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SCHOOL OF GRADUATE STUDIES ARBA MINCH UNIVERSITY Agricultural Water Management under Small Holder Irrigated Farms and its Impact on Soil fertility and Nutrient Management PhD Research Proposal By Demelash Wendemeneh INSTITUTE: Arbaminch Institute of Technology Department: Water Resource and Irrigation Engineering Program: Irrigation and Drainage Engineering Major Advisor: Mekonen Ayana (Asso. Professor) Co- Advisors: Pratap Singh (Professor) Petra Schmitter (PhD)

SCHOOL OF GRADUATE STUDIES ARBA MINCH UNIVERSITY · Co- Advisors: Pratap Singh (Professor) Petra Schmitter (PhD) ii LIST OF ABBREVIATIONS ADLI ... CRV Central Rift Valley CSA Central

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SCHOOL OF GRADUATE STUDIES

ARBA MINCH UNIVERSITY

Agricultural Water Management under Small Holder

Irrigated Farms and its Impact on Soil fertility and Nutrient

Management

PhD Research Proposal

By

Demelash Wendemeneh

INSTITUTE: Arbaminch Institute of Technology

Department: Water Resource and Irrigation Engineering

Program: Irrigation and Drainage Engineering

Major Advisor: Mekonen Ayana (Asso. Professor)

Co- Advisors: Pratap Singh (Professor)

Petra Schmitter (PhD)

ii

LIST OF ABBREVIATIONS

ADLI Agricultural Development Lead Industrialization

AMU Arbaminch University

AP Available Phosphorous

CEC Cation Exchange Capacity

CRV Central Rift Valley

CSA Central Statistics Authority

CUc

CWR

Christian’s uniformity coefficient

Crop Water Requirement

Df Deep percolation fraction

DU Distribution uniformity

Ea Application efficiency

EC Electrical Conductivity

EEA Ethiopian Economic Association

Er Requirement efficiency

ERD Effective Root Depth

ESP Exchangeable Sodium Percentage

ET Evapotranspiration

ETc

ETo

FAO

Actual evapotranspiration

Reference evapotranspiration

Food and Agriculture Organization

FC Field Capacity

GDP Gross Domestic Production

IMF International Monitory Fund

IWUE Irrigation Water Use Efficiency

masl Meters above sea level

MoARD Ministry of Agriculture and Rural Development

MP Motor Pump

OC Organic Carbon

OM Organic Matter

PWP Permanent Wilting Point

RAW Rope and Washer

Rf Runoff fraction

SAR Sodium Adsorption Ratio

SNNPRS Southern Nations, Nationalities and Peoples’ Regional State

SPT Soil Profiler Tube

TDR Time Domain Reflectometry

TEB Total Exchangeable Bases

TN Total Nitrogen

UNDP Unite Nation Development Program

WFD Wetting Front Detector

iii

TABLE OF CONTENTS

LIST OF ABBREVIATIONS ...................................................................................................... ii

1. INTRODUCTION..................................................................................................................... 1

1.2. Statement of Problem .............................................................................................................4

1.3. Objectives ...............................................................................................................................5

1.3.1. General Objectives ...........................................................................................................5

1.3.2. Specific Objectives ...........................................................................................................5

1.4. Research Questions .................................................................................................................6

1.5. Research Hypotheses ..............................................................................................................6

1.6. Significance of the Study.....................................................................................................7

1.7. Scope of the Study ...............................................................................................................7

2. LITERATURE REVIEW ........................................................................................................ 8

2.1. The Effect of Irrigation on Leaching of Nutrients ........................................................................ 8

2.2. The Effect of Irrigation Water quality on soil salinity ............................................................... 10

2.3. The Effect of Irrigation Water Management on Soil Fertility ................................................... 11

2.4. Performance Evaluation of Irrigation Methods .......................................................................... 13

2.5. Water Management in Rain-fed Agriculture .............................................................................. 15

2.6. Water Requirement of Crops........................................................................................................ 17

2.7. Irrigation Scheduling ..................................................................................................................... 18

2.8. Water Productivity ........................................................................................................................ 19

2.8. Nutrient Balance ......................................................................................................................... 20

3. MATERIALS AND METHODS ........................................................................................... 22

3.1. Descriptions of the Study Area ..................................................................................................... 22

3.1.1. Location and Topography ...................................................................................................... 22

3.1.2. Geology and Parent Materials ............................................................................................... 23

3.1.3. Soils of the Study Area ............................................................................................................ 24

3.1.4. Climate and Hydrology .......................................................................................................... 24

3.1.5. Land Use and Vegetation ....................................................................................................... 25

3.2. Methodologies ................................................................................................................................. 25

3.2.1. Pre-experiment Activities ....................................................................................................... 25

iv

3.2.2. Crop Water Requirement ...................................................................................................... 26

3.2.3. Experimental Setup................................................................................................................. 26

3.2.4. Data Collection and Analysis ................................................................................................. 29

4. WORK PLAN.......................................................................................................................... 31

5. FINANCIAL REQUIREMENT ............................................................................................ 32

5.1. Par-dime.......................................................................................................................................... 32

5.2. Transportation and Living Cost ................................................................................................... 32

5.3. Supplies/Miscellaneous Costs ........................................................................................................ 33

5.4. Labour Cost .................................................................................................................................... 33

5.5. Stationary Materials Cost ............................................................................................................. 34

5.6. Laboratory Soil Analysis Cost ...................................................................................................... 34

5.7. Laboratory Water Analysis Cost .................................................................................................. 35

5.8. Budget Summary ........................................................................................................................... 36

6. REFERENCES ........................................................................................................................ 37

1. INTRODUCTION

The Ethiopian economy as in most developing countries primarily based on agricultural

production. Agriculture constitutes almost half of the GDP (43%) and 85% of the total export

revenue (UNDP, 2014 and IMF, 2015), and employs more than 85% of the labor force in the

country (CSA, 2008 & EEA, 2008). Data from the Central Statistical Agency (2008) indicates

that about 16 million hectares of land were utilized for various agricultural purposes. In terms of

land use, about 79% was allocated for crop production, about 10% was allocated for grazing,

about 7% was allocated for fallow and the balance has been occupied by wood and other uses.

The average farm size was a little above one hectare, over 55% of the agricultural holders

cultivated farms less than one hectare. About 26 percent of the farmers cultivated farms larger

than one hectare but less than two hectares. Another 15% of the farmers cultivated farms that

vary between 2 and 5 hectares and about 1% of the farming community cultivated farms

exceeding 5 ha (CSA, 2008).

However, the agricultural production system is mainly rain fed and traditional, which is

characterized by low input of improved seeds, fertilizer and other technologies (CSA, 2008). In

Ethiopia, traditional rain fed agriculture is the dominant form of farming system in which the

peasant farm households contribute the largest proportion of the total agricultural production

(FAO, 2006). The problem is rainfall rarely meets the time with required amount of application

for plant growth. In most cases especially in dry regions, it is unreliable and erratic that can

affect plant growth which is a function of water, nutrient and climate. As a result average yield

of agricultural crops under rain fed agriculture is low compared to irrigation.

In order to improve this situation, the government of Ethiopia has given due attention to the

development of irrigated agriculture. Traditional irrigated agriculture was practiced in Ethiopia

since ancient times for producing subsistence food crops (Awulachew et al., 2007; Bacha et al.,

2011 and Bekele et al., 2012). However, modern irrigation was started in the early 1950’s by the

bilateral agreement between the government of Ethiopia and the Dutch company jointly known

as HVA-Ethiopia sugar cane plantation (MoA, 2011a and Bekele et al., 2012). Most of the

traditional irrigated lands in Ethiopia are dominantly supplied by surface water sources, while

ground water uses has just been started on a pilot basis in the East Amhara region (MoA, 2011a).

2

The rift valley is a place where modern irrigation in Ethiopia starts especially in the Awash River

Basin at which adoption of pump-irrigation commences. It has now got more attention in all

national, regional and local development agenda to minimize the dependence of agriculture on

rainfall. It is obvious that the major role of irrigation is to provide higher food and fiber

production in sustainable manner for the ever increasing population.

Irrigation enables smallholders to diversify cropping patterns and gives opportunity to change

from subsistence production system to high value market oriented production system. It can also

benefit the poor specifically through higher production, lower risks of crop failure, and higher

and all year round farm and non-farm employment (Hussain and Hanjra, 2004). It can provide

farmers with sustainable livelihoods and improve their well-being. This is substantially true

especially for those areas subjected to frequent drought periods, higher evaporative demand and

increasing population pressure. However, irrigation activities are dominantly under competition

for only surface water with other development sectors (Awulachew et al., 2007). This indicates

that ground water resource utilization didn’t get as such attention for agricultural development by

the government and non-governmental organizations. A reliable and suitable irrigation water

supply can improve agricultural production and assure the economic vitality in drought affected

areas.

With expansion of irrigation to enhance agricultural productivity, Ethiopia is making a

significant progress. It is known that, Ethiopia endowed with ample land resources that are

potentially suitable for irrigated agriculture. Awulachew et al., (2007) reported that Ethiopia has

an estimated irrigation potential of 3.5 million hectares of land. However, the total estimated area

of irrigated agriculture in the country in 2005/2006 was 625,819 hectares (MoWR, 2007). This

figure indicated that the country potential irrigable land is underutilized and only 18% of the

potential area has been developed for irrigation. Among the social and technical issue, one of the

reasons for the underutilization of the irrigable land is the lack of available irrigation water

during dry season.

Irrigated agriculture is not only dependent upon quantity of water, but it also needs adequate

supply of quality water. The quality of irrigation water which deserve consideration include salt

content, sodium concentration, presence and abundance of macro- and micro-nutrients and trace

3

elements, alkalinity, acidity, and hardness of the water (Abel et al., 2014) . Under some

circumstances, the suspended sediment concentration, bacterial content, and temperature of

irrigation water may also deserve attention. Salts generally comes from weathering of soil,

leaching of salts dissolved from geologic marine sediments into the soil solution or groundwater,

and flushing of salts off of roads, landscapes and stream banks during and following

precipitation events (Abel et al., 2014 ). The amount of salt found in irrigation water generally is

greater in arid and semi-arid areas than in humid and sub-humid areas due to inadequacy of

rainfall in arid and semi-arid areas. The amount of salt dissolved in water directly affects plant

growth, generally has an adverse effect on agricultural crop performance and can also affect soil

properties.

