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Climate Change Mitigation and Adaptation: Opportunities for Climate-Friendly Perennial Crop Farming Practices in East and West Africa and Southeast Asia. A Review of Literature Rainforest Alliance July, 2011

Opportunities for Climate-Friendly Perennial Crop Farming Practices. July, 2011 | 2

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Cover: A farmer from the smallholder Juremi coffee farm, in Lampung, Indonesia, in front of a shade tree on his land.

Photo: I. Kurniawan.


This study was made possible thanks to the generous support of The Rockefeller Foundation.

Author

The Rainforest Alliance (RA) works to conserve biodiversity and ensure sustainable livelihoods by transforming land-use practices, business practices and consumer behavior. Based in New York City, with offices throughout the United States and worldwide, the Rainforest Alliance works with people whose livelihoods depend on the land, helping them transform the way they grow food, harvest wood and host travelers. From large multinational corporations to small, community-based cooperatives, the organization involves businesses and consumers worldwide in its efforts to bring responsibly produced goods and services to a global marketplace where the demand for sustainability is growing steadily. The Rainforest Alliance’s Climate Program works to conserve biodiversity and enhance livelihoods by supporting sustainable land management practices to mitigate and adapt to climate change. The Climate Program is cross-cutting, involving the sustainable forestry, agriculture and tourism programs of the Rainforest Alliance. The principal strategies of the Climate Program are to: build capacity for REDD+ implementation through project facilitation and developing/deploying training and guidance materials; contribute to REDD-readiness initiatives at a national level in target tropical countries; innovate and implement projects leveraging carbon finance as tools for landscape-level conservation; shape forest carbon standards and REDD+ policy at the national and international level and amongst key climate investment funds; develop and scale adaptation-oriented tools and initiatives; and build demand and capacity for forest carbon validation, verification and methodology services in priority tropical regions. Rainforest Alliance Consultant Anne Christianson coordinated the literature review. Rainforest Alliance Consultant Dr. Lawrence Szott conducted the technical review.


Contributors

CIAT’s mission is to reduce hunger and poverty, and improve human health in the tropics through research aimed at increasing the eco-efficiency of agriculture. CIAT’s vision is to engage its key scientific competencies to achieve significant impact on the livelihoods of the poor in the tropics. Interdisciplinary and applied research will be conducted through partnerships with national programs, civil society organizations, and the private sector to produce international public goods that are directly relevant to their users. These goods include improved germplasm, technologies, methodologies, and knowledge. Drs. Peter Laderach and Richard Kent provided expert analyses and contributions on multiple elements of the review including sections dealing with adaptive capacity, IPM and pest management, and climate change and crop suitability modeling. Dr. Neville Millar, researcher at Michigan State University participating in the review in an independent capacity, provided expert analysis of the impact of various practices on nitrous oxide emissions and significant contributions to multiple sections of the review including on fertilizer treatments and residue management.

Acknowledgements We are grateful for the time, insights, contributions, critiques and analyses of many individuals, whose inputs and guidance helped strengthen the review. These individuals include Kevin Coleman, Sandra Corsi, Theodor Friedrich, Johannes Lehmann, Jessica Mullan, Rodney Nikkels, Henry Neufeldt, Christina Seeberg Everfeldt, Seth Shames, Piet van Asten, Louis Verchot, Lini Wollenberg, as well as Rainforest Alliance staff including Julianne Baroody, Adam Gibbon, Gianluca Gondolini, Mark Moroge and Jeff Hayward, amongst others. We are also grateful to the 4C Association for their in-kind support.


Executive Summary This literature review aims to identify climate‐friendly agricultural practices for coffee, cocoa, and tea that (a) reduce emissions of greenhouse gases (GHGs) from the use of land, machinery and chemicals, (b) lead to an increase of on‐farm carbon stocks, and/or (c) improve the resilience of agro‐ecosystems and farming communities to adapt to a changing climate, compared to local, business-as-usual practices (BAUs). This comparison is based on surveys of the scientific data related to GHGs and carbon storage, as well as predictions from models. In total, 19 farming practices were assessed, including improved fallows, reduced tillage, inorganic fertilizer use, on-farm processing, use of shade trees and others. More innovative practices, which are less widespread and for which limited research has been conducted (e.g. domestic wastewater management, biochar, household energy use), which also assessed in greater brevity. A number of farming practices are complementary in their ability to affect GHG emissions and C storage and combining them can result in more-than-additive gains. These include mainly the following: reduced tillage, cover crops, shade trees, prunings and organic residues, and inorganic fertilizers. In combination, these can interact to protect soils and reduce erosion, moderate soil temperature, reduce moisture evaporation and increase infiltration, maintain or increase soil fertility, reduce weeds, and lessen the use of purchased inputs by farmers. Further, some are also multi-purpose and can help play a number of beneficial roles in the cropping systems considered. For example, single CFPs, such as cover crops, shade trees, and organic mulch can affect simultaneously numerous system attributes such as weeds, pests, erosion, C and soil nutrients, and soil temperature and moisture. Usage of improved fallows, application of prunings and organic residues, and proper utilization of shade trees are three farming practices that offer the greatest potential for enhancing farm resiliency and adaptive capacity, as defined by their ability to moderate temperature, mitigate drgouth/conserve soil moisture, protect soils and reduce erosion, and enhance livelihoods through contributing to improvements in yield or productivity, or provisioning of secondary products.

Practices that result in “quick-win” emission reductions/enhances in carbon stocks, relative to others assessed, include: use of short-term improved fallows and cover crops, optimized usage of inorganic fertilizers, and improved irrigation practices (e.g. drip irrigation) and more efficient crop processing, although access to credit and capital may prevent many farmers from adopting some of these. Practices offering the greatest total gains include proper utilization of inorganic fertilizers and use of shade trees. Due to its immediacy of impact and scale of potential gains, improved fertilizer usage may be a first-order priority for implementation of climate-friendly practices. A growing number of tools, methodologies and models are available to quantify the emissions impacts of the farming practices. These, however, are predominantly for use by researchers or towards terrestrial carbon project development. Of the few tools geared towards application by farmers and other non-technical users, the Cool Farm Tool has the greatest promise, though it modification is required to enhance applicability for agroforestry crops. Barriers to adoption of given practices vary, however common themes emerge around: lack of land or seed availability, need for technical assistance and training to implement a given practice, capital and labour constraints. Further, implementation of a given practice must be assessed in the proper local context to minimize the risk of adverse impacts. For example, increasing cover crop or shade cover density, may reduce yields or increase insect pest presence or fungal infection of the production crop. Largely, research specific to the crop- and country-focus of this review is lacking across all practices except shade cover/agroforestry. For shade cover, additional studies on assessing the relative carbon storage impacts across different gradients of shaded systems are adviseable; at present much research categorizes “agroforestry” quite broadly. Establishment of comparable definitions of various types of agroforestry practices (e.g. simple production


shade; complex production shade; hedgerows; boundary planting; complex rustic agroforestry) and further research to delineate the relative benefits of each in these crops and countries, would be valuable. Further Research on the impacts of crop processing on methane emissions is also needed. In the context of facilitating farmer adoption of CFPs that enhance carbon storage, reduce emissions and can build adaptive capacity, the following take-home points are considered:

Increasing tree cover on-farm through adoption/more robust implementation of agroforestry practices offers one of the most comprehensive opportunities to transition tree-crop, based, perennial cropping systems such as coffee, tea and cocoa towards a more climate smart management regime.

In the context of perennial cropping practices, the ultimate impacts on carbon sequestration and GHG emissions reductions of adoption of reduced tillage and improved fallow alternatives is relatively low. Coupled with sometimes considerable barriers to adoption (e.g. significant labor; lack of access to specialized tools), and that net economic benefits may not accrue for several years, other CFP alternatives may be considered as higher priorities for adoption for smallholders.

Optimized use of inorganic fertilizers, in conjunction with organic amendments, offers a near-immediate and potentially (depending on scale and rigor of adoption) very significant source of emissions reductions.

In the context of smallholders, climate-friendly practices can only realistically be considered for adoption when they contribute tangible economic benefits to the farm economy, through reducing input costs, enhancing yields, etc. Climate-friendly farming should be coordinated with improved land management for enhanced economic livelihoods.


Table of Contents Executive Summary ................................................................................................................................................... 5

List of Acronyms and Conversions .......................................................................................................................... 10

1. Introduction ....................................................................................................................................................... 11

1.1 Objectives ................................................................................................................................................... 11

1.2 Scope .......................................................................................................................................................... 11

1.3 Methods ..................................................................................................................................................... 11

1.4 Navigating the Review................................................................................................................................ 12

2. Overview: Typology of Common Farming Systems ............................................................................................ 12

2.1 Cocoa: Introduction and Description of Common Farm Management Types ........................................... 12

2.2 Coffee: Introduction and Description of Common Farm Management Types ........................................... 14

2.3 Tea: Introduction and Description of Common Farm Management Types ............................................... 16

3. Comparative Assessment of Common BAUs and Alternative CFPs: Carbon Storage, GHG Emissions and Adaptive Capacity ........................................................................................................................................................ 18

3.1 Structure and Approach ............................................................................................................................. 18

3.2 Comparative Assessment of CFPs: Improved Fallows ................................................................................ 19

3.3 Comparative Assessment of CFPs: Reduced Tillage Alternatives ............................................................... 21

3.4 Comparative Assessment of CFPs: Application of Cover Crops ................................................................. 24

3.5 Comparative Assessment of CFPs: Inorganic Fertilizer Use ....................................................................... 25

3.6 Comparative Assessment of CFPs: Pruning and Organic Residue Management ....................................... 29

3.7 Comparative Assessment of CFPs: Shade Trees ......................................................................................... 32

3.8 Comparative Assessment of CFPs: Erosion Control Measures ................................................................... 37

3.9 Comparative Assessment of CFPs: Irrigation Alternatives ......................................................................... 38

3.10 Comparative Assessment of CFPs: Weed Control Practices .................................................................. 39

3.11 Comparative Assessment of CFPs: Pest and Disease Control Management ......................................... 40

3.12 Comparative Assessment of CFPs: On-farm Processing Practices ......................................................... 43

3.13 Level II Comparative Assessment of CFPs: Crop Waste Management Practices ................................... 45

3.14 Level II Comparative Assessment of CFPs: Fuel Wood Extraction ......................................................... 46

3.15 Level II Comparative Assessment of CFPs: Reclaiming Degraded Land ................................................. 47

3.17 Level II Comparative Assessment of CFPs: Household Energy Use ........................................................ 48

3.18 Level II Comparative Assessment of CFPs: Domestic Wastewater Management ................................. 50

3.19 Level II Comparative Assessment of CFPs: Biochar application ............................................................. 52

4. Interactions Among Level I CFPs ........................................................................................................................ 53

5. Indication of Potential for CFPs to Increase Adaptive Capacity ......................................................................... 55

6. Potential Relative Impact on GHG Emissions Rreductions and/or Enhanced C Storage of Proposed CFPs ....... 58

7. Sampling of Monitoring, Measurement, and Methodological Tools to Estimate GHG Emissions and Carbon Storage in the Farming Systems .................................................................................................................................. 61

8. Suggested Areas for Further Research ............................................................................................................... 64


9. Common Barriers to Adoption of CFPs .............................................................................................................. 67

10. Reflections on CFPs Identified ........................................................................................................................ 68

11. References ...................................................................................................................................................... 69

12. Annexes .......................................................................................................................................................... 90



List of Acronyms and Conversions Acronyms AGB: Above ground biomass AS: Ammonium sulfate ASN: Ammonium sulfate nitrate BAU: Business-as-usual BGB: Below ground biomass C: Carbon CA: Conservation Agriculture; Calcium CFP: Climate-friendly practice CE: Carbon equivalent CH4 : Methane CO: Carbon monoxide CO2: Carbon dioxide CAN: Calcium ammonium nitrate EEF: Enhanced-efficiency nitrogen fertilizers ENSO: El Nino Southern Oscillation GHG: Greenhouse gas GWP: Global warming potential K: Potassium MASL: Meters above sea level Mg: Megagram Mg: Magnesium N: Nitrogen N2O : Nitrous oxide NOx: NO + NO2 (ie. nitric oxide and nitrogen dioxide) NPK: Nitrogen-Phosphate-Potassium; primary minerals in most fertilizers NT: No-till NUE: Nitrogen use efficiency P: Phosphorus PV: Photovoltaic SALM: Sustainable agriculture land management SOM: Soil organic matter SOC: Soil organic carbon tCO2e: Tons of carbon dioxide equivalent emitted VCS(A): Verified Carbon Standard (Association) WFPS: Water-filled pore space; applies to soil structure Conversions 1 Mg (Megagram) = 1 metric ton (tonne) = 10

3 kg = 10

6 g

1 gigagram (Gg) = 103 Mg or tons = 10

6 kg = 10

9 g

1 teragram(Tg) = 106 Mg or metric tons = 10

12 g

1 Pg (Peta gram) = 1 Gt (Giga tonne) = 109

Mg or tons = 1015

g 1 kg C-CO2 = 3.667 kg CO2 eq Conversions from GWP to CO2 eq vary depending on the gas and timeframe under measurement. Common conversions are available on the Pew Center for Global Climate Change website at: http://www.pewclimate.org/global-warming-basics/facts_and_figures/gwp.cfm

http://www.pewclimate.org/global-warming-basics/facts_and_figures/gwp.cfm


1. Introduction

1.1 Objectives This literature review aims to identify climate‐friendly agricultural practices for coffee, cocoa, and tea that (a) reduce emissions of greenhouse gases (GHGs) from the use of land, machinery and chemicals, (b) lead to an increase of on‐farm carbon stocks, and/or (c) improve the resilience of agro‐ecosystems and farming communities to adapt to a changing climate, compared to local, business-as-usual practices (BAUs). This comparison is based on surveys of the scientific data related to GHGs and carbon storage, as well as predictions from models. It identifies barriers to farmer adoption of these CFPs and points out gaps in existing research related to the impact of certain tropical farming practices with respect to climate change. The review has been utilized, and continues to be used, primarily for the following purposes:

1) Inform the selection of the climate change adaptation and mitigation criteria of the Sustainable Agriculture Network (SAN) Climate Module, a voluntary-add on to the SAN Standard, a leading voluntary agriculture standard for certification of tropical farming systems for best environmental, social and economic practices

1.

2) Inform the selection of methods for verifying whether farms conform to the SAN Climate Module criteria. 3) Identify local, crop-specific CFPs that can be utilized to guide and train farmers on adoption of appropriate

practices that enhance carbon storage, reduce greenhouse gas emissions and/or increase adaptive capacity.

1.2 Scope The scope of the research consulted is largely limited to coffee, cocoa and tea farming in East and West Africa and Southeast Asia, with an explicit focus on Ghana, Indonesia, Kenya and Tanzania. However, due to the limited amount of scientific research specific to those country and crop combinations, information is also incorporated from other regions – principally Latin America. Practices analyzed are those which are presently implemented in farming systems common to these crops and countries, ranging from smallholder cooperatives (i.e. < 1 ha crop production area) to large, well-resourced estates with hundreds or thousands of hectares, and include: degraded land management/reclamation, improved fallows, tillage, cover crops and shade, organic residue and soil fertility management, weed and pest control, crop processing activities, and waste and water management among others. Although we attempt to provide quantitative estimates of the impact of these practices on carbon and other GHGs, related cost-benefit analyses for such practices are outside the scope of this review. Land clearing is not directly addressing within the scope of this review.

1.3 Methods Searches for scientific literature and published research reports from credible organizations and research institutions were conducted via Google, the University of Minnesota online database and various publically accessible online journals. Common search queries were utilized as appropriate for each practice and the geographic scope of the review, e.g. “agroforestry Kenya” or “fertilizer management tea”. Once found, relevant articles were annotated and their list of references searched for additional relevant publications. In instances where research was largely deficient in a given geographic region, articles from Latin American countries were incorporated; to the extent possible, usage of data from Latin America has been clearly indicated in the body of the review.

1 For more see: http://sanstandards.org/sitio/

http://sanstandards.org/sitio/


Additionally, a range of researchers, practitioners and experts in certain agricultural practices, cropping systems or geographies were contacted for guidance and/or suggestions for publications to be utilized in the review. Some of these experts appear in the Acknowledgements section. Draft versions of the literature review were also shared with a subset of these individuals for feedback. The literature search was limited to English-language publications.

1.4 Navigating the Review The review is broken into ten main sections: 1) an introduction, 2) a descriptive section on the cropping systems, 3) a comparative assessment of frequent BAU farming practices and their corresponding climate-friendly or climate-smart versions – including a brief assessment of specific climate benefits; 4) interactions among climate friendly management practices (CFPs); 5) the ability of CFPs to increase adaptive capacity to climate change; 6) a summary of the impacts of improved management practices and cropping systems; 7) identification of modeling tools available in order to synthesize knowledge, identify research needs, and aid prediction; 8) a summary of research needs; 9) an assessment of barriers of adoption of the proposed alternatives; and 10) summary section. These sections are enriched by various appendices which contain information on very targeted and specific CFP recommendations for certain crop/country scenarios, which, while valuable, was too specific to include elsewhere in this review. In many cases, an insufficient or highly variable data did not permit a robust quantitative estimation of impacts of farming practices on GHG emissions, carbon sequestration, or adaptive capacity in specific crop- and country-contexts. These are clearly areas where further research is needed. This review is envisioned as a living document, which will evolve as the database research on climate-smart farming in these regions grows. Conclusions drawn are based on best available knowledge, and not intended to preclude identification of alternative findings or best practices scenarios. We encourage feedback and suggestions for improvement. Comments may be directed to [email protected].

2. Overview: Typology of Common Farming Systems This section briefly introduces the range of common coffee, cocoa and tea farming systems in East and West African and Southeast Asian countries. This overview is intended to situate the subsequent analysis of individual BAU and CFP practices and their variations with farm type, crops and countries.

2.1 Cocoa: Introduction and Description of Common Farm Management Types

Cocoa (Theobrama cacao L.) is produced primarily in Latin America (Belize, Mexico, Ecuador, Peru, Costa Rica and Brazil), West Africa (Cote d’Ivoire, Cameroon, Ghana, Nigeria, and Sao Tome), and Indonesia (Sulawesi, Central Sumatra) (Franzen and Mulder 2007). In recent decades, West African production has dwarfed that of other regions: regional output doubled from 1988 to 2007, and West Africa now grows over 70% of global cocoa supplies, with Côte d’Ivoire, Ghana, Nigeria and Cameroon as the largest regional producers (FAOSTAT cited in Gockowski and Sonwa, 2010). In many of these countries, there has been a historical pattern of shifting agriculture on a regional scale – once the cocoa production landscape becomes exhausted, production has moved to other regions. Ghana is one example. Such trends can be interpreted as a macro-level indicator of the unsustainability of common cocoa production practices. In West and Central Africa cocoa is grown primarily by small-scale farmers (>80%) in shaded systems (Duguma et al. 2001), while Indonesia is the largest cocoa producer in South-east Asia (Moser et al. 2010).

mailto:[email protected]


Despite differences in management among farm types, a number of commonalities in management practices exist. These practices, mentioned below, are specific to African production, but some may be relevant globally.

- Though cocoa farmers are increasingly transitioning from shaded to full-sun systems, some form of

shaded system is still the most common practice in cocoa farming. In Cameroon, Cote d’Ivoire, Ghana and

Nigeria, 71%-97% of farmers surveyed utilized a shaded production system (Gockowski & Sonwa, 2010).

- Many farmers harvest and sell fruit and timber as secondary products of their shaded cocoa systems.

- The primary method of cocoa ans farm establishment is through shifting cultivation (slash-and-burn) or

planting cocoa under a thinned forest canopy.

- Agrochemicals are rarely applied at the recommended applications, even in full-sun systems.

- Along with the predominance of small-scale farming in overall cocoa production, there is a sector-wide

lack of access to capital required to implement farming practices that could increase productivity and

yield and enhance the ability of cocoa farming systems to contribute to biodiversity conservation and

carbon sequestration.

Cocoa farming systems are most commonly differentiated by the extent to which they use shade. For agroforestry crops like cocoa, shade serves as a proxy for myriad farm management processes including soil fertility maintenance, erosion control, maintenance of favorable microclimatic conditions, integrated pest management (IPM), and others. The literature differs in how different types of shaded systems are categorized. Table 1 presents a simplified summary of the breadth of classifications present in the literature, describing a range of common cocoa farm management systems and the general characteristics of each.

Table 1: Comparison of common management practices in a gradient of prevalent cocoa farming systems2

Characteristic/Management scenario Full-sun cocoa

Simple shaded cocoa Complex agroforestry

Traditional rustic agroforestry

Extent of shade canopy cover Minimal/none Low-moderate Moderate-high Highest

Management of non-cocoa shade

If present, trees are young and subject to frequent and heavy pruning to maintain high solar exposure

Minimal - moderate pruning Minimal pruning No pruning

Tree species diversity

Low - often additional production crops trees e.g. banana, plantain, palm, etc.

Moderate - often a mix of fruit trees and common leguminous shade species e.g. Gliricidia sepium

Presence of intact remnant trees from previous rainforest stand; planted shade trees both native (e.g. Nauclea diderichii, Entandrophragma angolense in Ghana) and non-native.

Largely intact canopy from mature rainforest species; cocoa replaces understory vegetation.

Native vs. non-native species Non-native Mix Mix

Mix - greatest diversity of native species

# of trees per ha (DBH > 31cm)

3 16 25 25.9-28.8 48.84

2 Data adapted from Bos M M et al, 2011, Gockowski and Sonwa, 2010, Moser et al. 2010, Adejumo 2005, Sanchez et al. 2003, Ntiamoah and Afrane 2008 and Lin et al. 2008. 3 Data compiled from Bos M M et al., 2011 – study was conducted in North Tivu, Democratic Republic of Congo


t C ha-1 (for trees DBH >31cm; above and below ground stock) 17.69 33.8 32.46-39.32 75.46

Application of fertilizers

More frequent and in higher dosage Less frequent, lower dosage

Lowest frequency and minimal dosage

Presence of ground covers (e.g. crop residues, litterfall, vegetation, amongst others)

Yes - primarily through cocoa litterfall Yes Yes Yes

Soil fertility management

Primarily through synthetic inputs and cocoa tree pruning

Through blend of synthetic inputs, ground cover vegetation, mulching and

litterfall/pruning from cocoa and shade trees

Minimal/no application of synthetic inputs.

