is a very sensitive issue. It is generally held by some farming communities that titleto land carried with it the individual right to farm the land as one pleases. Yet responsibilityshould be and is a voluntary act to manage land in the landholder’s own long term interests.Failing this hope of good will, soil conservation legislation must have clear objectives and providethe administrative and legal structures and procedures to attain those objectives.

Lease hold under land tenure creates incentives for land user to follow practices whichaccelerate the renewal of a lease. But the lack of full compensation for the land on termination of


lease creates insecurity for the leaseholder. The unregulated, self-interested use of land results indegradation.

A continuation of the present legislative policy based largely on voluntary action by landholders, is not the answer. But it is necessary to adopt the principles of adult education wherebyland holders learn through seeing the economic benefits and accepting to undertake theresponsibility of developing and implementing managing policies for their properties. Landholderson the other hand should be obliged to conserve their soil. This could be done through :

• strict liability -where soil degradation beyond a certain point be liable to prosecution,• carryout land utilization determinations which decides the use to which land should be put,• production and extension through demonstrations of proven soil management and

productivity enhancement packages.

REFERENCES

Aagaard, P.J. 1997. Conservation Farming Handbook for Small Holders in Regions I & II of Zambia.CFU/FAO Integrated crop Managment Food Legume Project.

ARPT 1992. Monitoring household food security in Mabumba, Luapula Province. Dept. of Agriculture,Mansa.

Bunyolo, A.M. 1989. Soil crop management for low-input systems, especially directed towards soil fertility,soil erosion and weed control. Possible Application to Region II of Zambia, Mount Makulu, Zambia.

Bunyolo, A.M. et al 1995. National Environmental Action Plan. Agriculture and the Environment. MountMakulu, Zambia.

Chiti, R.M. et al 1989. National Soil Conservation and Agroforestry Needs Assessment. NSCU, Department ofAgriculture, Lusaka, Zambia.

Clayton, D.B. 1985. A Geomorphic Legend for Zambia. Department of Agriculture, Lusaka, Zambia.

FAO. 1974. Shifting Cultivation and Soil Conservation in Africa. Soils Bulletin No. 24 .Rome.

FAO. 1984. Improved production systems as an alternative to shifting cultivation. Soils Bulletin No. 53. Rome.

Gossage, S.J. 1991. Soil and Water Conservation; a manual for extension workers with emphasis on smallscale farmers in Zambia. Department of Agriculture, Lusaka.

Grunder, M.; Herweg, K. Seventh Progress Report, Soil Conservation Research Project. Ministry ofAgriculture, Addis Abeba Ethiopia.

Grunder, M. 1993 Soil Erosion and Watershed Management. An issue paper presented at the first ZambianNational Forestry Action Plan Workshop.

ILACO B.V. 1981. Agricultural Compendium for rural development in the tropics and subtropics. Elsevier,Amsterdam.

Keyser, J.C. and Mwanza, H.M. 1996. Conservation tillage in Zambia. Findings of field survey of hand hoefarmers in Mumbwea District. Institute of African Studies, UNZA, Lusaka.

Kokwe, M. and Chileya, C.K. 1993. Farming systems update of Luapula Province. LRDP, Mansa.

Kwesiga, F. 1996. Agroforestry Research in Zambia. Highlights. Msekera Regional Research Station, Chipata,Zambia.

Mickels, G. 1994. Natural Resources and sustainability in Luapula. LRDP, Mansa.

Mukanda, N. and Grunder, M. 1993. Assessment and control of land degradation in Zambia. A countryAppraisal. Department of Agriculture, Research Branch, Chilanga, Zambia.

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Mukanda, N. 1994. Environmental Impact Assessment and sustainable agricultural development in Zambia. Aframework for understanding land degradation using the holistic approach. Department of Agriculture,Research Branch, Chilanga, Zambia.

National Soil Conservation Unit, Annual Report 1988. Department of Agriculture, Lusaka, Zambia.

Ndiyoi, C.M. & Tembo, S. 1995. Special Programme for Food Security Project Document. FAO, LUSAKA,Zambia.

Robinson, D.A. 1978. Soil Erosion and Soil Conservation in Zambia: A Geographical Appraisal. ZambiaGeographical association occasional study no. 9. Lusaka, Zambia.

Yerokun, O.A and Mukhala, E. 1995. A systems approach to long term soil productivity. Proceedings of thenational symposium. UNZA, Lusaka, Zambia.


Zimbabwe


The total area of the country is 389 000 km2. There are three major relief regions in Zimbabwewhich are recognized on the basis of their general elevation. These are the Lowveld (below 900m.a.s.l.), the Middleveld (900 - 1 200m a.s.l.) and the Highveld (1 200 – 2 000 m.a.s.l.). TheHighveld includes a relief region commonly referred to as the Eastern Highlands which consistsof a narrow belt of mountains and high plateau ranging in altitude from 2 000 m to 2 400 m.a.s.l.,and has a characteristic micro-climate and associated vegetation. The country receives almost allof its rainfall during the five summer months, November to March. The mean annual rainfallranges between 400 mm to 2 000 mm, depending on the relief region. A significant feature of therainfall is its unreliability both in terms of amount and duration. The onset of the rains, which iscritical for planting, is rather unpredictable. The variation from year to year is such that as littleas a quarter of the arithmetic mean may fall while in other years 200 - 300% of the mean may berealized.

Climatic factors are the major determining factors in crop production in any given situation.In Zimbabwe, rainfall has been used as the single most important parameter in defining agro-ecological zones and their potential for agricultural activities. As rainfall decreases, the seasonalvariability also increases, thereby increasing the risk of poor yields. Crop production inZimbabwe has tended to vary in relation to agro-ecological zones and also with seasonalvariations in weather patterns. Seasonal quality has tended to decline, with the frequency ofdroughts being significantly higher over the last 20 years than during the long term (1910 - 1997)period (Vhurumuku and Eilerts, 1997). Other factors that affect the levels of crop production,particularly in the smallholder sector are level of agronomic management, access to inputs suchas fertilizers, availability of finance and credit, infrastructure condition and availability ofmarketing facilities. These factors however, tend to be overshadowed by the impacts of seasonalquality.

Cereal production

Maize, pearl millet and sorghum are the most important cereal food crops that play a significantrole as carbohydrate sources in the diets of most Zimbabweans. These crops are allocated 45-50%, 15-20% and 10-15% of the cropped area respectively. Maize is the dominant staple foodcrop that is grown across all agro-ecological zones within the communal areas. This cropoccupies 50 - 70% of cropped areas in natural regions I and II; and 40 - 50% of cropped areas inNatural Regions III, IV and V within any given season. Conditions for crop production becomemore marginal as one moves from natural region I to natural region V.

C.F. Mushambi, L.M. Mugwira, J.K. Nzuma and G. NehandaChemistry and Soil Research Institute, Causeway, and Institute of Agricultural

Engineering, Borrowdale, Harare

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Sorghum and pearl millet are dominant in natural regions IV and V where rainfall isextremely low and unreliable. Table 1 illustrates the trends in food production from the 1980-81to the 1995-96 seasons. The figures in Table 1 show that there was a dramatic increase in maizeproduction in the early 1980s. This increase, particularly in the smallholder sector was influencedby provision of a whole package of support that included research and extension, price support,market infrastructure and finance. In spite of all the support, improvements in the levels ofproduction experienced in the smallholder sector were more due to expansion of land under maizerather than improved yields.

When real maize producer prices dropped during the late 1980s and emphasis was placedmore on industrial and horticultural crops, commercial farmers were more responsive than theircounterparts in the smallholder sector to price signals and market imperatives. Commercialfarmers quickly moved out of maize production when real producer prices for this commoditywere falling relative to oil seed and horticultural crops. The smallholder sub-sector, on the otherhand, increased production of maize, in spite of falling real producer prices (World Bank, 1991).On average, there was an increase in maize production in the communal areas during the 1980sas compared to the 1970s. This increase was eroded in the 1990s when more severe and frequentdroughts were experienced. The 1990s saw a significant 33% drop in food access and availabilitythan the 1980s averages.

TABLE 1Commercial and communal grain production over time in tonnes, 1980-96

Years Maize Sorghum Communal TotalCereals

Communal Commercial Communal Commerc. Munga Rapoko1980-81 1 000 000 1 833 400 100 25.1 81.31 50 194 3 090 0041981-82 595 1 213 400 50 17,4 1 875 8001982-83 285 624,8 44 7,5 55 932 5 164 1 022 3961983-84 670 678,5 37,4 18,1 51 344 42 989 1 498 3331984-85 1 558 000 1 153 000 76 54 252 539 111 524 3 205 0631985-86 1 348 000 1 064 00 66,2 65 71 382 45 491 2 660 0731986-87 627,7 466 40,4 11,9 68 349 33 223 1 247 5721987-88 1 609 300 643,8 163,1 12,7 177 166 81 473 2 687 5391988-89 1 188 200 743 65,3 16,1 81 168 51 953 2 145 7211989-90 1 262 300 7312,5 72 18,4 99 194 143 734 2 327 6281990-91 1 019 300 566,5 51,3 16,8 59 388 38 738 1 752 0261991-92 115,2 245,8 10,35 21,42 130 192 393 0921992-93 1 133 600 878 25 69 51 20 99 003 67 598 2 267 9611993-94 1 313 800 1 012 400 90,8 30,92 100 384 52 073 2 600 3771994-95 399,4 440,2 16,73 12,75 12 874 6 831 888 7851995-96 1 687 000 922 173 851 0 114 692 42 242 2 939 78580s Av. 1 014 350 915,14 71,49 24,62 104 264.89 62 860.56 2 176 012.990s Av. 944 716.67 677 525 68 756.83 16 981.67 64 411.83 34 612.33 1 807 004.33

Source: Economics Division Ministry of Agriculture

The high crop yields of the 1995/96 season may indicate that the low crop yields of the1990s were more due to droughts rather than deterioration of the fundamentals (i.e. soils, inputavailability etc.) of communal sector farming (Vhurumuku and Eilerts, 1997). Maize productionhas been declining consistently in the commercial farming sector from the 1970s to the 1990s asfarmers diversified into better paying enterprises such as horticulture.


Small grain crops have experienced a general decline in production from the 1970s to the1990s in spite of emphasis given by research and extension on these crops as security food cropsfor the marginal areas. This is most likely a reflection of farmers’ preference for maize over smallgrain crops. Table 2 demonstrates the negative impact of population growth on levels of availablemaize consumption. Population growth has reduced available maize consumption per caput to114 kg compared to the high figure of 157 kg/caput in some years of poor production (1991/92season). Food consumption has been declining over time, possibly due to reduced access. Overthe 90s food availability from production and stocks has generally been declining. Food importsto meet food shortfalls increased in the 1990s. This picture also demonstrates that the position ofZimbabwe as the breadbasket of the SADC region may have been eroded. Food shortfalls arelikely to increase in Zimbabwe as population continues to increase (growth rate is 3.1%) anddroughts become more severe and frequent. Currently, another severe drought has been predictedfor the 1997-98 season due to the activity of the El Nino phenomenon that normally bringsdroughts to the Southern Africa region.

TABLE 2Maize balance sheet for Zimbabwe, 1985 to 1996

Year 1985-86 1987-88 1989-90 1991-92 1993-94 1995-96 1996-97Populationthousand)

834 886 946 1 008 1 072 1 140 1 175

Consumption/capita(kg/ s/Yr)

142.5 414.5 119.7 156.8 153.2 142.5 114.6

Total supply 3 680 2 900 2 871 2 312 3 497 2 155 2 636Domesticavailability

3 680 2 900 2 871 2 229 2 829 2 029 2 636

Openingstocks

1 426 1 806 940 643 267 1 189 27

Monitored 1 426 1 806 940 643 267 822 7Unmonitored 0 0 0 0 0 367 20Grossharvest

2 254 1 094 1 931 1 586 2 562 840 2 609

Imports 0 0 0 83 668 126 0Commercialimports

0 0 0 83 668 126 316

Food aid 0 0 0 0 0 0 0Totalutilization

3 680 2 900 2 871 2 312 3 497 2 155 2 724

Domesticutilization

1 944 1 772 1 553 2 060 2 163 2 084 1 826

Food use 1 189 1 257 1 133 1 580 1 643 1 624 1 346Feed use 550 400 300 360 400 340 350Other usesand losses

205 115 120 120 120 120 130

Exports 310 373 170 187 0 44 298Closingstocks

1 426 755 1 148 65 1 334 27 600

Monitored 1 426 755 1 148 65 934 7 600Unmonitored 0 0 0 0 400 20 0Unbalancedresidual

0 0 0 0 0 0 210

Source : Vhurumuku and Eilerts, 1997

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The total land area of Zimbabwe is 39,075,900 ha, of which 42% is communal land. The rest ofthe land area is occupied by commercial farms, resettlement and urban area; forests, and gamereserves. This land area is shared by a population of approximately 11,933,000 with a naturalpopulation growth rate of approximately 3.1% per annum. Distribution of population bySector/land use type shows that half the population is in the communal areas. Population densityin Zimbabwe has risen from 19 persons/km2 in 1982 to 27 persons/km2 in 1992 (CSO, 1992).This density will continue to rise with respect to the rate of population growth.