Because of the growing concern over food security and increasing trend in the occurrences of

drought in the rift valley areas, there is considerable consensus to utilize the available water

resources economically. The policies on national land use, irrigation development and water

resource management emphasize on the utilization of water with maximum efficiency. If the

farming community get sufficient water for irrigation agriculture throughout the year, which

enables them to engage themselves in agricultural activity the whole year and get higher yield

from small farm fields.

The agricultural sector has been the priority of Ethiopia since the early 1990s, when the

Agricultural Development-led Industrialization (ADLI) and related policy frameworks were

adopted. Based on the lessons learned from previous practices the country has adopted new long

term vision, Growth and Transformation Plan (GTP) to provide the overarching framework

guiding development endeavors (MoFED, 2010). The documents highly stressed that there is no

readily identifiable yield increasing technologies other than integration of improved seed-water–

fertilizer approach. Irrigation will, therefore, play an increasingly important role now and in the

future both to increase the yield from already cultivated land and to permit the cultivation of

what is today called marginal or unusable land due to moisture deficiency (MoFED, 2010)

In addition, production intensification without irrigation in the face of vagaries of weather cannot

be imagined. Given the depth of knowledge, man has on the dynamics of soil water; there are

different irrigation water pumping technologies such as motor pump, solar pump, rope and

4

washer pump and the like could be implemented in irrigation development to sustain agricultural

productivity. Sustainable agricultural development and efficient management of irrigation water

is an increasingly complex challenge everywhere else in the world. Increasing population,

growing urbanization, and rapid industrialization combined with the need for raising agricultural

production generates competing claims for water (Awulachew et al., 2007).

In Ethiopia particularly in the rift valley basin, there is high groundwater potential and

opportunity to overcome dry spells and drought through supplementary irrigation leading to

possibility to increase production and productivity in high potential areas. A few places in

Ethiopia though have demonstrated the comparative advantages of groundwater irrigation over

rain fed agriculture and surface water irrigation (Awulachew et al., 2007). In Amhara and Tigray

for instance, groundwater from shallow aquifers is widely used for horticultural crop production.

In high technology, groundwater irrigation farms around Addis Ababa (flower farms) and

Debrezeit (Gneiss farm), remarkable success has been noted. According to World Bank report

(2004), more than 200 ha of land irrigated with groundwater for horticulture and flower farms in

the rift valley area of Ethiopia.

1.2. Statement of Problem

In Ethiopia particularly the rift valley basin is well known for shortage of rainfall but potentially

suitable for irrigated agriculture from ground water or lakes. The agricultural production system

at both sites is traditional, characterized by low input of improved seeds, fertilizer and other

technologies. In order to improve this situation, the government has given more attention to the

development of irrigated agriculture throughout the country. Because irrigated agriculture

enables smallholders to diversify cropping patterns and gives opportunity to change from

subsistence production system to market oriented production system. Small scale irrigation

practices are vital to the intensified crop-livestock mixed farming systems in these areas. The

water allocation for irrigation at farm system level is complex as domestic and livestock water

demands compete with irrigation activities. Moreover irrigated crop production is often more

input intensive as compared to rain-fed systems.

The country’s potential irrigable land is underutilized due to limitation of irrigation water during

dry period and other social and technical problems. In most cases irrigated agriculture is not only

5

dependent upon quantity of water, but it also needs adequate supply of good quality water. In

addition to that, soil salinity and sodicity are also major factors limiting agricultural productivity

in irrigated agriculture particularly in dry region like the present study area. Inappropriate

irrigation management might lead to increased nutrient leaching to shallow groundwater and

surface water sources which on its turn affects human and livestock health as resources have a

multi-purpose function. Hence more detailed understanding on water allocation and quality is

needed to assess the optimal irrigation production system within the farm system environment.

The study areas are dominated by rain-fed and mixed crop-livestock agriculture. It is difficult to

provide enough food for the ever increasing population by using such traditional rain fed

agriculture which is the dominant form of farming system at both sites. Therefore, this research

aimed to evaluate sustainability and productivity of agricultural development under irrigated

agriculture and productivity of irrigation water management practices. In addition to that it also

aimed to assess the quality of irrigation water in the study areas to understand how irrigation

water quality is related to the chemical properties of the soil.

.

1.3. Objectives

1.3.1. General Objectives

The general objective of this research is to evaluate sustainability and productivity of agricultural

development under irrigation agriculture and effect of irrigation water management on soil

quality in the study areas.

1.3.2. Specific Objectives

The specific objectives of this study are as follows;

o To study the effect of irrigated agriculture under farmers practice on soil salinity and

fertility

o To study the effects of agricultural water management practices on leaching of nutrients

from the root zone under irrigated agriculture

o To test different irrigation scheduling methods and evaluate their effects on water

productivity of different vegetable crops

6

1.4. Research Questions

o What is the relationship between irrigation water quality and soil chemical properties?

o Does irrigation water source and quality affect crop productivity?

o What is the effect of agricultural water management practices on leaching of nutrients?

o How does an agricultural water management practice affect leaching of nutrients?

o Does irrigated agriculture under farmers practice affect soil salinity?

o Is there any relationship between irrigated agriculture and soil quality?

o Does an irrigation scheduling influence water productivity of different vegetable crops?

o Is there any difference among irrigation scheduling methods regarding water

productivity of different vegetable crops?

1.5. Research Hypotheses

It is a suggested explanation of a phenomenon or reasoned proposal or it refers to a provisional

idea whose merit needs evaluation. It is used in an experiment to define the relationship between

two variables. The first variable is called the independent variable and it is part of the experiment

that can be changed and tested. The independent variable happens first and can be considered the

cause of any changes in the outcome. The outcome is called the dependent variable. They should

originate from the objectives and can be grouped in to two, null and alternative hypothesis. The

null hypothesis (H0) represents a theory that has been put forward, either because it is believed to

be true or because it is to be used as a basis for argument, but has not been proved. The

alternative hypothesis (H1) is a statement of what a hypothesis test is set up to establish. It is

opposite of Null Hypothesis and only reached if H0 is rejected. Having this, the hypothesis of

this study will be indicated in the following manner;

o The hypothesis is that the intensification through irrigation can have negative effects on

soil salinity and fertility if the irrigation water quality or agricultural water management

is poor

o The hypothesis is that the difference in agricultural water management system has

different effect on nutrient leaching

o The hypothesis is that irrigation scheduling has an improving effect on water

productivity of different vegetable crops

7

1.6. Significance of the Study

This study will try to provide a clear understanding on the effect of irrigation water quality on

soil and crop productivity. Because irrigation water quality has an adverse effect on agricultural

crop performance and soil properties. In addition to that it will also try to identify the risks

associated with soil salinity and sodosity because farmers are tending to over irrigate their fields

without clearly understanding the associated risks and they may damage their own lands. As a

result of over irrigation salinity is becoming the potential problem, which deteriorates the land

quality and significantly reduces crop yields. Salinity is becoming the potential problem

particularly in the lowlands where there is shortage of rainfall for maintaining natural leaching.

Likewise under over irrigation conditions, crop roots are not properly functioning and are not

able to take up adequate amount of nutrients from the soil. As a result, soil nutrients particularly

nitrogen will leach down beyond the active rooting depth of plants and thus results in a

significant amount of nutrient loss and yield reduction. On top of that it will also try to identify

the problems that are associated with small-scale irrigation agriculture particularly on-farm

irrigation water management and crop management practices. In most cases, farmers are

irrigating their fields with prolonged intervals which is not appropriate for most vegetable crops

because it may negatively affects crop yields. Therefore, it will try to determine how much

water and when it should be applied to a given crop.

1.7. Scope of the Study

The study will be conducted for two consecutive years (2015/16 – 2016/17) at Lemo and

Bochessa sites considering on farm irrigation practices. It is obvious that small scale irrigation

practices are vital to the intensified crop-livestock mixed farming systems in the rural areas. It

mainly focuses on evaluating sustainability and productivity of agricultural development under

irrigated agriculture and efficiency of irrigation water management practices. Agricultural water

management is generally perceived as a key step towards improving low yielding smallholder

farming systems in Ethiopia. In addition to that it also aimed to assess the quality of irrigation

water in the study area to understand how irrigation water quality is related to the chemical

properties of the soil.

8

2. LITERATURE REVIEW

2.1. The Effect of Irrigation on Leaching of Nutrients

Inappropriate soil, water and fertilizer management in irrigated agriculture can result in

environmental problems, including groundwater pollution with nitrates (Owino and Sigunga,

2012). Groundwater is contained beneath the surface in rocks of water-bearing formations called

aquifers. As we know, groundwater provides water in rivers, lakes, ponds, boreholes and

wetlands thus helping to maintain water levels and sustainability of the ecosystem. Man’s

activities on the Earth’s surface constitute major sources of aquifer contamination as we witness

in manufacturing, agricultural, processing, chemical, photographic and dyeing industries when

they use water to process and produce their goods (Chukwu and Nwachukwu, 2013). From

agricultural point of view, irrigation agriculture is known for leaching nutrients out of plant root

zones. Mitchell et al. (1994) reported that furrow irrigation is widely used type of irrigation

around the world and is considered as a major source of nitrate leaching (Mitchell et al., 1994).

Most of the N losses from agricultural soils are due to leaching (Nyamangara et al., 2003),

bypass flow (Sigunga et al., 2008), denitrification (Sigunga et al., 2002a; Sigunga et al., 2002b)

and/or ammonia volatilization (Sigunga et al., 2002c).