On-farm processing Unlikely - only on large operations No No No

Pest and disease management

Through frequent pruning, reduced shade, maintaining short trees to increase pruning & spraying access.

Through blend of synthetic inputs and other IPM practices (e.g. manual removal of pests,

and diseased fruits).

IPM practices such as manual removals, maintaining soil fertility, using biological controls.

Prevalence of system

Employs 3%-29% of cocoa farmers in 4 West African cocoa producing countries Trend towards full-sun production increasing.

Employs 71%-97% of cocoa farmers in 4 West African cocoa producing countries use some form of shade management. However, utilization of rustic agroforestry is declining.

2.2 Coffee: Introduction and Description of Common Farm Management Types

Coffee is the second most traded global commodity after oil. It is grown in over 80 countries around the world, primarily in Central America, South America, East and West Africa and Southeast Asia. In 2009, green coffee was harvested on over 9,841,317 hectares and production exceeded 8.3 million tons (FAOSTAT). While Brazil is by far the world’s largest producer, the East and West African and Southeast Asian countries of Cameroon, Cote d’Ivoire, Ethiopia, Indonesia, Kenya, Viet Nam, Tanzania and Uganda all number amongst the 20 producing countries with the largest area in production (FAOSTAT). About 70% of the world coffee crop is grown on smallholdings of less than 10 hectares, typically run as family businesses and providing livelihood for more than 25 million people worldwide (DaMatta et al. 2007). Although there are around 100 species of the Coffea genus (Davies et al. 2006), C. arabica L. (arabica coffee) and C. canephora Pierre ex A. Froehner (robusta coffee) constitute about 99% of world bean production (Fassio and Silva, 2007). Though coffee evolved in the forest as an under-story tree, it can be cultivated under a broad range of shade conditions and is increasingly grown under full-sun conditions. Many resource-poor, smallholder coffee farmers continue to grow coffee under shade, as doing so can reduce the amount of agrochemical inputs and labor required to grow and harvest their crop. In contrast, large, well-resourced holdings often manage intensive, full-


sun coffee monocultures; they are sufficiently capitalized to invest in the labor and agrochemical inputs needed to maximize short-term productivity and yields, making their operations more profitable. Coffee farming systems, like their cocoa counterparts, are most often classified by the extent to which they use shade. Table 2 presents a simplified summary of the range of management systems spanning the gradient from full shade to full sun, along with their general characteristics.

4 Data adapted from Moguel and Toledo, 1999

5 Note: true wild-grown coffee is exclusive to Ethiopia. This management system is included to present the complete spectrum

of high-intensity full-sun to low-intensity, full-shade systems.

Table 2: Comparison of common management practices in a gradient of prevalent coffee farming systems4

Characteristic/ Management scenario Full-sun coffee

Simple shaded coffee (e.g. intercropping)

Commercial agroforestry

Traditional rustic agroforestry

Wild-grown coffee

5

Management intensity Most intensive High intensity Moderate intensity Extensive - low inputs

Most extensive - no inputs, no active management.

Land conversion/land cover change to establish system

Removal of original forest, no replacement with tree species. High-density planting of coffee; coffee subject to full-sun conditions.

Removal of original forest cover. Shade cover dominated by 1 tree species, uniform height of shade tree strata

Removal of original forest cover, aside from remnant individuals, and introduction of multiple tree species selected to enhance coffee production.

Minimal - lower vegetation strata altered for coffee production, original forest canopy intact.

None - coffee grows wild under forest cover

Extent of shade canopy cover Minimal/none Low Moderate-high High High

Tree species diversity N/A Low

Moderate: presence of intact remnant trees from previous rainforest stand; planted shade trees both native and non-native.

Moderate/high: largely intact canopy from mature rainforest species; cocoa replaces understory vegetation. High

Application of agrochemicals

Most frequent and in highest dosage Moderate dosage/frequency

Lowest frequency and minimal dosage, if agrochemicals used at all None

Soil fertility management Through synthetic inputs (e.g. N

fertilizer).

Through blend of synthetic inputs, ground cover vegetation, mulching and litterfall/pruning from shade trees

Minimal/no application of synthetic inputs.

No management

Presence of secondary farm products (e.g. non-timber forest products, fuelwood, fruit, etc). No

Possible, depending on shade trees planted (e.g. banana) Yes Yes

On-farm processing Common, depending on size of farm Possible Highly unlikely/None


2.3 Tea: Introduction and Description of Common Farm Management Types Tea (Camellia sinensis L.) is grown in over 40 countries around the world, primarily in the humid and subhumid tropics. In 2009, the commodity crop was harvested on over 3,014,909 hectares and production exceeded 3.9 million tons (FAOSTAT). East and West Africa and Southeast Asia are significant regional producers, accounting for nearly 20% of global hectares under production and 25% of global production (FAOSTAT). In countries such as Kenya, Indonesia, Malawi, Myanmar, Tanzania, Thailand, Rwanda, Vietnam, and Uganda, tea is a main export commodity and, in some areas, the main source of economic activity. Tea production provides the livelihood for hundreds of thousands of farmers, farm workers, and rural communities. Globally, tea is grown under a broad range of environmental conditions. In general, tea is cultivated from 0 -2000 m above sea level (masl) (low-grown teas: 0 - 600 masl; mid-grown: 600 - 1,200 masl; high-grown: 1,200 -2,000 masl), though these values may vary considerably depending on the variety used and local climate (Hicks, 2001). Variance in altitude, soil types, precipitation regimes, slope gradients and other local climatic and environmental conditions all influence the management practices implemented. While in the wild, tea can reach heights exceeding 15m, under cultivation the perennial evergreen crop is frequently pruned and intensively managed to maintain an average height of roughly 1 meter. Under cultivation, tea bushes have a production lifetime of 50-80 years (Melican, unpublished data), and can store between 44-72 t C ha

-1 depending on age, variety, and planting density (see Table 3).

Table 3: Comparison of carbon stocks of

tea plantation types, Kenya

Age (yrs) t C ha-1

Tea density Tea Variety

76 69 low: 1.52m x 0.91m standard seedling

43 43 low: 1.22m x 1.22m standard seeding

29 72 high: 1.22m x 0.61m improved clonal cultivar

14 44 high: 1.22m x 0.76m improved clonal cultivar

Table adapted from Kamau et al. 2008

Unlike coffee and cocoa, which as agroforestry crops have management systems that can be categorized by degree of shade cover, tea is a leaf crop, thus requires much more direct access to sunlight than coffee or cocoa. In addition to its negative impacts on production, farmers are discouraged from utilizing shade due to cultural and practical reasons including increased litterfall, which gives the appearance of poor management, and presence of pest species. Nonetheless, shade is advantageous as a windbreak, and is utilized on tea estates in south India and Sri Lanka. Overall, tea farm management systems are best categorized as either estate or smallholder systems. Common characteristics of these systems are described in Table 4.

Table 4: Comparison of common management practices in estate and smallholder tea systems.

Characteristic / Management practice Estate system Smallholder system

Size 1,000s of ha. Varies by region: East Africa: often 0.25-0.50 ha. South America: 100s of ha.

Tea plucking Mechanical plucking – use of farm machinery.

Manual plucking.


Irrigation system Present, where needed: S. Africa: overhead spraying. E. Africa: not necessary.

None.

Trees within productive plots6 Minimal/none. Minimal/none.

Trees elsewhere on farm (e.g. boundary areas, conservation set-asides)

Extended, well-vegetated and forested buffer areas around waterways. Forested conservation set-asides present. Boundary plantings absent.

No vegetated buffer areas – cost-prohibitive. No forested set-asides – cost-prohibitive. Boundary plantings frequent, to delineate property. Farm boundaries may exhibit small patches of dense forest.

Presence of fuelwood lots Eucalyptus woodlots common practice. None, though on-farm trees may be harvested for domestic consumption.

On-farm processing Yes. Some estates have modernized, energy-efficient boilers, though most do not.

No –transport crop to a tea collection center.

Presence of ground covers (e.g. vegetation, mulch, prunings)

Infrequent – recommended by govt. as best practice, but prunings are often stolen by others.

Infrequent – recommended by govt. as best practice, but prunings are often stolen by others or s used for domestic purposes.

Fertilizer application Recommended rate of application for East African crop is between 150-250 kg N ha

-1 y

-1 (Owuor, 2007 & Melican, N.

pers. comm.)

No data found.

Pesticide application Frequent application of a wide range of insecticides (Hazarika et al., 2009)

? Wide variance depending on local context: from 63 – 200 t per year

7

Contour planting Yes. Yes.

Wastewater treatment facilities Yes – present on well-resourced estates (some/most).

No.

Many other common management practices are equally likely to be used (or not) in either estate or smallholder systems, depending on cultural practices, local environmental applicability or other factors. Examples include: presence of composting on-farm, presence of a “clean and orderly” production area (exhibited by the absence of any weeds, soil covers, prunings or unmanaged natural areas), application of biological controls or implementation of Integrated Pest Management (IPM) systems, and others. In section three these common management practices and their climate-friendly alternatives are discussed in greater detail.

6 An exception is found in Southern India and Sri Lanka, where shade coverage of roughly 20% is common to prevent scorching

under intense solar exposure and heat. In some rare instances, significant canopy coverage is achieved.

7 Field observations by Rainforest Alliance staff, collected in Rwandan tea farms.


3. Comparative Assessment of Common BAUs and Alternative CFPs: Carbon Storage, GHG Emissions and Adaptive Capacity

3.1 Structure and Approach This section assesses common “business-as-usual” practices (BAU) related to core aspects of farm management (i.e. vegetation and soil management, fertilizers, water, and energy use) and their climate friendly, best management practice (CFP) alternatives. In it, we provide a preliminary assessment of how CFP alternatives can result in reductions of GHG emissions and increases in carbon storage. Information on interactions among practices can be found in section 4 , increases in adaptive capacity of the farming systems to climate change in section 5, and barriers to their adoption in section 9. Not all management practices are of the same relative importance for mitigating GHG emissions or increasing C sequestration. The use of some practices may be geographically limited or socioeconomically confined to certain types of farmers. Other practices (e.g. improved fallows, land reclamation) may be used only prior to establishment commercial crops, some (e.g. cover crops) may be relevant only during the crop establishment phase of the overall cropping cycle, while others are recommended only for specific conditions (e.g. tillage on only non-sloping plots), and the majority differ in their natural ability to affect carbon sequestration. In section six, we try to provide a road map as to the relative potential importance of these practices. Findings presented here originate and are applicable to coffee, cocoa and/or tea farms in East Africa, West Africa, SE Asia, and, to a lesser degree, Central America and Brazil. The application of a particular practice, however, often varies with farm management system, climatic regimes, countries, regions, or specific localities. This variability complicates interpretations of the limited data base. Fine-scale, detailed information on very specific and/or locally restricted practices is found in the multiple appendices. We encourage the use of these appendices as they often hold the most specific and targeted information for practical implementation. It should be noted that many of these management practices have multiple impacts on plant growth, C sequestration, and GHG emissions (see section 3.18). Shade trees, for example, sequester carbon in their biomass; influence organic residue decomposition, soil organic carbon (SOC) mineralization, and GHG emissions through their effects on soil temperature and humidity; increase and recycle carbon and nutrients in soil; protect the soil surface from erosion; increase infiltration and water holding capacity; and may affect weed, insect pest and disease levels. The interaction of these myriad effects will determine the net result on the system´s GHG budgets, but at the same time, makes quantitative prediction of their impact difficult. Our survey of literature covered a broad spectrum of farm management practices that impact an array of common coffee, cocoa and tea farming systems. It became apparent early-on that the volume of literature for certain practices (i.e. tillage, shade trees, fallows) was much greater than for others (i.e. domestic wastewater management and biochar, most of which are not directly related to crop management, but are important for farm livelihoods). To account for these differences, we have categorized practices as either “Level I” or “Level II”, based on the below characteristics. Level I practices: Categorized as such due to widespread practice, considerable C sequestration and/or GHG mitigation potential, and sufficient existing research. For these reasons, the review focuses primarily on Level I practices. These include: improved fallows, reduced tillage, cover crops, inorganic fertilizers, prunings/organic residue management, shade trees, weed control, pest control, irrigation alternatives, and on-farm crop processing. It should be noted that erosion control can be considered as a practice as well as a result of one or more practices.


Level II practices: Categorized as such due to the lack of sufficient available research, the novelty of the practice, their indirect or unresolved potential impact on emissions reductions or C sequestration, and their indirect relation with crop production. For these reasons, Level II practices are addressed in greater brevity. Level II practices are: crop processing waste management, fuel wood production, household energy use, domestic wastewater management, degraded land reclamation, and biochar.

3.2 Comparative Assessment of CFPs: Improved Fallows ‘Fallow’ commonly refers to the resting state of an agricultural field, which is normally used to restore agricultural productivity once cropping ceases. Fallows have historically played an important role in maintaining the productivity of farming systems in both temperate and tropical areas (Ruthenberg, 1980; Loomis, 1984). Whereas fallows in temperate zones may or may not include secondary vegetation, tropical fallows are almost always vegetated (Szott et al. 1999). During vegetated fallows, the re-growth of natural vegetation restores above and below-ground biomass, soil C and nutrient stocks, soil physical characteristics, and reduces weeds and weed propagules.

3.2.1 BAU fallow management practices Many resource-poor farmers in the tropics still use traditional fallows as part of their farming systems. In the humid tropics, the traditional shifting cultivation cycle consists of three to 15 years of growth of unmanaged natural fallow or secondary vegetation, which is cut and burned at the initiation of a one- to four-year-long cropping cycle (Nye and Greenland, 1960; Sanchez, 1976). Growth of global demand for agricultural products, however, is leading to increasingly shorter fallow periods in tropical regions. The shortening of traditional fallow periods, combined with insufficient fertilizer applications, often leads to declining agricultural productivity and agroecosystem integrity. To compensate, researchers have sought to improve traditional fallows via the use of managed or ‘improved’ fallows that accelerate nutrient capture and/or reduce weeds.

3.2.2 CFP fallow management practices that can lead to climate benefits Improved fallows are used throughout the world as a means to reduce inorganic N inputs and weed or pest pressure resulting from unsustainable traditional natural fallows (Kwesiga and Coe, 1994, Amadalo et al. 2003, Kwesiga et al. 1999; Phiri et al. 1999; Tarawali et al. 1999, Cairns and Garrity 1999, Buckles and Triomphe 1999, Kass and Somarriba 1999). Improved fallow systems involve the planting of fast growing tree or herbaceous species, usually legumes, as part of a crop-fallow rotation. This fallow vegetation accumulates relatively large quantities of organic C and N in situ (Sanchez, 1999), mainly through atmospheric N2 fixation (Giller and Wilson, 1991), and may provide a “safety-net” for nutrient capture from the subsoil by deep-rooted fallow species (Hartemink et al., 1996). Improved fallows can thus shorten the time required to restore soil fertility (Mutuo et al. 2005), increase the sequestration of C, help improve farmland productivity, and supply other valuable products such as fuel wood and stakes (Amadalo et al. 2003, Arnold et al. 2006; Flynn and Smith 2010). In tea, coffee, or cocoa, improved fallows may aid in restoring degraded land to a productive state prior to plantation establishment or as part of the renovation of senescent commercial plantations. The use of improved fallows, of course, requires that farm plans adequately take into account the time and resources required for improved fallow growth prior to crop establishment. Two types of improved fallowing practices are used in perennial crop agroforestry: i) short-term (1 to 2 years in duration) improved fallows, where leguminous herbaceous plants are specifically planted to increase soil fertility more rapidly than natural vegetation, reportedly adding between 100 and 200 kg N ha

-1 yr

-1, and ii) long-term

improved fallows, where many species of trees are planted and grown over a longer time frame to improve soil fertility and produce timber or other products (Albrecht and Kandji 2003). For example, the planting of fast growing leguminous trees (Albizia adenocephala, A. guachapele, A. niopoides, A. plurijuga, A. saman and A. tomentosa) on degraded land in Ghana made it suitable for cocoa agroforestry (Anim-Kwapong 2003).


Figure 1. Correlations between total loge N2O (g N2O-N ha

-1) emitted at Dindi farm (Experiment 1) and Oloo

farm (Experiment 2) in western Kenya, with residue N (%) and C:N ratio (Millar et al. 2004). Figure reproduced from Millar et al., 2004.

Besides varying in duration, improved fallows can vary in vegetative composition, varying from monocultures to mixed species. Short-term fallows are usually established with one fast-growing fallow species that develop quickly dense canopies that smother weeds and provide nitrogen, for example Crotalaria grahamiana, Crotalaria paulina, Pueraria phaseoloides (kudzu), Centrosema macrocarpum, and Colopogonium mucunoides (mucuna) (see Annex 1 for some examples of short-term fallows used in Kenya). Long-term fallows are usually composed of mixed species planted in alternate rows or more complex spatial arrangements. Multi-species fallows may present a number of nutrient cycling benefits due to differences among the species in resource capture, growth patterns, or chemical characteristics of their litter. In Kenya, Cadisch et al. (2002), Gathumbi et al. (2002), and Ndufa et al. (2009), reported the beneficial effects of mixed fallows in terms of nutrient sourcing from different soil depths and complementarity in aboveground resource utilization that lead to increased biomass production and carbon sequestration. In addition, the vegetative complexity of fallows aids in increasing biodiversity. Mixed fallows may also benefit farmers through the provision of secondary products and reduction in the risk of failure of fallow establishment (Cadisch et al., 2002; Gathumbi et al., 2002), but their effects on pests and diseases may be locally variable (Sileshi et al., 2000). The following are some successful combinations for mixed-species fallows in western Kenya: sesbania + siratro/groundnut/Tephrosia vogelii or candida/Crotalaria grahamiana); and tephrosia + crotalaria (Amadalo et al. 2003). A comparison of fallow processes and their impacts on crop production and nitrogen availability is included in Annex 2.

3.2.3. Potential of improved fallows to reduce GHG emissions Leguminous improved fallows have the ability to sequester large quantities of nitrogen (100 - 200 kg N ha

-1 yr

-1),

but this nitrogen may be released and emitted more rapidly from litter or mulch than in natural fallows. Research conducted in western Kenya by Millar et al. (2004) indicates that replacing traditional natural fallows with improved-fallow systems in the humid tropics increased N2O emissions by up to 3.9 kg N2O-N ha

-1, over a four

month period during the maize cropping season in the short rains. N2O emissions were positively correlated with residue N content and decreasing C:N ratios (P < 0.05), indicating that residue chemical composition or “quality” is

an important consideration when proposing management practices to mitigate N2O emissions from these systems (Figure 1). (See also section on organic residue management).

In the same study, carbon dioxide emissions resulting from the application of improved-fallow residues (Sesbania sesban, Crotalaria grahamiana, Macroptilium atropurpureum) to agroforestry systems were also greater than those associated with natural-fallow residues (mainly consisting of Digitaria abyssibica, Habiscus cannabinus, Bidens pilosa, Guizotia scabra, Leonotis nepetifolia, Commelina benghalensis (Millar et al. 2004). Despite greater emissions of these elements, the use of improved fallows can result in greater net storage of carbon and nitrogen than natural fallows, if they accumulate larger absolute quantities of carbon and nitrogen than natural fallows. Additionally, even though improved fallows may result in an increase in N2O emissions, these


are likely to be less than those from systems where inorganic fertilizers replace fallows as a nitrogen source (Szott and Kass, 1993; Veldkamp and Keller, 1997).

3.2.4 Potential of improved fallows to increase carbon stocks As noted above, improved fallows can enhance carbon storage in biomass (Flynn and Smith 2010), and maintain soil organic carbon (SOC) levels needed for sustainable soil use (Lal 2005a). However, sequestration of carbon in biomass and soil is affected by the fallow species, soil conditions, climate, and length of the fallow. Mutuo et al. (2005) reported that an improved fallow system in the sub-humid tropics utilizing legumes and no-till practices increased soil C stocks by 0.5-1.6 Mg C ha

-1 y

-1. Improved fallows have also been reported to increase SOC stocks by

0.73 - 12.46 Mg ha-1

on 1-5 year old fallow plots in Togo and Kenya (Dreschsel et al. 1991, Onim et al. 1990, Impala 2001, cited in Albrecht and Kandji 2003). In the latter study, C. calothyrsus had the greatest biomass at 12 months, T. candida had the greatest biomass at 18 months, and in the 22-month fallow, Eucalyptus saligna produced the highest amount of biomass (Albrecht and Kandji 2003). In degraded soils of the sub-humid tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha

-1 y

-1 compared to continuous

maize cropping (Palm et al. 2005). Annex 3 provides examples of above- and below-ground biomass production in improved fallow trials in western Kenya.

3.3 Comparative Assessment of CFPs: Reduced Tillage Alternatives Conventional tillage, where soil is turned over completely, is practiced in agricultural systems across the globe, but researchers increasingly find that reduced tillage, also known as conservation tillage and no-till (NT), where the soil disturbance is minimal, is more sustainable (Li and Butterbach-Bahl 2005, Lal and Kimble 1997, Cole et al. 1997, Six et al. 2004) and can aid in the net sequestration of soil organic carbon (SOC). In general terms, conventional tillage completely inverts the soils through the use of plows, machines, hoes, and other manual tools in order to clear the soil, remove weeds, and prepare the seed bed (de Rouw et al. 2010, Zake 1993). No-till is a tillage management method where the soil is left undisturbed, except for the planting of seeds (Flynn and Smith 2010). Conservation tillage, or reduced tillage, is a variable management practice that may include reducing the amount or depth of tillage and timing tillage practice to reduce GHG emissions and sequester carbon (Flynn and Smith 2010). There is a debate, however, on whether conservation tillage systems alone are beneficial for C storage and GHG mitigation, or whether they need to be combined with cover crops, mulch, and judicious weed control as part of a broader conservation strategy known as conservation agriculture (CA).

3.3.1 BAU tillage practices Tillage practices in general vary across the tropics, and depend on soil, topographic, climate, crop, and socioeconomic factors (Zake 1993). Although there are many papers detailing tillage practices for annual cropping systems in tropical countries, the literature describing tillage practices for coffee, tea, and cocoa in tropical countries is sparse. With respect to these crops, conventional tillage may be used on large commercial plantations, but reduced tillage or no-till is often the rule in coffee, cocoa, and tea managed by small farmers on slopes. For example, Zake (1993) mentions the use of no-till and mulch tillage, where crop residues are left on the soil surface, on coffee farms in Tanzania.