Total area of land cultivated in the communal areas has been expanding over the years as thepopulation continued to grow and the need to grow more food crops increased. Since land is astatic resource, land cultivated per caput or per household has declined in relation to populationincrease. Table 3 shows the trends of total amount of land in the communal and commercial sub-sectors allocated to the main cereal food crops from 1980 to 1995. The total area under crops incommunal areas in 1996 stood at 2,234,616 hectares; an increase of 26% over the 1990s averageof 1 773 658 and 24% over the 1980s average of 1 794 855 (Vhurumuku and Eilerts, 1997).Total area cropped to maize, millets and cash crops per caput in the 1980s stood at 0.393 ha. Inthe 1990s this dropped to 0.325 ha. In 1996, the per caput area cultivated increased marginallyover the 1990s average to 0.376 ha. The vulnerability of communal areas may be rising due to adeclining land area available for cropping relative to a fast expanding population. In fact as earlyas 1975; 57% of the communal areas had been described as overpopulated or grossly overpopulated (Kay, 1975). Maize area cultivated per caput followed the same trend as describedabove. During the 1980s total land cropped to maize per caput equalled 0.210 ha. This figure fellduring the 1990s on average to 0.168 ha and then recovered to 0.203 has in the 1996 season.Expansion has generally been due to encroachment onto previously unused marginal lands; adevelopment which renders communal areas more prone to forces of land degradation. Smallgrains area cultivated per caput dropped from 0.101 ha in the 1980s to 0.075 ha in the 1990s andthen rose slightly to 0.087 ha in the 1996, season.

TABLE 3Communal and commercial land area planted to cereal food crops (hectares), 1980-96

Maize Sorghum CommunalYearsCommun. Comm. Commun. Commerc. Munga Rapoko

Total Area

1980-81 1 000 000 363 400 200 000 9 300 171 636 108 870 1 853 2061982-83 1 050 000 283 900 280 000 7 700 220 107 35 459 1 877 1661984-85 1 018 000 238 000 210 000 15 000 297 438 148 813 1 927 2511986-87 1 064 000 147 100 172 700 7 500 196 2224 107 205 1 694 7291988-89 1 030 000 168 300 158 000 7 300 144 070 113 508 1 621 1781990-91 926 200 175 000 106 200 7 600 139 735 111 765 1 466 5001992-93 1 040 000 198 000 138 000 10 110 147 652 93 750 1 628 1121994-95 1 209 200 188 700 126 000 4 250 224 976 40 489 1 794 3551995-96 1 330 000 205 000 234 714 0 183 779 93 063 2 046 556

80s Average 1 059 250 231 050 186 750 10 230 192 725 116 553 1 765 62990s Average 1 067 100 191 950 138 815.6 7 410 167 703 93 430 1 666 409

Source : Economics Division Ministry of Agriculture

The declining land holding per caput with time paints a gloomy picture in terms of foodproduction to meet food security requirements in the communal areas. This decline has not beenmatched by intensive production on a per hectare basis. Instead crop yields have tended to declineor remain stagnant over time. Table 4 illustrates the yield trends of cereal grain crops from the1980 to the 1995 season. In the 1970s average maize yields in the communal areas were 623


kg/ha. Yields went up to 957.6 kg/ha in the 1980s that marked the peak of maize production inthe smallholder sector. N fertilizer and hybrid seed have had the greatest impact on the yield ofmaize. the increased use of N fertilizer in the communal areas in the 1980s can be attributed tothe sector’s improved access to AFC seasonal loans. During the drier regime of the 1990s yieldlevels dropped to an average of 885.3 kg/ha. Sorghum shows a decline in yields in the communalareas from 1031.1 kg/ha in the 1970s to 382.8 kg/per ha in the 1980s. The crop shows a slightrecovery in the 1990s to a yield level of 495.3 kg/ha. Munga and rapoko show a decline in yieldsfrom 541 kg/ha and 539.3 kg/ha in the 1980s to 384.1 kg/ha and 370.5 kg/ha in the 1990srespectively.

From the 1980s to the 1990s yields of all crops fell due to frequent droughts (Table 4). Butjudging by the yields of 1996, which were generally better than the 1980s yields, it appears likethe droughts were the main feature of those declines and continuing good rains in future yearsmight reverse those temporary declines. Looking at the general trends of rainfall, there has been adecline from the 1970s to the 1990s. More frequent and severe droughts have been experiencedduring the 1990s. If this trend of events continues, yields will continue to fall, further reducingfood security chances in the communal areas in particular, and in Zimbabwe in general. Thissituation will be exacerbated by a rapidly expanding, population that is expected to increase to 18million by the year 2025 before stabilizing at 28 million.

TABLE 4Yield trends of cereal grain crops, 1980-95

Crops Maize Sorghum CommunalYears Communal

(kg/ha)Commercial

(kg/ha)Communal

(kg/ha)Commercial

(kg/ha)Munga(kg/ha)

Rapoko (kg/ha)

1980-81 1 000 5 045 500 2 699 474 4611981-82 541 3 835 250 2 1221982-83 271 2 201 157 974 254 1461983-84 590 3 021 240 1 828 391 3421984-85 1 530 4 845 362 3 600 849 7491985-86 1 255 4 433 441 2 955 383 4391986-87 590 3 168 234 1 587 348 3101987-88 1 400 4 292 766 1 814 815 7181988-89 1 154 4 415 413 2 205 563 4581989-90 1 300 4 091 567 2 190 583 7471990-91 1 101 3 237 483 2 211 425 3471991-92 158 1 607 162 2 121 1 21992-93 1 090 4 436 502 1 978 671 7211993-94 1 124 4 364 558 2 494 492 4951994-95 330 2 333 132 3 000 57 1691995-96 1 268 4 498 741 64 454

80s Average 957.6 3960.8 382.8 2406.6 541.0 539.390s Average 885.3 3529.7 495.3 2291.7 384.1 370.5

Source : Vhurumuku and Eilerts, 1997


Soil degradation can be described as a loss of soil productivity through various physical andchemical processes such as wind erosion, water erosion, depletion of plant nutrients in soils,salinization, waterlogging, deterioration of soil structure and pollution. The most serious forms ofphysical degradation in Zimbabwe are erosion and removal/decline in organic matter due todevegetation. The most serious forms of chemical degradation are acidification and nutrientdepletion and/or leaching. Both these physical and chemical forms of soil degradation are more

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prevalent and more intense in the smallholder farming sectors, particularly the communal areas(CAs) than in large-scale commercial farming areas. The CAs have both the most fragileenvironments and the highest population densities.

Erosion

Soil erosion is the most widespread type of land degradation in Zimbabwe. It has been estimatedthat there are about 1.8 million hectares or 4.7 % of the land in Zimbabwe which is eroded, about83% of which is in the communal areas (Whitlow, 1988). The erosion distribution was estimatedas: negligible (about 40%), very limited (25%, limited-moderate 20%) and the rest as beingsevere-very severe. The importance of the land tenure system was further reflected in that 48.7%of the commercial farming areas have negligible erosion compared with 18.5% in the CAs and79.7% in non-agricultural land. The corresponding percentages of severely- very severely erodedland were 27% in the CAs, 2% in the commercial farming areas and 0.5% in the non-agriculturalland. Levels of soil loss in CAs have been estimated at 50 t/ha/year (Elwell, 1985; Vogel, 1993).This is far in excess of rates of soil formation, estimated at 400 kg/ ha/year for granite-derivedsands (Whitlow, 1988). At this rate of erosion about 30% of the available rainfall is lost assurface runoff, along with an estimated 535 kg/ ha of organic carbon and about 50 kg of nitrogenand 8 kg/ha of phosphorus (Elwell and Stocking, 1988).


Most soils of Zimbabwe are naturally of low potential productivity but much of the actualproduction depends on their management. In the communal areas, their condition is made worseoff by poor management, usually reflecting a poor resource base. It has been estimated that about30% of croplands in the communal areas have been fallowed/abandoned due to reasons ofdepleted soil fertility (Anderson et al., 1993; FSRU, 1993). However, recent surveys inChinamhora, Murehwa and Mhondoro communal areas have revealed that about 44% of the 500maize fields sampled had depleted levels of at least one nutrient. Normally such soils arecharacterized by multiple nutrients of N, P and S, and at advanced stages the depletion of Mg andZn (Grant, 1970). Maize yields on depleted sands in the communal areas may be as low as 0.2tonnes per hectare without fertilizer or manure, and yet with proper fertilization using manureand/or fertilizer, organic yields can be increased and maintained in the range of 3 to 5 tonnes(Grant, 1970; Grant, 1981). The available N values in worked out sands indicate that often themaximum yields without added fertility would be about 0.2 t/ha, as has been found in practice(Grant, 1976).

Salinization

In Zimbabwe saline soils are of very limited occurrence. Saline and sodic soils are found in areasof low rainfall and high temperatures (Natural Regions IV and V). However, deteriorating yieldsof many crops have been attributed to the salinization and/or sodication of soils in manyirrigation projects (Kanyanda and Mushiri, 1991). Irrigation is often used to supplement naturalrainfall for main season crops, and to supply water for winter crops in the dry season. The twotypes of water that may give rise to salinity problems are "regeneration waters" i.e. undergroundwaters and drainage waters from irrigated area (du Toit, 1972). Underground water resources inlow rainfall areas have more dissolved salts than those from high rainfall areas due to highevapotranspiration rates. An assessment of 204 irrigation waters, samples in tobacco growingdistricts indicated that 95% of the samples had low to medium salinity. However, water qualitydownstream of some urban centres is usually poor as a result of serious pollution of streams anddams that are fed directly by domestic, commercial and industrial effluent (Zvomuya, 1996).


Therefore, in some parts of the country such as the Save Valley, salinization has been artificiallyinduced by irrigation since most schemes in such areas do not have drainage installations and thewater is unsuitable. With the Government's drive to improve crop production and sustainability inthe communal areas part through irrigation, various problems of salinization and/or sodicationare bound to increase in future.

Highlights of soil fertility decline

Decline in soil fertility is a major constraint to agricultural production and economic growth inthe smallholder sectors of Zimbabwe; with its impacts reverberating throughout themationaleconomic sectors. Fertility decline results in food insecurity in the smallholder sector, therebyputting enormous pressure on national resources as the government is called upon to feed theaffected communities. Some of the most important consequences of soil fertility decline in thesmallholder sector economy have been summarized by Huchu and Sithole (1994) and otherworkers. These include the following socio-economic consequences:

• poor crop yields which leads to decline in household and national food security, labourproduction and revenues, and increased urban drift,

• the need for large capital investments for procurement of on fertilizer to improve soil fertilityin order to get satisfactory crop yields on these soils. These costs increase with degree of soildegradation, further impoverishing resource-poor farmers,

• cropping encroachment into marginal areas which is done in an effort to get sufficientproduce. A most assured consequence of this practice is increased environmental degradation,

• encroachment of cropping into grazing areas which leads to overgrazing on the remainingareas, contributing to erosion and decline of soil fertility on the "new" cropping after a fewyears,

• encroachment of cropping into vleis and other wet areas which has resulted in the formationof gullies due to erosion, and in the siltation of rivers and dams.

The Department of Research and Specialist Services (DR&SS) has conducted two types oflong-term trials on changes in the fertility of sandveld soils which may be used to quantifyproduction losses and economic costs of declining in soil fertility. The first type of trials were onthe restoration of productivity of depleted sands in the CAs which were started in 1956. Thesecond type was on the assessment of changes in the fertility of a sandveld soil under continuouscultivation which was started in 1962 at Grasslands Research Station. As soil N, P and K datafor the different cropping seasons is apparently not available in published literature productionlosses and replacement costs are based on optimum yields obtained and corresponding fertilizerrates recommended for such yields under normal or un-degraded soil conditions. Degradedconditions are represented by low or no fertilizer and yields obtained. Manure was used in thesetrials and data from its application are included purely for comparisons with data from inorganicfertilizers. Table 5 shows production losses and replacement costs in the maintenance of thefertility of a sandveld soil under continuous cultivation with plots on new land as reference.