Improved soil, water and fertilizer management practices are needed to improve the production

and environmental performance of furrow irrigated agriculture. The quality of soils, ground and

surface water resources is always at risk in areas where agricultural production is dominated by

irrigation as in rift valley areas of Ethiopia and many other semiarid and arid regions of the

world. Excessive and improper application of nitrogenous fertilizers with irrigation water leads

to an increase in nitrate concentration in the ground and surface water in these areas (Owino and

Sigunga, 2012). One of the most common contaminants found in groundwater worldwide is

nitrate (NO3−), an oxidized form of dissolved nitrogen. As reported by Owino and Sigunga

(2012) Nitrogen (N) is the most limiting nutrient to crop productivity in the majority of tropical

soils.

Traditional cropping practices in many regions of the world involve application of significant

quantities of nitrogenous fertilizers and large quantities of irrigation water, which can result in

significant leaching of nitrate due to excess deep drainage (Owino and Sigunga, 2012). This not

9

only decreases the availability of nitrogen to plants but also creates environmental problems by

degrading the quality of the groundwater. The problem of nitrate leaching is aggravated in

agricultural areas when soils are coarse textured (Waddell and Weil, 2006). Pilbeam et al.,

(2004) estimated losses of nitrogen by leaching to be in the range 0–63.5 kgNha-1, assuming

runoff losses to be zero.

In about 90% of the irrigated area of the world, crops are irrigated with surface irrigation

methods, most often using furrow irrigation (Tiercelin and Vidal, 2006), which is considered as a

more water use efficient method than basin and border irrigation methods. Furrow irrigation is

commonly used in arid and semiarid regions of the world to irrigate vegetables and row crops.

Wylie et al. (1994) reported furrow that irrigated corn as a major source of nitrate leaching and

groundwater pollution. Hence, there is a need to improve water, fertilizer and soil surface

management strategies for furrow irrigation to increase irrigation efficiency and reduce nitrogen

losses by leaching to groundwater.

Leaching of nitrate below the root zone can be affected by a range of factors, including

application rates and timing of applications. A field study conducted by Benjamin et al. (1998)

showed that placing fertilizer in the non-irrigated furrow in alternate furrow irrigated systems

increased water use efficiency and reduced fertilizer leaching. Mailhol et al. (2007) reported that

fertilizer application near the top of the ridge followed by heavy irrigation has a beneficial

impact on both yield and nitrogen leaching. Waddell and Weil (2006) also found that by placing

fertilizer near the top of the ridge, corn crop yields increased and the risk of nitrogen leaching

decreased.

Most of the research to date on reducing leaching of nitrogen from furrow irrigation has focused

on fertilizer placement (Mailhol et al., 2007; Waddell and Weil, 2006) and managing water

application and water depth (Abbasi et al., 2003 and Mailhol et al., 2007). Little work has been

done on reducing deep percolation and solute leaching from furrow irrigation using a

combination of water management and fertilizer placement strategies.

10

2.2. The Effect of Irrigation Water quality on soil salinity

The quality of irrigation water available to farmers and other irrigators has a considerable impact

on what plants can be successfully grown, the productivity of these plants, and water infiltration

and other soil physical conditions (Bauder, et al., 2014). The first step in understanding how an

irrigation water source can affect a soil-plant system is to have it analyzed in laboratory. The

most influential water quality guideline on crop productivity is the water salinity hazard as

measured by electrical conductivity (Bauder, et al., 2014). The primary effect of high ECw water

on crop productivity is the inability of the plant to compete with ions in the soil solution for

water which causes physiological drought. The higher the EC, the less water is available to

plants, even though the soil may appear wet (Maggio et al., 2004). Because plants can only

transpire pure water, usable plant water in the soil solution decreases dramatically as EC

increases.

The effect of the quality of irrigation water on soil properties has been discussed by many

researchers (Romic et al., 2005; Burkhalter and Gates, 2006; Galvani, 2007). Ragab (2000)

found that soil electrical conductivity (ECs) values increased with increasing salinity of irrigation

water and decreased soil moisture depletion in calcareous soil. Also, Ragab (2000) found that the

increasing of irrigation salinity from 0.58 to 3.67 dSm-1 increased total soil salinity from 1.87 to

24.83 dS m-1. Thus, the salts accumulation in soil was closely related to the salts concentration of

irrigation water. Ragab (2000) observed that, there was a progressive and significant increase in

soil salinity values as the salinity of irrigation water increases. But, Mwenja (2000) reported that

the soil salinization does not entirely depend on water quality, and concluded that other factors,

including level of water application, drainage, management practices, and some climactic factors

influence salinization. Maggio et al. (2004) reported that salinity reduced total plant water uptake

and seemed to be a very important variable affecting total plant water uptake.

Crowley and Arpaia (2008) showed that when the total dissolved salt concentrations in the soil

solution exceed an electrical conductivity (EC) of 4 dS m-1, avocado trees are no longer able to

extract water even if the soil is water saturated. Wenju et al. (2008) found that the use of saline

water causes the ECe of the top soil to be higher and more variable than the subsoil. Also the use

of poor quality water for irrigation could have detrimental effects on specific absorption rate

11

(SAR) and EC. In order to prevent such problems or curtail further problems, Volschenk (2005)

Showed that effects of salinity on soil properties are not restricted to low salinity and high SAR,

but that clay dispersion may occur where irrigation water with a SAR of below or about 1 and

EC of less than 0.1 dS m-1 is applied to soil. Kafi et al. (2010) observed that growth stimulation

by 15 dS m-1 salinity suggests that longer term field trials would be justified to evaluate the

growth potential to reuse second-generation drainage water, saline and shallow ground waters,

and even seawater for irrigation.

One of the important agricultural problems in arid and semi-arid areas is the shortage of rainfall

and suitable sources of water. The increasing demand for domestic, industrial, environmental and

recreational water will force agriculturists to manage irrigation water carefully in order to

address food security issues. In parallel, poor water quality sources could be employed for

irrigation if greater knowledge of salt tolerance and proper technology are developed. Crop

species with threshold level of yield reduction above the salinity of the irrigation water is needed

to get good yield in arid and semi-arid areas (Khan, 2009; Munns and Tester, 2008; Yensen and

Biel, 2006).

Knowledge of the chemical composition of the water is necessary but not sufficient to evaluate

its suitability for irrigation. Other factors such as climate, soil characteristics, drainage conditions

and the irrigation method should be considered in order to define the appropriate land use and

water management (Bauder, et al., 2014). Al-Ghobari (2011) indicated that in the near future the

limitation of water resources in the arid areas will be increased. Therefore, it is important to

study the effect of using different source of irrigation water in agriculture. The challenge of the

future will be to maintain or even increase water productivity with less water or water with poor

quality.

2.3. The Effect of Irrigation Water Management on Soil Fertility

Salinity and sodicity have been extensively reported among the major problems of irrigated

agriculture across the world (Abel et al., 2014). Soil salinity and sodicity are major factors

limiting agricultural productivity through reducing soil fertility in irrigated agriculture located in

semi-arid areas. As indicated by Vanlauwe et al. (2010), soil fertility involves examining the

forms in which plant nutrients occur in the soil, how these become available to the plant and

12

factors that influence their uptake. This in turn leads to a study of the measures that can be taken

to improve soil fertility and crop yields by supplying nutrients to the soil-plant system. This is

usually done by adding fertilizers, manures and amendments to the soil but sometimes by

supplying nutrients directly to the plant parts by means of sprays. Irrigation water management

involves the managed allocation of water and related inputs in irrigated crop production, such

that economic returns are enhanced relative to available water. Conservation and allocation of

limited water supplies is central to irrigation management decisions, whether at the field, farm,

irrigation-district, or river-basin level.

Effective and efficient irrigation begins with a basic understanding of the relation-ships among

soil, water, and plants. The amount of water that soil can hold, its water holding capacity, is a

key factor in irrigation planning and management since the soil provides the reservoir of water

that the plant draws upon for growth. Water savings at the farm level can help to offset the effect

of rising water costs and restricted water supplies on producer income. Improved water

management may also reduce expenditures for energy, chemicals, and labor inputs, while

enhancing revenues through higher crop yields and improved crop quality (USDC, 1994).

Irrigation management reduces runoff and leachate losses, controls deep percolation and along

with cropland sediment control, reduces erosion and sediment delivery to waterways.

It has been shown that an increase in agricultural production can strongly contribute to the

alleviation of food insecurity and the reduction of poverty (Irz et al., 2001; Kaya et al., 2013). It

is possible through using different agricultural technologies like integrated soil fertility

management (ISFM) practices. The fundamentals of ISFM are that agricultural intensification

cannot occur without investments in soil fertility, and that both organic and mineral inputs are

needed to sustain soil health and increase crop production (Vanlauwe et al., 2010). ISFM

necessarily includes the use of improved germ-plasma, organic inputs, and mineral fertilizer,

applied using good agronomic practices, and adapted to local conditions (Vanlauwe et al., 2010).

A mineral element is considered essential to plant growth and development if the element is

involved in plant metabolic functions and plant cannot complete its life cycle without the

element. Usually the plant exhibits a visual symptom indicating a deficiency in specific nutrient,

which normally can be corrected or prevented by supplying that nutrient (Tisdale et al., 1995).

13

However, visual nutrient symptoms can be caused by many other plant stress factors. Therefore,

caution should be exercised when diagnosing deficiency symptoms. Plants feed mainly by taking

essential elements through their roots, but nutrients can also be absorbed by the leaves and other

plant parts, particularly through leaf stomata (Vanlauwe et al., 2010).

The importance of soil fertility and plant nutrition to health and survival of all life cannot be

understated as human population continue to increase, human disturbance of earth's ecosystem to

produce food and fiber will place greater demand on soils to supply essential nutrients.

Therefore, it is critical that we increase our understanding of the chemical, biological and

physical properties and relationships in the soil plant atmosphere continuum that control nutrient

availability (Tisdale et al, 1995).

The evidence is clear that the soils native ability to supply sufficient nutrients has decreased with

the plant productivity levels with increased human demand for food. One of the greatest

challenges for our generation will be to develop and implement soil, water and nutrient

management technologies that enhance the quality of soil, water and air. If we do not improve

and/or sustain the productive capacity of our fragile soil, we cannot continue to support the food

and fiber demand of our growing population (Tisdale et al., 1995).