3.3.2 CFP reduced tillage practices that can lead to climate benefits No-till (NT) and conservation tillage are recommended CFP alternatives to conventional tillage practices. No-till is often coupled with soil covers, in the form of litter, weeds, and soil crops, to protect the soil from sun, rain, and erosion while providing nutrients to the soil and preventing/reducing growth of unwanted weeds (de Rouw et al. 2010). As a result, it is difficult to tease out the effect of tillage alone on GHG emissions and carbon storage (see also sections on cover crops, pruning and organic residue management, and weed management). Some argue that NT increases weed infestation, resulting in an increase in herbicide use and their concomitant GHG emissions (de Rouw et al. 2010, Bellarby et al. 2008). Other findings suggest that the effects of reduced tillage or NT on C stocks are variable.


It is important to recall that the impacts of these practices are sensitive to local conditions and vary across regions. For example, in a recent meta–analysis, Helgason et al. (2005) found varying effects of no–till on N2O emissions, with humid regions having increased N2O emissions, while an opposite pattern was observed in arid regions. Ultimately, the effects of conservation tillage on emissions from fossil fuel and agrochemical use may be more important than its direct effect on soil C or N. Trade-offs between C sequestration and increased use of chemical inputs in NT need to be explored further.

3.3.3 Potential of reduced tillage CFPs to reduce GHG emissions No-till and conservation tillage have been promoted as a means of reducing emissions of GHGs from agricultural land (CAST 2004), increasing soil C (Flynn and Smith 2010), and indirectly reducing GHG emissions by reducing the consumption and use of fossil fuels on the farm (Flynn and Smith 2010, Li et al. 2005). However, there are very few studies of NT in the tropics (Six et al. 2002; de Rouw et al. 2010), and no literature has been found which directly addresses GHG calculations relating to tillage practices within coffee, cocoa and tea farms in East and West Africa, and Southeast Asia. Nevertheless, tillage practices and their GHG emissions have been studied in other regions, particularly in northern temperate zones. It is estimated that fossil fuel and energy use by conventional tillage practices throughout the world emit between 4.0-73.6 kg CO2 eq ha

-1, or 0.7-0.113 Pg CO2 eq of GHG emissions (Bellarby et al. 2008).

Robertson et al. (2000) measured GWP in no-till and conventional tillage systems in the Midwest United States. The net GWP of a no-till system was estimated to be 14 g CO2 eq m

-2y

-1, while the conventional tillage system had

an estimated GWP of 114 g CO2 eq m-2

y-1

(Robertson et al. 2000). The net GHG balance of conservation tillage is still being debated in the literature, since no-till and conservation tillage can affect a number of factors that can influence N2O production, diffusion and emission. These include the decomposition of soil organic matter (SOM), soil C and N availability, soil density, water content and aeration. Soil organic C and organic residue additions are positively correlated with N2O emissions. Hence, the use of reduced tillage methods in combination with organic inputs can result in greater N2O emissions (Li et al. 2005,) and no-till systems may have greater N2O fluxes than conventional tillage systems (Robertson et al. 2000). However, Six et al. (2002), stress that data for N2O fluxes in tropical soils is limited. A study conducted in Laos found that conventional tillage increased N stocks more than NT (de Rouw et al. 2010). Tillage practices also affect methane emissions. Conventional tillage results in deterioration of soil structure that decreases the soil´s ability to function as a methane sink (Mutuo et al. 2005); in contrast, reducing the amount of soil disturbance, via conservation tillage practices, enables the soil to retain this function. Six et al. (2004) determined that over 20 years, no-till agriculture will produce a decrease in GWP for SOC, N2O, and CH4 in humid temperate climates (Table 5), however they caution that more research is needed to make more informed policy decisions.

Table 5 : Annual differences in GHG emissions and GWP in different tillage systems. Reproduced from Six, et al. 2004.


Carbon and nitrogen emissions of conventional and conservation tillage also vary with the incorporation of organic residues into the soil (Table 6). Table 6: Interaction between tillage method and soil organic inputs. Tillage Method Crop/Location CO2 emissions

ha-1

,

standard error in parentheses

N2O emissions ha

-1, standard

error in parentheses 1

CH4 emissions , standard error in parentheses

Comments Citation

Conventional tillage, no residues

Agroforesty system/Western Kenya

~2.05 g N2O-N

99 day study Millar, N. pers. communications from unpublished data.

Conventional tillage, natural fallow residues

Agroforestry system/Western Kenya

759-967 (432) kg CO2-C

2.1-2.8 (1.0) g N2O-N

30-146 (14.7) g CH4-C

Baggs et al. 2006

Conservation tillage, Tephrosia residues

Agroforestry system/Western Kenya

635 kg CO2-C 1.77 g N2O-N ~43g CH4-C Baggs et al., 2006

3.3.4 Potential of reduced tillage CFPs to increase C stocks Conventional tillage increases C loss and GHG emissions in three ways: 1) by disrupting soil aggregates, thus increasing the accessibility of SOM to microbial decomposition, 2) by stimulating microbial activity, which increases releases of CO2 and other GHGs, and 3) by mixing residues into the soil, which speeds up the decomposition of these residues (Cerri et al. 2007, Bellarby et. al. 2008). Conservation tillage, on the other hand, increases soil C by decreasing soil erosion, disruption of soil aggregates, and SOM decomposition rates (Six et al. 2002, de Rouw et al. 2010).


Various researchers (Lal and Kimble 1997; Paustian et al. 1997; Six et al. 2002) estimate that conservation tillage results in a C sequestration of about 0.1% ha

-1 y

-1, or about 10 Mg in 25-30 years, equivalent to about 325 kg C ha

-1

y-1

. Despite evidence that NT increases C stocks, de Rouw et al. (2010) found in their study of tillage systems in Laos that C stocks in the NT system decreased, even with organic matter inputs, while conventional tillage C stocks increased, possibly due to the slow incorporation of organic residues into the soil in the NT system (de Rouw et al. 2010).This result shows that more research is needed on NT in this area to understand these findings, as well as provide sound recommendations for farmers.

3.4 Comparative Assessment of CFPs: Application of Cover Crops Cover crops are usually non-commercial, herbaceous, low-statured, plants associated with crop plants to provide soil protection, suppress weeds, and recycle nutrients principally via nitrogen fixation and the formation of a natural layer of mulch on top of the soil by litterfall (Baligar and Fageria 2007). Cover crops can take two forms: 1) weeds allowed to cover the soil (Sarno et al. 2004), which are, in some cases, actively managed by farmers (see weed management), and 2) the living foliage and litter of cover crops specifically planted on the agricultural plot. The use of shade trees, which also provide cover to associated crops, are of great importance in coffee and cocoa production systems and are dealt with in a separate section on shade; similarly, the effects of mulch and prunings are treated in the section on pruning and organic residue management.

3.4.1 BAU cover crop practices With the advent of chemical inputs in agriculture, the use of traditional cover crops has decreased in favor of fertilizer applications, herbicides, and insecticides (Baligar and Fageria 2007, Scholberg et al. 2010a). Unprotected soil, however, is more prone to soil erosion and nutrient leaching, and can thereby reduce the inherent fertility of the soil (Bellarby et. al. 2008, Scholberg et al. 2010a), as well as resulting in increased runoff and water pollution, production costs, and problems with pests and weeds (Scholberg et al. 2010b). For well-resourced farms, particularly tea estates, the absence of any soil cover, coupled with an increase in inorganic soil amendments to maintain crop productivity, is a common BAU practice. For smallholder coffee and cocoa farmers, however, soil covers are often present.

3.4.2 CFP cover crop practices that can lead to climate benefits Planted cover crops sequester more carbon in biomass and soil than leaving soil bare; they also protect soil from erosion and nutrient leaching, loosen the subsoil, and may reduce pests, while requiring low amounts of maintenance and water (Scholberg et al. 2010a, Baligar and Fageria 2007). Additional benefits may include nitrogen fixing capacity, resistance to release of allelochemicals, the generation of additional income to a farmer (for example, from forage), and C sequestration (Dinesh et al. 2009, Baligar and Fageria 2007, Scholberg et al. 2010a). In some cases, however, cover crops may compete with commercial crops. Maximizing the benefits of cover crops requires choosing the correct species for the soil, climate, and commercial crop of interest in order to minimize negative effects on the associated crop. Kone et al. (2008), found in their study of cover crops that the benefits of cover crops are achieved more quickly when initial soil quality is higher. Nonetheless, it is recognized that degraded soils have the highest potential for improvement (Stevenson 1986). Data on cover crops associated with coffee, cocoa, or tea are sparse. Nevertheless, peak biomass of herbaceous cover crops usually occurs within 2 - 3 years after planting and usually does not exceed 10 – 15 Mg ha

-1.

Afterwards, the presence of cover crops and weeds usually decreases as crop and shade tree canopies develop. See Annex 4 for a list of common cover crops used in coffee, tea and/or cocoa farms in East and West Africa and/or SE Asia.

3.4.3 Potential of cover crop CFPs to reduce GHG emissions and/or increase C stocks Since crop covers can increase soil fertility, reduce presence of noxious weeds, reduce erosion, and control numbers of certain pests, utilizing cover crops reduces the need for fertilizer, herbicides, and pesticides, thereby


limiting the emissions associated with these chemicals (see fertilizer use, weed control, and pest control for specific GHG emission reduction estimates). However, it should be noted that the effect of cover crops on carbon stocks and GHG emissions is apt to be largest during the first year or two following planting, since cover crop biomass may decrease with time due to shading by the crop plants or trees. Cover crops sequester C and N in the soil, particularly if N-fixing leguminous species are utilized (Baligar and Fageria 2007), and have been shown to produce significantly greater levels of soil C than agricultural land without cover crops (Dinesh et al. 2009). In the latter study, three crop-associated cover crops accumulated 2.1 - 4.3 Mg C ha-1 over a 12-year study period; these values were significantly higher than those of control treatments without cover crops. Sarno et al. (2004) found that plots covered with weeds maintained significantly greater C stocks, due to a larger input of organic materials and reduced soil temperature, than weeded plots. See applicable comments from the reduced tillage section regarding the relation between SOC and N2O fluxes.

3.5 Comparative Assessment of CFPs: Inorganic Fertilizer Use Primarily due to the growing demand and use of N in agricultural systems, there has been a dramatic increase in reactive N in the biosphere (Galloway et al. 2003, 2004). There is an increasing recognition that increased agricultural N inputs can lead to severely damaged environmental systems, and that ways to mitigate these negative consequences require an integrated, interdisciplinary approach (Galloway et al. 2008).

3.5.1 BAU inorganic fertilizer use practices Nitrogen fertilizers, either synthetic or organic, are oftentimes over-applied, resulting in N becoming a major gaseous and hydrologic pollutant. Nitrogen losses of particular environmental concern are emissions of nitrous oxide (N2O) and nitric oxide (NO), volatilization of ammonia (NH3), and the leaching and runoff of nitrate (NO3

-) and

dissolved organic nitrogen (DON) (e.g., Mosier 2001; Peterson et al 2001; Follett and Delgado 2002; Robertson and Groffman 2007). Table 7 identifies various default emissions factors for N inputs from a range of synthetic and organic sources. Note that organic amendment emissions factors range from 0.00 to 4.400 kg CO2 eq kg

-1 N, with compost releasing more

CO2 eq kg-1

N than several synthetic fertilizers, i.e. the use of organic amendment does not de-facto reduce emissions. Table 7: Default CO2 emissions from inorganic or organic nutrient sources (Soil & More International, 2011).

CO2 emissions from fertilizer application

Fertilizer Emission Factor Citation

N-Fertilizer 7.607 kg CO2 eq kg-1

N GEMIS 4.6, 2010, cited in in Soil & More International, 2011)

P-Fertilizer 1.232 kg CO2 eq kg-1

P

K-Fertilizer 1.180 kg CO2 eq kg-1

K

Limestone or Dolomite 0.306 kg CO2 eq kg-1

Ca

Compost 4.400 kg CO2 eq kg-1

N Williams et al, 2006

Crop yield is generally related to crop N requirement; greater yields typically require increased N inputs. In tropical agricultural operations with large financial resources, N fertilizer may be relatively inexpensive in comparison with other farm costs. Over-fertilization, i.e. application in excess of plant needs, may therefore be common, as producers will tend to hedge against a perceived risk of insufficient N and other nutrients.

Common N fertilizer types applied in a number of studies investigating N dynamics in coffee plantations in Costa Rica (Harmand et al. 2007; Babbar and Zak (1994,1995) and Brazil (Fenilli et al. 2007a,b, 2008; Hergoualc’h et al. 2008) were urea, ammonium sulfate (AS), ammonium nitrate (AN), and NPK combination fertilizers (Table 8). Table 8: Characteristics of common nitrogenous inorganic fertilizers (de Geus 1973, Tisdale and Nelson 1975,) Fertilizer Name Chemical Composition Volatilization Equivalent Acidity kg

CaCO3 Mg-1

product


Urea (NH2)2CO 10% - 50% 750

Ammonium sulfate (NH4)2SO4 < 5% 1,100

Ammonium nitrate NH4NO3 < 15% 600

3.5.2 CFP inorganic fertilizer use practices that can lead to climate benefits The underlying principles of fertilizer use CFPs are to apply the correct nutrient in the amount needed, timed and placed to meet crop demand, i.e., right product, right rate, right time, and right placement – the 4 Rs (Roberts 2006). This management framework can be utilized irrespective of the source of N, e.g., either from synthetic inorganic N fertilizers or organic crop residues and animal manures that contain N. Additional benefits from the use of organic amendments and crop residues are discussed elsewhere.

Fertilizer type Conventional or readily soluble synthetic N fertilizer is sold in a variety of forms and formulations, including granular urea (the most consumed globally), anhydrous ammonia, ammonium sulfate, ammonium nitrate, and solutions of urea ammonium nitrate. Soluble NH4

+ from all of these fertilizers can quickly nitrify to NO3

-, and be

subject to N loss prior to plant uptake.

Advanced fertilizer formulations that delay the exposure of NH4+ to nitrifiers, and microbial inhibitors that

biochemically inhibit nitrifiers, can potentially delay nitrification, reduce N losses, and provide a means for better delivery of N to plants. There is great interest in using enhanced–efficiency N fertilizers (EEF), such as slow, controlled release, or stabilized N fertilizers, to enhance crop recovery of N (Snyder et al. 2007). Slow-release fertilizers are commonly pelletized formulations of conventional fertilizers coated with a substance or membrane that slows solubility. Sulfur and, more recently, polymer coatings are used. Coating thickness and additional sealants aim to provide specific release rates, which are typically temperature and moisture dependent. There is some evidence that these fertilizers reduce N losses (e.g. Delgado and Mosier 1996; Halvorson et al. 2008), however longer-term unequivocal studies are lacking, particularly in tropical agricultural systems. Due to the relative high costs of these chemicals they are likely to have very little utility and/or availability in the majority of commercial crop smallholdings that constitute much of the coffee and cacao crop growing area (DaMatta et al. 2007). Nitrifying bacteria can be inhibited by natural and manufactured compounds. The most common natural compounds are neem extracts. Common manufactured inhibitors include nitrapyrin [2-chloro-6-(trichloromethyl) pyridine], dicyandiamide [H2NC (=NH) NHCN], encapsulated calcium carbide (CaC2), and 3,4-dimethyl pyrazole phosphate (DMPP).

Fertilizer timing For synthetic N fertilizers to be considered effective N sources, they must provide temporal synchrony between N availability and crop demand. This synchrony requires that the temporal pattern of N release into a plant–available form mimics closely the pattern of plant growth and N demand (e.g., Swift et al. 1980; Myers et al. 1994).

The timing of fertilizer applications is of utmost importance when attempting to enhance synchrony in agricultural systems that have different plant N demand patterns and scales. Synchrony can be considered on a short or a long–term basis. A short–term time scale is important in the case of annual crops; perennial crops are less dependent on short-term nutrient synchrony. For example, tree litterfall is continuous and can exercise a relatively constant influence on N supply. Nutrient reallocation from woody tissue can also help satisfy the nutrient demand of more metabolically active plant components, in effect partially decoupling plant nutrient demand from soil supply.

Synthetic N fertilizer application should ideally be comprised of several small doses when crop demand is greatest. However, the timing and quantity of fertilizer application may be dictated by other factors such as weather, capital, and the availability of equipment and labor. For example, typical recommendations for coffee suggest applying N fertilizer in four (equal) split doses. However, this practice has some drawbacks, namely the

http://en.wikipedia.org/wiki/Nitrogen


http://en.wikipedia.org/wiki/Sulfur

http://en.wikipedia.org/wiki/Sulfur






unavailability of labor and unsuitable weather conditions at desired times, and increased labor costs which add to the cost of cultivation. Where available, the application of N fertilizer through fertigation or the use of slow release fertilizers is recommended.

Fertilizer Placement Synlocation – the spatial concurrence between available N resources and crop root N demand (Van Noordwijk et al. 1993) - can be considered an important component of the synchrony concept. The spatial arrangement of crops can influence synchrony through modifying root distribution and the temporal and spatial patterns of plant nutrient demand; increased planting densities result in competition for light which, in turn, can reduce N demand. The mismatching of plant roots and the location of N additions promotes N loss from the system. From a management perspective in coffee, cocoa, and tea plantations, two important scales of heterogeneity may be considered. These are i) row–interrow, i.e. plant scale, variability, and ii) heterogeneity across whole cropping areas or plantations.

i) Plant scale variability Row-interrow differences in N availability and turnover are well known (Linn and Doran 1984; Klemedtsson et al. 1987), and a number of management strategies based on these differences have been used to increase nutrient use efficiency (NUE) and decrease N losses in row crops. Fertilizer banding, for example – placing fertilizer in a concentrated band within or very close to crop rows rather than between them – is common in field crops and can reduce surface N loss (CAST 2004, Malhi and Nyborg 1985). Hultgreen and Leduc (2003) determined that there was a trend for greater emissions of N2O when urea was broadcast rather than banded, and when fertilizer N was placed mid-row, rather than side-banded.

The placement of N fertilizer at varying depths has proved less consistent with regards to the potential reduction of N2O emissions (Liu et al. 2006 Drury et al. 2006). In a coffee study in Brazil, Hergoualc’h et al. (2008) found that surface application of granular fertilizer in close proximity to the coffee tree base can lead to high emissions of N2O and substantial N loss from the system. It may be beneficial to incorporate granular urea for this reason, particularly when the potential for volatilization is high.

ii) Field scale

Field–scale variability is likely to be generic to most cropping systems and needs careful evaluation when alternate management strategies are considered. A consequence of this heterogeneity is spatial variability in crop productivity, which has profound implications for the efficient use of N at the field scale.

Applying N fertilizer to a field at spatially and temporally variable rates selected to coincide with crop production potentials could substantially increase N fertilizer use efficiency and reduce N losses to the environment. Precision agriculture technology harnesses the potential to reduce overall N fertilizer application, and there is a growing body of literature detailing the effects of precision agriculture N fertilizer management practices on crop yield, plant N content, plant protein content, nitrate loss and nitrogen use efficiency. However, the ability to obtain crop and soil characteristics relevant for informing N management practices rapidly and inexpensively is fundamental for widespread adoption of precision agriculture techniques.

Fertilizer rate Yield-based equations have typically been used to calculate crop N rate recommendations. The yield-goal approach provides an N fertilizer recommendation for a particular field based on the expected maximum yield for the field multiplied by an N yield factor.

Soil N tests prior to fertilization can improve yield-goal N recommendations, particularly when legumes or other non-fertilizer N inputs are present. However, these pre-fertilization soil tests, including the pre-season nitrate test (PSNT), the amino sugar–N test (ASNT) the Illinois soil N test (ISNT) and the late spring soil nitrate test, have only sporadically been effective predictors of future N needs in areas where they have been tested (Barker et al. 2006; Spargo et al.2009; Blackmer et al., 1989).


Recently, a newly developed initiative to optimize crop yield has been developed based on the site-specific N rate at which the value from increased yield just matches the cost of added N (Iowa State University Agronomy Extension 2008). In this approach, any additional N cannot be economically justified in the absence of higher crop or cheaper fertilizer prices. By definition, the economically optimum N rate (EONR) will be lower than the agronomic optimum N rate at which yields are maximized; how much lower is determined by the ratio of N price to crop price. As N becomes more expensive or crop prices decline (increasing the ratio), producers will reap the same profit with less fertilizer N (Nafziger et al. 2004, Sawyer et al. 2006). Although developed for temperate annual row crops, a similar approach may be useful in tropical tree and shrub-based plantations. Several studies in cropping systems have implied the existence of non–linear relationship between N input and N loss. For example, concentrations of leached nitrate in soils have been shown to increase sharply at N fertilizer rates above those required for maximum grain yield (e.g., Andraski et al. 2000; Gehl et al. 2005, Lawlor et al. 2005). Non-linear responses of N2O emissions to increasing N rate have also been reported (McSwiney and Robertson 2005; Hoben et al. 2010), especially when the availability of inorganic N exceeded the requirements of competing biota (Erickson et al. 2001). In all cases where a non–linear curve best describes an N loss response to increasing amounts of N, small increases in applied N fertilizer result in proportionately higher N losses at higher N application rates. The shape of N loss response curves may have significant implications for favouring the adoption of reduced fertilizer N rate strategies, and may play a role in the generation of N2O emission reduction credits in agricultural offset projects within the carbon market (Millar et al. 2010).