The data shown in Table 5 lead to the following conclusions:

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TABLE 5Production losses and replacement costs in the maintenance of soil productivity fertilizer andmanure on new land and land under continuous maize cropping at Grasslands

Nitrogen Manure Yield (t/ha) Lost Production (Z$) Replacement Cost(Z$)

Cropping

kg/ha/yr Yearly Yr 1 Yr 5 Yr 10 Yr 1 Yr 5 Yr 10 Yr 1 Yr 5 Yr 10

New land 130 0 4.52 5.11 6.56continuous 20 0 2.17 1.07 2.03 2 820 4 848 5 436 740continuous 130 10 4.52 5.06 3.86 0 0 3 240continuous 20 7t/ha 2.94 3.88 5.38 1 896 1476 5 436continuous 130 7t/ha 5.70 6.70 7.61 -1 416 -1 908 -1 260

Source: Original yield data (Grant, 1976)Note: All plots received 66 P205, 55 K2O and 25S kg/ha/yr. Production 1997 maize sale price $1200/t;replacement costs : Ammonium nitrate $2490/t, single superphosphate $1725/t.

• when little fertilizer (20 kg/ N/ha/yr) was used yields remained at about 2 t/ha for about 10years of the trial,

• good yields were maintained with high fertilizer (130 kg/N/ha/yr) for 5 years and thenresponse to nitrogen decreased to 59% of the potential yield in the tenth year, presumably dueto deficiencies of other nutrients which developed and limited yields,

• years of Continuous cropping with high rate of unbalanced or single-nutrient (130kg/N/ha/yr) eventually resulted in lost production,

• lost production increased with continuous cropping but it could be reduced by application ofeven small amounts of manure i.e. 7 t/ha.

Major causes of soil fertility decline

The major causes of soil fertility decline in the smallholder sectors of Zimbabwe are continuouscultivation without adequate fertility inputs, organic residues such as manure and/or fertilizer, toreplenish nutrients removed by crop and other losses. Specific practices which contribute todecline in soil nutrient levels include the following:

• low adoption of fertilizer use. Growth in fertilizer consumption in the smallholder sectors ofZimbabwe since 1984/85 has not been sustained (Conroy, 1990),

• application of sub-optimal rates of fertilizer. Only about one-third of communal farmers evenin the high rainfall NR I and NR II who use fertilizer apply the recommended rates (Page andChonyera, 1994) Little or no fertilizer is applied in the semi- arid areas NR 3, NR 4 and NRV because of the associated risk factors,

• non-application of fertilizer/manure to crops in rotation with maize. Crops in rotation withmaize such as groundnut (Huchu and Sithole, 1994) or pearl millet and sorghum grown in thesemi- arid areas (Ahmed et al, 1977) often receive little or no fertilizer,

• use of blanket fertilizer recommendations which do not allocate scarce fertilizer sourcesefficiently since they do not take into account important variability in soil fertility. During the1987/88 to 1990/91 seasons the number of soil samples submitted to the Soil TestingLaboratory from the communal Areas decreased annually from 593, 391, 165 to 72 (CSRI,1991),

• lack of application of lime which leads to acidification of soils and leaching of nutrients,


• loss of topsoil including nutrients and organic matter through erosion due to lack ofinadequate conservation works,

• poor resource base i.e. inadequate amounts and/or sources of nutrients e.g. manure,

• use of depleted/marginal lands. More than 67% of the communal areas exceed their carryingcapacity in terms of human and livestock populations (Huchu and Sithole, 1994). Populationpressure has resulted in the use of depleted/marginal soil for crop production which has leadto losses of topsoil and nutrients,

• removal of crop residues from fields. Crop residues are removed from fields and used aslivestock feed in the dry season. This contributes to nutrient and organic matter removal fromcultivated lands.

Major constraints

Poor soil fertility and climatic risk are the major factors that directly affect Zimbabwe farmers'ability to produce enough food for subsistence and for cash (Huchu and Sithole, 1994). Thenatural poor soil fertility is further exacerbated by the following factors:

• inadequate supply of organic sources of plant nutrients. Manure, the traditional organicfertilizer, is becoming more scarce due to poor grazing, while litter for composting is now notavailable in many communal areas,

• lack of capital to purchase chemical fertilizers. There are no reliable credit facilities forcommunal area farmers because financial institutions are reluctant to lend money to farmerswho cannot provide security e.g. title deeds,

• population pressures. High population pressure in the communal areas forces farmers tocultivate continuously the same pieces of land usually with little/or no rotation. Crop residueshave to be removed from fields to supplement feeding of livestock during the dry season dueto poor grazing i.e. overgrazing due to high livestock densities.


Technological options for improving soil fertility and crop production emanate from workprogrammes within DR&SS, extension and development agencies. To sustain agriculturalproduction under soil and climatic risk experienced by the small holder farmer, there is need tofill in gaps that exist between research technology and farmer innovations. This process beginswith the recognition that the search for management options for sustaining soil fertility requirescommunity input and the integration of indigenous knowledge into scientific research andagricultural development. Farmers have some indigenous technology judging from conditions ofhigh variability and uncertainty in which they live. There is a great potential of indigenousinformation to be expanded into scientific technological information which will benefit its ownersi.e. small holder farmers. This section looks at available technological options for improving soilfertility in the small holder sector, Tables 6, 7, 8 and 9 illustrate this picture. However, not all ofthe promising technologies have been tested on-farm for adoption.

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TABLE 6Soil fertility constraints and possible solutions

Soil Fertility Constraints Possible Solutions◊ sandy soils inherently infertile i.e.◊ low cation exchange capacity, low

pH◊ ranges (4.2 to 4.8 (CaCl2)◊ low available soil N (<30ppm=45

kg/ha)◊ low P content (< 25 ppm)◊ low organic matter content(o.3% to

0.5%).◊ soils cultivate 40 to 50 years ago

without regular application offertility ameliorants now show

◊ multiple deficiencies not only in N,P and S but in Cu, Zn, Mn, Mo andBo.

◊ use of lime to reduce imbalances in some nutrients (Mgand Ca) (increase awareness)

◊ use of appropriate recommended mineral fertilizers (usestrategies to increase fertilizer use-efficiency

◊ supplementation with high quality manure with a narrowC/N ration and low % lignin provide readily available N,energy and nutrients to the soil ecosystem and build soilfertility and structure over the long term. (Usemanagement options to increase quality of manure

◊ use of other available organics on farm for composts◊ exercise recommended crop sequencing (i.e. crop

rotation)◊ legume intercropping contribute to N budget of cereals

and have residual N to subsequent crop (estimated netN of 23-110 kg/ha from pigeon pea;

◊ 50 kg/ha from dolichos beans; 25 kg/ha fromgroundnuts).

◊ use of improve fallowing with legumes (increaseawareness)

◊ agroforestry (increase awareness)

TABLE 7Available strategies for increasing fertilizer use efficiency

Reasons for low fertilizer use-efficiency Strategies for increasing fertilizer use-efficiency◊ blanket fertilizer recommendations

not appropriate to farmer'sproblems which are locationspecific,

◊ declining levels of organic matter(OM) in communal soils,

◊ application of low quality organicmatter

◊ high fertilizer costs.

◊ appropriate recommendations based upon soil analysis,◊ increase proportion of locally produced OM to maintain

soil OM,◊ apply high quality organic matter to reduce cash cost for

mineral fertilizers; to improve nutrient◊ cycling and to reduce nutrient losses from leaching and

denitrification,◊ maximize use of limited amounts of fertilizer that a

typical small holder is able to purchase by exercising thefollowing:

i. appropriateness of types and amounts ii. timing iii. placement: a) use planter with fertilizer attachment, b) fertilizer in furrows made by ox driven tine, c) complementary tillage plus basal fertilizer application at planting


After drought, the problem of soil fertility has been identified as the most limiting environmentalconstraint to agricultural production. This has led to a decline in crop production and yields,particularly in the small holder sector. Various technologies have been developed to minimizeboth soil fertility and climatic risks in the sector. Techniques such as crop rotations, tied ridging,winter ploughing, use of fertility inputs such as inorganic fertilizers and organic materials likemanure have been promoted. However, local literature reports low adoption rates to some of thesetechnologies. Several factors have contributed to the limited performance of agriculture especiallyof the resource-poor farmer. These include inappropriateness of agronomic research, which haslargely been on-station. The physical, social and economic conditions of the resource poorfarmers are considerably different from those of research stations.


TABLE 8Management options for improving quality of manure in the small holder sector

Reasons for low quality manure management options for improving quality of manure◊ poor quality grazing, ◊ ambient temperature, moisture

levels and length of exposure to theenvironment can trigger nutrientlosses (particularly as NH3 byvolatilization and leaching),

◊ imperfect storage and handlingconditions (manure is stored inheaps which allow for aeration andresults in aerobically dried anddecomposed manure low innutrient supply (N content less than1.2%).

◊ low use of residues in the kraal

results in dung contamination withsand (50 to 90%) and loss of Nfrom urine

◊ little amounts available.

◊ improvement of pastures by planting legumes,◊ manipulation of biological processes during storage and

handling of manure reduce N losses and increaseavailability of nutrients,

◊ anaerobic treatment results in better quality manurethan aerobic treatment,

◊ storage of manure in pits minimize drying and leachingduring hot and rainy seasons and maintains theavailable N in organic fractions,

◊ co-composting with inorganic fertilizers (however, thereis need to establish whether farmers are likely to putfertilizers in kraals rather than on maize crops),

◊ use of DPR (Dorowa rock phosphate during composting)which is a cheap source of P,

◊ use of stover as a urine absorbent is a promising toolwhich can minimize losses by volatilization (efficacy ofresidues needs to be established),

◊ increase bulk with the use of grass, residues and leaflitter both in summer and winter storage.

TABLE 9Available options for controlling soil and water loss

Reasons for soil and water loss Possible solutions for controlling soil and water loss

◊ surface run-off and sheet erosion

◊ soil erosion arising from poor covercrops

◊ rill erosion

◊ winter-ploughing◊ mixed cropping◊ conservation contours◊ conservation tillage: a. no-till tied ridging b. mulch tillage (more grass from fallows) c. no-till strip cropping d. furrow planting e. tillage rotation

◊ reduction of areas planted to maize◊ increase area planted to drought resistant crops

◊ contour ridges◊ storm drains◊ grassed waterways

active farmer involvement all options (extension bottom-upapproach)

Simple and high input packages do not fit in well with the complexity and diversity of thesmall holder farming systems. Resource-poor farmers also lack reliable access to purchasedinputs which are often expensive. However, cost is not only the overriding factor as farmers mayshow resistance to adoption of low-cost innovations. The reason why technologies are often notadopted is because researchers have inadequate understanding of the circumstances and

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production objectives of the small holder farmer. Identifying farmers' priorities and constraintsand helping farmers to meet them often leads to innovations which are environmentallysustainable and are subsequently adopted. This section highlights the history of researchapproaches in Zimbabwe. It reviews the extent to which available technologies for improving soilfertility and controlling soil degradation have been adopted by the small holder farmer. Thesection also sites a case study in which "participatory" or "interactive approaches" have beenimplemented to generate new innovations (to effectively interact with farmers without resorting tothe top-down approach).

History of research approaches in Zimbabwe

Prior to 1980, agronomic research was biased towards developing technologies for the highpotential and input intensive agriculture. The "resource- poor" small holder farmer did not benefitmuch considering the population dependent upon this type of agriculture. The little effortsdirected towards the communal farmer saw an emphasis on maize monoculture, crop rotationsand tillage (using the plough). Dissemination of these technologies tended to be top-downfollowing a package approach based on ecological zones and being transferred through a mediumof a special class of farmers. Small holder research was tackled in the same way in whichagronomic research was conducted for the commercial sector. Unfortunately, results of such anapproach failed dismally when applied to the small holder farming systems and farmers continuedto use their traditional practices. After independence in 1980, the Department of Research andSpecialist Services (DR&SS) (the major player in agricultural research) was also tasked todesign appropriate technologies for the "resource- poor" farmer taking into cognizance specificproblems common to a large proportion of these farmers namely:

• climatic risk (low and erratic rainfall,

• soil fertility risk (sandy soils poor in nutrient reserves, low water holding capacities andhighly acidic),

• limited resource procurrence capacity,

• limited scope to take risks due to fragility of most of the enterprises.