2.4. Performance Evaluation of Irrigation Methods

Irrigation efficiency measures are commonly used to characterize the water-conserving potential

of irrigation methods. Application uniformity is one of performance evaluation of irrigation

methods and concerns the distribution of water over the actual field, divided by the average

infiltrated depth over the whole field. Two of the most commonly used uniformity indices in

surface irrigation are; distribution uniformity (DU) and Christian’s uniformity coefficient (UCC).

It is defined as the ratio of the difference between the average infiltrated amount and the average

deviation from the average infiltrated amount (Zerihun et al., 1997; Al-Ghobari, 2011).

Application uniformity concerns the distribution of water over the actual field. A number of

technical sources suggest the Christiansen Coefficient as a measure of uniformity. Others argue

in favor of an index more in line with the skewed distribution.

14

Distribution uniformity is defined as the average infiltrated depth in the low quarter of the field,

divided by the average infiltrated depth over the whole field. This term can be represented by the

symbol, DU. the same authors also suggest an 'absolute distribution uniformity', DU which is the

minimum depth divided by the average depth (Walker, 1989).

Application efficiency is also considered as one of performance evaluation of irrigation methods

and can be defined as the ratio of the volume of water stored in the subject region to the volume

of water diverted into the subject region (Zerihun, et al., 1997). Losses from the field occur as

deep percolation and as field tail water or runoff. To compute Ea, it is necessary to identify at

least one of these losses as well as the amount of water stored in the root zone. This implies that

the difference between the total amount of root zone storage capacity available at the time of

irrigation and the actual water stored due to irrigation be separated, i.e. the amount of under

irrigation in the soil profile must be determined as well as the losses (Walker,1989).

According to Kassa (2001), evaluation of the performance of surface irrigation methods at

Melka-Were, middle awash valley, indicated that the maximum possible application efficiency

(Ea) for furrow irrigation computed was 64.5% for inlet flow rate 2.5 l/s and 0.8 m furrow

spacing. Whereas the total irrigation water losses (due to deep percolation and runoff) was 56-

62%. Water application efficiency gives a general sense of how well an irrigation system

performs its primary task of getting water to the plant roots (Hanson et al., 1995; Smith et al.,

2005).

However, it is possible to have a high Ea but have the irrigation water so poorly distributed that

crop stress exists in areas of the field. It is also possible to have nearly 100 percent Ea but have

crop failure if the soil profile is not filled sufficiently to meet crop water requirements. Any

irrigation system from the worst to the best can be operated in a fashion to achieve nearly 100

percent Ea if water delivered to field (Wf) is sufficiently low. Increasing Ea in this manner

totally ignores the need for irrigation uniformity. For Ea to have practical meaning, water

available for use by the crop needs to be sufficient to avoid undesirable water stress.

Determination of application efficiency of a specific irrigation system is generally time

consuming and often difficult (Smith et al., J 2005). One difficulty is that efficiency varies in

15

time due to changing soil, crop and climatic conditions. A reported range of application

efficiency (Ea) for furrow irrigation is from 50 to 70% (Rogers et al., 1997).

Water requirement efficiency is the other means of performance evaluation of irrigation methods

and can be defined as the ratio of the volume of water actually stored in the subject region to the

volume of water that can be stored (Zerihun et al., 1997). The adequacy of irrigation is the

percent of the field receiving sufficient water to maintain the quantity and quality of crop

production at a profitable level. Storage efficiency (Er) is the measure of adequacy when the

desired depth of irrigation fills the soil to field capacity (Al-Ghobari, 2011).

The storage efficiency is an indicator of how well the irrigation meets its objective of refilling

the root zone. The value of Er is important either when the irrigations tend to leave major

portions of the field under-irrigated or where under-irrigation is purposely practiced to use

precipitation as it occurs. This parameter is the most directly related to the crop yield since it will

reflect the degree of soil moisture stress. Usually, under-irrigation in high probability rainfall

areas is a good practice to conserve water but the degree of under-irrigation is a difficult question

to answer at the farm level (Walker, 1989).

2.5. Water Management in Rain-fed Agriculture

Rain fed agriculture refers to those agricultural systems that are not irrigated and rely solely on

rainfall for their water supply. The majority of agricultural production systems in the Rift Valley

of Ethiopia are rain fed and vulnerable to climate variability. There is great potential for

improving productivity and sustainability in this system, particularly by controlling water

resources better (FAO, 2006). The temporal and spatial variability of climate, especially rainfall,

is a major constraint to yield improvements, competitiveness and commercialization of rain-fed

crops and livestock systems in most of the tropics (Rockstrom, 2003). However, reducing the

rainfall related risks cannot be achieved in the absence of the needed investments in water

management as they are the entry point to unlock the potential in rain-fed agriculture. Evidence

from water balance analyses on farmers’ fields around the world shows that only a small fraction

of rainfall, generally, less than 30%, is used as productive green water flow (plant transpiration)

supporting plant growth (Rockstrom, 2003). In arid areas, only as little as 10% of rainfall is

consumed as productive green water flow with most of the remainder going to non-productive

16

evaporation flow (Oweis and Hachum, 2001). These conditions imply that investments should be

directed for the improvement of rainwater management which is truly poor generating excessive

runoff, causing soil erosion and poor yields due to a shortage of soil moisture.

Water management to upgrade rain-fed agriculture encompasses a wide spectrum from water

conservation practices for improving rainwater management on the farmers’ field to managing

runoff water for supplying supplemental irrigation water to rain-fed food production. Improving

water management in rain-fed agriculture is a long term process and requires learning by doing

using an adaptive approach (Fisher et al., 2009). Such adaptive management approach should be

responsive to the variability within systems as well as to the long term and slow ones changes. In

addition, the management approach should carefully consider the increasing rainfall variability

and frequency of extreme events such as drought and floods due to the emerging climatic

changes. The work done by Critchley and Siegert (1991) indicated that there are three major

rainwater management strategies; water harvesting, soil and water conservation and evaporation

management.

Under water harvesting strategy there are several management options to be practiced using

several tools including surface micro-dams, subsurface tanks, farm ponds and percolation dams

as well as diversion and recharging structure (Fisher et al., 2009). Harvested water within such

tools are to be used for upgrading rain-fed agriculture through mitigating dry spells, recharging

groundwater, enabling off season irrigation and facilitating multiple uses of water. Soil and

water conservation strategy basically aiming to concentrate on rainfall through diverting runoff

to cropped area in order to maximize rainfall infiltration (FAO, 2006). To put this strategy in

action there are several management options which are technically simple and economically

sounding and, therefore, they have wide use by farmers in many arid and semi-arid regions to

capture and reduce losses in rainfall. For instance, to maximize rainfall infiltration, this can be

effectively achieved through terracing, contour cultivation, conservation agriculture and

staggered trenches. On the other hand, bunds, ridges, micro-strips, broad-beds and furrows are

the management options to capture and concentrate rainfall.

The main purpose of evaporation management strategy is to reduce non-productive evaporation.

This is a key window for improving green water productivity through shifting non-productive

17

evaporation to productive transpiration. Oweis and Hachum (2001) indicated that in semi-arid

areas up to half the rainwater falling on agricultural land is lost as non-productive evaporation.

This strategy can change the evaporative loss into useful transpiration by a plant which is used to

upgrade rain-fed agriculture in arid, semi-arid and dry sub-humid regions. Research findings

(Rockstrom, 2003; Oweis et al., 1998) indicated that large opportunities for improving water

productivity are found in low yielding farming systems, particularly in rain-fed agriculture.

There seems to be ample room for improvements in water productivity through rainwater

management. In rain-fed system evidence shows that the adoption of in-situ water harvesting

improves rainfall infiltration and that enhances productive transpiration. Reducing non-

productive evaporation means more water available in the root zone that could lead to an

increase in food production and thereby a simultaneous increase in water productivity (FAO,

2006).

2.6. Water Requirement of Crops

Crop water requirement or evapotranspiration (ET) is defined as evaporation of water from land

and water surfaces and transpiration by vegetation (FAO, 1984; Jensen et al., 1990).

Evapotranspiration is important in water resources planning, efficient water management, and

water permit management for both irrigated crops and dry land crops. Understanding crop water

needs is important for optimal crop production by either meeting the crop water requirement or

avoiding crop water stress during critical periods. Measurements of ET rates are difficult to

obtain and insitu measurements are time consuming and costly (Doorenbos and Pruitt, 1977).

The ET rates vary among crop types, varieties, growth stages, soil wetness, and climate

conditions.

The ET can be determined using direct and indirect methods. Direct ET measurement can be

achieved by soil water depletion, lysimeter, water balance, energy balance, mass transfer, and

eddy correlation, combination of energy and heat, and mass transfer methods (Jensen et al.,

1990). Normally, the actual crop ET (ETc) is determined indirectly, i.e., ETc is estimated by

relating a reference evapotranspiration (ETr) to a crop coefficient (Kc). The relationship is

represented by ETc = Kc * ETr (Doorenbos and Pruitt, 1977). Crop water requirement

determination is very important for proper irrigation scheduling, efficient water management,

18

optimum yield and profit. Weather parameters, crop characteristics, management and

environmental aspects are factors affecting evaporation and transpiration (Allen, et al., 1998).

The crop type, variety and development stage should be considered when assessing the water

requirement of crops that are grown in large and well-managed fields.

2.7. Irrigation Scheduling

The maximum yield per unit area may be economically justified when water supplies are readily

available and irrigation costs are low (Howell, 2001). All production practices and inputs must

be at yield optimizing levels and daily cycles of plant water potentials must usually be managed

within limits conducive to maximize seasonal net photosynthesis (Brouwer and Heibloem,

1986). Precise management criteria for plant water potentials are, however, not well developed

(Stegman et al., 1983). From an applied water management viewpoint as stated by Stegman et

al., (1983) shown that maximum yield per unit area is attained when irrigation systems are

operated to supply sufficient water for plants to meet the day-to-day evaporative demand and

with a frequency that maintains high soil water potential in the upper root zone. As the

requirement for high soil water potential is satisfied, the daily depression in leaf water potential

is minimized and net photosynthesis is likely optimized with in practical limits.