Annual reported N inputs to coffee plantations vary greatly, but have generally been reported to be between 60 - 200 kg N ha

-1 (Wintgens 2009). In studies of coffee from Costa Rica and Brazil, inorganic fertilizer was applied at

high levels (250 – 350 kg N ha-1

y-1

), irrespective of the presence or absence of shade trees. However, much higher inputs of up to 400 kg N ha

-1 are not uncommon. In the systems studied by Harmand et al. (2007), reductions in N

fertilizer rate and the number of split applications were associated with decreases in coffee prices. Coffee-specific applications The Coffee Guide (http://www.thecoffeeguide.org), an industry publication commonly utilized by many coffee producers and export groups, recommended the following N fertilizer inputs for mature Arabica coffee, where clean coffee yields do not exceed ‘one metric ton (MT) per acre’: A sustenance dose of 20 kg of N per acre per year (49 kg N ha

-1 y

-1), and for every 100 kg (0.1 MT) of clean coffee production, application of a further 10 kg N per

acre. Therefore if we assume a clean coffee yield of one MT per acre per year (2.47 MT ha-1

y-1

), this recommendation translates into a N fertilizer rate of 120 kg N per acre, or 296 kg N ha

-1 y

-1. This value is in the

middle of the typical fertilizer range of 250 - 350 kg N ha-1

y-1

encountered in the above studies. In areas where the production levels are between 1 to 1.5 MT the sustenance dose is 30 kg N per acre or 74 kg N ha

-1 for a total of 321

kg N ha-1

y-1

. The same source estimates that one MT of clean coffee removes approximately 40 kg of N in the case of Arabica and 45 kg of N in the case of Robusta respectively from the soil, although Wintgens (2009) noted that in general Robusta requires less N fertilization than Arabica coffee. This value is higher than that estimated from Arabica coffee in Costa Rica, where N export in the coffee harvest was 34 and 25 kg N ha

-1 y

-1 in the non-shaded

and shaded plantations, respectively (Harmand et al. 2007). Tea-specific applications Globally, N is the major fertilizer applied to tea plantations, mostly in the form of ammonium sulfate (Morita et al. 2002). However, for greater N use efficiency, Verma (1997) recommends that of total N applied, 20% should be in the form of ammonium sulphate, 65% in the form of urea and the remaining 15% in the form of ammonium nitrate. Tea plants have been shown to be well-adapted to NH4

+ rich environments by exhibiting a high capacity for

NH4+

assimilation in their roots, as reflected in strongly increased key enzyme activities and improved carbohydrate status. Poor plant growth with NO3

- has largely been associated with inefficient absorption of this N source (Ruan

et al. 2007). Oh et al. (2006), showed that the use of calcium cyanamide mixed with conventional fertilizer at the rate of 400 kg ha

-1 y

-1 did not reduce tea yield or tea quality, but helped reduce soil acidification and nitrogen loss

http://www.thecoffeeguide.org/


from NO3- leaching and N2O emissions. Calcium cyanamide may therefore be a valuable tool in controlling

environmental N problems in tea-growing regions. In Kenya, Cheruiyot et al. (2010) found that increasing rates of N fertilizers exacerbated the effect of drought on tea through disproportionate assimilate partitioning to leaves that consequently weakened the ability of tea to tolerate water stress. Their results suggested an indirect contribution of N fertilizer supply to drought susceptibility in tea. Their study corroborated other studies in Kenya (Ng’etich 1999) and provided strong evidence that though fertilizer improves performance of tea, application rates above 200 kg N ha

-1 y

-1 limits growth and yield of tea

during drought periods. Consequently, the recommended N rate that gives the best compromise for both yield and quality of black tea in Kenya has been estimated as 150–200 kg N ha

-1 y

-1 (Owuor, 1997). Kamau et al. (2008)

concluded that the ageing of tea plantations is associated with increased stocks of C and N and other major nutrients per bush and per unit area. Assessments of C and nutrient stocks should therefore be carried out per unit area to avoid effects of variation in population density; tea bushes with higher N reserves will also likely require lower N fertilizer applications and will depend less on nutrient uptake under adverse weather conditions.

3.5.3 Potential of inorganic fertilizer use CFPs to reduce GHG emissions and/or increase C stocks Soil NOx emissions can vary depending on soil type (Veldkamp and Keller 1997). Proper fertilizer application, taking into account type, timing, and placement, helps to reduce fertilizer usage, and therefore the GHG emissions associated with fertilizers. For example, studies in Costa Rica and Brazil have indicated that inorganic N fertilizer applications can exceed optimal dosages by up to 200 kg N ha

-1 (Wintgens 2009). Oh et al. (2006) compared a

conventional high N application treatment (1,100 kg N ha-1

) and a ‘low’ N application (400 kg N ha-1

) with calcium cyanamide (CaCN2) in the Makinohara tea area in Shizuoka Prefecture, Japan and found that nitrous oxide emissions increased with N inputs. Improved synchrony of the fertilizers applied can also increase plant uptake and reduce GHG emissions. Increased plant productivity related to fertilizer use can result in an increase in C stocks in soil and biomass. Reduction or substitution of inorganic fertilizers can result in a reduction of up to 3.16 kg CO2 eq kg

-1 product.

3.6 Comparative Assessment of CFPs: Pruning and Organic Residue Management In this review, soil fertility refers to soil nutrient status, although it is recognized that soil fertility includes other factors, i.e. structure, that are important determinants of fertility. Maintaining soil fertility is important in agriculture to ensure continued, high crop productivity. As agriculture has intensified, and the use of monoculture agriculture has spread, traditional techniques for maintaining soil fertility based on organic residues supplied by crop residues, litterfall, or prunings have been replaced with inorganic fertilizers, which reduce soil carbon sequestration and may contribute to GHG emissions (see previous section on inorganic fertilizers). Organic residue management includes the use of litter, prunings, and mulch to provide benefits to crops. Coffee, cocoa, and tea require pruning as part of their management regime. Moreover, in shaded systems the shade trees produce litter and may be pruned to provide mulch (Beer 1988). Mulch is the placement of any protective layer over the soil, which may include crop residues, leaf litter, and prunings (the use of artificial mulches such as plastic sheeting is beyond the scope of this review). The benefits of mulch and litter are fivefold: they retain moisture, protect the soil surface and reduce erosion, moderate soil temperature, suppress weed growth, and can add nutrients and C to the soil (Hillocks 2000). The addition of pruning residues, especially, can increase the productivity of the crop and lessen the amount of chemical inputs required (Beer 1988).

3.6.1 BAU pruning and organic residue management practices As agricultural systems around the world intensify, inorganic fertilizers are increasingly replacing organic amendments, especially in non-shaded systems that require more chemical inputs. The absence of a conscientious management regime for utilizing and profiting from prunings and crop residues is common practice. As noted in


the previous section, in lieu of maximizing the potential of these organic sources, synthetic fertilizers are often used instead of, or in addition to, crop residues to provide nutrients, particularly N, to the soil. The cost of chemical inputs, however, may be more than small farmers can afford (Beer 1987). The elimination of organic residues via burning also results in significant GHG emissions that could be partially avoided if these residues were applied to cropping areas (Table 9).

Table 9. Country emissions due to burning of agricultural residues. Emissions (Gg y

-1)

Country CH4 N2O CO CO2 Citation

Ghana (1996) 1.08 0.041 NA NA MEST 2001

Indonesia (1994) 15.73 0.52 330.73 NA Sugundhy et al. 1999

Tanzania (1990) 2.483 0.0170 27.158 727.060 MECEEST 2003

3.6.2 CFPs for pruning/organic residue management practices that can lead to climate benefits Although a large amount of information is devoted to the study of organic residue dynamics and management, much of this information is not coffee, tea, and cacao specific. Generally, all cropping systems result in a loss of soil carbon following land clearing. The rate of soil carbon loss is exponential, with most losses occurring within the first few years of land conversion and within the upper soil horizon (Davidson and Ackerman, 1993). The estimated mean annual rate of decay for tropical soils following land clearing is 24% (Davidson and Ackerman, 1993). Some cropping systems, however, lose less soil C than others due to the organic inputs they produce and the microclimate of the cropped plots. Watanabe et al. (2001) investigated the effect of land use changes on tropical soils under primary forest, secondary forest, coffee plantations, and arable crops at three sites in south Sumatra, Indonesia. They found that topsoil total C was 1.7 to 4.3 times greater, and total N was 1.1 to 2.8 times greater, under primary forest than under the other types of land use. The degree of C sequestration in tree-based systems depends on the rate of biomass accumulation, the quality and quantity of organic matter returned to the soil (Mutuo et al. 2005), soil properties, and climate. The quantity of litter and prunings produced is usually greater in humid/sub humid environments compared to drier environments (Mutuo et al. 2005), but decomposition in the former is usually faster as well. In mature shaded coffee systems in southwestern Togo, Dossa et al. (2008) measured pruning inputs of 1.0 – 5.2 Mg C ha

-1 y

-1.

Applying prunings from crops and shade trees to the soil reduces the need for inorganic fertilizers, thereby decreasing GHG emissions associated with their production and use. Organic residues are usually applied as: i) monospecific (single crop) residues, ii) a mixture of residue types, and iii) a mixture of crop residue(s) with inorganic fertilizer. Appropriate application of crop residues, organic residue mixtures, and the combined use of synthetic fertilizers and organic residues have demonstrated significant potential to reduce GHG emissions and increase SOC, however, specific outcomes from organic additions are difficult to predict due to the factors described below. Organic residues Organic residue decomposition and N release patterns are governed by climatic, edaphic, and resource quality factors (Swift et al. 1979). Generally, organic residue decomposition increases with temperature and humidity and decreasing clay content of the soil and surface-applied residues usually decompose more slowly than those that are incorporated in the soil (Ambus et al. 2001).


Once in the soil, soil aggregation plays in important role in organic C and N retention, since SOM is physically protected by soil aggregates, whose formation is in part dependent on soil texture, mineralogy, and fauna. (Davidson 2005, Anim-Kwapong 2003, Bellarby et. al. 2008, Flynn and Smith 2010, Montagnini and Nair 2004). Soil aggregate stability and C sequestration have also been directly related to the chemical composition of plant residues added, through the stabilization by the latter of soil aggregates. Plant residue quality parameters, such as phenolic acid content have been shown to be important in aggregate stability and may help predict C sequestration potential (Martens 2000).

Residue quality parameters can be useful indices for predicting short-term decomposition and N availability for annual crops, which may help inform management decisions regarding suitable plant species for inclusion in a rotation. These indices include total N content and C:N ratio, usually considered robust (Constantinides and Fownes 1994), and also lignin and polyphenol content and ratios derived from them (Palm and Sanchez 1991, Mafongoya et al. 1998). A N concentration of 2% is typically the critical threshold for the transition between net immobilization to net mineralization, however high lignin and polyphenol concentrations > 15% and > 4% respectively can result in net immobilization of N, irrespective of total N concentration (Palm 1995). In a 10-year field trial in Northeast Thailand, Samahadthai et al. (2010) assessed how the quality of four different organic residues applied annually to a tropical sandy loam soil affected particulate organic matter (POM) pools, important in SOC retention, and the development of soil aggregates. They applied rice straw, groundnut (Arachis hypogea) stover, and tree litter from Dipterocarpus tuberculatus, and tamarind (Tamarindus indica). They found that tamarind, with intermediate contents of N and recalcitrant compounds (lignin and polyphenolics), appeared to best promote small macro-aggregate formation, and that C stabilized in small macro-aggregates accounted for the tamarind treatment showing the largest SOC (<1 mm) accumulation, with rice straw having the lowest accumulation. However, in two field trials in Kenya on a clayey soil and a loamy sand soil, residue inputs of different quality (no input, high quality Tithonia diversifolia, medium quality Calliandra calothyrsus, and low quality Zea mays stover) did not affect the stabilization of soil organic C and N; the quantity of C added (regardless of quality) and the soil stabilization capacity were more important controls on stabilization of SOM (Gentile et al. 2010). Decomposition and nutrient mineralization patterns of organic residue mixtures may be the average of the component litters or may show positive or negative interactions (Mafongoya et al. 1998). Interactions can include one residue altering the physical environment of another (Tian et al. 1992). There is still a great deal of uncertainty in the N mineralization patterns and N losses resulting from mixed residue interactions. Research has revealed both advantages and disadvantages of combining organic and inorganic N sources (Palm et al. 1997). Under low-input conditions, it may be beneficial to use as much organic nutrient as possible supplemented with inorganic N sources (Mugendi 1997, Palm et al. 1997, Jama et al. 2000, Vanlauwe et al. 2001) There is limited predictive understanding of the management of organic inputs especially in tropical agro-ecosystems, however an organic resource database and farmer decision tools for assessing organic matter quality and management have been developed Palm et al. (2001), and Giller et al. (2000). While there is much evidence that residue quality parameters such as N, lignin, and polyphenol contents control short-term C and N dynamics (see above) less is known about the medium- to long-term fate of C and N from different quality residues. Knowledge of longer-term dynamics will help inform management decisions regarding the potential for inclusion of particular species in perennial cropping systems, such as under or over-story tree choices in plantations.

3.6.3 Potential of pruning and organic residue management CFPs to reduce GHG emissions Substituting organic inputs, such as litter and prunings, root turnover (Albrecht and Kandji 2003, Anim-Kwapong 2003), manure, and mulch, for inorganic fertilizers reduces the amount of GHG emissions associated with fertilizer production and application (Glover and Beer 1986) (see inorganic fertilizer section). The ability of organic material


to provide nutrients at a level similar to fertilizers is dependent on several factors, especially the polyphenol, lignin, and nutrient contents of the organic residues, as well as soil moisture. For example, in the sub-humid highlands of Kenya, Kimetu et al. (2004) found that the application of organic residues produced 50% - 118% of the crop yields attained with the application of an equivalent amount of inorganic N fertilizer, presumably due to the addition of other nutrients in the organic residues.

Organic residue quality can also directly affect denitrification rates and N2O emissions (Aulakh et al. 1991a, b; Baggs et al. 2000; Millar et al. 2004) through their effects on the quantity of N in the system, their mineralization-immobilization patterns, their role as a microbial energy source, and as precursors to SOM (Palm and Rowland 1997). Higher emissions of N2O have been measured following addition of residues with a low C:N ratio when compared to residues with a high C:N ratio (Baggs et al. 2000, Baggs et al. 2003). However, other residue quality parameters (e.g. N, lignin and polyphenol concentration) have also been shown to be robust in predicting emissions of N2O (Millar and Baggs 2004, Millar et al. 2004, Millar et al. 2005). Nitrogen losses may be reduced by the application of mixed species residues of varying qualities that improve the synchrony between N availability and crop N demands (Ndufa 2001, Gathumbi et al 2002; Schimel and Hattenschwiler 2007). The timing of pruning and residue application to the soil is beneficial when nutrient mineralization from those residues is in synchrony with crop demand (Anim-Kwapong 2003, Carr 2010b).

3.6.4 Potential of pruning and residue management CFPs to increase carbon stocks In a comparison between a shaded and open coffee plantation in Togo, Dossa et al (2008) found total C stocks were almost four times greater in the shaded than in the open coffee system; the authors suggested that periodic pruning of shade trees increased the return of organic inputs and nutrients to the soil. Diels et al. (2004) showed that after 16 years of cropping SOC levels were between 10.7 and 13.2 Mg C ha

-1 in pruned shade tree systems and

7.3-8.0 Mg C ha-1

in cropping systems without trees. Soil organic C levels in both systems, however, were lower than those measured initially (15.4 Mg C ha

-1). Other studies of hedgerow pruning applications showed that SOC in

the surface layer increased from 11.4 g kg-1

to 15.3 g kg-1

after four years (Lal 2005a).

3.7 Comparative Assessment of CFPs: Shade Trees Pruned or non-pruned shade trees are widely used with coffee and cocoa cultivation, but less so with tea, particularly by smallholder farmers throughout the tropics (Beer 1987). Coffee and cacao are commonly grown in several types of systems: i) traditional rustic agroforestry, where crop plants replace natural trees in the forest understory, ii) traditional polyculture “coffee garden”, iii) less species-rich commercial polyculture, iv) shaded crop monocultures, and v) high input intensive, full-sun monoculture systems, which are becoming increasingly common (Lin et al. 2008, adapted from Moguel and Toledo 1999; Rice and Greenberg, 2000). Within shade systems, there are 3 common tree arrangements i) complex or multistrata agroforestry systems, where the crop is grown interspersed with a single species or several species of shade trees, ii) boundary planting, which takes the form of planting trees as windbreaks or fences, and iii) hedgerow intercropping, where crops are grown in rows between the shade tree species (Albrecht and Kandji 2003). Whether or not an association with shade trees (i.e., agroforestry) is beneficial to the economic and biological productivity of coffee has been debated in the literature for over a century (e.g., Lock, 1888; Mayne, 1966; Beer et al., 1998; DaMatta and Rena, 2002; DaMatta, 2004a,b; van der Vossen, 2005; DaMatta et al., 2007, Moraes et al. 2010). Nevertheless, the use of shade trees in coffee and cacao plantations can be ecologically beneficial, since they aid in natural resource conservation and in increasing biodiversity. Furthermore, financial benefits may accrue from income derived from fruits, nuts or timber products which may compensate for potential reduction in yields due to shade trees (Lin et al 2008).

3.7.1 BAU shade tree practices The 1970s saw a push for the modernization of coffee and cocoa plantations, changing from traditional agroforestry systems to non-shaded systems planted with crop varieties that responded well to large amounts of


chemical inputs. Modern coffee cultivars selected in test-trials conducted under full sunlight, with close spacing and high-external inputs (including N fertilizer), have shown greatly increased yields compared to shaded coffee (DaMatta and Rena 2002), however these yield increases have typically been achieved without due regard to increases in GHG emissions resulting from the clearing of vegetation, the increased use of chemical inputs (see inorganic fertilizer use), and the loss of soil carbon through increased decomposition and erosion (Mutuo et al. 2005, Beer 1987, Lin et al. 2008).

Across the tropics today, large, intensively managed, plantations are more likely to grow coffee and cocoa in full sun (Beer 1987, Bos 2007, Lin et al. 2008, Franzen and Mulder 2007, Siebert 2002, Belsky and Siebert 2003), whereas resource-poor farmers tend to use shaded systems. In cocoa, most smallholder farmers use a multi-strata system whereby forests are selectively thinned so that cocoa and other trees (e.g. fruit trees) can be planted beneath the remaining canopy (Clay 2004). The areas are adaptively managed - fields may be abandoned and converted to pasture (Johns 1999) when prices are low or full-sun production when prices are high (Saatchi et al. 2001; Alger and Caldas 1994; Donald 2004). In contrast, tea is mostly grown under full-sun conditions.

3.7.2 CFPs for shade tree practices that can lead to climate benefits Using shade with coffee, cocoa, and to a lesser extent tea, involves planting woody perennials with the crop plant in a specific arrangement or rotation, or thinning the undergrowth of forest associated with the commercial crops (Mutuo et al. 2005 cites Lundgren 1982, Bellarby et. al. 2008). The type of shade system, and the trees used, depends on the region and traditions. Beer (1987) presents an extensive list of the desirable characteristics of shade species (reproduced in Annex 5). Shade trees produce multiple benefits. They protect the soil surface and moderate soil temperature through their foliage and the production of leaf litter, which, in turn, can also increase soil fertility and help conserve soil moisture (Hairiah et al. 2006). As shaded systems become more diverse and complex, the amount of C sequestered, N uptake, and the ability of the system to act as methane sink also increases. Secondary financial and environmental benefits, such as the availability of non-timber forests products and biodiversity, can also increase as well. A study conducted along a gradient of coffee production systems in West Lampung, Indonesia showed that the amount of litter produced in shaded perennial crop systems increases with the complexity of the plantings. Forest remnants produced an estimated 14.1 Mg ha

-1 y

-1 of leaf litter, while multi-strata shade, simple shade, and full-sun

systems were estimated to produce 9.8, 6.6, and 4.0 Mg ha-1

y-1

, respectively (Hairiah et al. 2006). In some cases, commercial crop-specific pests can be maintained in leaf litter, however, and may necessitate the removal of leaf litter from fields.

3.7.3 Potential of shade tree CFPs to reduce GHG emissions There are few studies of GHG emissions in tropical shaded systems. The literature suggests that well-managed shaded agroforestry production systems can mitigate CO2 and N2O emissions while maintaining or increasing CH4

sink strength compared to less complex cropping systems (Mutuo et al. 2005, Mendez, Laderach 2010). Furthermore, shade systems implemented on degraded land have higher net carbon sequestration than shaded systems which replace natural forests, presumably due to the low C status of degraded land planted to shade systems and continued losses of C from recently converted forested land (see reclaiming degraded land). Researchers differ as to the degree to which shade systems reduce GHG emissions and what is the optimal management system to reduce emissions to the greatest extent. Because shade systems are found in varying environmental conditions (precipitation, elevation, soil, and management), it is difficult to predict the optimal shade level (Lin et al. 2008) and this introduces uncertainty as to whether shade systems produce less GHG emissions than full-sun systems. Lower yielding shade systems may also cause more land to be deforested and put into production compared to full-sun systems, which might result in greater GHG emissions overall. Below is a brief summary of the impact shade planting has on the principal GHGs.


Methane: There is very little long-term data on methane emissions in tropical agroforestry systems (Mutuo et al. 2005). Primary and secondary forests act as CH4 sinks, whereas high input cropping systems eliminate that sink and produce net methane emissions (Mutuo et al. 2005). Agroforestry systems, however, have been shown to maintain CH4 sinks at 60% the capacity of a secondary forest (Mutuo et al. 2005, citing Palm 2002), however the precise dynamics of CH4 within agroforestry systems is not clearly understood (Flynn and Smith 2010) In one study in Sumatra, average methane consumption by soil was highest in native and logged forests, ranging from 28 to 38 µg C m

–2 h

–1 (96 kg CO2 eq ha

-1 y

-1, scaled up by Flynn and Smith 2010), followed by agroforestry systems averaging

about 22 µg C m–2

h–1

(39-93 kg CO2 eq ha-1

y-1

). Verchot et al. (2007) note that CH4 uptake can be slightly suppressed in coffee agroforestry systems which utilize nitrogen fixing trees.

Nitrogen: Studies have shown that N2O emissions from low-input agroforestry systems are lower than those of cropping systems, and similar to those from forests (Mutuo et al. 2005). In a review of tropical agroforestry system GHG emissions and C sequestration, Mutuo et al. (2005) found that N2O emissions range from 5.8-12.5 µg N m

–2

h–1

for agroforestry systems, compared to a range of 7.1-31.2 µg N m–2

h–1

for cropping systems and 5.0-9.2 µg N m

–2 h

–1 for forests. Verchot et al. (2007) note that using nitrogen fixing trees in shaded coffee systems can increase

N2O emissions. Carbon Dioxide: Shade systems are generally low input, which means that less petroleum-based chemicals are applied and C emissions from their manufacture are avoided. Since shade systems can be productive for longer periods of time than full-sun systems (Beer et al. 1990), long-term savings in avoided C emissions from agrochemicals can be significant. However, debate exists on whether shade systems in fact reduce pressures on forests, deforestation, and the conversion of forests via shifting agriculture (Montagnini and Nair 2004), all of which are major emitters of CO2.