The establishment of the Farming Systems Research Unit (FSRU) in 1984, saw anothermajor shift in focus of research towards improving productivity of resources devoted to particularcrops. The research involved characterization of farming systems, testing and adoptingagricultural technologies as well as methodologies with a "systems perspective (FSRU, 1993).Several technologies were tested (both on station and on-farm) on new crop varieties, generalcrop husbandry, soil fertility management and minimizing drought. In most on-farm trials, thefarmer's role was limited to providing land, and researchers would identify problems, solutions,design and implement trials, monitoring and evaluation. Farmers would normally gather atresearch initiated field days to learn successful stories of crop production and soil fertilitymanagement. Recent approaches (i.e. participatory rural appraisal) which encourage farmers toparticipate in technology generation have made it possible for researchers, extension agents andfarmers to become equal and active partners in agricultural research, technology generation,transfer and adoption process.


Rates of adoption of soil fertility management practices in the small holder sector

The majority of technologies aimed at enhancing soil fertility have been targeted for areasgrowing hybrid maize and high value crops like cotton. The most common practices that havebeen promoted by researchers and extension agents include:

• inorganic fertilizers• organic materials (e.g. manure)• crop rotations• contour ridges• soil and water conservation strategies

The successes and limitations of these strategies are highlighted below.

Use of inorganic fertilizers. A survey conducted in Mangwende communal area (Mudhara andChibulu, 1996) reported extensive use of inorganic fertilizers. Over 98% of farmers indicated thatthey use both Compound D (8%N, 14%P, 7%) as basal fertilizer and ammonium nitrate (AN)(34.5%N) as top dressing on maize. Only about 2% of farmers do not apply any mineral fertilizerto their crops. Different fertilizer types are also applied to other crops. Compound L (5%N,18%P, 10%K and AN are used in sunflower and cotton. Gypsum (17.5%S) is used by 35.7% offarmers as top dressing in groundnuts. This scenario implies that fertilizer usage by small holderfarmers is dependent among other factors on value of the crop to the farmer. The bulk of thefertilizer goes to the maize crop which is a staple food crop (Table 10).

TABLE 10Adoption of basal fertilizer in selected crops in Wedza & Shurungwi-Chiwundura in 1990-91

Crop Wedza (% growers) Shurungwi - Chiwundura Maize 48.8 41.7 Groundnut 19.6 21.8 Sunflower 4.4 3.8

Source : Huchu and Sithole, 1993

It is well documented that one of the major costs faced by small holder farmers in producingmaize is fertilizer. In many households, cash required to buy fertilizer and other inputs outweighstotal cash income. The lack of cash is the dominating factor governing decision making athousehold level and also influence the development of adoptable technology.

Inorganic fertilizers are expensive. The use of chemical fertilizer in the small holder sector hasbeen declining with each announcement of new fertilizer prices. Poor farmers simply can notafford it. In a study carried by Sithole and Shoko (1991), lack of money was given by 60.4% ofnon-users as the main reason for not using fertilizers. In general, non-farm income and use ofinorganic fertilizers declines from the wealthiest stratum to the poorest. Poorest households applyless inputs on both fields and gardens although they have a more diverse range of inputs forgardens. Although there are credit facilities such as the Agricultural Finance Company (AFC)many farmers particularly those in the semi-arid areas are afraid to take risks. Theseshortcomings have forced farmers to review their fertility management systems. A significantnumber of farmers have reduced their application rates. In Mangwende communal area 370 kg/haof compound D is applied in maize systems by about 70% of farmers whilst 270 kg/ha of AN isused by 75% of farmers. In crops like sunflower, application rates of 120 kg/ha for both basaland topdressing are common (Mombeshora, Mudhara 1994). These levels are well below the crop

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and soil maintenance requirements. Although these levels reflect in inefficiency use of fertilizer,studies carried out in Wedza communal area (Sithole and Shoko, 1991), indicated thattopdressing is better adopted than basal fertilizers. Farmers who have livestock substitute manurefor basal fertilizers. In the 1990-91 season 40.8% of farmers in Wedza who applied manure didnot use initial fertilizers. Top dressing on the other hand has no substitute which could explainpartly its higher adoption relative to initial fertilizer (Table 11).

TABLE 11Fertilizer use on maize in Wedza and Shurungwi - Chiwundura

Fertilizer Application % of Users in Wedza % Users in Chiwundura Basal 48.8 41.7 Top dressing 28.9 90.9

Source : Huchu and Sithole, 1993

Apart from high costs in fertilizer prices, several authors have reported that fertilizerrecommendations are frequently unattractive to the small holder farmers. Recommendations oftenignore soil and climatic variation in the area farmed by small holders and are incompatible withtheir resources. Of The 32% of farmers who followed fertilizer recommendations for their maizecrop in the satisfactory season of 1990/91, 48% failed to recover the value of the fertilizer (Pageand Chonyera, 1994). Thus the profitability of fertilizer usage was reduced. An example ofinappropriate recommendation is related to the application of basal fertilizers. Farmers areinstructed to apply basal fertilizer for maize at planting. Instead farmers almost always apply thistype of fertilizer at 3 to 4 weeks after establishment which is easier and less risky and results innegligible loss of yields under their circumstances (Shumba, 1985). This practice allows farmersto plant a larger area and get better crop establishment.

Another example cited of an inappropriate recommendation is based on the type of fertilizerused. Mashiringwani ( 1983). A rare response to K on sandy soils common in the small holdersector is reported. The recommended compound fertilizer contains K as well as N and P.Adoption of could be enhanced by applying a cheap N alone immediately after planting andcheaper forms of P at other times. Adoption of inorganic fertilizer has also been influenced byfarmer's attitude. Informal interviews in Mutoko communal area (Carter, 1993) revealed thatsome farmers will not apply inorganic fertilizers particularly basal dressings because they believeit weakens the soil structure. In Gokwe, although cotton is a priority crop, the majority of farmerswere found not to use basal fertilizers (76%) or top dressing (77%) on this crop (Mudhara 1993).The main reason was that soils were still fertile. This, however, contradicts to extension messageswhich encourage farmers to apply inorganics. Where fertilizer was applied by users, there weremarked differences in yields. Average yields of cotton were 38% higher where basal dressingswere used and 30% higher where AN was applied (Table 12).

TABLE 12Effect of fertilizer on average farmer's, yields (kg/ha) of cotton in Gokwe in 1990-91 season

Used Basal fertilizer No Basal Fertilizer Used Top Dressing No Top Dressing 723 523 704 542

Source : Mudiwa, 1993

Use of organic amendments. Cattle manure is one of the low cost management options whichfarmers use to sustain soil fertility and cropping programmes. This has become evidentparticularly with the increases in commercial fertilizer costs. Substantial use of manure is onlylimited to those farmers who own a large number of livestock. A survey conducted in Mangwendecommunal area in 1982 indicated variation in cattle ownership (from 20% to 70% of householdswith average of 46%). The survey reflected that 73% of farmers owned cattle some ten years ago,


with an average of 6.86 compared to 3.29 at the time of the survey. Amongst owners 52%applied manure in the first year of a maize - maize - legume small grain rotation compared to12% of non-owners. Additional 75% applied manure in the same field in the consecutive yearscompared to non-among non-owners of cattle.

Supplementation of manure with chemical fertilizers is quite common particularly in maize-based system. However, farmers lack knowledge and understanding of the combined use of the 2nutrient sources together. To make recommendations for combined nutrient use, information onfertilizer equivalency of organics is needed. Farmers also lack knowledge on how much of manureor other different quality organics to apply to get yields equivalent to those obtained frominorganic fertilizers. Manure application rates range from 4.5 to 20 t/ha depending uponavailability. The Alvord rotation recommended for small holder areas of Zimbabwe applicationrates of 30 - 40 t/ha to a maize crop followed by another maize-crop, then by groundnuts andlastly by a fine rooted crop such as pearl millet (Grant 1987). This system has collapsed due toscarcity of manure in most households. The situation has been made worse by poor quality ofmanure produced, which is attributed to poor quality of the veld, imperfect storage and handlingconditions in the kraal (which trigger nutrient losses particularly NH3 by volatilization), moisturelevels, ambient temperature and exposure to the environment, (Nzuma and Murwira, 1997).

Cattle manure is applied in a dried, aerobically decomposed form often with a high sandcontent (50% to 90%) and an N of less than 2% (Mugwira and Shumba, 1986).. The samescenario prevails even today. Recent studies in Mangwende CA reported low nutrient status ofmanure samples collected from households. Ninety-seven percent of samples collected wereacutely deficient in N whilst 94% were deficient in P. (Nzuma and Murwira 1997). Currentefforts are being made to improve the quality of communal area manure by minimizing nutrientlosses through manipulation of biological processes (Nzuma Murwira, 1997). Dhliwayo andMukurumbira (1996) initiated benefaction cattle manure with P fertilizers. However, thesustainability these systems is questionable. Although CA farmers have traditionally used manureas a soil amendment, there are other less common soil fertility management practices such as useof wood ash, compost, anthill, leaf litter and incorporation of crop residues along with croprotations (Carter and Murwira 1995, FSRU 1993). Nyathi and Campbell (1993) reported that73% of farmers in Masvingo collect large amounts of miombo leaf litter, most of which werecured in kraals. Further, 86% of farmers mix their litter with manure or with manure andfertilizer before application. Though it appears that there are satisfactory quantities of organicmaterials on and around the farm, most of these materials have a low nutrient supplying capacity.The challenge is to get more higher quality organic materials on farm.

Use of hybrid seed. The major success in maize research in Zimbabwe has been in maizebreeding. This is indicated by high adoption rates of hybrid maize even though average yields are1t/ha (Rohrbach 1989). Adoption of hybrid seed particularly early maturing varieties have beenstrongly recommended for CAs with poor rainfall. The advantage is short growing season andattainment of maturity stage before rains cease. Adoption of hybrid seed, particularly maize hasbeen very high. Study carried out in Wedza (Sithole and Shoko 1991) showed that 98% of theCommunal farmers used hybrid seed.

Crop rotation. Crop rotation is vigorously promoted by extension agents for improving soilstructure and facilitating the transfer of nutrients between crops via soil. It also helps controlpests and diseases. Adoption of crop rotation is high, perhaps because of no labour and no directcash costs involved into the practice. The rotation is not a planned sequence of different types ofcrops but rather a haphazard movement of crops to areas within the fields. Most farmers rotatethe grain crops mainly and rarely include leguminous crops because of limited area grown to

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them. In studies carried out in Wedza in 1991, 74.8% of communal farmers interviewed werefound to practice crop rotation in their fields. A similar percentage of farmers (75%) inMangwende were reported to practice some crop rotation. The figure for Gokwe and Nyanga wasfound to average 76% in 1992 for both areas. In some areas adoption of this practice is quite low.The main factor limiting adoption of crop rotation is poor access to resources such as land labourand agricultural inputs, maize tend to be the dominant crop using 80% of the arable land and verysmall acreages are left for other crops. Thus much of the land is always under continuous maizecrop and only small portions are rotated with groundnuts, sunflower and cotton.

Soil and water conservation

The majority of small holder farmers (75%) in Zimbabwe are concentrated in semi-arid areas ofthe country. These areas are situated in natural regions IV and V and marginally some parts ofnatural region III. Rainfall in these areas is low (about 600 mm per annum) and erratic. Droughtinduced crop failure occurs in one out of every 4 years. Soils are generally sandy inherentlyinfertile (Grant 1967, 1981). High water losses are common from arable lands. Sheet erosionresults in further soil loss, and the agricultural potential of the area continues to deteriorate eachseason. Soil losses in the order of 50t/ha per year through sheet erosion, and run-off losses of theorder of 35% of total seasonal rainfall have been estimated (Elwell, 1985). Tillage offers the mostpromising tool to manipulate and control erosion and ameliorate the fragile semi-arid soils(Chuma and Hagmann, 1995). Experience has shown that adoption of new interventions has beenhampered by the lack of participation by beneficiaries in the development process (Chambers etal 1989). Various agencies in Zimbabwe have shown a necessity for change in agricultural andrural development towards farmer participation in order to increase efficiency of developmentactivities and to effect adoption (FSRU 1993, Mlambo, 1994; Makado 1994). It has beenrealized that sustainable resource management utilization can only be achieved if communitybased participatory approaches are developed and applied rather than present top-downapproaches which do not involve farmer participation (Hagmann, et al 1995). In view of thesefacts, researchers/extension/development agencies Zimbabwe are currently working towards soiland water conservation packages that can be adopted by the small holder farmer (GTZ-ARDA/PPU,1995). This approach requires new roles and attitudes of both parties involved intechnology generation and its dissemination.