The requirements of high soil water potential for maximized net photosynthesis may actually

exceed the requirements for maximized transpiration. Ritchie (1974) has estimated that actual net

photosynthesis probably falls below potential rates when root zone extractable water is only 20

to 25 percent depleted. But, this experimental evidence (Ritchie, 1974) shows plants can meet

most evaporative demand until their root zone extractable water is about 70 to 80 percent

depleted between field capacity (FC) to permanent wilting point (PWP). Many research findings

have also shown that for many crops, yields will be near their maximum when root zone

available water is not depleted by more than 25 to 40 percent between irrigation's.

Brouwer and Heibloem (1986) suggested that some crops may require programs of stress

management in each growth stage which have been locally calibrated to most consistently

produce the desired yield and quality levels. In many soils, about 50 to 60 percent depletion of

plant available water should be permitted in the effective root zone prior to irrigations. Timing of

the last seasonal irrigation is determined largely by soil texture in the root zone and the given

19

climate. The last seasonal irrigation is often also critical to the degree of maturity attainment in

the harvest period.

Stegman et al. (1983) revealed that, as irrigation water supplies become more limited or as water

costs increase in an area, the management might shift to optimize production per unit of applied

water. There is a functional relationship of crop yield with seasonal ET and with seasonal

irrigation is separated by the seasonal non-evapotranspiration (ET) losses. Typically these losses

increase with increasing seasonal irrigation amount, giving the yield versus seasonal irrigation

function a convex shape that curves away from the yield versus evapotranspiration function. It

can be visualized that the ratio of Y/IRR will increase as non-ET losses are reduced. In fact, with

accurate scheduling methods and efficient irrigation systems, the Y/IRR ratio will likely

maximize near the maximum evapotranspiration (ETmax) yield potential. Thus, with unlimited

water supply, the scheduling goal should be to minimize the seasonal non-ET losses.

2.8. Water Productivity

Water productivity is the amount of beneficial output per unit of water depleted. In its broadest

sense, it reflects the objectives of producing more food and the associated income, livelihood and

ecological benefits, at a lower social and environmental cost per unit of water used (Molden et

al., 2007). Usually, water productivity can be defined with respect to the different sectors of

production involving water (e.g. crop production, fishery, forestry, domestic and industrial water

use). Water productivity with respect to crop production is referred to as crop water productivity

(CWP), and is defined as the amount of crop produced per volume of water used. The unit of

crop water productivity is kg/m3. It can also be defined in monetary terms, expressed in terms of

economic return from crop produced per volume of water, with the unit expressed in equivalent

of any currency (e.g. $/m3 ) (SWMRG, 2003; Kadigi et al., 2004). Water use efficiency and

water productivity are often used in the same context of increasing agricultural outputs while

using or degrading fewer resources. Although definitions vary, water use efficiency usually takes

into account the water input, whereas water productivity uses the water consumption in its

calculation.

20

Improving agricultural water productivity is about increasing the production of rain-fed or

irrigated crops. Crop water productivity has been the subject of many years of research and its

assessment and means for improvement are well documented (Kijne et al., 2003; Bouman, 2007;

Molden, 2007; Rockström and Barron, 2007). Opportunities for improving crop water

productivity mainly lie in choosing adapted, water-efficient crops, reducing unproductive water

losses and ensuring ideal agronomic conditions for crop production (Kijne et al., 2003; Bouman,

2007; Rockström and Barron, 2007). In general, agronomic measures directed at healthy,

vigorously growing crops favor transpiration and productive water losses over unproductive loss.

As many of the world’s poorest people live in currently low-yielding rain-fed areas, improving

the productivity of water and land in these areas would result in multiple benefits. Thus, by

getting more value out of currently underutilized rainwater, agricultural land expansion would be

limited, and the livelihoods of these poor men and women would be improved, without

threatening other ecosystem services (WRI et al., 2008). A recent global analysis on closing

yield gaps indicated that appropriate nutrient and water management are essential and have to go

hand in hand (Mueller et al., 2012).

2.8. Nutrient Balance

The nutrient balance is defined as the difference between the nutrient inputs entering a farming

system and the nutrient outputs leaving the system. The crop nutrient balance is the comparison

of nutrients applied to cropland in relation to those removed by crops. It is an important indicator

of the sustainability performance of crop production (Nandwa and Bekunda, 1998). Deficits in

the nutrient balance can limit crop yields and deplete soil fertility and surpluses can cause

economic waste and increase the risk of harm to water and air. Inputs of nutrients are necessary

in farming systems as they are critical in maintaining and raising crop and forage productivity.

The net nutrient balance is the total of nutrient inputs minus nutrient outputs expressed in

kilogram nutrients ha-1 yr-1. Positive balances indicate that nutrients are accumulating in the soil

and negative balances indicate that the soil is being mined for nutrients (Nandwa and Bekunda,

1998).

𝐹𝑁𝐵 = (IN1 + IN2 + IN3 + IN4 + IN5) – (OUT1 + OUT2 + OUT3 + OUT4 + OUT5) ---- (Eq.1)

21

Removal of harvested products and crop residues are usually the major pathways of nutrient

losses from agricultural soils. The amount varies considerably depending on crop type, soil type,

agronomic practices and plant nutrient uptake (Brady and Weil, 2002; Mengel and Kirkby,

1996). Fluxes are directly related to farm management, like inorganic fertilizer input, organic

fertilizer input, harvested products and residues removed. Plants require at least 14 elements as

essential mineral nutrients. Each of the 14 is equally crucial to the plant's survival, but some are

more likely to become deficient than others. Supplies of the three primary nutrients; nitrogen,

phosphorus and potassium need the closest attention to ensure adequate quantities for crop

growth.

Nutrient balance studies are valuable tools to assess the sustainability of agro-ecosystems and

potential consequences for agricultural productivity. It can be conducted at different spatial

scales ranging from field and farm, via watershed to national and continental scales. At national

and continental scales, nutrient balances have been used to draw attention to nutrient depletion as

a principal cause for low agricultural productivity and food insecurity in Africa (Sanchez, 2002;

De Jager et al., 1998; Fresco et al., 1990). In many farming systems nutrient management of

different fields belonging to single farm households may vary considerably (Smaling et al.,

1996).

Farmers’ decisions of fertility management are influenced by both socio-economic and

biophysical environments, resource endowment and objectives of production. Therefore, field

and farm scale nutrient balance studies can provide information on how environmental

conditions and agricultural management practices affect the variation in nutrient flows between

and within the fields of a farm. This information is also indispensable for properly understanding

variations in nutrient flux studies at higher spatial scales and their limitations (Smaling, 1993;

Van den Bosch et al., 1998; Wijnhoud et al., 2003).

Nutrient balance studies that were carried out in different areas indicated that there is a

significant heterogeneity and diversity in farming system. As a result, it is not well known how

nutrient management practices are affected by or embedded in the livelihood strategies of rural

households. Furthermore, it is uncertain how the location of a farmer’s plot within the landscape

affects nutrient management.

22

3. MATERIALS AND METHODS

3.1. Descriptions of the Study Area

3.1.1. Location and Topography

This study will be carried out in two sites, Adami-tullu (Bochessa) and Lemo (Upper Gana) in

the coming two years (2015-2017). Adami-tullu (Bochessa) site is found in South Western

Shewa Zone in Oromiya Region. It is geographically situated at longitude about 38° 30’ E

longitude and 6° 27’ N latitude. It is located at about 163 km away from Addis Ababa toward

south direction in the vicinity of Lake Ziway. In the woreda, there are 43 rural Kebeles of which

some have access to irrigation water. The altitude of the area is about 1600 meters above sea

level in the tropical semi-arid zone in the middle part of the Ethiopian rift valley system. Since

Ethiopia lies about between latitudes 4oN and 18oN, there is only a small variation in day length

both between season and latitudes and the area is suitable for short day plants. The topography is

characterized by plain to undulated hills that is located adjacent to the escarpment of the southern

part of the Ethiopian mountain channels that limits the rift valley expansion towards the Eastern

direction.

The other site is Lemo (Upper-gana) which is found in Hadiya Zone in Southern Ethiopia. It is

geographically located between 37°.40’ - 38°.00’ E longitude and 7°.22’ - 7.45’ N latitude and it

covers an area of 38,140 ha. It is located at about 232 km away from Addis Ababa towards south

direction along with the main road that connects Oromiya Region with Southern Ethiopia via

Butajira – Hosana road. The research site (Upper-gana) is found in Lemo Woreda about 17 km

away from Hosanna town towards west direction. The land mass of the area lies between 1900 –

2700 m above sea level. The topography of the site is characterized by moderately undulated to

undulated hills that are located adjacent to the escarpment of the southern part of the Ethiopian

mountain channels that limits the rift valley expansion towards the western direction.

23

Fig 1. Location map of the study areas

3.1.2. Geology and Parent Materials

As the study area is part of the Southern Rift Valley System of Ethiopia, the geology is complex

and characterized by tertiary and quaternary age rhyolite and basalt volcanic materials (FAO,

1984a). Moreover, in the highlands and middle altitude areas of Ethiopia, the distributions of

soils are related to parent material and the major geological materials are tertiary and quaternary

basalt-deposits and granite rocks. The parent material of most of the study area is basalt rocks,

24

lacustrine sediments of sand, silt, pyroclastic deposits and ditomites. Alluvial/colluvial cones and

fans are found bordering the main river valleys and the foot of higher plateau areas.

According to the Ethiopian Institute of Geological Survey (1996), two geological formations

cover the area. The major geological occurrences that affected the area were the first continued

uplift of the Ethiopian plateaus and at large the East African Plateaus which began at the end of

the Mesozoic era. The event was accompanied by the out pouring of immense lava. The second

geological occurrence was the quaternary period which was characterized by the extremely

heavy rainfall known in Africa as Pluvial Rain. This again has led to the formation of large lakes

within the floor of the Rift Valley and the deposition of eroded materials in the lakes from the

surrounding plateau. The lakes were much larger and deeper than they are today. However,

because of siltation and other problems their depths and sizes have declined from time to time.