3.7.4 Potential of shade tree CFPs to increase carbon stocks Among agricultural land use options, agroforestry systems have the greatest potential to sequester carbon besides primary forest, however their ability to sequester C does not equal that of primary forest. In a study conducted by Isaac et al. (2005), within the first 2 years after land conversion to an agroforestry system, 16% of the original C stock had been lost, and a further 22% of soil C was lost between two and 15 years after land conversion. However, by 25 years, 3.3% of the soil C had re-accumulated. This study shows that although agroforestry systems have the potential to accumulate C, they do so over the course of decades. The amount of C sequestered depends on the type of shade planting system used and is dependent on spacing, soil characteristics, and management (Albrecht and Kandji 2003). Boundary planting systems do not provide a large amount of C storage in biomass, and sequester less C in soil, compared to complex, multi-strata agroforestry systems because only a small proportion of the plot is occupied by the boundary plantings. Biomass sequestration by hedgerow intercropping varies, but C sequestered in biomass in these systems is often temporary, since the trees are often pruned or used for firewood (Lal 2005a, Albrecht and Kandji 2003) (Table 10). Table 10. Estimates of carbon sequestered in soil and biomass in common agroforestry systems (adapted from Albrecht and Kanji 2003).

System Plant biomass C (Mg C ha

-1)

Plant Biomass Production (Mg C

ha-1

y -1

)

C sequestered in soil

(Mg C ha-1

)

Citation

Complex agroforestry 7-25 6 8-21 Beer et al. 1990, Jensen 1993a, Jensen 1993b

Boundary plantings 20-35 NA NA Baggio and Heuveldop 1984, Romero et al. 1991, de Jong et al. 1995


Hedgerow Intercropping 1-37 NA 6-10 Albrecht and Kandji 2003, Kang 1997

Data on carbon sequestration in shaded systems varies widely, ranging from 29 - 53 Mg C ha

-1 in the tropical

African highlands, to 39 -195 Mg C ha-1

in Southeast Asia (Albrecht and Kandji, 2003; Mutuo et al., 2005) (Table 11). Even so, shaded systems have consistently been shown to sequester much greater amounts of C than non-shaded systems (Dawoe and Isaac 2010), due to C storage in shade tree biomass and increased SOC resulting from C additions to soil by leaf and root litter and lower soil temperatures. Dossa et al. (2008) measured 81 Mg C ha

-1 in

shaded coffee systems, and only 22.9 Mg C ha-1

in non-shaded systems (see Figure 2 below). These values are still less than primary forest, however; Duguma et al. (2001) found that soil C in cocoa agroforests was 62% of the carbon stock in primary forests.

Table 11: Carbon sequestration for various coffee and cocoa farming systems in selected regions.

Crop System Region Climate Age of System

C sequestered (Mg ha

-1 unless

otherwise noted) Citation Comments

Not specified Agrosilvicultural

Subsarahan Africa

Humid Tropical

Not specified 29-53

Kandji et al., 2006

Value estimated for a 50 year rotation


South America

Humid Tropical

Not specified 39-102

Kandji et al., 2006

Value estimated or a 50 year rotation


Southeast Asia

Humid Tropical

Not specified 12-228

Kandji et al., 2006

Value estimated for a 50 year rotation

Not specified Agroforestry Global

Humid Tropics

Not specified 63

Montagnini and Nair, 2004

Indicated as average; accrual timeframe unspecified

Not specified Agroforestry Global

Subhumid Tropics

Not specified 50



Cocoa Simple shade Central America

Humid Tropics

Not specified

3.08-4.28 Mg C ha

-1y

-1



Coffee Full sun Southeast Asia

Humid Tropics

Not specified 1 Mg C ha

-1y

-1


AGB; system establishment post-slash and burn

Coffee Simple shade Southeast Asia

Humid Tropics

Not specified 2 Mg C ha

-1y

-1


AGB; system establishment post-slash and burn

Coffee/ Cocoa

Single shade species (Gliricidia sepium)

Central America

Humid Tropics 30 51.6

Kursten and Burschel, 1993 AGB.

Coffee/ Cocoa

Single shade species (Inga densiflora)

Central America



Coffee/ Cocoa

Single shade species (Cordia alliodora)

Central America



Coffee/ Cocoa

Single shade species (E. poeppigiana)

Central America

Humid Tropics 10 19

Kursten and Burschel, AGB.


Figure 2. Above ground (A) and belowground (B) carbon and distribution in biomass components in shaded and open-grown coffee systems. Vertical bars represent standard error of means. Reproduced from Dossa et al. 2008.

1993

Coffee/Cocoa

Single shade species (Mimosa scarabella)

Central America



With respect to biomass carbon, Palm and colleagues (2005) found that simple shaded coffee systems (1 - 3 tree species) in Brazil sequestered an additional 55 Mg C ha

-1 in above ground biomass than a non-shaded coffee

monoculture. A separate study in Tanzania found that simple agroforestry (dispersed intercropping) can sequester up to 23 Mg C ha

-1 (based on a long-term average over 25 years) (Onyango et al. 2010a), whereas boundary

plantings in the same region over the same period of time sequestered 1.5 tons C ha-1

(Onyango et al. 2010b). In Sumatra, conversion from full-sun to shaded coffee system was projected to increase C stocks over the landscape at the rate of 0.5 Mg C ha

-1 y

-1 over a 20-year period (van Noordwijk et al 2002 cited in Montagnini and Nair, 2004).

The ability of shaded systems to sequester more carbon than simpler or non-shaded systems is also due in part to greater litter production in shaded systems. In shaded plantations of cocoa or coffee, the total annual litterfall from the crop and shade trees, including pruning residues, is between 5.0 and 20.0 Mg ha

-1 y

-1 (Beer 1988,

Montagnini and Nair 2004) see Annex 6), within the range reported for tropical forests (Vitousek 1984, Glover and Beer 1986). These litter inputs can maintain soil organic matter (SOM), reduce the risk of NO3

- leaching, and permit

a more efficient use of any inorganic fertilizers leading to reduced potential for N2O emissions. Moreover, in the cocoa context, higher surface soil C:N ratios, maintained by continuous litter inputs, are positively correlated with cocoa productivity. In coffee systems, Glover and Beer (1986) and Beer (1988) found that the nutrients recycled in litter and prunings in two coffee agroforestry systems were similar to the recommended fertilizer additions needed for coffee production. The amount of nutrients delivered to the soil from litterfall, however, varies depending on the species of shade tree used (Beer 1988, see Annex 6), soil fertility, and the age of the agroforest stand (Dawoe et al. 2010).

Root turnover may contribute a significant proportion of nutrients recycled in agroforestry systems, but is difficult to measure (Mutuo et al. 2005). Fine root litter production is generally estimated to be about 20% or less of aboveground litterfall, but estimation of root C inputs to soil are fraught with methodological difficulties. A study of cocoa farms shaded by E. poeppigiana or C. alliodora demonstrated that N inputs from fine root turnover could total as 23–24 kg ha

-1 y

-1,

representing 6–13% and 3–6% of the total N input in organic matter in the C. alliodora and E. poeppigiana systems, respectively (Muñoz and Beer 2001).


Contour hedgerows of multipurpose tree species on sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. De Costa and Atapattu (2001) found that annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. The authors concluded that species such as Calliandra and Flemingia may be more suitable for contour hedgerows in Sri Lanka because of their greater biomass production and slower biomass decomposition and nutrient release which would minimize leaching losses (and likely reduce N2O emissions) and ensure long-term build up soil organic matter. While shade systems can increase carbon stocks, the effect of these systems on long-term carbon sequestration depends on where the carbon is stored (biomass or soil), the timeframe over which it is stored, and how carbon stored in biomass is eventually used (see fuel wood extraction; erosion control).

3.8 Comparative Assessment of CFPs: Erosion Control Measures Soil erosion, where soil is displaced by water and wind, is a major cause of GHG emissions, which may reach 0.8-1.2 Pg C y

-1 globally (Lal 2003). Erosion redistributes C, but also causes increased CO2 emissions via SOM

mineralization and CH4 emissions by methanogenesis, among other processes (Lal 2003). Erosion also indirectly contributes to GHG emissions by decreasing soil fertility, which leads to increased fertilizer use (see fertilizer use) and land conversion for agriculture.

3.8.1 BAU erosion control practices As farmers change from traditional (i.e. low-input and shaded) cropping to monoculture systems, erosion controls such as soil cover, shade trees, and conservation tillage usually decrease or are eliminated entirely and erosion increases (Mutuo et al. 2005). Under these circumstances, erosion losses are high from recently planted or underdeveloped plantations (van de Wal 2008), plantings on slopes (van de Wal 2008), and those that use conventional tillage practices. Conversion of forestlands to tea estates can result in annual soil losses ranging from 20 - 160 Mg of soil ha

-1 (Van de Wal 2008).

3.8.2 CFPs for erosion control that can lead to climate benefits CFPs that decrease soil erosion include shade plantings, conservation and no tillage, and soil cover. Avoiding the use of marginal areas could also potentially reduce soil erosion as well as improve moisture and nutrient retention (Eger, Fleischhauer et al. 1996). Shade trees have been shown to reduce soil erosion (Davidson 2005). In one study of coffee plantations in Indonesia, coffee alley cropping with shrubs and shade trees reduced erosion by 64%, without compromising growth or yields of coffee plants (Iijima et al. 2003). No tillage and conservation tillage management practices also decrease soil erosion (Sims et al. 2009). In a study of coffee plantations on steep Indonesian hillsides, Iijima et al. (2003) found that eliminating tillage practices reduced soil erosion by 37%. Soil cover, in the form of leaf litter, mulches and cover crops, also aids in decreasing erosion. Hairiah et al. (2006) report that with increasing age of the coffee plots, erosion rapidly decreased, due to increased presence of leaf area and surface litter, while surface runoff decreased gradually. Cover crops, microcatchments and grass mulches reduce soil erosion and runoff on tea plantations (Carr 2010b), and regular tea prunings applied as mulch may reduce soil erosion and run-off, while maintaining soil fertility (Kamau et al. 2008, Carr 2010b) (see organic residue management, cover crops).

3.8.3 Potential of erosion control CFPs to reduce GHG emissions and/or increase C stocks Decreasing soil erosion reduces GHG emissions by reducing SOM mineralization and by contributing to the maintenance of soil fertility, which decreases the need for fertilizer use and maintains the suitability of land for


agriculture (Iijima et al. 2003). This, in turn, can reduce GHG emissions associated with fertilizer production and the clearance of forested land, both of which result in GHG emissions. Erosion itself redistributes soil C, but may or may not decrease net soil C stocks. All of the CFPs to reduce erosion discussed above, however, sequester C in soil and above-ground biomass and hence have the ability to increase soil C stocks (see shade trees, cover crops, and prunings/organic residue management).

3.9 Comparative Assessment of CFPs: Irrigation Alternatives In many areas, irrigation is necessary for the production of crops such as coffee, tea, and cocoa. Coffee and cocoa fruit production, for example, is susceptible to the timing and amount of precipitation (Lin et al. 2008). The amount of irrigation needed is determined by a number of factors, including the variety of coffee plant, elevation, local temperature and rainfall, plant age, and degree of shade (Carr 2001).

3.9.1 BAU irrigation practices Farms may or may not have an irrigation management system: its presence or absence in coffee, tea, or cocoa farms is typically determined by the size and capitalization of the farm. Large plantations for all three crops oftentimes rely on irrigation, particularly full-sun crops which do not have the microclimate controls of shade systems. In southern Tanzania, for example, large tea plantation systems are typically irrigated, while smaller farms are rain-fed (Carr 2010b). Most cocoa farms in Ghana rely on rainfall, due to the small size of a typical farm and the economic limitations associated with small-scale farming (Ntiamoah and Afrane 2008).

When agricultural systems are irrigated, a sprinkler system is typically used. These high pressure systems usually require fossil fuels for their use, which produce GHG emissions, and are subject to factors which reduce efficiency, such as wind and wide spacing between crops.

3.9.2 CFPs for irrigation practices that can lead to climate benefits Drought mitigation and drought tolerance management strategies are the primary CFPs for small-scale farms where irrigation may be cost-prohibitive. These strategies may be particularly useful in Kenya, Uganda, and Northern Tanzania, where two wet seasons occur (Carr 2010a). The cova system, planting two or more trees at each station, is beneficial in drought conditions because the system encourages deeper root systems (Carr 2001). Mulching, which reduces the effects of drought by reducing soil evaporation and increasing water infiltration into the soil, is also a beneficial practice to reduce irrigation needs, and has proven its importance in Kenya and Tanzania (Carr 2001). Weed control is also recommended as a way to limit irrigation needs (Carr 2001). As stated in previous sections, shade trees help reduce evapotranspiration and plant transpiration and control microclimates, which helps manage drought stress (see shade trees). Another drought mitigation strategy, which requires considerable advance planning, involves a two-step approach of 1) utilizing cover crops to maintain soil fertility and reduce surface water loss pre-planting, then 2) planting tea bushes at high-densities, “crowding out” the cover crops and thus minimizing competition for water resources while maintaining a dense canopy cover to reduce rainfall-induced erosion (Carr 2010b).

When irrigation is necessary, a drip irrigation system, which saves energy and water, should be used, especially for larger operations (Carr 2001, Carr 2010b). Kigalu et al. (2008) found that drip irrigation reduced water loss and saved on labor when employed in a tea system in southern Tanzania. The authors found that drip irrigation treatments on a tea plantation produced higher yields (4,113-5,868 kg dried tea ha

-1) than overhead sprinkler

systems (4,200 kg dried tea ha-1

), while saving 50% on irrigation costs, 85% on labor requirements, and using 50% less water.

Irrigation systems are driven by various types of fuels, which produce GHG emissions. A clean energy alternative to typical electrical or fossil fuel-driven pumps is the harnessing of wind energy for water pumping. An area requires a wind energy potential of 3 m sec

-1 to run a wind energy water pumping system (Karekezi and Kithyoma 2002).


Kenya, for example, has a wind energy potential of 3 m sec-1

, and Karekezi and Kithyoma (2002) report the use of 360 wind pumps in that country. Another clean energy alternative is photovoltaic electricity used for water pumping. Admittedly, these recommendations are only feasible for highly capitalized operations, since access to these technologies in rural landscapes is limited and the costs of installation and maintenance are prohibitive for smallholder farmers.

3.9.3 Potential of irrigation CFPs to reduce GHG emissions and/or increase C stocks GHG emissions in irrigation systems are derived from the energy required to run water pumps. It may be possible to decrease GHG emissions by eliminating or lessening the need for an irrigation system through drought mitigation strategies. Further, as drip irrigation systems are low pressure, and reduce the amount of pumping, the amount of fuel necessary to run the pump is reduced. Clean energy alternatives to fossil fuel driven pumps may reduce the GHG emissions associated with the conventional pump systems. More research is needed to compare the energy intensiveness and GHG emissions tradeoffs of the various potential irrigation CFPs. No evidence has been found to date that particular irrigation systems increase carbon stocks, although increased soil moisture would be expected to increase plant productivity and C sequestration as well as decomposition rates. On the other hand, certain drought mitigation and tolerance management strategies, such as organic mulches or shade trees, may lead to increased carbon stocks.

3.10 Comparative Assessment of CFPs: Weed Control Practices The threat of undesirable plants, or weeds, exists throughout agricultural systems. Weeds can compete with crops for nutrients, water, and sunlight, harbour pests, impact the growth of young crops, and decrease yields. Weeds also have some beneficial uses, however, as protective soil covers (Sarno et al. 2004) (see cover crops), hosts for beneficial insects, and as a nutrient source. Generally, however, undesired plants in an agricultural system are regarded as pests and removed from productive areas. There is some uncertainty in the literature whether herbicide use increases or decreases overall GHG emissions. One study of herbicides applied to cereal crops showed that applying herbicides increases CO2 emissions by 4.4%, however herbicide application increased energy efficiency overall (Deike et al. 2008, cited in Flynn and Smith 2010), and emissions per unit grain equivalent produced decreased by 36.4%. Some scientists argue that reduced yields from a lack of agrochemical applications would result in an increased amount of land under cultivation, hence GHG emissions (Flynn and Smith 2010).

3.10.1 BAU weed control practices The use of herbicides to eliminate undesired plants from agricultural systems is the common BAU scenario in East and West Africa and Southeast Asian countries, if not across the tropics. Weeds are typically controlled with broad-scale application of herbicides, along with manual removal, oftentimes by slashing with machete o hoeing (Aguilar et al. 2003). In full-sun coffee monocultures, presences of weeds is inversely correlated to shade density (Staver et al. 2001).

3.10.2 CFPs for weed control that can lead to climate benefits Although the literature contains information on practices that can be implemented to avoid the use of herbicides in coffee, cocoa, and tea crops, the literature on GHG emission reductions and C sequestration associated with these CFPs is scarce or non-existent. An approximate value for CO2 emissions from herbicide use is 20.5 kg CO2 eq dose

-1 ha

-1 (data from Cool Farm Tool).

There are several management strategies that can reduce or eliminate the need for herbicides. As mentioned in previous sections, a ground cover of benign plants, either naturally grown or planted, can aid in repressing weeds during coffee establishment (Aguilar et al. 2003, Barberi 2002, Bradshaw and Lanini 1995, Hillocks 2000). Leaf litter and pruning mulch can also be used to suppress weed growth (Hillocks 2000, Staver et al. 2001). Mulch has also shown to reduce weed numbers by up to 60 days compared to non-mulched systems (Staver et al. 2001).Research


has shown that shade suppresses weed growth as well (Beer 1987, Carr 2001, Soto-Pinto et al. 2002), with less biomass from weeds and fewer species of weed recorded as the system ages (Aguilar et al. 2003). In one study, shaded coffee systems in Costa Rica reported less than 0.1 Mg weeds ha

-1 in systems with 50% or more shade,

compared to 3.6 Mg weeds ha-1

in non-shaded coffee systems (Staver et al. 2001). A study in Mexico found twice as many weeds in open-sun systems than shaded coffee systems (Staver et al. 2001). Manual removal of weeds, by hoeing or slashing, is also a non-herbicide, low-climate impact alternative to weed removal (Staver et al. 2001). All of the above CFP variations apply to perennial crop plantations. Prematilake et al. (2004) found that the best way to inhibit weed growth while maintaining optimal tea yields was integration of mulch, herbicide treatment, and selective weeding. Combining reduced pesticide applications with mulching and manual weeding is a stepwise improvement over the common BAU practice of relying solely on herbicide use to control weeds. In some cases, weeds can also be used as a soil cover. Weeds can adequately reduce erosion (Sarno et al. 2004), while also increasing soil nutrients; Sarno et al. (2004) showed that allowing Paspalum conjugatum on a coffee plantation in Indonesia resulted in significantly increased levels of C, N, available P, and Mg. However, utilizing weeds as a soil cover may cause the suppression of coffee plant growth. A study by Prematilake et al. (2004) found that weed cover suppressed tea growth; the authors recommended a combination of mulch cover and herbicide application to suppress weed growth and benefit tea yields.

3.10.3 Potential of weed control CFPs to reduce GHG emissions and/or increase C stocks Although there is very little information on GHG emissions from herbicide applications in coffee, cocoa and tea farms in East and West Africa and Southeast Asia, the GHG emissions associated with the general application of agrochemicals, including herbicides, have been calculated. Bellarby et al (2008) estimate that agrochemical application produces GHG emissions of 1.8-37.0 kg CO2 eq ha

-1. Lal (2004) reported that spraying herbicides

produces 0.7-2.2 + 1.4 equivalent carbon emissions (kg CE ha-1

). Neither of these figures are crop or country specific. However, there is some dispute whether limiting herbicide use ultimately decreases emissions, due to the trade-offs between fertilizer use and productivity and GHG emissions (Flynn and Smith 2010). The effect of alternative to agrochemical use on C stocks and GHG emissions can be found in other sections of this review (see cover crops, pruning/organic residue management, and shade trees). Growing cover crops and using prunings or litter as mulch can increase carbon stocks directly, through the addition of biomass to the system, if biomass production of the alternatives is greater than that produced by weeds. Increasing shade plantings can increase carbon storage on the farm over a longer timeframe due to the greater capacity of trees to accumulate C in biomass, litter, and soil.

3.11 Comparative Assessment of CFPs: Pest and Disease Control Management Pests and diseases are a problem within coffee, cocoa, and tea systems. In coffee, the coffee berry borer, Hypothenemus hampei, is the prime pest of coffee production. This pest affects coffee production in tropical countries around the world, including Ghana, Kenya, Tanzania, and Indonesia; in Tanzania, coffee berry borer has infested 90% of untreated plantations (Jaramillo et al. 2006). Coffee berry disease and African coffee root-knot nematode have similarly high infestation and yield loss rates (Nyambo et al. 1996). Other pests are numerous as well, and drive the need for pest management strategies (See Annex 7).

In tea, pests attack all parts of the tea plant, and can cause yield reductions of 5% - 55% if no pest management strategy is employed (Hazarika et al. 2009). At least 1,031 different species of arthropods are associated with tea production (Hazarika et al. 2009).

Cocoa loses, on average, 30% of its annual yield to pests and diseases (Dormon et al. 2007). The main pests include capsid bugs, shield bugs, and mealy bugs, while diseases like blackpod and epiphyte weeds also affect the plants. In Western Africa, cocoa losses, mainly to black pod disease and capsids, can be between 10% - 80% a year (Sonwa


et al. 2005). The majority of cocoa in Africa is produced by small farmers (Coulibaly et al. 2002), who struggle to buy pesticides and herbicides to combat pest and disease outbreaks (Dormon et al. 2007).

3.11.1 BAU pest control practices Pesticide use has become widespread in coffee (Adejuma 2005, Nyambo et al. 1996), cocoa systems (Ntiamoah and Afrane 2008), and tea systems (Hazarika et al. 2009, van de Wal 2008). Years of chemical use have led to a number of problems including chemical resistance of pests, outbreaks of new pests, environmental problems, human and livestock health issues, decreases in natural predators of pests, degraded drinking water, and an increase in the costs related to crop production (Nyambo et al. 1996, Dormon et al. 2007, Hazarika et al. 2009). Oftentimes farmers in developing countries with limited access to information will use insecticides improperly, with faulty equipment, or use an inappropriate insecticide for a particular task (Hillocks et al. 1999). Disposal of pesticide containers and unused pesticides is also problematic. Pest control using chemical sprays is expensive. For example, in Kenya pest control accounts for 25% - 30% of the total cost of production, primarily from the use of fungicides (Nyambo et al. 1996). As monoculture full-sun coffee production proliferates, the use of pesticides increases as well, since full-sun systems have little natural resistance to pests.