Farmer Participatory Research In soil and water Conservation Tillage. The ConservationTillage (Contil) for sustainable crop production systems project was initiated in 1988 and is on-going. It is a collaborative program between GTZ (German Aid Agency) and Institute ofAgricultural Engineering (IAE, Agritex). A very positive development of this Contil project wasthe initiation of complementary adaptive on-farm trials (Hagmann, 1993), which uses aconservation tillage approach known as the "KUTURAYA". The "Kuturaya" (meaning to try) isfocused towards research and farmer participatory in soil and water conservation. (Nyagumbo1996) It plays a role in influencing adoption of technologies by creating awareness and inspiringfarmers to try and assess the feasibility of certain animal powered conservation techniques underfarmer's management. These techniques include:

• conventional (or clean ripping)• tied ridging• mulch ripping• hand hoeing• bare fallow


Specific objectives are to develop these systems further and to adapt them to the farmingsystems of small holders in various natural regions. The approach is based on the hypothesis thatonly farmers themselves can develop and or adapt a technology to their specific needs andrequirements. This approach inter links technical and socio-economic aspects of agriculturalproduction systems. The trial is voluntary and farmers participate out of their own interest. Oncefarmers have become familiar with experimentation the research process becomes solely farmerdriven and the role of researchers is only to facilitate the process. (Nyagumbo, 1996). To enhanceactive farmer participation in the Kuturaya process, training for transformation (TFT) (Hope etal., 1984) is applied in farmer workshops. TFT has increased farmers evaluation capabilities andstrengthened the social Organisation of communities (Hagmann 1993). The impact achievedduring the last 3 years in Gutu, Zaka and Chivi communal areas has been encouraging in terms offarmer participation (Hagmann et all 1995). Farmers are reported to have initiated their owntrials resulting in gain in confidence. Farmers have also shared their experiences in farmerinitiated and self organized field days. Results from the 4 years of data indicate that no - till tiedridging (Inttr) is the best conservation and production technique for the sub-humid north ofZimbabwe whilst mulch ripping has been recognized as the most favourable tillage option for thesemi-arid areas.

TABLE 13Advantage of no-till tied ridging as perceived by both participants and non participants

Advantage Participants % Non-participant %Moisture conservation 57.5 27.7Soil conservation 27.5 8.4Crops mature fast 7.5 0Better yields 2.5 4.8No idea of importance 2.5 30.1

However due to limitations in availability of residue, (residues grazed by livestock) no mulchis available and tied ridging with its reduction in the run-off losses and associated low soil lossappeared to be the most applicable sustainable tillage system. Nutrient losses under tied ridginghave been reported to be lower than in the conventional till as water infiltration losses areconfided to the furrow leaving nutrients in the ridge (Hagmann 1994). A majority of farmersinvolved in the demonstration and trials (57.5%) have indicated appreciation of this system as amoisture conserver, while 27.7% of non participants shared the same view. The aspect of soilconservation was appreciated by 27.5% participants and 8.4% of the less informed non-participants (Table 13). The beneficial effects of tied ridging have been reflected in yields ofcotton in Gokwe Sanyati and Sebungwe communal area where it is currently extensively used(Mudiwa 1993). This is illustrated in Table 14.


Government objectives since Independence in 1980 have been to create an enabling institutionaland policy environment to stimulate production and sustainable development in the smallholdersector. A number of institutions previously set up to service the large scale commercial farmingsector had their mandates changed either to give priority to the smallholder sector or to take thesmallholder sector on board. A whole package of support which included research, technical andextension services, marketing infrastructure, finance and favourable prices was given to stimulateproduction in the smallholder sector. Smallholder farmers responded to this gesture by increasingproduction levels significantly. However this increase in output was due to more land beingbrought into production rather than improvement in yields on a per hectare basis. The benefitsbrought about by the change in institutional and policy environment were short lived as problems

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associated with the magnitude of the change and declining resources began to surface.Institutional support by government could not be sustained at the required levels. Whilstgovernment policy statements have continued to be dominated by the need to increase productionin the smallholder sector, environmental problems and rural poverty have continued to take centrestage.

TABLE 14Average yield responses of seed cotton (kg/ha) to four moisture conservation techniques by twolevels of fertility for Gokwe, Sanyati and Sebungwe Communal Areas, 1984-90

Season1984-85 1985-86 1986-87 1988-89 1989-90 1990-91 Mean Flat

%No. sites 9 10 12 8 4 5Average Rainfall(mm)

668 786 378 587 542 516

Planting andfertilizer treatmentFlat

1,319 1,212 741 1,672 569 1,067 1,207 100

Flat fertilized 1,529 1,626 861 2,080 756 1,166 1,500 124Flat + potholes 1,473 201 781 1,778 600 1,295 1317 109Flat + potholes +fertilizer

1,824 1,651 920 2,061 711 1,407 1,631 135

Ridges 1,323 1,221 930 1,601 675 1,450 1,321 109Ridges + fertilizer 1,620 1,743 1,031 2,000 880 1,515 1,675 139Ridge + cross ties 1,412 1,294 946 1,596 723 1,597 1,375 114Ridge + cross ties+ fertilizer

1,713 1,857 1,134 1,996 982 1,932 1,814 150

s.e. (conservationmean)

52.3 42.6 26.3 65.4 43.8 81.5

s.e (fertilizermean)

17.5 30.1 18.6 46.3 27.0 41.6

Mean (unfertilized) 1,375 1,232 849 1,662 642 1,352 1,304Mean (fertilized) 1,672 1,719 987 2,034 832 1,505 1,655significance:conservation

NS * *** NS ** ***

significance:fertilizer

*** *** *** *** *** *

conservation lsd0.05

- 118.1 72.9 - 121.4 225.9

fertilizer lsd 0.05 48.5 83.4 51.5 128.3 74.8 115.3Source: CRI

Institutional framework

There are a number of government institutions whose functions have a bearing on environmentalmanagement. These institutions are sectorally structured, an arrangement which leads toconfusion of hierarchy, duplication of programmes; and ultimately inefficiency. Conflicts havearisen from uncoordinated parcelling out of responsibilities among departments. A good exampleis the allocation of conservation responsibilities between the Department of Natural Resources(DNR) and the department of Agricultural Technical and Extension Services (Agritex). WhilstDNR is responsible for policing the state of conservation, and more recently extension in thesame area; Agritex is responsible for extension and providing technical solutions to the problems.Another example is the parcelling out of responsibilities between the department of Agritex andthe department of Rural Development under the Ministry of local Government in Land UsePlanning (LUP) programmes. Agritex is responsible for determining issues of access and use of


resources through LUP, while local government is responsible for implementing land use re-Organisation programmes.

Following independence in 1980, government adopted a policy of decentralizing planninginstitutions to provincial, district, ward and village levels. These institutions have in practicehowever proved to be more politically oriented than developmental oriented. These planninglevels have virtually no power to plan or allocate resources. Prior to independence in 1980,powers to allocate and manage resources in the communal areas were vested in the traditionalleadership. They used to set rules and regulations on utilization of resources which wererespected and followed by their subjects. This type of arrangement proved to be fairly effective inthe management of natural resources. Traditional leadership were however relegated to non-functional roles after 1980 and replaced by local government structures. This actuallyundermined the traditional power structures which used to control natural resources effectively.

Planning for resource management initiatives has proved difficult within the constraints ofthe new administrative structure of the Village Development Committee (VIDCO) due to artificialboundaries demarcated to fit an administratively defined user group. A VIDCO was defined as100 households in each village irrespective of existing boundaries, kinship and without takingcognizance of the underlying resource endowments. The institutional framework suffers from aserious problem of fragmentation and poor co-ordination. there is insufficient co-ordination of theresponsibilities of institutions at various levels (national, provincial, district, ward and village) formanaging or enforcing policy, planning ; and monitoring information and technical programmes.The framework, especially at implementation level in the communal areas has remainedregulatory with a conspicuous absence of appropriate incentives.

Policy and legislation

There are several pieces of legislation that deal with land issues in Zimbabwe. These include; theNatural Resources Act (1941), Forest Act (Amended in 1981) Mines and Minerals Act (1961),Rural District Councils Act (1988) and the communal Land Act (1982). These pieces oflegislation suffer from two main problems:

• There is lack of hierarchy, i.e. there is no one act which supersedes others in terms ofenvironmental protection. The legislation is sectionalized and overlaps, allowing too manyministries decision making powers on environmental issues. The end result is a fragmentedapproach to management of natural resources.

• Legislative and organizational apparatus have not been designed in a manner whichencourages people to participate in improving their environments. Most of them place greateremphasis on controls (criminalization) than providing incentives for sustainable resource useand encouraging communities to develop their own resource management solutions.

In general terms, there is insufficient co-ordination of policy and legislation. The current

policy environment has failed to address the population pressures on agricultural land and theenvironment at large. There is need to put in place policies that encourage investment intechnology and research in order to increase production in low potential areas and minimizeenvironmental pressures. Clear policies on issues such as tenure and environmental management;together with clearly elaborated action plans that take all stakeholders on board, would berequired to facilitate effective natural resources management.

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Research and extension linkages

The Ministry of Lands and Agriculture through the departments of research and specialistservices (DR&SS) and Agricultural Technical and Extension Services (Agritex) play a pivotalrole in influencing land-use patterns and productivity in the communal areas. DR&SS is aresearch department which carries the mandate to do research in all agricultural commodities withthe exception of tea, coffee, tobacco and pig production. Agritex is the main extension arm of theMinistry with extension personnel deployed throughout the country. The need for strengtheningresearch and extension linkages was realized during the early 1980s when the Committee for on-farm research and extension (COFRE) was established in 1986. The objectives of COFRE wereto co-ordinate on-farm trials and demonstrations as well as give researchers and extension staffan opportunity to interact in a real farm situation (Pazvakavambwa, 1990). The COFREmechanism, while well intentioned has not resulted in a focused and quality research programmegoing for smallholders. The activities of COFRE were severely curtailed by institutionalproblems such as inadequate funding, shortage of experienced staff and shortage of transport.The following paragraphs give a description of specific problem that have affected the activitiesof each department.

Department of Research and Specialist Services. Upon attainment of independence, priority forresearch and extension was focused on the smallholder sector forcing the government to increasethe size of the institution in terms of scientist staffing levels. However, this expansion was notmatched by resources with which scientists would carryout their investigations. Most of theresources were channelled towards meeting salaries rather than developing technologies suitablefor smallholder farmers. Added on to this, was the brain drain problem resulting in the loss ofexperienced staff at a time when the real challenge was to address the complicated research needsof communal areas. In 1981, DR & SS initiated an adaptive on-farm research programme. Thiswas intended to improve research - extension - farmer linkages. This programme was short livedas it was frustrated by lack of resources such as vehicles and travel allowances, resources whichare absolutely essential to keep such programmes running. The budget of DR & SS was reducedby 25% in real terms between 1980 and 1989. This forced DR & SS to scale down on on-farmresearch which had been well intentioned to benefit small-holder farmers. (Shumba, 1990).Importantly, DR & SS has not had resources to address itself to the agricultural problems of thepoorest, less developed sectors of the rural economy who try to farm in areas that have long beenrecognized as having low agricultural potential. This has contributed to serious land degradationproblems in the smallholder sector.

Department of Agricultural Technical and Extension Services. The Department of AgriculturalTechnical and Extension Services (Agritex), as an institution, was not spared from the problemsof brain drain and under funding which afflicted its sister department, DR&SS. Although innominal terms, the funds allocated for extension have been increasing, there has beenconsiderable fluctuations in real terms, with annual allocations between 1984 and 1993 averagingZ$13.8 million and with the allocation for 1993/94 well below the level for 1980/81. The nationalallocation to agricultural extension as a proportion of national expenditure actually declined by50% from 0.8% of national recurrent budget in 1980/81 to 0.4% in 1993/94. At the same time,the operating part of the budget has declined from about 30% in 1980/81 to 20% in recent years,with the balance of expenditure going into salaries.