3.1.3. Soils of the Study Area

According to FAO reports the soils of Ethiopia are much varied from place to place and the same

is true in the study areas as well. The soils of the Rift Valley areas of Ethiopia are quite diverse

in nature and derived from young rocks of volcanic origin (FAO, 1984a). The soil of the area

ranges from slightly alkaline to alkaline and the texture of the soil is sandy loam. The soils are

good in nutrient status since leaching has not proceeded to a very marked degree. Constraints to

crop production in the area associated with low phosphorus levels, micronutrient imbalances and

in some cases poor physical structure. In case of Lemo area, the soil textural class encompasses

clay, silt, loamy and other mixed textures that always exposed to the risk of erosion due to

topographic features of the area.

3.1.4. Climate and Hydrology

In the Bochessa site mean annual rainfall ranges from 600 mm to 1000 mm and the rain fall

pattern is erratic and unreliable in terms of both amount and timing and shows a bimodal

distribution pattern. The mean annual potential evapo-transpiration (PET) is 1662 mm and

monthly PET during October to May exceeds monthly rainfall implying the importance of dry

season irrigation. The site is drained by major stream called Bulibula in Eest-West direction that

flows into Lake Abijata. It then forms part of the rift valley lakes drainage basin. Current status

25

of groundwater utilization in the area indicates that high proportion for domestic water supply

and less proportion to irrigation purposes.

In the Lemo site the annual mean minimum and maximum temperature respectively are 13°C

and 23°C. The amount of rainfall received ranges from 750 mm to 1200 mm and rainfall

distribution is seasonal. The rainy seasons are Belg (January to April) and the main rainy season

(June to August). Most of time the area is known for its rain fed agriculture and irrigation is

newly introduced technology in the area.

3.1.5. Land Use and Vegetation

The major land use types in both sites are cultivated land and grazing land. Most of the cultivated

land use types are concentrated on the undulating to rolling landform type in Lemo area while in

Bochessa site it is practiced in flat areas. The major cash crops that grown in Bochessa site are;

tomato, cabbage, onion and haricot beans whereas maize, teff and wheat are considered as main

food crops. In Lemo site; wheat, teff, potato and faba bean are the most important cash crops

whereas enset, vegetables, teff, wheat and potato are main food crops. However, enset

production has been declining due to disease infestation. Most of the grazing lands are located on

the plain to level areas in both sites. The natural vegetation is situated nearby lake and river

banks in Bochessa site while in the steep mountainside slope area in lemo site. The types of

vegetation composed of mainly bushes and acacia species in Bochessa site and dominantly

eucalyptus trees in Lemo area.

3.2. Methodologies

3.2.1. Pre-experiment Activities

Before starting the main work, a preliminary survey of the area will be carried out to gather

required physical information’s about the sites. The location of each farmer’s experimental plot

will be indicated (geo-referenced) by using GPS. Nursery site will be prepared to raise vegetable

seedlings to supply as planting material for selected farmers at both sites. About 0.025 ha (MP

group) and 0.015 ha (RAW group) of land will prepared on farmers field for experimental

activity and tilled using animal drawn implements. Different vegetable seeds and fertilizers will

be prepared and supplied for target groups. Framers in both sites will be trained about the aim of

26

the experiment and how irrigation will be monitored during the growing seasons. Field data book

will be prepared and distributed for the farmers who are involved in the research activity before

the commencement of each growing seasons.

3.2.2. Crop Water Requirement

Evapotranspiration (ET) is taking place within a particular crop is considered as crop water

requirement or consumptive use of crop. It is important in water resources planning and efficient

water management for both irrigated and rain-fed agriculture. It will be determined by using the

relationship between reference evapotranspiration and crop coefficient (Doorenbos and Pruitt,

1977). The relationship is represented by the following equation;

ETcr = Kc ∗ ETo

Where, ETcr - Crop Water Requirement

Kc - Crop Coefficient

ETo - Reference Evapotranspiration

Reference evapotranspiration (ETo) will be determined by using FAO Penman-Monteith equation

(Allen et al., 1998) from climatic dates that will be collected from metrological stations that are

found in both experimental sites. Crop coefficient (Kc) will be determined by using already

developed values from FAO manuals. In addition to that, cropwat/aqua-crop software will be

used to generate the crop water requirement and irrigation schedule for selected vegetable crops

in the study areas. To evaluate irrigation methods, different irrigation efficiency variables will be

employed.

3.2.3. Experimental Setup

The effect of irrigated agriculture on soil salinity and fertility will be evaluated through doing

experimentation on 44 farmer’s field at Bochessa and Lemo site (Table 1) for two consecutive

years. Soil fertility and land productivity of farmers having two and one irrigation seasons per

year will be compared against farmers that have no irrigation. Soil sampling will be done from

different horizons (layers) from each selected farmer’s field during the experimentation period

(before planting and after harvesting) for each dry seasons by using auger. The collected soil

samples will be analyzed for selected chemical properties such as; pH, EC, K, Ca2+, Mg2+, Na+,

TEB, CEC, TN, OM and soluble phosphorous at National Soil Laboratory/Arbaminch University

27

Water Quality Laboratory Center to see the effect of irrigated agriculture on soil quality at

different depths. Soil samples will be also collected from four none irrigated farmer’s field and

analyzed to compere the level of salinity that occurred due to irrigation.

Water samples will be collected from each water source used in irrigation and analyzed to see the

effect of irrigation water quality on salinity level of the soil. The collected water samples will be

analyzed for PH, EC, nitrate, total nitrogen, soluble phosphate, total phosphate, calcium,

magnesium, boron and fluoride. The analysis for different chemical parameters of water samples

will be carried out following the established analytical methods at Arbaminch University Water

Quality Analysis Laboratory Center. In addition to that N, P & K will be measured at a monthly

time interval to assess partial nutrient balances (to assess soil fertility).

The soil of the study area will be classified based on salinity and fertility level according to the

standards established by Ayers and Westcot (1985). The suitability of ground and surface water

for irrigation agriculture will be also assessed according to the standards established by Ayers

and Westcot (1985). Soil moisture will be regularly measured in all selected farm plots before

and after irrigation using TDR and SPT to know moisture content of the soil. Agronomic data

(planting date, plant height, length of growth stages, yield) will be collected from each farmers

field throughout the cropping season. Irrigation quantity and rainfall amounts will be monitored

throughout the season. Productivity will be determined by dividing total economical yield to the

total depth of irrigation water used in the process.

28

Table1. Treatment arrangement for all objectives which are carrying out at both sites

The effects of agricultural water management practices on leaching of nutrients from the root

zone under irrigated agriculture will be conducted for the same farmers as those under objective

one (Table 1). The leaching of nutrients will be collected by installing wetting front detectors

below the root zone/by using partial nutrient analysis methods. The collected water samples will

be analyzed for NPK. The measured NPK content in the extracted water will be used to quantify

the amount of NPK leached throughout each season for both farmers practice and irrigation

scheduled plots. The amount of leached nutrients will be determined by using transfer function

as indicated by Stoorvogel and Smaling (1990). Soil moisture will be regularly measured in all

selected farm plots before and after irrigation using TDR and SPT to know moisture content of

the soil. The nutrient content in the irrigation water and fertilizer will be measured throughout

the season in order to know nutrient depletion due to irrigation.

No Site Source of

water

Water lifting

methods

Water

Management Type of field

Number of

farmers

1 Bochessa Groundwater Motorized

pump WFD Irrigated 4

2 Bochessa Groundwater Motorized

pump

Farmers

practice Irrigated 4

3 Bochessa Surface

water

Motorized

pump WFD Irrigated 4

4 Bochessa Surface

water

Motorized

pump

Farmers

practice Irrigated 4

5 Bochessa - - Farmers

practice

Non

irrigated/rain-fed 4

6 Bochesa Groundwater RAW WFD Irrigated 4

7 Bochesa Groundwater RAW Farmers

practice Irrigated 4

8 Upper-gana Groundwater RAW WFD Irrigated 4

9 Upper-gana Groundwater RAW Farmers

practice Irrigated 4

10 Upper-gana Groundwater Solar pump Farmers

practice Irrigated 4

11 Upper-gana - - Farmers

practice

Non

irrigated/rain-fed 4

29

Soil samples from each experimental plot taken as described under objective one will be

analyzed on nutrient content. Agronomic data (planting date, plant height, length of growth

stages, yield) will be collected from each farmers field throughout the cropping season. Produce

and plant residue will be collected at harvest and analyzed on nutrient composition (NPK).

Irrigation water quantity will be monitored throughout the season for each farmer. The nutrient

balances will be determined using the differences between the inputs (mainly from chemical and

organic fertilizer and irrigation water) and the outputs (crop residues and grain).

Testing and validating different irrigation scheduling methods and evaluating their effects on

water productivity will be carried out at the same irrigating farmers field as described in

objective one (table 1). Irrigation scheduling will be estimated by using historical climatic data

for the WFD group. The irrigation management treatment consists out of following the WFD

indicator on how much to irrigate this will be compared against control farmers. To monitor the

functioning of the wetting front detector and determine potential deep percolation, soil moisture

access tubes will be installed. Soil moisture will be regularly measured by using TDR and SPT in

all selected farm plots before and after irrigation. Available soil moisture content at field

capacity and permanent wilting point will be determined by using pressure plate method.

Agronomic data (planting date, plant height, length of growth stages, yield) will be collected

from each farmers field throughout the cropping season. The growth of crop root will be

measured during different growth stages. Irrigation water quantity applied and rainfall will be

monitored throughout each season. Water productivity will be calculated as the ratio of crop

yield (marketable yield) and depth of total water applied (Michael, 2008)

3. 3. Data Analysis

Analysis of collected data will be carried out by using different appropriate statistical software’s

SAS/GLM and if the result showing significant, it will be subjected to Tukey test for mean

separation. Correlations between parameters will be computed when applicable according to

Gomez and Gomez (1984).