The use of pesticides in cocoa production is particularly widespread in Ghana, the greatest cocoa producer country in the world where 60% of agricultural labor is employed in the cocoa industry. Ghana initiated a Cocoa Disease and Pest Control Project (CODAPEC) to address disease and pests, the two major causes of reduced cocoa production (Dormon et al. 2007, Ntiamoah and Afrane 2008). This program allowed cocoa farmers to spray crops with insecticides and fungicides at no cost to the farmers, and resulted in increased cocoa yields (Ntiamoah and Afrane 2008), but increased environmental degradation and a financial and logistical burden for the government (Dormon et al. 2007). Tea production also utilizes a large amount of pesticides, resulting from the practice of growing tea in large monoculture plantations that have little natural resistance to pests and disease (Hazarika et al. 2009, van de Wal 2008).

3.11.2 CFPs for pest and disease control that can lead to climate benefits The environmental and economic drawbacks of agrochemical use have led to a push for a more holistic pest management strategy, termed integrated pest management (IPM) (Nyambo et al. 1996). It is stressed here, however, that pest management strategies are very site-specific, and we are unable to recommend an overarching CFP for coffee, tea, or cocoa. Some natural pesticides used in Africa are shown in Annex 8. These IPM strategies for reducing agrochemical use and concomitant GHG emissions include biological controls, farm management strategies, minimal chemical use, and improving the health and resilience of the entire system, but they are discussed below in general terms only. Utilizing shade trees is often mentioned as a way to reduce pest and disease incidence, however due to the complex interactions between shade trees and pest incidence, management recommendations can be only devised on a case-by-case basis (Rao et al. 2000). Coffee The environmental drawbacks of insecticides, and the potential risk of pest populations becoming resistant to chemicals, have fueled a push for a different approach to controlling the coffee berry borer. IPM strategies differ depending on the pests, and include the use of sprays, manual removal of pests, and farm management strategies (see Table 12 and Annex 9).

Table 12. Coffee pests and IPM strategies used to address them (from Jaramillo et al. 2006). Pest IPM Strategy Country/Region Citation

H. hampei Biological control Americas Jamarillo et al. 2006

Coffee berry borer Manual removal of berries from trees Global Jamarillo et al. 2006


and ground post and inter-harvest periods

Antestia bug Farm management: keep picked berries in mesh bags to trap emerging borers; cover containers at washing station, cover coffee dryer with mesh to prevent escaping borers

Global Jamarillo et al. 2006

Green scale Manual killing individuals; avoid overshading

Global Hillocks 2000

Coffee leaf rust Use of sprays made of soaps and botanicals

Global Hillocks 2000

Coffee leaf rust Mulching (conserves moisture, increases N fixation, decreases soil temperature, helps keep plants resilient in dry season)

Global Adejumo 2005

Cocoa IPM strategies recommended for cocoa production include changes in farm management, including the manual removal of weeds, pests, and diseased parts of trees, pruning, reducing shade to increase ventilation and reduce humidity, maintaining shorter trees for better pruning and spraying access, removing epiphytes, removing diseased fruits, removing and burying pod husk heaps, improving soil fertility, and using high-yield, pest-resistant, cocoa varieties (Adejumo 2005, Sanchez et al. 2003, Ntiamoah and Afrane 2008).

Tea For tea, IPM is also an alternative to pesticide use (van de Wal 2008). Only 3% of the arthropod pest species associated with tea are common throughout the world, therefore devising a panacea pest management strategy is difficult due to local variation in pests in different regions (Hazarika et al. 2009).

IPM strategies for tea include pruning, plucking, sanitation, tillage, application of fertilizers, water management, and manual removal of pests. Increasing pruning and plucking to every two to six years reduces pest density and population (Hazarika et al. 2009). Keeping fields free of farm animals such as cattle and goats can limit the spread of pests. Weed growth on tea plantations can harbour pests and compete with tea plants for nutrients; however weed growth also provides benefits for tea plantations, such as protecting natural predators and providing protective ground cover (Hazarika et al. 2009). Conservation tillage may increase the health of the tea plants, aiding in their natural resistance to pests (Hazarika et al. 2009). Maintaining tea plant nutrient levels with fertilizers, manure, and organic residues, also sustains plant health and increases resistance to pests (Hazarika et al. 2009). Although water is necessary for the growth of tea, water logging can create ideal environments for some pests, and should be avoided by proper drainage and mulching (Hazarika et al. 2009). Manual removal of pests can be feasible on small plantation or plantations with a large workforce. Using insect traps has also proven to be a successful strategy (Hazarika et al. 2009). Biological controls are also used in IPM strategies, however the predator released to control the pest differs by region and pest.

The role of shade trees Maintaining shade trees in a coffee, tea, or cocoa system is a pest management strategy, although the literature varies widely on how successful shade trees are in reducing pests, since shade trees’ effect on pests and diseases is complex.

One reason pest incidence can be less in agroforestry systems is that shade species are not intensively grown and the balance between insect pests and predators is maintained to a greater extent (Rao et al. 2000). Pest incidence is also influenced by the species of tree used and type of agroforestry system established. Pests on interspersed shade trees, shelterbelts and boundary plantings may only affect the crops in their vicinity, but may also act as barriers to the spread of insects (Rao et al. 2000). Vegetation outside of the cropped area affects pest populations


as well; although trees and shrubs can act as a haven for pests, they also house pest predators, and having trees and shrubs near cropped areas can allow migration of these predators into the fields. Some literature recommends the thinning of shade trees to reduce pests, particularly capsids, while other studies have shown that a greater degree of shade will have the same effect (Sonwa et al. 2005). Furthermore, variable levels of shade cover affect separate pests, disease and weeds differently (Sonwa et al. 2005) and complex shaded systems influence pests and growth in more complex ways (Rao et al. 2000). Increased heterogeneity throughout a complex system can decrease the spread of insects (Teodoro et al. 2009, Bos et al. 2007, Klein et al. 2002), as well as increase the incidence of pest predators (Klein et al. 2002), however it is the combination of certain species which reduce pests, not necessarily the overall diversity (Rao et al. 2000).

Soil interactions and temperature and humidity within the plot must also be taken into account. In systems where shade trees compete for resources and provide poor quality leaf litter, crop vitality, and therefore resistance to pests, may decrease (Rao et al. 2000). The microclimate created by shade trees may either positively or negatively affect pests, depending on the pest and crop plant involved (Rao et al. 2000). In one study, pests were positively influenced by temperature, but negatively influenced by humidity, characteristics found in less structurally diverse agroforestry systems (Teodoro et al. 2009).

3.11.3 Potential for pest and disease control CFPs to reduce GHG emissions and/or increase C stocks This review has not uncovered data that isolate the direct or indirect impacts of CFP alternatives to BAU pesticide usage specific to the crop and country focus of this study. Proxies can be ascertained by referring to sections on tillage, shade planting, fertilizer use, etc., as these individual practices in combination often comprise components of an IPM strategy.

3.12 Comparative Assessment of CFPs: On-farm Processing Practices On-farm processing of coffee, cocoa, and tea generates GHG emissions. After the crop is grown and harvested, it needs to be processed quickly. Each crop requires particular processing methods, and some of these methods use fuel sources which emit GHGs. In this section we discuss alternatives to current processing methods. Coffee: Coffee fruits must be processed immediately after harvesting to ensure that the pulp does not ferment and deteriorate (Hicks 2001). There are two main types of processing in preparation for roasting: the dry and the wet methods (Thompson et al. 2001). The dry method is the more traditional of the two methods, and is also the least expensive. This method entails separating and cleaning the ripe berries, spreading them in the sun, and regularly raking to dry them uniformly and avoid fermentation (Hicks 2001). After a few days the berries are placed in a drying room to remove excess moisture (Hicks 2001). The wet method removes pulp from the beans by machine, without drying them first. This method is used in Kenya and Tanzania and produces “washed” or “mild” coffees with a higher quality homogeneous bean; however, it requires more water, money, and labor (Hicks 2001). Cocoa: Ninety per cent of the world’s cocoa crop is grown on small farms with mixed cropping systems (Fowler 2009). Immediately after harvesting cocoa, fermentation and drying are carried out on the farm (also known as “curing”) (Thompson et al. 2001). Fermentation is necessary to create the correct color, flavor and smell for chocolate production; without curing, cocoa is bitter and astringent (Thompson et al. 2001). Fermentation requires that the fresh beans, which have been manually removed from the cocoa pods, be put in a pile, box, or basket where the pulp is naturally broken down into a liquid (called sweatings), which drains away (Thompson et al. 2001, Fowler 2009). Drying follows fermentation. On small-scale farms when the drying stage coincides with the dry season, the beans are spread out into the sun to be dried naturally and cheaply (Thompson et al. 2001, Fowler 2009). Other methods of drying include solar drying, where the beans are covered by a plastic roof and are sometimes aided by solar energy collectors or artificial drying, which involves heating the drying platform with firewood or other fuel (Thompson et al. 2001, Fowler 2009). Ghana and Indonesia typically do not use artificial drying methods (Fowler 2009).


Tea: Unlike cocoa and coffee, tea is usually grown on large-scale plantations, although 62% of Kenya’s tea production is attributed to small-scale farming (van de Wal 2008). Kenya and Indonesia are fourth and sixth in the world, respectively, for tea production, while Tanzania is a distant 13

th. There are two main types of tea produced:

green, which is unfermented, and black, which is fully fermented (van de Wal 2008). Processing tea involves drying and crushing the leaves, which are mechanized processes that involve withering, rolling, oxidation, and drying (van de Wal 2008).

3.12.1 BAU on-farm processing practices The impact of farm processing on GHG emissions varies greatly with the crop. For coffee, processing contributes less than 1.7% of the total GHGs emitted in production and processing (Salomone, 2003); for cocoa, processing accounts for 64% of GHG emissions, equivalent to 2.27 kg CO2 kg

-1 cocoa (Ntiamoah and Afrane, 2009). Energy

consumption for tea processing (withering, rolling drying, sorting and packing) accounts for roughly 30% of all production costs at the factory level; while GHG emission equivalencies for these energy inputs are not available, this is indicative of the significant impact tea processing has on the crops’ farm and factory-level emissions footprint (Jayasekara and Anandacoomaraswamy 2008). Coffee: Historically, coffee and cocoa have been sun-dried (Sharma et al. 2009). Sun-drying, however, is time intensive and when improperly done can be susceptible to disease, insect loss, deterioration from rain, wind, and moisture, and contamination (Sharma et al. 2009). Artificial mechanical drying has been developed to combat the drawbacks of sun-drying, however it is expensive and energy intensive. Cocoa: A typical cocoa farm operation employs the ‘sun drying’ method to dry cocoa beans, which is sustainable since it is based on solar energy (Ntiamoah and Afrane 2008). The industrial processing of cocoa, however, is one of the main contributors to the environmental impact of cocoa production due to the use of fossil fuels to heat boilers and roasters (Ntiamoah and Afrane 2008).

Tea: Tea processing uses a great deal of energy. The process of withering, drying, grading and packing uses 4 - 18 kWh kg

-1 of tea; 85% of the energy is used for heating (van de Wal 2008). The energy sources used for processing

include firewood, oil, natural gas, electricity, and hydroelectricity.

3.12.2 CFPs for on-farm processing that can lead to climate benefits A CFP to replace artificial mechanical drying is solar drying, which can be used for coffee, tea, and cocoa. Sharma et al. (2009) argue that solar drying, which uses the sun’s energy but which does not involve open-air drying, saves time, improves quality, is efficient, requires fewer start-up costs than mechanical drying, and produces no energy costs, but may be less effective in cloudy climates. This technology has not seen widespread use, however. Generally there are two categories of solar driers, active and passive. Passive dryers allow natural movement of heated air and can be made with local materials for small farms. Active dryers use fans or pumps to move heated air over the product (Sharma et al. 2009).

Improving the energy efficiency of cocoa processing is key to reducing the environmental impact of cocoa production. Ntiamoah and Afrane (2008) propose substituting diesel fuel by natural gas. Using natural gas instead of diesel lowers the GWP of a Ghana processing plant from 81% to 47% (Ntiamoah and Afrane 2008).

Reducing the amount of energy used for tea processing requires the use of renewable fuel wood sources and energy efficient machinery (van de Wal 2008). More energy efficient machines are needed because machines in current use are usually old and inefficient, but are rarely replaced because the energy costs associated with the machines are comparatively small to the entire cost or production (van de Wal 2008). Fuel wood, if available and well managed, can replace fossil fuels. However, the use of fuel wood for processing has led to extensive deforestation, particularly in Kenya. In response to this deforestation, Kenya has promoted fuel wood tree plantings. Natural gas and renewable energy may be better alternatives.


Some modern energy technologies can be employed on-farm to reduce energy use. Photovoltaic technologies, wind pumps, and bio-fuel cookstoves can be used for certain stages of crop drying and processing.

3.12.3 Potential of on-farm processing CFPs to reduce GHG emissions and/or increase C stocks Using solar drying or a drying system based on renewable energy instead of artificial drying based on fossil fuels directly eliminates or reduces GHG emissions caused by burning fossil fuels. In the case of fuel wood-based drying, the use of fuel wood plantations can reduce emissions from deforestation, and transitioning from oil-based fuels to natural gas to power cocoa processing facilities also reduces emissions. Using alternative fuel sources for the processing of tea, for example, can lead to a reduction of deforestation caused by the consumption of fuel wood from natural forests and will aid in maintaining forest C stocks.

3.13 Level II Comparative Assessment of CFPs: Crop Waste Management Practices Processing coffee and cocoa produces several types of solid and liquid waste. Current waste disposal practices for coffee and cocoa processing are inefficient and increase environmental degradation from processing. Processing and industrial wastewater can be treated in two different ways, on-site, or released into the domestic sewer systems and treatment plants. If it is treated in domestic sewer systems, the emissions are included in measurements of domestic use wastewater treatment (Doorn et al. 2006). Industrial wastewater with significant carbon loading treated under anaerobic conditions produces methane emissions, while N2O emissions from industrial wastewater occur to a minor extent directly from treatment plants, or indirectly after the water is released into natural bodies of water (Doorn et al. 2006).

3.13.1 BAU crop waste management practices Coffee processing creates a very large amount of organic waste materials in the form of pulp, residual water, and parchment (Rice and Ward 1996). In Latin America, this waste is released into waterways, decreasing oxygen available for marine life and creating a massive ecological problem.

Producing cocoa also produces a large amount of pod husk waste, whose disposal is difficult (Ntiamoah and Afrane 2008). An additional waste is the pulp which surrounds the cocoa seeds, which is allowed to drain off as liquid waste (Ntiamoah and Afrane 2008).

3.13.2 CFPs for crop waste management practices that can lead to climate benefits Recommendations to reduce coffee waste include using less water for the wet processing of the beans, which would reduce waste water, and composting husks with animal manure to use as fertilizer.

Coffee chafes and grounds should be composted and used as fertilizer (Salamone 2003). Turning coffee pulp into compost can help alleviate the amount of waste generated from coffee processing. Composted coffee pulp can also partially substitute inorganic soil fertilizer in sustainable coffee production (Chemura et al. 2009). Reusing wastewater is also recommended. Wastewater reuse in agriculture is recognized worldwide as an alternative water and/or nutrient source. In a study by Herpin et al. (2007), secondary treated wastewater (STW) from an anaerobic/ facultative pond system in Sao Paulo State, Brazil was used to irrigate coffee. They found that STW can effectively increase water resources for irrigation, however, innovative and adapted fertilizer/STW management strategies are needed to diminish the risk of sodicity and to sustain adequate and balanced nutritional conditions in the soil–plant system.


3.13.3 Potential of crop waste management CFPs to reduce GHG emissions and/or increase C stocks No studies have been identified that directly relate and quantify the potential of alternative crop waste management CFPs to reductions in GHG emissions or increases in carbon storage.

3.14 Level II Comparative Assessment of CFPs: Fuel Wood Extraction Fuel wood is the main source of energy used in rural households throughout sub-Saharan Africa (Jama et al. 2008). While data specific to fuel wood consumption in agricultural communities in Sub-Saharan Africa was not discovered, it is assumed that many rural households engage in farming activities. Some estimate that fuel wood accounts for 80% of the total energy used in sub-Saharan Africa (Jama et al. 2008), while others put the figure between 92 and 96% for Tanzania, Ghana, and Kenya (Bailis et al. 2005). The use of fuel wood and charcoal are projected to increase over the next thirty years, particularly in rural areas of Africa (Arnold et al. 2006). This demand for fuel wood, along with the demand for construction supplies, other wood products, and as a processing material for crops, such as tea, is putting a strain on remaining forests (Jama et al. 2008).

3.14.1 BAU fuel wood extraction practices Forests are thinned, degraded, or removed entirely in response to the need for wood products. Fuel wood extracted for the processing of tea and for charcoal production has led to massive deforestation in Kenya and other countries (van de Wal 2008). In Ghana, rural demand for fuel, furniture, and construction materials drives deforestation (Appiah et al. 2009).

3.14.2 CFPs for fuel wood extraction that can lead to climate benefits The suggested CFPs alternatives for fuel wood extraction reduce fuel wood use, through the use of alternative fuels and efficient stoves, (see household energy use for more discussion), or decrease wood extraction from primary forests.

In order to decrease fuel wood extraction from primary forest, one CFP option is to utilize timber and fuel wood from on-farm trees. Prunings from shade trees as well as coffee and cocoa plants can be used as fuel and construction materials (Rice 2008), thus reduce the pressure on natural forces for these materials.

Planting fallows or fuel lots on unused land is also a strategy to ease pressure on forests (see also degraded land reclamation). Farmers should be encouraged to cultivate and use these sources of wood before extracting wood from forests. The amount of wood available depends on planting density, tree growth rates and pruning regimes (Rice 2008). A study by Jama et al. (2008) found that a six month fallow on 0.25 ha of land could produce enough fuel wood to satisfy a household’s needs for 0.7-1.5 years, depending on the fallow species.

3.14.3 Potential of fuel wood CFPs to reduce GHG emissions and/or increase C stocks Fuel wood CFPs mainly decrease GHG emissions by reducing deforestation and forest degradation (Albrecht and Kandji 2003, Cooke et al. 2008). Primary forests have greater C stocks than degraded or agricultural land and f orest conversion caused by fuel wood extraction results in loss of C stocks. In order to avoid these losses, it is preferable to grow fuel wood on already degraded land or in fallows; by doing so, C stocks of this reforested land may actually increase (see also the section on reclaiming degraded land). Furthermore, since fuel wood extraction causes increased erosion in some areas, decreased fuel wood extraction may reduce C losses due to erosion (Cooke et al. 2008).


3.15 Level II Comparative Assessment of CFPs: Reclaiming Degraded Land Degraded land is land that has lost basic ecosystem functions, such as erosion control, carbon storage, nutrient cycling, water retention, climate regulation, or desired levels of productivity (Verchot et al. 2010). Vegetative as well as soil physical or chemical degradation can occur and, in many cases, these processes interact. Land can be reclaimed for agricultural purposes, or returned to a natural state, and in so doing, may increase C sequestration and decrease GHG emissions. However, the potential amount of emission reduction and carbon storage depends on the status of the degraded land, the climate, the species, and the time scale for recovery (Silver et al. 2002, Mutuo et al. 2005, Verchot et al. 2010). Severely degraded land may produce few GHG emissions due to previous large losses of C and N and the lack of environmental conditions conducive to plant growth, but can serve as a sink for GHGs under appropriate conditions.

3.15.1 BAU practices for degraded land reclamation Land is often abandoned in a degraded state as a result of logging, shifting agricultural systems, mining, and other exploitative disturbances (Blay et al. 2008). Such actions have degraded 32% of reserved forests and 70% of non-reserved forests in Ghana (Blay et al. 2008). These lands may have problems of erosion, salinization, acidification, loss of organic matter, and loss of plant productivity (UNFCCC 2008). Degraded land is often found amongst productive agricultural land and forest remnants and is frequently fragmented (Lamb et al. 2005).

3.15.2 CFPs for degraded land reclamation that can lead to climate benefits In the tropics, no converted land stores as much carbon as natural ecosystems, thus avoiding initial deforestation and reclaiming and using previously degraded land should be a priority (Bellarby et. al. 2008). Restoration of degraded land can be aimed towards 1) a return to the natural climax ecosystem or 2) recuperation of agricultural productivity. Restoration efforts are often focused on buffer zones, steep slopes, corridors, and riparian areas due to their fragility or ecological importance (Lamb et al. 2005). While it is preferable to return degraded lands to their climax state, in practice farmers must assess the trade-offs and feasibility between maximizing carbon sequestration and the economic value of recovering degraded lands for agricultural production or other uses. When agricultural land is not in high demand or the area is of low productivity, farmers can allow natural reclamation to occur, or plant forest plantations. Natural reclamation can occur at a very slow rate or not at all, particularly when the land is severely degraded (Uhl et al. 1982, Lamb et al. 2005, Parrotta et al. 1997, Omeja et al. 2011). Restoration plantings may aid natural reclamation, however this strategy is often costly and difficult (Lamb et al. 2005, Parrotta et al. 1997, Macedo et al. 2008, Omeja et al. 2011). Forest plantations are stands of trees that are purposefully planted for commercial purposes with one or more species of indigenous or exotic trees, usually of the same age and planted at a regular spacing (IPCC 2006). Forest plantations, although not as ideal as natural reclamation because of their lower carbon sequestration potential and lower diversity compared to natural forests (Lamb et al. 2005), nevertheless can provide goods and services to farmers, while sequestering C (Lal 2009), but usually have high up-front costs and long pay-off periods. Forest plantations planted with diverse native tree species can result in greater biodiversity and enhanced ecosystem services (Lamb et al. 2005) and can also aid the natural regeneration process, if the restoration of a climax ecosystem is the ultimate goal (Parrotta et al. 1997, Omeja et al. 2011).

3.16.3 Potential of CFPs for reclaiming degraded land to reduce GHG emissions and/or increase C stocks Restoring degraded land with natural vegetation or planted trees can sequester C at a higher rate than leaving it in a degraded form (Silver et al. 2000, Macedo et al. 2008, Lal 2005b, Lal 2009).