The Extension Worker to farmer ratio of approximately 1:800 is too low for effectivecoverage. Group approaches have been adopted to make up for the gap, but these strategies tendto leave out the poor farmers who regard these as elitist groupings. Extension staff also need


mobility in order to do their work effectively. Transport is one area were the extensiondepartment has been hit hard, and therefore has far reaching negative implications with respect toenvironmental conservation.

Financial support to the smallholder sector

In the early 1980s, the government of Zimbabwe adopted a policy of financial support throughprovision of credit as a strategy for smallholder farmer development. This was done through theAgricultural Finance Co-operation (AFC), a parastatal lending institution. AFC loans to thesmallholder sector increased from 18 000 in 1980 to 77 526 in 1985; but the in attention to soundlending practices meant a collapse of smallholder lending, with a decline in loans to a low 15 973in 1993 (AFC, 1993). The decline in the loan portfolio was due to both reduced demand andstricter procedures on the part of AFC. Improved access to loans was associated with increases inthe use of inorganic fertilizers in the smallholder sector. There is now a general decline in thefertilizer market share of the smallholder sector since the late 1980s. This has been linked to loanrepayment problems and the rising cost of fertilizers on the market. But even at its lending peakin 1985/86, AFC was only reaching 10% of communal area farmers.

Extent of data/information on land resources

Most information relating to land resources is unconsolidated and lies with different institutionsinvolved with land management issues. The department of the surveyor general normally flies thecountry every five years to produce aerial photographs. These are produced for the consumptionof institutions involved with land use planning, land surveys, environmental management andeven individual land owners. The department of Agritex is a key player in producing farm,village, ward and resettlement plans. Most of these plans are available as hard copies at theAgritex offices. Efforts are now under way to store some of the information in digital formthrough the Remote Sensing/GIS project. To date, information from 6 wards of Lupanecommunal area and some parts of Gokwe has been computerized. This information includesdrainage systems, and capability classification, vegetation, contour lines, Ward boundaries andInfrastructure. Some information on soils is available with the department of research andspecialist services. The department of Natural Resources produced a fairly comprehensive reporton Land Degradation in Zimbabwe (Whitlow, 1988). There have been very little efforts to updatethe report in recent years.

Land tenure

There are five major land use types in Zimbabwe. These are communal areas, commercial farms,resettlement areas, state land and national parks, and urban areas. Communal areas occupy 42%of Zimbabwean surface area and accommodate about 75% of the population of approximately11.9 million people. The majority of communal areas are located in the marginal areas of thecountry where rainfall is low and poorly distributed. The soils are mostly granitic sands with verylow inherent fertility. Communal farms are small and are allocated by traditional leaders. Landdegradation in the communal areas is primarily a result of mismanagement problems related toploughing, stream bank cultivation and insufficient application of organic and inorganicfertilizers. Continuous cultivation of land, lack of crop rotations and poor soil managementschemes have resulted in poor soil structure and declining crop yields. Communal farmers havegenerally not adopted technologies developed for large scale commercial farmers because most ofthese technologies are not appropriate to their circumstances

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Changes in soil fertility

In the majority of research trials conducted in Zimbabwe on the use of cattle manure for soilfertility the increase in crop yield has been employed as the sole indicator of soil fertilityimprovement. Comparatively few trials have assessed the effects of manure on specific soilproperties such as increases in pH, CEC, N mineralization and available P etc. As done by Grant(1967a, b). There is a need to assess the effects of CA manure on changes in soil fertility factorsand other soil conditions which may indirectly affect soil fertility. These investigations include:

• assessment of changes in available soil P as affected by repeated application of manure andfertilizers in the CAs to establish if application of CA manure helps to increase availability ofP applied with fertilizers, and incipient soil P,

• establishing critical evidence on the residual effects of manure which will be useful forassessing the value of manure as a liming and nutrient source when considering integratednutrient management in the CAs,

• assessment of rates and frequency of application of CA manure which would help maize towithstand soil pests such as nematodes which adversely affect yield on sandy soils and limitfertilizer response, as found by application of heavy rates of manure at Grasslands by Grant(1987).

Restoration of soil productivity to depleted croplands

• A quantitative survey of depleted lands should be conducted by DR&SS and Agritex to findout where most of these lands are located with a view to properly targeting research on therestoration of soil productivity.

• Soil characterization under conditions of nutrient depletion should be made to establishbaseline levels of pH, organic matter and nutrients as well as physical properties related tosoil productivity.

• It is necessary to establish nutrient requirements for the restoration of depleted lands since therates of manure and inorganic fertilizer normally used in croplands are obviously too lowunder depleted conditions. Elements of a high input strategy to recapitalize the soil fertility ofexhausted soils are needed.

• Long-term trials on the same fields should be conducted to enable proper evaluation of soilfertility changes due to fertility inputs with a view to extrapolation the technologies.

• Screening to establish the most appropriate legumes for different areas should be conducted.

• The need to raise the availability of green manure seed should be addressed.

Improving capacity and use of site-specific or location specific fertilizer recommendations

Mapping crop and nutrient status for improved fertilizer recommendations in the CAs.

Targeting research to neglected soils and agro-economical zones

Most of the research on soil fertility, particularly the use of manure, has been concentrated onupland soils in NRII and relatively little has been done in Regions III, IV, and V. The followingresearch is suggested:


• investigations on crop responses to manure application in NR III, IV and V, both in terms ofquantity and quality,

• investigations on crop responses to manure applications on vlei (hydromorphic) soils whichplay a major and unique role in the CA agriculture,

• further investigations on the use of small amount of manure applied annually in combinationswith inorganic fertilizers on the restoration and maintenance of soil productivity on a widescale.

Strategies for combining organic and inorganic fertilizing materials to optimize nutrientavailability to plants

Establishing fertilizer equivalency of organic materials: in order to make meaningfulrecommendations for the combined use of organics with mineral fertilizers it is necessary todetermine first the fertilizer equivalence of the organic materials, then:

• conduct research on fertilizer N equivalencies of organic materials of different quality in thefield trials using crop yield response as basis for effectiveness of these materials, and

• combine the organic and inorganic sources based on the results from the fertilizer equivalencyvalues.

Establishing manure and fertilizer requirements:

• there is a need for research specifically aimed at establishing the quantities of manure andfertilizer necessary to maintain soil productivity or fertility (Mugwira and Murwira), 1997.This calls for closer collaboration between researchers in the country in establishing amountsof manure and fertilizer to be tested in trials, taking into account that manure is applied tosoils primarily as a fertilizer and as such, its a fertilizer replacement value,

• develop research for establishing optimum application rates based on the N content andespecially the rate of release of N from manure. From established rates of release, it could bepossible to make estimates of residual N availability in later seasons,

• develop a rational basis for the use of manure based on decomposition rates and tests ofnutrient availability for making proper recommendations,

• the time of application of N fertilizer to fields which have received manure should be furtherinvestigated in order to synchronize N supply in the soil and N demand by the crop.

Improving the effectiveness of manure

Improving of manure quality: it has been firmly established that cattle manure from the CAs ofZimbabwe is low in nutrient contents and that this poor quality contributes to the loweffectiveness of manure in improving plant growth and crop yield (Tanner and Mugwira, 1984;Mugwira and Mukurumbira 1984; 1986). The following research options are recommended toameliorate the quality of manure:

• expand the work on beneficiating cattle manure in the CAs through co-composting withchemical fertilizers (see Dhliwayo and Mukurumbira, 1996) under different environmentalconditions,

• investigate technologies and management of resources within the reach of the farmer such as:- improvement of pastures by planting legumes at village level or small watershed scale.

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- management practices at kraal level which will reduce nutrient losses and sand content ofmanure

- the efficacy of crop residues and other plant materials as absorbents of urine to reducenutrient losses

- handling techniques for anaerobically treated manures to improve quality.

Improving techniques for manure application for optimizing crop response: the most efficient andeffective way of applying cattle manure for meeting crop nutrient requirements and producingoptimum yields is a very important aspect for the smallholder farmers who often have limitedamounts of manure to apply at recommended rates to their croplands. Research should emphasizethe following aspects:

• systematic assessment of method and rate of application of cattle manure on crop yields indifferent agro-ecological zones,

• further research on comparisons of different methods of application of varying manure ratesfor optimizing the efficiency and effectiveness of the limited amounts for the potential benefitof the resource-poor farmers on sandy soils,

• more research comparing the benefits of applying small rates of manure more frequently, andthose of larger rates applied at longer intervals,

• management strategy for application of inorganic N by delaying so as to reduce N losses andincrease synchrony of N availability and uptake by the crop. A simplified approach is todevelop a relationship between total N content of manure, N mineralization rate andminimum fertilizer to be added (Mugwira and Murwira, 1997),

• identify obvious characteristics associated with manure that can be used by extensionworkers and farmers to determine manure quality.

Fertilization for all crops in rotation

As the starch staple for most Zimbabwean maize receives better fertilization through both organicand inorganic inputs than other crops grown in the smallholder sectors. Manure is usually applieddirectly for maize in rotations with subsequent crops while inorganic fertilizers are applied atsmall rates or not applied at all to other crops (e.g. sunflower). These factors are major causes ofsoil fertility decline. The following aspects need to be investigated:

• rationalization of nutrient-use efficiency in the common rotations currently practised indifferent areas of the country with a view to improving these rotations and/or introducingmore efficient crop sequences,

• assessment of the cost effectiveness of organic and inorganic fertilizer inputs on crops suchas groundnut or sunflower which are becoming increasingly important not only because oftheir food value but also due to their increasingly commercial value as cash crops under thefree market systems i.e. crops now perceived by smallholder farmers as having niches in theirfood security and income generation.


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Chambers, R. et. al (eds.), 1989. Farmer first. Farmer innovation and agricultural research. IT publ.London.

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FSRU. 1993. Soil Fertility Management by Small Holder Farmers. A Participatory rapid appraisal inChivi and Mangwende communal areas, Zimbabwe. Farming Systems Research Unit. Departmentof Research and Specialist Services, Causeway, Harare, Zimbabwe.

Grant, P.M. 1967. The fertility of sandveld soils under continuous cultivation. The Rhodesia, Zambiaand Malawi Journal of Agricultural Research. 5 pp 71-79 and pp 117-128.

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Annex 1

Opening and closing addresses

WELCOME ADDRESS: Ms. V. Sekitoleko, FAO Subregional Representative

Distinguished Country Delegates, Director of AGRITEX, Ladies and Gentlemen

FAO is particularly honoured in organizing this workshop in cooperation with the Government ofZimbabwe on one of today's most important subjects, particularly in Africa: Integrated SoilManagement for Sustainable Agriculture and Food Security.

The majority of developing countries are faced with great challenges to sustain and increasefood production for their rapidly growing population. Countries with limited land resources,particularly those which cannot easily finance increased food imports, will be faced with serioushardship. The various forms of' land degradation are seriously affecting the land resources basecontributing to considerable yield decline and loss in food production. It is evident that no foodsecurity could be expected without effective planning and improved management of land, waterand nutrient resources to ensure sustainable and increased production.

Technical options and appropriate soil management and conservation practices are availablefor correcting or minimizing the degradation of' the soil base, for maintaining and enhancing landproductivity, and thus improving food production and security.

Nearly 1,4 billion ha of' land in developing countries are subjected to various forms ofdegradation, resulting in severe decline in productivity. About 490 million ha, in Africa alone, areaffected by degradation. Poor and inappropriate soil management is the main cause ofdegradation of cultivated lands. Increasing population pressure, particularly in vulnerableregions, has caused serious soil fertility decline, especially under extensive farming practices. Asa result, farm productivity and revenues from agriculture are falling, migration to urban areas isincreasing and household and national food security is declining.

With recent emphasis and priority programme of FAO for food security, issues relateddegradation and its negative impacts on food production as well as land improvement forenhanced productivity are receiving special attention. Successful experiences and initiatives forsoil improvement in a specific country or socio-economic and agro-ecological environment havetaken place, but their wider dissemination for the benefit of other countries, even in the sameregion, is still limited.

At present there are 86 low-income food deficit countries (LIFDCs), including 43 countriesin Africa and 9 in Latin America and the Caribbean. These countries are home to majority of theworld's 800 million chronically undernourished people. Many LIFDCs, particularly in Africa, donot grow enough food to meet their needs and lack sufficient foreign exchange to fill the gap bypurchasing food on the international market.