30

Fig1. Conceptual framework for agricultural water management under small holder

irrigated farms and its impact on soil fertility and nutrient management

Issues

Strategies

Effect

s

SUSTAINABLE AGRICULTURAL DEVELOPMENT

Improve water

use efficiency Improve soil

quality

Increase

production (yield)

Reduce

pollution

IMPROVING IRRIGATION WATER MANAGEMENT

Irrigation

Scheduling

Use suitable

irrigation water

Monitoring Soil

Moisture

Soil salinity

problem

Wastage of

irrigation water

Fertility

Problem

Leaching of

Nutrients

Production

Problem

POOR IRRIGATION WATER MANAGEMENT

31

4. WORK PLAN

No Activities Year I Year II Year III

Quarter I Quarter II

Quarter

III

Quarter

IV

Quarter

I Quarter II

Quarter

III

Quarter

IV

Quarter

I

Quarter

II

Quarter

III Quarter IV

Months O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S

1 Research proposal

2 Site visiting

3 Location reading

4 Soil & water Sampling

5 Farmers training

6 Laboratory analysis

7 Field book preparation

8 Land preparation

9 Nursery establishment

10 Raising seedlings

11 Nursery management

12 Field preparation

13 Transplanting

14 Field managements

15 Data collection

16 Harvesting

17 Data analysis

18 Workshop participation

19 Model training

20 Paper writing

21 Submitting 1st draft

22 Correcting it

23 Submitting 2nd draft

24 Correcting it

25 Publishing papers

26 Submitting final report

27 Defense

32

5. FINANCIAL REQUIREMENT

5.1. Par-dime

No. Item Number No. of days Rate/day (Birr) Total cost

1 Advisors 2 20 500 20000

2 Researchers 1 80 500 40000

2 Driver 1 20 500 15000

Subtotal 75000.00

5.2. Transportation and Living Cost

No. Item Place (round trips) No. of

travel

Unit cost

(Birr)

Total cost

(Birr)

1 Researcher A/minch to Hosana 30 100 3000

“ Hosana to A/minch 30 100 3000

“ A/minch to Ziway 30 150 4500

“ Ziway to A/minch 30 150 4500

“ A/minch to Addis 20 285 5700

“ Addis to A/minch 20 285 5700

“ Hosana to upper gana 50 300 15000

“ Ziway to bochessa 50 150 7500

2 Soil & water sample Hosana to A/minch 4 500 2000

“ Ziway to A/minch 6 750 4500

“ Hosana to Addis 4 500 2000

“ A/minch to Awassa 4 500 2000

3. Stipend fund For both sites - - 60,000

Sub total 119400.00

33

5.3. Supplies/Miscellaneous Costs

No. Item Unit Unit cost Quantity Total cost

1 Sample bags Kg 100 32 3200

3 Safety Shoes No 1000 2 2000

4 Sample bottles No 10 50 500

5 Glove No 10 50 500

5 Field bag No 1000 2 2000

6 GPS battery Pk 5 200 1000

6 Balance No. 500 1 500

7 Printing No 4 1000 4000

8 Photocopy No 1 1000 1000

9 Communication fee/card No 100 30 3000

Sub total 24,700.00

5.4. Labour Cost

No. Item Number of

days/month

Unit cost Total cost

1 Auguring 2*80 50 8000

2 Data collector 3*12 1000 36000

3 Field assistant 2*60 50 6000

4 Sample collection

Subtotal

2*40 50 8000

58,000.00

34

5.5. Stationary Materials Cost

No. Item Unit Quantity Unit price (Birr) Total cost (Birr)

1 Computer printing paper Pk 40 100 4000

2 Note book No 40 20 800

3 Pen Pk. 1 500 500

4 Fixer lead No 10 25 250

5 Writing pad Pk 20 100 2000

6 Parker No 50 30 1500

7 Classer No 100 5 500

6 Photocopy paper Pk 20 100 2000

Sub total 11,550.00

5.6. Laboratory Soil Analysis Cost No. Item Quantity Unit cost Total cost

1 Texture 50 100 5000

2 Bulk density 120 25 3000

3 CEC 120 150 18000

4 PH 120 25 3000

5 EC 120 25 3000

6 Total nitrogen 120 150 18000

7 Available Phosphorus 120 150 18000

8 Organic matter 120 150 18000

9 Available potassium 120 100 12000

9 Exchangeable bases 120 100 12000

10 Field capacity 46 150 6900

11 Permanent wilting point 46 150 6900

12 Soil preparation 120 25 3000

Subtotal 126,800.00

35

5.7. Laboratory Water Analysis Cost

No. Item Quantity Unit cost Total cost

1 Soluble Phosphate 90 75 6750

2 Total phosphate 90 75 6750

3 Nitrate 90 75 6750

4 Total nitrogen 90 75 6750

5 Calcium 90 75 6750

6 Magnesium 90 75 6750

7 Sodium 90 75 6750

8 Potassium 90 75 6750

9 Bicarbonate 90 75 6750

10 Fluoride 90 75 6750

11 Boron 90 75 6750

12 PH 90 30 2700

13 Electrical conductivity 90 30 2700

Subtotal 79,650.00

36

5.8. Budget Summary

No. Description Subtotal

1 Par-dime 75000.00

2 Transportation and stiffened fund 119400.00

3 Supplies/miscellaneous costs 24,700.00

4 Labour cost 58,000.00

5 Stationary materials cost 11,550.00

6 Laboratory soil analysis cost 126,800.00

7 Laboratory water analysis cost 79,650.00

Total cost 452,350.00

Contingency (5%) 24,505.00

Grand total 514,605.00

37

6. REFERENCES

Abel C., D. Kutywayo, T. M. Chagwesha, P. Chidoko, 2014. An Assessment of Irrigation Water

Quality and Selected Soil Parameters at Mutema Irrigation Scheme, Zimbabwe. Journal of Water

Resource and Protection. 6: 132-140.

Al-Ghobari, H. M., 2011. Effect of Irrigation Water Quality on Soil Salinity and Application

Uniformity under Center Pivot Systems in Arid Region. Australian Journal of Basic and Applied

Sciences, 5(7): 72-80.

Allen R, Pereira L, Raes D, Smith M (1998). Crop evapotranspiration: guidelines for computing

crop water requirements. FAO Irrigation and Drainage. Rome, Italy: FAO. p. 56.

Andreas P. Savva and Karen Frenken, 2002. Crop Water Requirements and Irrigation

Scheduling. FAO Sub-Regional Office for East and Southern Africa. Harare, Zimbabwe.

Awulachew, S. B.; Yilma, A. D.; Loulseged, M.; Loiskandl, W., Ayana, M.; Alamirew, T. 2007.

Water Resources and Irrigation Development in Ethiopia. Colombo, Sri Lanka: International

Water Management Institute. 78p. (Working Paper 123)

Ayenew, T., 2004. Environmental implications of changes in the levels of lakes in the Ethiopian

rift since 1970. Regional Environmental Change 4, 192–204.

Ayenew, T., 2006. Water management problems in the Ethiopian rift: Challenges for

development. Journal of African Earth Sciences 48:222–236.

Ayers, R.S. and D.W. Westcot, 1985 Water quality for agriculture. FAO Irri.& Drain. 29: 13-56.

Bauder, T. A., Waskom, R. M., Sutherland, P. L. and Davis, J. G., 2014. Irrigation Water

Quality Criteria. Colorado State University, U.S.A.

Benjamin, J.G., Porter, L.K., Duke, H.R., Ahuja, L.R., Butters, G., 1998. Nitrogen move-ment

with furrow irrigation method and fertilizer band placement. Soil Science Society of America

Journal 62, 1103–1108.

Brouwer, C., Heibloem, M., 1986. A report on irrigation water needs. Irrigation water

management: Training Manual, FAO (Food and Agriculture Organization), Rome, Italy. Draft

document.

Burkhalter, J and T. Gates, 2006 Evaluating regional solutions to salinization and waterlogging

in an irrigated river valley. J. Irrg.Drain. Eng., 132(1): 21-32.

Burt, C. M. and S. W. Styles, 1999. International program for technology and research in

irrigation and drainage the World Bank FAO, Water Reports 19. FAO, Rome.

38

Central Statistical Agency (CSA), 2008. Agricultural Sample Survey 2007/08. Report on Land

Utilization. Volume IV. Statistical Bulletin No. 417. Addis Ababa, Ethiopia.

Chukwu, GU and Nwachukwu, E., 2013. Ground water quality assessment of some functional

boreholes in Ikwuano from bacteriological and physicochemical studies. Journal of

Environmental Science and Water Resources Vol. 2(10), pp. 330 – 335

Critchley, W. and Siegert, K.C. (1991). Water harvesting: a manual for the design and

construction of water harvesting schemes for plant production. Rome: Food and Agriculture

Organizations (FAO).

Doorenbos, J., and W.O. Pruitt. 1977. Guidelines for predicting crop water requirements. FAO

Irrig. andDrain. Paper No. 24. 2nd ed., FAO, Rome.

EEA (Ethiopian Economics Association), 2007/08. Report on the Ethiopian Economy, Vol. VII,

Addis Ababa, Ethiopia.

Ethiopian Institute of Geological Survey, 1996. The Geological Map of Ethiopia, scale

1:2,000,000. Addis Ababa.

FAO (Food and Agriculture Organization), 1984. Ethiopian geomorphology and soils

(1:1,000,000 scales). Assistance to land use Planning. Addis Ababa, Ethiopia.

FAO and IFAD, 2006. Water for food: agriculture and rural livelihoods. In: Water shared

responsibility. The United World Water Development Report (2) pp. 244-273.

FAO. 1984. Crop water requirements. By: J. Doorenbos and W.O. Pruitt. FAO Irrigation and

Drainage Paper 24. Rome, Italy.