An indirect benefit of reclaiming degraded land is to reduce the pressure for forest conversion to agriculture. By reclaiming deforested and degraded land and using it for commercial crop cultivation, further deforestation can be avoided; carbon stocks and biodiversity can also increase during the reclamation process (Anim-Kwapong 2003). Fire wood may also be produced, thus reducing pressure on natural forest. Although it may be difficult to restore C stocks of degraded land to levels similar to natural forest, significant opportunities exist to increase rates of carbon storage of degraded land (Silver et al. 2000, Lal 2005b, Lal 2009, Macedo et al. 2008). A study conducted by Macedo et al. (2008) found that recovering forests in Brazil contained greater C and N stocks than degraded land, but less than native forest. Forest plantations also sequester C, but not on as large of a scale as natural forest. Silver et al. (2000) found in their literature review of tropical reforestation that AGB increased significantly with an increase in time; however the rate of increase for biomass and soil carbon was faster in the first 20 years of growth than the next 80 years. Reforestation of previously forested sites accumulated the most C (1.17 Mg C ha

-1 y

-1),

while reforestation of land previously used for agriculture sequestered the least C (0.25 Mg C ha-1

y-1

). Verchot et al. (2011) found that soil C accumulation in improved fallows on degraded land resulted in only a small amount of the soil C being stored in long-term pools, while the majority was subject to more rapid turnover, particularly with declining inputs.

3.17 Level II Comparative Assessment of CFPs: Household Energy Use Household energy use includes energy used in non-processing/manufacturing or transportation areas of a farm, such as the energy used for cooking, cleaning, boiling water, heating, and lighting buildings on the farm. Biofuels or solid fuels, including charcoal, dung, wood, and crop residues, supply energy for between one third and one half of the world’s population (Bailis et al. 2003). Although the use of biomass was not initially considered to be a major contributor to global climate change, it is gaining more attention, as burning biomass as fuel makes up 10% of global energy use (Johnson and Lambe 2009), and is projected to increase over the next 30 years, particularly in rural Africa (Table 13).

Table 13. Past and projected fuel wood use in Asia and Africa (Arnold et al. 2006 adapted from Broadhead et al. 2001)

Region 1970 1980 1990 2000 2010 2020 2030

Fuelwood (million cubic meters)

South Asia 234.5 286.6 336.4 359.9 372.5 361.5 338.6

Southeast Asia 294.6 263.1 221.7 178.0 139.1 107.5 81.3

East Asia 293.4 311.4 282.5 224.3 186.3 155.4 127.1

Africa 261.1 305.1 364.6 440.0 485.7 526.0 544.8

South America 88.6 92.0 96.4 100.2 107.1 114.9 122.0

Charcoal (million tons)

South Asia 1.3 1.6 1.9 2.1 2.2 2.4 2.5

Southeast Asia 0.8 1.2 1.4 1.6 1.9 2.1 2.3

East Asia 2.1 2.3 2.3 2.2 2.1 2.0 1.8

Africa 8.1 11.0 16.1 23.0 30.2 38.4 46.1

South America 7.2 9.0 12.1 14.4 16.7 18.6 20.0

Solid fuel is typically burned over an open fire, or in mud, clay or metal stoves, which leads to inefficient combustion and fuel use, as well as emissions of GHGs, including CO, NO and CH4 (Bhattacharya et al. 2000, Johnson and Lambe 2009). The percentage of rural households that use fuel wood for cooking is 96% in Tanzania, 88% in Ghana, and 81% in Kenya (Table 14). Charcoal, although widely used in these countries, is used predominantly in urban areas (Bailis et al. 2005). Fuel wood emits 200-400 g C kg

-1 of fuel, while charcoal releases

2600 g C kg-1

of fuel throughout its life cycle (Bailis et al. 2003).


Table 14. Percentage of households using bio- or solid fuels (adapted from Mehta et al. 2006). Country Percentage of household using solid

fuels Year

Ghana 88% 2003

Kenya 81% 2004

Tanzania 96% 1992-1993

Indonesia 72% 2003

In developing countries such as Kenya, these solid fuel-derived GHG emissions can equal those from fossil fuel use (Bailis et al. 2003). Furthermore charcoal and fuel wood production leads to deforestation and its ensuing GHG emissions (van Beukering et al. 2007); indeed, the main cause of deforestation in Tanzania is charcoal production (van Beukering et al. 2007). Although fuel wood is not an ideal fuel source, fuel wood scarcity causes other problems for smallholder farmers. Lack of fuel wood can cause farmers to use dung and crop residues as fuel, thereby limiting the amount remaining for use as fertilizers (Jama et al. 2008). Such inputs can be better used as fertilizers for crops (Cabraal et al. 2005). In Kenya, using residues and dung caused less organic matter to be returned to the soil, which led to decreased production (Jama et al. 2008).

3.17.1 BAU practices for household energy use Biomass fuels are used throughout Africa mainly for cooking, which may make up to 90% of the household energy demand (Johnson and Lambe 2009), but also for lighting, space heating, charcoal production and agro-processing (Karekezi and Kithyoma 2002). Fuel wood emits most of its GHGs during combustion, and the majority of stoves burning fuel wood are inefficient. Although fuel wood is predominantly used in rural areas, charcoal is often produced in rural areas and then sold to urban areas, as is the case in Tanzania (van Beukering et al. 2007). Charcoal production emits large amounts of GHGs, directly from its production and indirectly through the effects of deforestation (Bailis 2009). Although charcoal can be made from agricultural residues and timber waste (see section on biochar), a large amount of charcoal is produced from native forest vegetation (Bailis 2009, van Beukering et al. 2007).

3.17.2 CFPs for household energy use that can lead to climate benefits The literature is somewhat divided on the best fuel to use to decrease GHG emissions. While some literature cites fossil fuels such as LPG and kerosene to release a higher amount of GHGs than solid fuels, other sources argue that switching from solid fuels to fossil fuels reduces the amount of GHGs emitted worldwide by 1% - 10% (Cooke et al. 2008). Fossil fuel use may also decrease deforestation. A program started in 1974 in Senegal, aimed at substituting biomass fuel with LPG, was estimated to have avoided, by 2002, the use of 334,500 tons of charcoal and the deforestation of 40,500 ha of forest (Johnson and Lambe 2009). The CFPs for household energy use are: improved kilns for charcoal production, selective and sustainable fuel wood extraction, improved stoves for household use, and the use of renewable energy technologies, when available. Bailis et al. (2005) argue that the most effective household energy use strategy for reducing GHG emission from sub-Saharan Africa would be the use of sustainable fuel wood lots, more efficient charcoal production, and more efficient charcoal use using improved kilns and stoves. Charcoal production has proven to be a major emitter of GHG. Charcoal production can take many forms; pyrolysis takes place in pits, earthmound, brick, or metal kilns. These traditional kilns can be replaced by more efficient kilns (see Annex 10). Ensuring that fuel wood and charcoal are extracted from sustainable sources, such as fallow land , shade trees , crop prunings , and reclaimed degraded or unused land, can decrease the net emissions from deforestation (Bailis


et al. 2005, Bailis 2009) (see fuel wood extraction). The use of fossil fuels such as LPG can also reduce deforestation and GHG emissions compared to fuel wood extraction from natural forests. The use of improved stoves is championed as a way to decrease GHG emissions associated with biomass fuels. Improved charcoal stoves increase the efficiency of burning charcoal by letting less heat escape, which allows energy to be directed to where it is needed, resulting in less fuel used (van Beukering et al. 2007). Improved woodstoves work much the same way in reducing heat loss, increasing combustion efficiency, and increasing heat transfer (Karekezi and Kithyoma 2002). Other renewable energy options that have been suggested and/or introduced to African regions are wind pumps for water pumping, pico- and micro-hydropower, and phovoltaic (PV) energy. The latter is mostly useful for lighting and communications, but does not provide enough energy for most agricultural practices (Karekezi and Kithyoma 2002).

3.17.3 Potential of CFPs for household energy use to reduce GHG emissions and/or increase C stocks The majority of emissions from charcoal originate from its production. The production of 1 kg of charcoal has been shown to produce 1800 g of CO2, 220 g of CO, and 44 g of CH4, and accounts for 70% of total non-CO2 GHG emissions from charcoal production and use (Bailis et al. 2003). The use of improved kilns can make charcoal production more efficient and hence lessen GHG emissions from fuel use. Improved kilns have efficiency ratings of 20% -35%, while traditional kilns have efficiency ratings of 10% - 20% (van Beukering et al. 2007). Annex 10 shows the efficiency percentage of traditional kilns and improved kilns. The reduction of charcoal and fuel wood use due to more efficient stoves will also reduce deforestation and loss of biomass and soil C stocks (van Beukering et al. 2007). Improved stoves reduce total emissions from the combustion of fuel wood and charcoal by improving efficiency (Bailis et al. 2003, Cooke et al. 2008). Improved stoves emit about 40% less CO2 equivalent per kg of fuel than traditional stoves (Bhattacharya and Abdul Salam 2002). Annex 11 compares the emissions for traditional stoves, improved stoves, and fossil fuel stoves. Due to the greater efficiency of improved stoves, less fuel is needed, thus decreasing the pressure on forested areas (Bhattacharya and Abdul Salam 2002). Ensuring that fuel wood and charcoal come from sustainable sources is important in limiting indirect GHG emissions from forest degradation and soil C loss resulting from fuel wood extraction (see fuel wood extraction); to this end, on-farm sustainable fuel wood lots and fallows can be employed.

Renewable energy systems, such as PV energy, wind pumps, and hydropower, use renewable sources of energy that do not emit any GHG emissions, unlike solid fuels which, although renewable, produce extensive GHG emissions. The use of these energy technologies helps to decrease the use of solid fuels (Karekezi and Kithyoma 2002). Insulating a household and increasing natural lighting decreases fuel consumption, as fires are typically kept burning for heat and light, which increases fuel consumption (Bailis et al. 2003).

3.18 Level II Comparative Assessment of CFPs: Domestic Wastewater Management Wastewater

8 from domestic sources includes human sewage along with other wastewater such as water from

showers, sinks, and washing machines. Wastewater from housing or domestic use can be treated in a variety of ways: on site (uncollected), in a sewage plant (collected), or can be of disposed of untreated (Doorn et al. 2006).

8 To date little/no literature has been found specific to wastewater management in the tropical agricultural systems this review

focuses on, thus literature cited is from broader studies on wastewater from any domestic sources in east and west Africa and southeast Asia.


Wastewater can be a source of both methane, when treated or disposed anaerobically, and nitrous oxide emissions (Doorn et al. 2006).

3.18.1 BAU practices for domestic wastewater management GHG emissions from domestic wastewater differ depending on the type of sewer and treatment facility used. Closed underground sewers, more likely found in developed countries or developed urban areas, are not thought to be a major source of methane emissions (Doorn et al. 2006). Open sewers, however, are subjected to the sun’s rays, which create ideal anaerobic conditions for methane emissions (Doorn et al. 2006). As temperatures increase, the rate of CH4 production, and therefore emissions, increases as well (Doorn et al. 2006). N2O is another GHG emitted from wastewater, and is caused by the degradation of nitrogen components, such as urea, nitrate, and protein (Doorn et al. 2006). Nitrification and dentrification processes produce N2O emissions in treatment plants and other water bodies that contain wastewater (Doorn et al. 2006). The treatment of wastewater also emits CO2 through the treatment process itself, and also through the energy required to run the treatment facility (Cakir and Stenstrom 2005).

3.18.2. CFPs for domestic wastewater management that can lead to climate benefits The CFPs suggested depend on the concentration and volume of wastewater in question. For low strength wastewater, an aerobic treatment process will release less GHGs, however for wastewater of higher strengths, anaerobic methods release less GHGs, although the turnover point depends on the efficiency of the treatment system (Cakir and Stenstrom 2005).

Clearly defined CFPS have not been established, however the type of treatment that wastewater receives can inform the selection of a CFP in accordance with the farm wastewater management scenarios and capacity for improving wastewater management systems. A preliminary indication of the amount of emissions that certain wastewater systems produce is provided below (Table 15).

Table 15. GHG emissions potential from wastewater systems (from Doorn et al. (2006).

CH4 and N20 Emission Potentials for Wastewater and Sludge Treatment and Discharge Systems

Types of Treatment and Disposal CH4 and N20 emission potentials

Co

llect

ed

Un

trea

ted

River Discharge

Stagnant, oxygen-deficient rivers and lakes may allow for anaerobic decomposition to produce CH4. Rivers, lakes and estuaries likely sources of N20.

Sewers (closed and underground) Not a source of CH4/N20.

Sewers (open) Stagnant, overloaded open collection sewers or ditches/canals are likely significant sources of CH4.

Trea

ted

Aerobic Treatment

Centralized aerobic wastewater treatment plants

May produce limited CH4 from anerobic pockets. Poorly designed or managed aerobic treatment systems produce CH4. Advanced plants with nutrient removal (nitrification and denitrification) are small but distinct sources of N20.

Sludge anaerobic treatment in centralized aerboci wastewater treatment plant

Sludge may be a significant source of CH4 if emitted CH4 is not recovered and flared.

Aerobic shallow ponds

Unlikely source of CH4/N20. Poorly designed or managed aerobic systems produce CH4.


Anaerobic Treatment

Anaerobic lagoons Likely source of CH4. Not source of N20.

Anaerobic reactors May be significant source of CH4 if emitted CH4 not recovered and flared.

Un

colle

cted

Septic Tanks Frequent solids removal reduces CH4 production.

Open pits/Latrines Pits/latrines likely to produce CH4 when temp and retention time favorable.

River Discharge See above.

3.19 Level II Comparative Assessment of CFPs: Biochar application Biochar is created by combusting biomass in the absence of oxygen. This process converts biomass, such as wood, grasses, and crop residues, into bio-oil (syngas) and a charcoal-like solid called biochar or agri-char (Lehmann 2007, Gaunt and Lehmann 2008, Verheijin et al. 2009). Biochar can be used as a biofuel, as well as a soil amendment. When used as a soil amendment, biochar has the potential to sequester large amounts of carbon from the atmosphere for hundreds, or possibly thousands of years (Lehmann 2007, Laird 2008).

3.19.1 BAU practices for biochar application Creating and applying biochar to soil is a new and somewhat controversial response to climate change. Ideally, biochar production would make productive use of agricultural residues, processing waste, non-commercial timber, and municipal green waste (Sohi et al. 2010), that is typically discarded and left to decompose or burned. The use of biochar as a biofuel would be expected to produce GHG emissions similar to those from charcoal production. Perhaps greater benefits would be produced by adding it to soil, since studies have shown that emissions are reduced by 12% - 84% if biochar is added to the soil instead of burned (Gaunt and Lehmann 2008, Lehmann 2007, Fowles 2007).

3.19.2 CFPs for biochar application that can lead to climate benefits A potential CFP for biochar is to produce biochar from usually discarded biomass and use it to amend agricultural soils. Although the use of coffee and cocoa waste has not been cited in the literature, rice husks and groundnut shells have been used to produce biochar (Lehmann et al. 2006). Biochar yields, however, depend on the type of residue used and the duration and temperature of pyrolysis; further information on GHG emissions during this process is needed. Charcoal waste, or pieces of charcoal too small to be sold or used as fuel, which in some locations amounts to 40-50% of total charcoal production (Lehmann et al. 2006), can also be added to soil as biochar. Applying biochar to soils may increase soil C storage and soil charge and nutrient retention. Studies indicate that that incorporated biochar can increase soil fertility, biomass productivity (some estimates at 20-200%), nutrient availability, fertilizer efficiency, and improve soil structure and water retention (Roberts et al. 2010, Gaunt and Lehmann 2008, Renner 2007, Sohi et al. 2010); more research in this area would be valuable. If crop residues, prunings, or other organic materials are used to produce biochar, the trade-offs of using these materials in this way vs. adding them to soil as un-combusted organic nutrient sources need to be considered. Application rates and the placement of biochar to maximize crop production benefits are not sufficiently explored in the literature. Crop production has been reported to increase with biochar loading up to 140 Mg C ha

-1

(Lehmann et al. 2006), however some studies show that biomass production decreases with high rates of biochar applications, though exact numbers are difficult to verify (Verheijen et al. 2009). High application rates such as those mentioned above raise the question of whether such large quantities of residues are available, especially on small farms, and the magnitude of the costs of their collection and processing.


With regards to placement, biochar can be incorporated into the topsoil using tillage, applied to depth via pneumatic systems or repeated plowing, or surface applied. The former two methods have associated C losses due to soil disturbance, whereas with surface application, the incorporation of biochar is slow and susceptible to loss by erosion.

3.19.3 Potential of CFPs for biochar application to reduce GHG emissions and/or increase C stocks Application of biochar to soil has been shown to directly reduce emissions of CH4 and N2O (Renner 2007); the former has been shown to be completely eliminated in one study, while the latter was reduced by 14-90%, depending on soil type and structure (Gaunt and Lehmann 2008). Underlying mechanisms are unclear (Gaunt and Lehmann 2008) and merit further research. A study by Yanai et al. (2007) suggests that the relationship between N2O suppression and biochar application is related to the moisture and aeration conditions of the soil. Biochar may also reduce GHG emissions if increased nutrient retention in soils caused by biochar results in decreased fertilizer applications (Gaunt and Lehmann 2008, Roberts et al. 2010). The process of creating biochar from biomass results in emission of 50% of the C stored in the biomass; the remaining C is largely microbially recalcitrant and its further decomposition is limited. As a result, 20% - 50% of the original C is stored as biochar, with a mean residence time of several hundred to thousands of years (Renner 2007). In comparison, unpyrolyzed organic residues applied to soil emit C more slowly, but for longer periods of time, resulting in only 10% - 20% of the original C remaining after 5-10 years (Lehmann et al. 2006).

4. Interactions Among Level I CFPs A number of CFPs are complementary in their ability to affect GHG emissions and C storage and combining them can result in more-than-additive gains. These include mainly the following: reduced tillage, cover crops, shade trees, prunings and organic residues, and inorganic fertilizers (Table 16 and Annex 12). In combination, they can interact to protect soils and reduce erosion, moderate soil temperature, reduce moisture evaporation and increase infiltration, maintain or increase soil fertility, reduce weeds, and lessen the use of purchased inputs by farmers. On the other hand, sequential practices such as improved fallows, fuel wood lots, and forest plantations can increase C stocks of degraded agricultural land, provide fuel wood and secondary forest products, and increase biodiversity. Some CFPs are also multi-purpose and can help play a number of beneficial roles in the cropping systems considered (Table 17). For example, single CFPs, such as cover crops, shade trees, and organic mulch can affect simultaneously numerous system attributes such as weeds, pests, erosion, C and soil nutrients, and soil temperature and moisture. The matrices below indicate the principal interactions among CFPs and the multi-functionality of some practices. A short narrative follows to provide further explanation. Table 16. Complementarity among Tier I CFPs

CFPs Improved fallows

Reduced tillage

Cover crops

Inorganic fertilizers

Prunings, Organic residues

Shade trees

Irrigation alternatives

Improved

fallows

X

Reduced

tillage

X X X

Cover crops X X X X

Inorganic X X X X X


Table 17. Multi-functionality of some Level I CFPs

Improved fallows: Improved fallows can improve the soil physical properties and nutrient status of abandoned land and reduce weeds and weed propagules, thereby reducing the need for inorganic fertilizer and herbicides during subsequent cropping cycles. Depending on species composition, improved fallows may also provide secondary forest or non-timber forest products to farmers. Reduced tillage: Reduced tillage is often coupled with soil covers, in the form of litter, weeds, and cover crops, to protect the soil from sun, rain, and erosion while providing nutrients to the soil and suppressing unwanted weeds (de Rouw et al. 2010). Some argue that reduced or no-till should be part of a package that includes mulch, cover crops, herbicides, fertilizers, and crop rotations, without which reduced tillage does not provide the intended results (de Rouw et al. 2010). Cover crops: Cover crops can be associated with other forms of organic residue management such as pruning applications and shade plantings, both of which add litter to soil and can increase soil nutrients and soil C, besides aiding in weed and pest control. Leguminous cover crops can also be coupled with no-till systems to increase carbon sequestration, aggregate stability, SOM, soil enzymes, and microbial biomass (Scholberg et al. 2010a). Inorganic fertilizers: Combined application of inorganic fertilizers with organic inputs (plant residues, prunings, manure), instead of purely synthetic applications, can enrich soil carbon stocks by adding C to the soil and reducing outlays for purchased inputs. Pruning/organic residue management: Organic residues can be produced by crops, tree prunings, litterfall, and cover crops and hence are affected by these practices. In turn, organic inputs can reduce inorganic fertilizer use

fertilizers

Pruning/org-

anic residues

X X X X X

Shade trees X X X X

Irrigation

alternatives

X X

CFPs

Function of CFP

Soil protection/

Erosion control

Temperature moderation

Water retention/ Reduced

evapotranspo-ration

Soil nutrients

and C stocks

Weed control

Pest control

Energy use

Secondary products

Improved

fallows

X X X X X X

Reduced

tillage

X X X X

Cover

crops

X X X X X ? X

Inorganic

fertilizers

X

Pruning/

Organic

residues

X X X X X ? X X

Shade trees X X X X X ? X X

Irrigation

alternatives

X X X x


and associated GHG emissions, as well as protect the soil, conserve soil moisture and improve water holding capacity, moderate soil temperatures, and reduce weeds. Shade trees: Shade trees often provide multiple benefits alone or in combination with other management practices, which increases their impact on total net C sequestration and GHG emissions. Benefits from shade trees include soil protection/erosion control, moderation of soil temperature, increased infiltration and soil water holding capacity, reduced evapotranspiration, increased nutrient and C stocks, and secondary forest products for the farm economy. Irrigation: Shade trees and organic residues can contribute to reduced temperatures and increased moisture retention thus contributing to drought mitigation and crop drought tolerance and the reduction of energy use for irrigation. These trees may also produce secondary forest products. Weed control: Although the elimination of herbicides causes a direct reduction of GHG emissions related to their manufacture, reductions of GHG emissions and increase in C stocks can result from weed control practices such as shade planting, cover crops, and prunings used as mulch. Shade produced by cover crops or shade trees can limit weed growth or promote a shift in weed composition (Soto-Pinto et al. 2002). Shade trees also help to maintain a mulch layer, which is advantageous for weed control (Staver et al. 2001). Employing several of these weed control practices can increase net C sequestration and lower net GHG emissions.

5. Indication of Potential for CFPs to Increase Adaptive Capacity Depending on geographic location, climate change is expected to result in changes in the quantity and seasonal distribution of rainfall, increased temperatures, or more frequent extreme weather events (Gay et al. 2006, Kandji et al. 2006, Verchot et al. 2007, Lin 2010). Changes in local climates will increasingly affect the production of coffee and cocoa, since their production responds significantly to temperature changes and stress (Gay et al. 2006). The ability of CFPs to affect coffee, cocoa, or tea´s resilience to climate change differs by practice. In general, CFPs can be classified according to their ability to 1) moderate air and soil temperature, 2) mitigate drought or conserve soil moisture, 3) protect the soil surface from rainfall impact and erosion, and 4) enhance economic adaptability to climate or market fluctuations. These characteristics of the CFPs are summarized in the table below, which is followed by a fuller explanation.