Annex 1: Opening and closing addresses384

After the approval of the Council in June 1994, a special programme for food security waslaunched by FAO and at present it is operational in 20 countries. Initially launched with modestFAO regular programme funds, the SPFS is now supported by several donor countries andinternational agencies, including the World Bank, African Development Bank, WFP and UNDP.In the short and medium term the technical packages for enhancing productivity in the SPFS mayheavily rely on low-cost/low-risk options. As such, appropriate and integrated soil and nutrientmanagement for conservation and improvement of the soil base, besides proper water harvestingand small irrigation management, are among the essential elements for enhancing crop productionand ensuring food security.

The FAO strategic framework for the Post World Food Summit Period, consists of two mainstreams of priority programme areas: one emanating from the objective of "Food security” andthe other is arising from the objectives embodied in "SARD" (Sustainable Agricultural and RuralDevelopment, Chapter 14) of Agenda 21. In both streams, areas relevant to land resources,integrated soil, nutrient and water management are emphasized.

I have no doubt that this expert consultation is an excellent opportunity to discuss criticalissues of appropriate soil and water management to address food security. I am sure that yourcontributions to this workshop will make it a turning point and a success with the appropriateactions.

Thank you.

OPENING ADDRESS: Cde Kumbirai Kangai, Honourable Minister of Lands and Agriculture

FAO Subregional Representative for Southern and East Africa, Ms Sekitoleko, DistinguishedGuests, Ladies and Gentlemen

I would like to thank you for according me this opportunity to address this expert consultation onIntegrated Soil Management for Sustainable Agriculture and Food Security in and EasternAfrica. Mr Chairman, I believe this to be one of the most complex issues we face today not onlyin this country but in the continent and the world at large. I am glad this forum is going to addressthe issue of integrated soil management and I stress because problems of soil management aremulti-sectoral.

The goal of achieving and sustaining farming resources is now the top priority concerns forpolicy makers in agricultural and environmental policy in many countries. Mr. Chairman, bothrenewable and non-renewable resources are inputs to and outputs from the agricultural system.Agricultural systems convert these resources into food and other agricultural products, ensuringfood security for the communities. Sustainable agriculture, therefore, calls for a growth strategythat does not comprise the welfare of our future generations. Such a strategy is possible onlywhen policy makers in general and farmers in particular, recognize that management of theenvironment and economic development are basically connected.

The environment consists of closely intricate systems. Trees and grass for example onlyprovide fuel and fodder but also build soil fertility, prevent soil erosion, provide water catchment,reduce effects of climatic changes and provide wildlife habitats. These systems undersign humanwelfare now and in the future since it is these that man must utilize wisely in order to maximizeeconomic gains over the years ahead.


About 320 million hectares in Africa alone are affected by moderate to excessivedegradation. The main causes of physical and chemical degradation of cultivated land have beencited as poor and inappropriate soil management. It is also estimated that, without properconservation measures, one heavy storm at the start of a season can remove up to 20 tonnes ofsoil from every hectare of land. Thus, 100 tonnes of soil can easily be lost every season if soundenvironmental practices are not adopted.

Increasing population pressure particularly in vulnerable regions has caused serious fertilitydecline, especially under extensive farming practices and this is manifested by declining yields,decreasing vegetation cover and increasing soil erosion. As a result, farm labour productivity andrevenues from agriculture are falling, migration to urban areas is increasing and household andnational food security is declining. If this vicious cycle of land degradation cannot be stopped, thesource of existence of' the majority of the population especially in Africa will be severelyaffected. Africa will not only be left at the periphery of development but will increasingly find itdifficult to meet food requirements of her increasing population.

There exists much information on land degradation and its implications for the sustainablemanagement of soil resources. However, the information is either wholly empirical or vague andunsubstantiated. There is a need to synthesize and consolidate the best quality experimentallyderived quantitative information on the relationship between sustainability and productivity. Tomake predictions of long term trends on the quality of soil resources and of agriculturalproduction for food security, scenarios relevant to tropical Eastern and African situations, arealso required in order to examine the range of control measure which could address thesepredicted outcomes. The demand for this information is increasing given the threats of droughtsthe region is facing.

Earlier approaches to the management of 'our environment were based on assessment of theimpact of individual projects and investment programmes in terms of' pollution control,afforestation or water management. However, this project by project approach has tended toaddress symptoms rather than root causes of environmental problems. Sound strategies shouldlook beyond individual projects to the broader issues, to take full account of the links betweensectors. The problem of soil erosion has in the past been regarded as a physical process to becontrolled by the correct physical methods such as terraces, contours and check dams. Theproblems were regarded as requiring engineers alone. However, land planners have realized thatthe basic causes are land management strategies which require an integrated approach thusdrawing planners, farmers, policy makers and scientists together to make plans on landdegradation. I believe even in this workshop we have a mixture of these to plan for an integratedsoil management.

I am glad to note that FAO since 1984 has been supporting the Network on Erosion InducedLoss in Soil Productivity which provides information which helps in identifying the agro-ecologies where concerted action is needed now or in the near future to avert substantialagricultural production loss and the consequent food security threats brought about by soilerosion.

Let me conclude by giving special thanks to FAO and AGRITEX for organizing thisconsultation. 1 do hope that at the end of the consultation, strategies for better soil managementwould be designed. It is important to note that much of the land being lost due to erosion or hasbecome dangerously saline could be reclaimed and brought back into full production in an


environmentally sound manner. Corrective measures are needed in order to achieve a sustainablefood production base. The responsibility for this lies on the governments and people of ourcountries. Rectifying land degradation and sustaining crop production through appropriate soiland water management and conservation are, therefore, important components in the effortstowards food security. Mr Chairman, there is an urgent need to develop and implement sub-regional and national programmes as well as community based projects, to control landdegradation and to improve land productivity. I do hope you will come up with soundcollaborative programmes for the sub-region.

Thank you.

CLOSING STATEMENT: Honourable S.K. Moyo, Minister of Mines, Environment andTourism

Mr Chairman, Representatives of FAO and AGRITEX, Distinguished Guests and Participants,Ladies and Gentlemen

First of all, 1 would like in my capacity as Minister for Mines, Environment and Tourism, towelcome you all to Zimbabwe.

Particular welcome goes to Dr Mashali, the Technical Officer for the Soils ResourceManagement and Conservation Services of the FAO Headquarters in Rome, Ms Sekitoleko, theFAO Subregional Representative of Southern and East Africa, FAO resource persons, and therest of the countries who were invited to this Expert Consultative workshop (Eritrea, Ethiopia,Kenya, Tanzania, Uganda, Malawi, Zambia, Namibia, Africa and Zimbabwe). I also wish torecognize the efforts put by the Department of Agricultural Technical and Extension Services(AGRITEX), the FAO Land and Water Development Division based in Harare, and the rest ofthe organizers for the tremendous effort that you put into organizing this workshop.

Land degradation is an issue that affects every country and is at the heart of everyGovernment in this region. All our countries are dependent on Agriculture for food sufficiency,and food security. Since land degradation results in a decline in the capacity of soil to producemore, governments are concerned about the continued land degradation processes taking place,because the end-results will have negative impacts on the economy of each country.

The excellent papers presented by the Resource persons as well as your country papershighlighted various issues regarding land degradation. Of particular reference were issuesconcerning wind and water erosion, deforestation/devegetation, crusting/compaction,acidifícation, salinization, soil nutrient depletion, excessive leaching, and many others. Theseprocesses have caused great havoc in our countries resulting in reduced land for crop cultivationand grazing for livestock.

Deforestation has contributed to reduced soil cover with the end-results being erosiondepleted soil organic matter. People are being encouraged to plant trees in their respective areasas a way of replacing the lost vegetation. Only last Saturday His Excellency President Mugabeled the nation in commemorating the beginning of our tree-planting season in Zimbabwe. Forthose forests that are still available, the public is being discouraged from cutting more.Overgrazing is extensive in many parts of the region where livestock and wildlife populations are


high. This scenario leads to serious land degradation such as soil compaction, erosion, etc,resulting in gully formation.

Fires occur widely in communal areas, and this practice exposes the land to both winderosion during the dry seasons and water erosion during the on-set of rains. Vast areas ofZimbabwe suffered from extensive fires and my Ministry is taking the necessary steps to reducethe incidence of fires.

Decline in soil fertility is basically due to poor or inappropriate farming practices, whichinclude population pressure resulting in land pressure. For the majority of countries SaharanAfrica, the use of fertilizers is restricted to large estates and large farms, because most small-scale subsistence farmers cannot afford them. Furthermore, the quality of used in this sector is ofpoor quality.

The causes of soil/land degradation are complex and involve interaction between severalfactors. Land tenure and the related socio-economic factors are among the important causes ofsoil degradation. Because of Africa's high population growth rate, coupled with increased landpressure, agriculture land is continuously cultivated for decades with minimum inputs. As aresult, the land becomes highly degraded and very expensive to reclaim. It is hoped thatgovernments will raise the standards of living for their people so that they can afford financiallyto take care of agricultural land around them, for sustainable production of food and cash crops.

It is with pleasure to learn that your field visit to Mangwende on Wednesday 10 December1997 was good and informative. You managed to see the reclamation as well as the bankconservation programme that my Ministry is undertaking at Juru Growth Point. I hope theseexamples you saw were educative and will help in your programmes back home. I also hope thatother conservation programmes both in this country and in your countries will be able to reversethe degradation processes taking place and then up-lift the standards of living for our people.

Finally, Mr Chairman, 1 want to reiterate the importance of conservation and sustainableuse of our natural resources especially in our regions as most of our economies are agro-based.We should step up our efforts to achieve sustainable development without destroyingenvironment.

With these few words it is my singular honour to declare your Workshop closed. I wish youall a safe journey to your homes and Merry Xmas and Prosperous New Year to all of you.

I thank you.



Annex 2

Programme

Monday, 8 December 1997

08.00 – 09.00 hrs Registration

09.00 – 09.15 hrs Welcome address by the FAO Subregional Representative, Ms. Sekitoleko

09.15 – 09.45 hrs Objective of the consultation and adoption of agendaIntroduction to the technical sessions (P. Koohafkan, AGLS-FAO, Rome)

09.45 – 10.15 hrs Coffee break

SESSION I Land degradation and its impact on food security

Chairperson: Van der Merwe, AGLS-FAO, RomeRapporteur Mushambi

10.15 – 11.20 hrs Land degradation and its impact, with focus on salinity and fertility declineand their management(Amin Mashali, AGLS-FAO, Rome)

11.20 – 12.00 hrs Erosion induced loss in soil productivity, its implication on land use andfood security(Michael Stocking)Discussion

12.00 – 12.15 hrs Summary by chairperson

12.15 – 13.45 hrs Lunch break

Session II Enabling environment and technologies for controlling soildegradation and improving productivity

Chairperson: P. Nyathi, Deputy Director, Department of Research & Specialist ServicesRapporteur Mushambi

13.45 – 14.30 hrs Socio-economic and policy issues (AGRITEX/DR&SS)Discussion

Annex 2: Programme390

14.30 – 15.15 hrs Methodologies of soil degradation assessment, with focus onASSOD/SOTER, Asian experience(G. van Lynden - ISRIC)Discussion

15.15 16.00 hrs African soils, constraints and potentials with focus on ISCRAL (OmarKhayre, APO FAORAF, Accra)Discussion


16.30 – 17.30 hrs Presentation of the country papers by the country participants anddiscussionBotswana, Eritrea, Ethiopia (20 minutes each)


19.00 – 21.00 hrs Cocktail at St. Lucia Park

Tuesday, 9 December 1997

Session III Land degradation, management technologies and proposals for landimprovement schemes/projects in the countries of the subregion

Chairperson: Mashali, AGLS-FAO RomeRapporteur: Mushambi

08.30 – 10.10 hrs Presentation of the country papers by the country participants anddiscussions: Kenya, Malawi, Namibia, South Africa, Tanzania (20minutes each)


10.40 – 11.40 hrs Presentation of the country papers by the country participants anddiscussions: Uganda, Zambia Zimbabwe (20 minutes each)

11.40 – 12.30 hrs Land degradation and food security, synthesis of country papers(Mushanibi)Discussion

12.30 – 12.45 hrs General discussion


SESSION IV Approaches and technologies for overcoming soil physicaldeterioration improving water harvesting and irrigation

Chairperson: Senzanje, University of Zimbabwe


Rapporteurs Mushambi

14.15 – 15.00 hrs Soil and water conservation, soil moisture management and conservation tillagein Zimbabwe(AGRITEX - Nehanda)Discussion

15.00 – 15.45 hrs Water harvesting and/or small-scale irrigation(AGRITEX Chitsiko)Discussion


16.15 – 17.30 hrs Testing and scenarios of soil productivity changes in relation todegradation and field evidence by slidesDiscussion