Fischer G.; Van Velthuizen, H.; Hizsnyik, E.; Wiberg, D., 2009. Potentially obtainable yields in

the semi-arid tropics. Global Theme on Agro ecosystems Report no. 54. Andhra Pradesh, India;

International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). 68p.

Fuentes, I., Casanova, M., Seguel, O., Nájera, F., Salazar, O., 2014. Morpho-physical pedo-

transfer functions for groundwater pollution by nitrate leaching in Central Chile. Chil. J. Agric.

Res. 74, 340–348.

Galvani, A., 2007. The challenge of the food sufficiency through salt tolerant crops. Rev Environ

SciBiotechnol, 6: 3-16.

Hanson, B., A. Fauton, D.W. Bendixen and D. May. 1995. Drip irrigation of row crops: An

overview. Irrigation Science l, 45(3), 8-11.

Howell, T.A., 2001. Enhancing water use efficiency in irrigated agriculture. Journal of

Agronomy 93:281-289.

39

Irz, X., Lin, L., Thirtle, C., Wiggins, S., 2001. Agricultural Productivity Growth and Poverty

Alleviation. Dev Pol Rev. 19(4), 449-466.

Jensen, M. E., R. D. Burman, and R. G. Allen. 1990. Evapotranspiration and irrigation water

requirements: ASCE manual No. 70, New York, N.Y.

Kafi, M.H., A. Asadi and A. Ganjeali, 2010. Possible utilization of high-salinity waters and

application of low amounts of water for production of the halophyte Kochia scoparia as

alternative fodder in saline agroecosystems. J. Agric.Water .Management, 97(1): 139-147.

Kaya, O., Kaya, I., Gunter, L., 2013. Foreign Aid and the Quest for Poverty Reduction: Is Aid to

Agriculture Effective? J Agr. Econ. 64(3), 583-596.

Khan, M.A., R. Ansari, H. Ali, B. Gul and B.L. Nielsen, 2009. Panicum turgidum, a potentially

sustainable cattle feed alternative to maize for saline areas. Agric. Ecosys. Environ., 129: 542-

546.

Maggio, A., S. Angelino and C. Barbieri, 2004. Physiological response of tomato to saline

irrigation in long term salinezd soils. Eur. J. Agron. 21: 149-159.

Mailhol, J.C., Crevoisier, D., Triki, K., 2007. Impact of water application conditions on nitrogen

leaching under furrow irrigation: experimental and modeling approaches. Agricultural Water

Management 87 (3), 275–284.

Martin, A. P. 1993. Tropical soils and fertilizer use. Intermediate tropical agriculture series.

University of Nairibi, Kenya.

Michael, A. M., 2008. Irrigation Theory and Practice. Indian Agriculture Research Institute. New

Delhi. India. pp. 427-429.

Mitchell, A.R., Shock, C.C., Barnum, J.M., 1994. Furrow irrigation modeling and management

for reduced nitrate leaching. Ground water quality management. In: Proceedings of the GQM 93

Conference, (IAHS Publ. No. 220).

MoFED (Ministry of finance and economic development), 2010. Growth and Transformation

Plan (GTP), Addis Ababa: Ethiopia.

Mohorjy, A.M. and N.S. Grigg, 1995. Water resources management system for Saudi Arabia. J.

Water Resour. Plng. And mgmt., 121(2): 205-215.

MoWR (Ministry of Water Resources), 2002. Water Sector Development Program (WSDP),

Addis Ababa: Ethiopia.

Munns, R. and M. Tester, 2008. Mechanism of salinity tolerance. Annu. Rev. Plant Biol., 59:

651-681.

40

Murphy, H. F., 1968. A report on fertility status and other data on some soils of Ethiopia.

College of Agriculture, Haile Sellasie I University. Experiment Station Bulletin No. 44. Dire

Dawa, Ethiopia. An OSU-USAID Contract Publication. 551p.

Mwenja, A., 2000. Saline irrigation effect on some soil physical and chemical properties .MSc.

Thesis, Fac. of Agric. (soil science), Texas University, Texas. U.S.A.

Nyamangara J, Bergstron LF, Piha MI, Giller KE (2003). Fertilizer Use Efficiency and Nitrate

Leaching in a tropical Sandy Soil. J. Environ. Qual., 32: 599-606

Oad R. and Sampath R. K. 1995. Performance measure for improving irrigation management.

Irrigation and Drainage Systems, 9:357-370.

Oweis, T. and Hachum, A. (2001). Reducing peak supplemental irrigation demands by extending

sowing dates. Agricultural Water Management 10(1): 21-34.

Oweis, T.; Pala, M. and Ryan, J. (1998). Stabilizing rain-fed wheat yields with supplementary

irrigation and nitrogen in a Mediterranean climate. Agronomy Journal 90 (5): 672-8/

Owino, C.O. and Sigunga, D.O., 2012. Effects of rainfall pattern and fertilizer nitrogen on

nitrogen loss in bypass flow in vertisols at the onset of rain season under tropical environments.

Journal of Environmental Science and Water Resources Vol. 1(9), pp. 207 – 215

Pilbeam CJ, Gregory PJ, Munankarmy RC, Tripathi BP. 2004. Leaching of nitrate from cropped

rain fed terraces in the mid-hills of Nepal. Nutrient Cycling in Agro ecosystems 69: 221–232.

Ragab, A.A.M., 2000. Physical properties of some Egyptian soils. Ph.D. Thesis, Fac. of Agric.

Cairo University, Egypt.

Richard Kraaijvanger and Tom Veldkamp, 2014. Grain productivity, fertilizer response and

nutrient balance of farming systems in tigray, Ethiopia: a multi-perspective view in relation to

soil fertility degradation. Land Degrad. Develop. 26: 701–710 (2015).

Ritchie, J.T. 1974. Atmosphere and soil water influence on plant water balances. Agr. Meteorol.

14: 183-198.

Rockstrom J., (2003). Water for food and nature in drought-prone Tropics: vapour shift in rain-

fed agriculture. Royal Society Transactions B Biological Science 358 (1440): 1997-2009.

Roger, D. H., Lamm, F. R., Mahbub, A., Trooien, T. P., Clark, G. A., Barnes, P. L., and Kyle, M.

1997. Efficiencies and water Losses of Irrigation System. Irrigation management series. Kansas,

USA.

Romic, D.O., R. Gabrijel, V. Marija, A. Mijo and P. Dragutin, 2005. Salinity and Irrigation

Method Affect Crop Yield and Soil Quality. ICID 21st European Regional Conference. 15-19

May - Frankfurt – Germany.

41

Sigunga DO, Janssen BH and Oenema O (2008). Effects of fertilizer nitrogen on short-term

nitrogen loss in bypass flow in a Vertisol. Communication in Soil Science and Plant Analysis 39

(17): 2534- 2549

Sigunga DO, Janssen BH, and Oenema O (2002b). Denitrification risks in relation to fertilizer

nitrogen losses from Vertisols and Phaoezems. Communication in Soil Science and Plant

Analysis 33 (3and4):561- 578.

Sigunga DO, Janssen BH, Oenema O (2002a). Effects of improved drainage and nitrogen

sources on yields, nutrient uptake and utilization efficiencies by maize (Zea mays L.) on

Vertisols in subhumid environments. Nutrient Cycling in Agroecosystems 62: 263- 275.

Sigunga DO, Janssen BH, Oenema O (2002c). Ammonia volatilization from Vertisols. Eur. J.

Soil Sci., 53: 1-8.

Smith, RJ, Raine, SR, and Minkevich, J (2005). Irrigation application efficiency and deep

drainage potential under surface irrigated cotton. Agricultural Water Management, 71(2): 117-

130.

Stegman, E.C., J. T. Musick, and J.I. Stewart, 1983. Irrigation water management. In: Design and

operation of farm irrigation system. University of California, Davis.

Tiercelin, J.R., Vidal, A., 2006. Traiteˇı d’Irrigation, 2nd ed. Lavoisier, Technique and

Documentation, Paris, France.

Tisdale, S.L., W.L. Nelson, J.D. Beaton, and J.L. Havlin, 1995. Soil Fertility and Fertilizers.

Macmillan Publishing Company, New York.

UNDP (United Nations Development program), 2014. Country Economic Brief. Analysis

Issue No. 1/Feb.2014.

Vanlauwe, B., Bationo, A., Giller, K. E., Merckx, R., Mokwunye, U., Ohiokpehai, O., Pypers, P.,

Tabo, R., Shepherd, K.D., Smaling, E.M.A., Woomer, P.L., Sanginga, N., 2010. Integrated Soil

Fertility Management. Operational definition and consequences for implementation and

dissemination. Outlook Agr. 39(1), 17-24.

Volschenk, T., 2005. The effect of saline irrigation on selected soil properties, plant physiology

and vegetative and reproductive growth of plsteyn apricots. Ph.D. Thesis, Fac. of Agric. (soil

science) Univ.Stellenbosch .South Africa.

Waddell, J.T., Weil, R.R., 2006. Effect of fertilizer placement on solute leaching under ridge

tillage and no till. Soil and Tillage Research 90, 194–204.

Walker, W. R., Gaylord V. Skogeroboe, 1987. Surface Irrigation, Theory and Practice, Prentice

Hall, New Jersey.

42

Wenju, M., Z. Yu and Z. Mao, 2008. Effects of saline water irrigation on soil salinity and yield

of winter wheat–maize in North China Plain. Irrig Drainage Syst, 22: 3-18.

Wylie, B.K., Shaffer, M.J., Brodahl, M.K., Dubois, D., Wagner, D.G., 1994. Predicting spatial

distributions of nitrate leaching in northeastern Colorado. Journal of Soil and Water

Conservation 49, 288–293.

Yensen, N.P. and K.Y. Biel, 2006. Soil remediation via salt-conduction and the hypotheses of

halosynthesis and photo protection. Tasks for vegetation science series-40. Ecophysiology of

high salinity tolerant plants, pp: 313-344

Zerihun, D., J. M. Reddy, J. Feyen and G. Breinburg. 1993. Design and management monograph

for furrow irrigation. Irrigation and Drainage Systems 17: 29-41.