WEDNESDAY, 10 DECEMBER 1997

08.30 – 16.00 Field visit

THURSDAY, 11 DECEMBER 1997

Opening session

Chairperson: Permanent SecretaryMinistry of Lands and Agriculture, Government of Zimbabwe

8.30 - 09.15 hrs Opening address by the Honourable Minister of Lands and Agriculture,Government of Zimbabwe

Working groupsessions

08.15 – 09.15 hrs Introduction to working group (Mushambi/Mashali/Stocking)Selection of chairperson, facilitators and rapporteurs for 2 or 3 workinggroups

09.15 – 12.30 hrs Working groups discussion

Optional working groups (two or three groups of countries/participantsaccording to geographical distribution/climate or agro-ecological conditionand interest):Suggested issues to be discussed:- Present and outlook for food production

Annex 2: Programme392

- Identification of land degradation, dominant type, magnitude, extent anddistribution

- Causes and processes of land degradation- Existing assessment of degradation, methodologies for assessment- Interpretation and prediction methods and availability of methods- Bio-physical, environmental and socio-economic impacts- Technologies available for improving for the productivity: constraints for

adoption and solutions- Policy and land tenure, institutional set-up, government responsibility,

monitoring, farmer participation and extension services, decisionmaker awareness

- Applied research requirements, integrated approach, monitoring system- National and regional plans, regional co-ordination, proposal for national

follow up actions- Network proposal on management of degraded soils in Africa- Country and sub-regional project proposals - potential donors - national

support


14.00 – 15.30 hrs Working groups discussions (continued)


16.00 – 18.00 hrs Drafting the working groups' findings, conclusions and recommendations

FRIDAY 12 DECEMBER 1997

Chairperson: Stocking, AGLS-FAO RomeRapporteurs Mushambi

08.30 – 10.00 hrs Plenary presentation and discussion of the findings, conclusions andrecommendations of the working groups


10.30 – 11.30 hrs Presentation and adoption of the recommendations of the Consultation(Mushambi)

Closing session

Chairperson: Permanent SecretaryMinistry of Mines, Environment and Tourism of Zimbabwe

11.30 hrs Closing address by the Honourable Minister of Mines, Environment andTourism, Government of Zimbabwe


Annex 3

List of participants

COUNTRY SPECIALISTS

ERITREAAnwar ul-HaqHead-Soil and Water ConservationDepartment, University of AsmaraP 0 Box 1220Asmara, EritreaTel: 291-1-162607Fax: 291-1-162236E-mail: [email protected]

ETHIOPIASahlemedhin SertsuHead of the National Soil Research LaboratoryEthiopia Agricultural Research OrganizationP 0 Box 147Addis Ababa, EthiopiaTel: 251-1-517657Fax: 251-1-515288E-mail: [email protected]

KENYAPatrick Thuku GicheruHead of Kenya Soil SurveyKenya Agricultural Research InstituteNational Agricultural Research LaboratoriesP 0 Box 14733Nairobi, KenyaTel: 254-2-444140-44, 444029-32, 444250-56Fax: 254-2-443376E-mail: [email protected]

MALAWIA. SakaAssistant Deputy Director Department of ResearchMinistry of Agriculture, and IrrigationPO Box 30750Lilongwe, MalawiTel: 265-767 222, 252/784299Fax: 265-784 184

NAMIBIAJ. KauriviAgricultural Extension OfficeMinistry of Agriculture, Water and RuralDevelopmentP 0 Box 272Tsumeb, NamibiaTel: 264-67-220263Fax: 264-67-220323

SOUTH AFRICADries Van der MerweInstitutefor Soil, Climate and Water (ISCW)P 0 Box 79, PretoriaSouth AfricaTel: 27-12-3264205Fax: 27-12-3231157E-mail: [email protected]

TANZANIAAdolf S. NyakiDirectorAgricultural Research InstituteMlinganoP 0 Box 5088Tanga, TanzaniaTel: 255-53-42577Fax: 255-53-42577E-mail: [email protected]

UGANDAJulius Yefusa Kitungulu-ZakeDepartment of Soil ScienceMakerere UniversityP 0 Box 7062Kampala, UgandaTel: 256-41-540707 Home: 256-41-541128Fax: 256-41-541641E-mail: [email protected]

Annex 3: List of participants394

ZAMBIANawa MukandaSoil ScientistSoil & Water Management DivisionMount Makulu Research Centre P 0 Box 7Chilanga, ZambiaTel: Office: 260-1-278087/278429/278008Fax: 260-1-278390/278130/278141

ZIMBABWE

J.M. MakadhoDirectorDepartment of Agricultural, Technical &Extension Services (AGRITEX)P 0 Box CY 639, CausewayHarare, Zimbabwetel: 263-4-707311/6-794601/6Fax: 263-4-730525E-mail: [email protected]

R.J. ChitsikoDeputy Director (Engineering)Department of Agricultural, Technical andExtension Services (AGRITEX)P 0 Box CY 639CausewayHarare, ZimbabweTel: 263-4-707311/6-794601/6Fax: 263-4-730525E-MAIL: [email protected]

Michal OppenheimerDepartment of Agriculture, Technical andExtension Services (AGRITEX)P 0 Box CY 639CausewayHarare, ZimbabweTel: 263-4-707311/6Fax: 263-4-730525E-mail: [email protected]

P. Nothando SitholeDepartment of Agricultural, Technical andExtension Services (AGRITEX)P 0 Box CY 639CausewayHarare, ZimbabweTel: 263-4-707311/6Fax: 263-4-730525E-mail :[email protected]

D. TaonezviDepartment of Agricultural, Technical &Extension Services (AGRITEX)P 0 Box CY 639CausewayHarare, ZimbabweTel: 263-4-707311/6Fax: 263-4-730525E-mail :[email protected]

C.F. MushambiHead, Chemistry and Soil Research InstituteDepartment of Research & Specialist ServicesP 0 Box CY 550CausewayHarare, ZimbabweTel: 263-4-704531Home: 263-4-307602

Katherine VerbeekDepartment of Soil Science & AgriculturalEngineeringUniversity of 'ZimbabweP 0 Box MP 167Harare, ZimbabweTel: 263-4-303211 ext. 1721E-mail: [email protected]

A. SenzanjeDepartment of Soil Scíence & AgriculturalEngineeringUniversity of ZimbabweP 0 Box MP 167Harare, ZimbabweTel 263-4-303211 ext 1412

Joseph Zvakwidza ChizororoUSAID/HarareP 0 Box 6988Harare, ZimbabweTel: 263-4-720630Fax: 263-4-720722E-mail: [email protected]

G. NehandaInstitute of Agricultural EngineeringP 0 Box BW 330BorrowdaleHarare, ZimababweTel: 263-4-860136Fax: 263-4-860136


Jane U. GoneseTobacco Research BoardP 0 Box 1909Harare, ZimbabweE-mail: Jane- [email protected]

TROPICAL SOIL BIOLOGY AND FERTILITYPROGRAMME (TSBF)

Mwenja GichuruTSBF/AFNET CoordinatorUN Complex, GigiriUNESCO~TSBFP 0 Box 30592Nairobi, KenyaTel: 254-2-622635Fax: 254-2-622733E-mail: mwenja.gichuru@@tsbf.unon-org

Stephen NandwaHead, Soil Fertility & Plant Nutrition ResearchProgrammeKenya Agricultural Research InstituteNational Agricultural Research LaboratoriesP 0 Box 14733Nairobi, KenyaFax: 254-2-444029/443376E-mail: [email protected]

Jean NiyungekoDRC - ex - Zairec/o TSBF/UNESCO UN Complex, GigiriP 0 Box 30592Nairobi, KenyaTel: 254-2-622584Fax: 254-2-622733E-mail: [email protected]

George LeyNational CoordinatorSoil and Water Management ResearchProgrammeNational Soil ServiceAgricultural Research InstituteMLINGANOP 0 Box 5088Tanga, TanzaniaFax: 255-53-42577

Susan T. lkerraResearch OfficerTSBF/AFNET Liaison OfficerNational Soil ServiceAgricultural Research InstituteMlinganoP 0 Box 5088Tanga, TanzaniaFax: 255-53-42577

Mary J.N. OkwakolAssociate ProfessorDepartment of ZoologyMakerere UniversityP 0 Box 7062Kampala, UgandaTel: 256-41-533803/531902Fax: 256-41-533528/530134E-mail: [email protected]

Humphrey GomaSoil ScientistMisamfu Research CentreP 0 Box 410055Kasama, ZambiaTel: 260-4-221215/221135Tel: Home: 260-1-221863Fax: 260-4-221135/221092/221664E-mail: [email protected]

Petros NyathiDepartment of Research & Specialist ServicesP 0 Box CY 594CausewayHarare, ZimbabweTel: 263-4-704531E-mail: [email protected]

RESOURCE PERSONS

Godert W. Van LyndenInternational Soil Reference and InformationCentreP 0 Box 3536700AJ Wageningen, The NetherlandsTel: 31-317-471711Fax: 31 317 471700E-mail: VANLYNDEN@ISRIC [email protected]

Annex 3: List of participants396

Anna TengbergPhysical GeographyEarth Sciences CentreGuidhedsgatan 5AS-413 81 GoteborgSwedenTel: 46 31 773 1000Fax: 46 31 773 1986E-mail: [email protected]

Michael StockingProfessor of Natural Resource DevelopmentSchool of Development StudiesUniversity of East AngliaNorwich NR4 7TJUnited KingdomTel: 44-1603-592339Fax: 44-1603-451999E-mail: [email protected]

FAO

Parviz KoohafkanChief, Soil Resources Management andConservation ServiceLand and Water Development DivisionViale delle Terme di Caracalla00100 Rome, ItalyTel: 39-06-57053843Fax: 39-06-57056275E-mail : [email protected]: www.FAO.org/agriculture/AGL

A. M. MashaliTechnical Officer, Soil ReclamationSoil Resources Management and ConservationServiceLand and Water Development DivisionViale delle Terme di Caracalla00100 Rome, ItalyTel: 39-06-57053418Tlx: 625852 FAOIFax: 39-06-57056275E-mail: [email protected]

Karen FrenkenFAO Sub-regional OfficeP 0 Box 3730Harare, ZimbabweTel: 263-4-791407Fax: 263-4-703497E-mail: [email protected]

Omar KhayreAPO, SoilsFAO Regional Office for AfricaP 0 Box 1628Accra, GhanaTel: 233-21-666851-4/665389Tlx: 2139 Foodagri(GH)Fax: 233-21-668427/233999E-mail: [email protected]

René van VeenhuizenFAO FarmesaP 0 Box 3730Harare, ZimbabweTel: 263-4-758055E-mail: [email protected]


Annex 4

Maps

Soil degradation severity

Annex 4: Maps398

Water erosion severity


Salinization

Annex 4: Maps400

Chemical deterioration severity


Loss of nutrients

Annex 4: Maps402

Acidification


Areas affected by overgrazing

Annex 4: Maps404

Areas affected by agricultural activities


Areas affected by overexploitation of vegetation

Annex 4: Maps406

Areas affected by deforestation

The FAO Land and Water Development Division, in collaboration with the SubregionalOffice for Southern and East Africa and the Agricultural Technical and Extension

Services of Zimbabwe, organized an Expert Consultation on “Integrated SoilManagement for Sustainable Agriculture and Food Security”, held in Harare from 8 to 12December 1997. The main objectives of the Consultation were to discuss the status ofland degradation under contrasting agro-ecological and socio-economic conditions;exchange experiences on constraints for controlling land degradation and examinepossible solutions to overcome these constraints; and proposals for enhancing soilproductivity, in support of food security in the region. This publication includes the

overview and country papers presented by senior specialists from ten African countriesof Southern and East Africa, FAO Headquarters and from some relevant national,

regional and international institutions. Addressing and reversing the process of soildegradation and sustaining crop productivity through appropriate soil management andconservation are important aspects of food security. Although cost-effective options areavailable to address soil degradation, there is a need to increase the awareness, at high

policy-making level, with sound scientific evidence, about impacts of degradation onproductivity in order to achieve the food security goals. It is, therefore, important to

document the information on the extent of soil degradation, its biophysical, economicand social impacts as well as successful examples of soil improvement programmes

within the region.

Documents

INTEGRATED SOIL MANAGEMENT FOR SUSTAINABLE … · different production constraints (soil acidity, vertic properties, low fertility, shallow soils, saline and poorly drained soils)