Table 18. Ability of Tier I CFPs to aid in mitigation or adaptation to climate change.

CFPs

Adaptive Characteristic

Moderate temperature

Mitigate drought/conserve

soil moisture

Soil protection/erosion

reduction

Enhance livelihoods (increase revenue)

Improved fallows X X X X

Reduced tillage X X

Cover crops X X X

Inorganic fertilizers X X

Prunings, organic residues

X X X X

Shade trees X X X X

IPM pest control X


X X X

Improved fallows: Improved fallows may mitigate changes in rainfall and an increase in dry seasons and temperatures, since they have been shown to reduce soil temperatures, erosion, and to increase water infiltration and water holding capacities compared to natural fallows (Kandji et al. 2006). Reduced tillage: No-till and conservation tillage can increase adaptive capacity by improving soil structure and infiltration rates, which allows soil to better resist flooding and erosion from extreme weather events (Sims et al. 2009). Cover crops: Cover crop CFPs, particularly in combination with shade trees, can help maintain a favorable microclimate for associated commercial crops (Scholberg et al. 2010a). These CFPs may also help a farmer adapt to extreme weather events such as heavy rain and hail, by protecting the soil from compaction or erosion (Scholberg et al. 2010a), as well as conserving soil moisture. Pruning and organic residues: Many organic residue management CFPs increase adaptive capacity directly, by increasing protection of crops from extreme weather events. For example, maintaining mulch on the soil surface is expected to moderate soil temperature, help retain moisture, and protect the soil surface. Indirectly, these CFPs are expected to reduce the need for agrochemicals, resulting in lower GHG emissions and lower capital costs for small farmers. Shade trees: Shade trees protect crops from extreme weather events, provide a more stable and moderated microclimate, reduce evapotranspiration of crops, conserve water, and protect the soil (Beer 1987, Beer 1998, Albrecht and Kanji 2003, Anim-Kwapong 2003, Lin et al. 2008, Brenner 1996; Jackson and Wallace, 1999). This benefit has been shown with coffee (Dossa et al. 2008, Beer 1987, Lin et al. 2008) and tea in Tanzania (Beer 1987). However, although shade trees reduce evapotranspiration of crops, the whole system per unit area may have greater evapotranspiration rates than a non-shaded system (Verchot et al. 2007). These functions of shaded systems are important because coffee cultivation has increasingly spread towards marginal lands, where water shortage and unfavourable temperatures constitute major constraints to coffee yield (DaMatta and Ramalho 2006). For smallholders who have little access to improved agricultural technologies, shade trees may be a sustainable and financially viable coping strategy to mitigate the harmful consequences of changing global climate (Lin, 2007).


The use of windbreaks as a drought mitigation technique for tea has produced mixed results. Although it is widely believed that windbreaks reduce drought stress, a study in southern Tanzania showed that wind-exposed tea suffered less water stress in the dry season than tea sheltered from wind, perhaps because of the cooling effect of wind on tea (Carr 2010b). Wind-sheltered tea did, however, produce greater yields when drought stress was negligible (Carr 2010b). These various results show that broad recommendations are difficult to make regarding shelter belts for tea. In cases where water supply is limited, careful selection of shade species may yield additional adaptive benefits. For example, intercropping Gliricidia spp. with cocoa trees in Southeast Asia may limit drought stress of cocoa trees, since Gliricidia and cocoa trees exhibit different root structures that reduce competition for water in times of scarcity while maintaining microclimate benefits provided by shading (Moser et al. 2010, Schwendenmann et al. 2010). These features can reduce farmer economic vulnerability to drought events. Shade cover provides economic benefits as well. Shade cover, in the form of complex agroforestry, is an adaptive practice that can help farmers hedge against volatile commodities markets, by decreasing input costs and providing other crops and products for sale (Albrecht and Kandji 2003; Beer et al. 1998). Shade trees can provide fuel wood as well as increase the adaptive capacity of associated crops. Planting additional trees on one’s land can increase farmers´ financial adaptive capacity, but usually involves some additional costs. Timber and firewood, when sold, can help a farmer avoid economic downturns when commercial crop prices are low, by providing a separate source of income (Peeters et al. 2003). The savings generated by the substitution of farm-grown wood for purchased materials may also exceed the income from the sale of timber in some markets (Rice 2008). Pest control: A changing climate, and accompanying extreme weather events, may affect market prices of coffee, tea, and cocoa. Since pesticides and fungicides are generally expensive, decreasing pesticide use via IPM allows farmers to reduce their costs, which enables them to weather market fluctuations to a greater degree. Irrigation: Alternatives to irrigation, such as shade trees, can increase drought tolerance by limiting transpiration and soil evaporation, increasing infiltration, and decreasing runoff (Brenner 1996, Jackson and Wallace 1999, Lin et al. 2008, Lin 2010). In one study (Lin 2010), soil evaporation and evaporative demand for crop transpiration were compared in coffee systems under different levels of shade canopy during both the wet season and dry season. With 60% - 80% shade cover, daily soil evaporation rates decreased by 41% compared to sites with 10% - 30% shade; in the dry season, high levels of soil moisture were maintained with 30% - 65% shade cover (Lin 2010).


6. Potential Relative Impact on GHG Emissions Rreductions and/or Enhanced C Storage of Proposed CFPs

The table below (Table 19) summarizes the potential impacts of adoption of the Level I CFPs mentioned in this review. Given the limited data base and large uncertainty surrounding many of the CFPs, impact is classified in qualitative, rather than quantitative, terms. The degree of impact is defined as: Table 19: Degree of Impact Definition

Degree of Impact Definition

Low The CFP shows a noticeable, but small change in either reduction of GHG emissions or increase in C stocks, over the BAU practice.

Moderate

The CFP shows a noticeable and significant change in either the reduction of GHG emissions or increase in C stocks over the BAU practice, through direct benefits, and a low to moderate change in GHG emission from indirect benefits (e.g. reduction of GHG emissions from agrochemical production due to their substitution by other CFPs).

High The CFP shows noticeable, significant, and substantial change in reduction of GHG emissions and an increase in C stocks over the BAU practices, through direct benefits, and moderate change in GHG emissions due to indirect benefits.

The time-scale for these impacts is defined below: Table 20: Impact Accrual Timeframe.

Impact Accrual Timeframe

Description Timeframe for substantive accrual of impacts

Immediate Upon implementation

Short-term < 1 yr from implementation

Mid-term 1-5 yrs from implementation

Long-term 5-20 yrs from implementation


Table 21. The degree and time scale of impact of Level I CFPs. CFP Degree of Impact Time Scale

Improved fallows

Low-Moderate: Relatively small amount of C is stored in above- and below-ground biomass in improved fallow systems. Improved fallows have higher C and NOx emissions relative to BAU. Given this review´s emphasis on perennial crops, the impact of improved fallows is considerably less than for other annual cropping systems.

Short-term: Soil fertility improvements are quick, increasing productivity. Can be implemented in just 1 season.

Cover Crops Low: The degree of impact of cover crops depends on its ability to limit the use of chemical inputs, as well as its ability to sequester C and fix N in the soil, which itself is dependent on cover crop species. In this regard, cover crops are similar to short-term improved fallows.

Short-term: Cover crops are grown over a short time-scale and their benefits are realized quickly.

Reduced tillage Low-Moderate: Most literature indicates that reduced tillage will have a low but significant impact on GHG emissions and soil C sequestration, though there is still debate. Given this review´s emphasis on perennial crops, the impact of improved fallows is considerably less than for other annual cropping systems.

Mid - Long-term: The degree of impact changes over time (see Table 5), with GWP decreasing in some instances as soils remain untilled; however, in other cases emissions increased under NT during a moderate time period, only decreasing over the long term.

Shade trees Moderate-High: Complex shade planting systems mimic secondary forests in their C sequestration in soil and biomass, and their mitigation of GHG emissions. Shade trees also increase impact via their effects on soil microclimate and soil protection. Furthermore, shaded systems have secondary impacts, such as reduction of fuel wood extraction from primary forests, increase of soil fertility, and reduction of GHGs from chemical inputs. A system employing boundary plantings or windbreaks will have a lower impact compared to adoption of complex agroforestry systems.

Mid – Long-term: Although the sequestration of C and mitigation of GHG emissions begins almost immediately, upon planting of shade trees, the most significant impact effects of shade planting are realized during the first 20 years, due to more rapid growth sequestering C and N and the indirect benefits due to avoided deforestation accruing from the sustainability of shaded systems.

Non-herbicide weed control

Low-Moderate: The degree of impact of weed suppression depends primarily on the reduction of the use of herbicides, which has a low GHG mitigation potential.

Short – Mid-term: Reduction of herbicide use is realized almost immediately with mulching, manual weed removal, and cover crops; shading by trees requires longer time for canopy development

Pruning/ Organic residue management

Low-Moderate: The degree of impact of pruning and incorporating residues into agricultural systems depends on the degree of substitution of inorganic fertilizers by this practice. Using prunings, mulches, and manure to increase soil fertility reduces the need of fertilizers, thereby reducing the GHG emissions associated with fertilizers and adding C to soil.

Short-term: Pruning is conducted at several times during the year, adding nutrients and C to the soil in a relatively short amount of time. The effects of litterfall on soil nutrients are realized over the mid-term.

IPM practices Moderate: These CFPs depend on the elimination of pesticide use for their GHG impact. Using CFPs such as shade plantings, however, increase the impact of IPM because of the high impact shade planting has on GHG emissions and C stocks.

Short – Mid-term: Many of these practices can be realized right away, leading to an immediate impact. Other CFPs, such as shade planting, requires a longer period of time to be effective.


Erosion control practices

Low-Moderate: The degree of impact depends on the degree of erosion potential. If erosion potential is moderate, measures to reduce erosion will have low overall impact on climate change mitigation. If, however, erosion potential is high and results in the loss of soil fertility that in turn leads to further deforestation and land conversion, than avoiding or mitigating erosion is particularly important, since the drawbacks of erosion in this instance are extremely detrimental.

Short – Mid-term: Implementing erosion controls immediately can lead to a reduction in the need for fertilizers and their associated GHG impacts. Implementing a CFP such as shade cover, however, requires more time to realize benefits.

Inorganic fertilizer (4R’s)

Moderate – High: The use of inorganic fertilizers is often a major source of on-farm GHG emissions for coffee, tea and cocoa farming systems. Any mechanism that results in a reduction or greater efficiency of inorganic fertilizer use will have a relatively high impact on GHGs.

Immediate/Short-term: The impact of reduced fertilizer use is immediate. Substitution of fertilizers for organic residues may require more time if residues are grown in situ.


Low-Moderate: For farms which rely on rainwater to irrigate crops, the degree of impact of drought mitigation will be small to nonexistent, while installing an irrigation system, even drip irrigation, will increase GHG emissions. For large plantations which use irrigation systems, the degree of impact is moderate if they employ drip irrigation or reduce the amount of irrigation with drought mitigation strategies.

Immediate: The degree of impact with any irrigation CFP is realized immediately.

On-farm crop processing

Low – Moderate: Many farmers currently use sun drying for coffee and cocoa thus limiting the scope for further benefits.

Immediate: The application of the CFPs for crop drying mitigate immediately GHG emissions.


7. Sampling of Monitoring, Measurement, and Methodological Tools to Estimate GHG Emissions and Carbon Storage in the Farming Systems

Simulation models exist that incorporate some of the crop-friendly practices, including improved fallows, shade trees, weed control, organic residue and inorganic fertilizer management, reclamation or reforestation of degraded land, and waste management. Other practices, such as pest management, irrigation, fuel wood extraction, on-farm processing, household energy use, domestic wastewater management, are difficult to model due to site specificity or complexity. In the case of inorganic fertilizers, several methodologies and models exist to quantify fertilizer emissions, however most methodologies are too cumbersome and complex for tropical farmers to implement. The most practical appears to be the Cool Farm Tool. For wastewater management, the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (Doorn et al. 2006) provide several equations with input values to determine the amount of GHG emissions from particular wastewater disposal systems in different countries, which could be useful in determining GHG emissions of wastewater emissions on a case by case basis. A partial listing of potential models, applications, advantages and disadvantages is presented below.

Table 22: Potentially useful tools, methodologies and models for quantifying CFPs Model, Tool or Methodology

Available at

Applicable for CFPs: Summary Advantages Disadvantages

A/R Methodological Tool

http://cdm.unfccc.int/methodologies/ARmethodologies/tools/ar-am-tool-14-v1.pdf Shade Trees

Estimates changes in carbon stocks of trees and shrubs with carbon project area.

High accuracy of measurements on carbon storage

Level of effort and technical knowledge required prohibitive except in instances of carbon project development in coordination with farm management activities.

Adoption of Sustainable Agricultural Land Management (SALM) - VCSA Methodology

http://www.v-c-s.org/methodologies/adoption-sustainable-agricultural-land-management-salm

Various, including: Shade trees; Pruning and Organic Residue Management; Inorganic Fertilizer Use; Improved Fallows; Application of Cover Crops

The methodology quantifies the GHG emission reductions of project activities that apply sustainable land management practices (SALM), and accounts for above ground, below ground and soil carbon pools.

Applicable for use for a broad range of farming practices. Includes tools to estimate direct nitrous oxide emission from N-fixing species and crop residues; and non-CO2 emissions from crop-residue burning.

As of July, 2011, the methodology had not been approved by the VCSA. Like all carbon project methodologies, level of effort and technical knowledge required is prohibitive except in instances of carbon project development in coordination with farm management activities.

Approved afforestation and reforestation baseline and monitoring methodology AR-AM0004

http://cdm.unfccc.int/UserManagement/FileStorage/KYBDLQFMI6R20X58OGH3Z71N9TSU4A.

Shade trees; Fallows

For reforestation or afforestation of land currently under agricultural use.



http://cdm.unfccc.int/methodologies/ARmethodologies/tools/ar-am-tool-14-v1.pdf


























Approved afforestation and reforestation baseline and monitoring methodology AR-AM0006

http://cdm.unfccc.int/UserManagement/FileStorage/T05CO1LWYIJ7EHD9GBVAKZPUSQ2N8X

Shade trees; Reclaiming degraded lands

Applicable for afforestation or reforestation of degraded land, under threat of further degradation, or which remains in a low carbon steady state through tree planting. Applicable for nitrogen-fixing species and intercropping between tree rows may be used, and considers living biomass and soil organic carbon pools.



CENTURY Soil Organic Matter Model

http://www.nrel.colostate.edu/projects/century5/

Pruning and Organic Residue Management; Improved Fallows

Model developed to apply across a wide range of cropping system rotations and tillage practices, to enable systemic analysis of the effects of management and global change on productivity and sustainability of agroecosystems.

Models C, N, P, and S dynamics through an annual cycle over long time frames (centuries).

Most farmers and management groups do not consider management over such long timeframes, better applied as natural resource management and planning tool.

CO2Fix

http://www.efi.int/projects/casfor/models.htm

Shade Trees; Pruning and Organic Residue Management

A tool to quantify the carbon stocks and fluxes in forest biomass, soil organic matter and wood products value chains.

Applicable for agroforestry, afforestation and improved forest management projects, includes carbon accounting module that could facilitate the development of feasibility studies for farmers to understand potential to engage in carbon markets

Complexity of model, like many, is significant barrier to adoption for uses other than development of carbon-credit generating projects. Value may be limited to farms with large forested reserve areas.

Cool Farm Tool

http://www.growingforthefuture.com/content/Cool+Farm+Tool


"Applicable for farmers, supply chain managers and companies interested in quantifying their agricultural carbon footprint and finding practical ways of reducing it. It calculates the greenhouse gas balance of farming, including emissions from fields, inputs, livestock, land use and land use change and primary processing. It uses 'Tier2-type' methods, offering users simple menu choices for parameters that farmers can influence to reduce their carbon footprint. "

One of most user-friendly tools and most accessible for non-technical users and farmers.

Tools applicability in tree-cropping systems could be enhanced through additional tailoring and modification. In spite of simplicity vis-à-vis other systems, significant training may still be required to enable accurate usage by farmers and extensionists.

Cropster

http://www.cropster.org/


Online platform to enable farmers keep track of production and processing techniques and associated impacts. The system is designed to help small producers as well as larger plantations. Carbon footprinting module utilizes/is coordinated with the Cool Farm Tool.

Similar to Cool Farm Tool, enables relatively rapid assimilation of farm-level production and processing data to understand GHG impacts.

Specifically designed for coffee industry; applicability in other crop contexts is uncertain.



























FALLOW

http://www.worldagroforestrycentre.org/SEA/fallow

Fallows; Soil Fertility

Impact assessment tool at landscape level to help integrate our understanding of landscape-mosaic-resource interactions; comprises the following dynamic processes: soil fertility dynamics and impacts on crop production; market linkages; farmer decision-making and impacts on land-use; land clearance scenarios; integrated impact assessment of how above factors influence regional ecosystem service provision.

Facilitates landscape-level understanding of agricultural impacts on natural environment; useful natural resource planning tool or by sophisticated network of farming associations.

Beyond scope of farmer needs; too complex for application by non-technical users

Guidance on Coffee Carbon Project Development Using the Simplified Agroforestry Methodology

http://www.rainforest-alliance.org/sites/default/files/site-documents/climate/documents/coffee_carbon_guidance.pdf Shade Trees;

Aim is to provide those who own or manage coffee farms and the companies or associations who trade coffee with practical, how-to information on developing a carbon-credit generating agroforestry, afforestation or reforestation project.

A bridge to facilitate understanding of application of carbon project methodologies by less technical users.

Designed for use in conjunction with CDM Methodology AR-AMS0004, so primarily applicable only for carbon project development. Exclusive for use by coffee farms.

Rothamsted C model

http://www.rothamsted.bbsrc.ac.uk/aen/carbon/rothc.htm

Fallows; Organic Residue Management

Models turnover of organic C in soil using basic biophysical and climatic data inputs. Models total organic C content in t C ha over several decades, as well as microbial biomass C content in t C ha, both in top soil layers.

Adequately simulates alternative scenarios for improved fallows (Kaonga and Coleman, 2008), applicable for use in Africa and Asia. Data input requirements do not appear overly burdensome for farmer associations.

Needs enhanced accuracy for measuring intercropped systems (Kamoni et al. 2007; Diels et al. 2004).

SALUS

http://140.134.48.19/salus/

Inorganic Fertilizer Use; Irrigation

Computer simulation model designed to enhance understanding of crop production and reduce environmental impact. Data inputs include soil type, planting details, fertilizer usage, irrigation, etc.) and outputs include data on carbon sequestration, crop yield and nitrate leaching.

Tracks against an array of common farming practices - high applicability and holistic approach.

Simplified interface developed that enables easier utilization of program.

SExI-FS (Spatially Explicit Individual-based Forest Simulator)

http://www.worldagroforestrycentre.org/SEA/Products/AFModels/SExI/download.htm Shade Trees

Model aims to facilitate understanding of tree-tree interactions in a mixed, multi-species agroforest

Could be utilized to enhance understanding of the impacts of canopy/shade cover on crop production, to make informed shade tree management decisions.

Applicability limited to complex, multi-story agroforestry systems.

WaNuLCAS

http://www.worldagroforestry.org/sea/products/AFModels/wanulcas/index.htm

Shade Trees, Irrigation.

Models tree, soil, crop and water interactions in a range of agroforestry systems.

Modeling of tree and crop growth in context of water balance can help farming groups in drought-prone areas enhance understanding of farming practices on water-use.

Like many models, requires robust amount of varied data for inputting that many farmers may not monitor or have access to.






http://www.rainforest-alliance.org/sites/default/files/site-documents/climate/documents/coffee_carbon_guidance.pdf















http://140.134.48.19/salus/

http://140.134.48.19/salus/

http://140.134.48.19/salus/

http://www.worldagroforestrycentre.org/SEA/Products/AFModels/SExI/download.htm















8. Suggested Areas for Further Research The table below summarizes the research gaps identified for many of the CFPs discussed in section three. In general, more research is needed of the indirect effects of CFPs, for example, the avoidance of GHG emissions due to fertilizers as a result of their substitution by organic sources and trade-offs between some CFPs (e.g. reduced tillage) and agrochemical use. These, and other areas of research, are addressed in greater detail in Table 23.

Table 23. Suggested future research related to CFPs.

CFP Suggested Areas for Further Research

Improved fallows Effects of fallow species atn various sites (i.e. climate, soils, and fallow length) on C sequestration and GHG emissions

Effects of fallow quality on NOx.

Consideration: At present, variability may be too high to enable development of accurate emissions accounting approaches.

Reduced tillage Studies of effects of tillage and interactions with other CFPs on C sequestration and GHG emissions by coffee, cocoa, and tea: at present, consensus is lacking regarding the ultimate GHG impacts and carbon storage benefits of reduced tillage, due to the nature of carbon sampling methods employed, the variability of N2O emissions over time (Flynn and Smith 2010), and the interactions between reduced tillage and other complementary management practices such as cover crops and inorganic/organic fertilizers (Six et al. 2002).

Studies to enhance understanding of which types of organic residues have the highest relative NOx and other GHG emissions, especially in coffee, cocoa, and tea.

Studies to identify the time needed to maximize GHG reductions achieved through employing conservation tillage or NT methods (Six et al. 2004).

Cover crops Measurements are needed of the temporal dynamics of cover crops in coffee, tea, and cacao, and their direct effect on GHG emission and C sequestrations in order to determine which are best or unadvisable in certain contexts/countries/crops.

Estimates of indirect reductions of GHGs due to cover crops, such as decreased use of fertilizers, herbicides, and pesticides are needed.

Models specifically addressing cover crops are also lacking.

Scholberg et al (2010a, b) argue that to facilitate the use of cover crops for farmers, a decision framework needs to be developed which identifies potential cover crops based on system constraints, behavior, alternatives, and design.

Inorganic fertilizer use Need for a greater predictive understanding of mixtures of inorganic fertilizers and organic inputs and impacts on GHG emissions and C sequestration.

Identification of cost-effective techniques for improving fertilizer use efficiency and synchrony with crop demand, especially placement depth and use of EEF and synthetic nitrification inhibitors.

In relation to tillage systems, future studies may need to focus on improving N use efficiency within a particular tillage system.

Valued technical interventions would include:

The development of inexpensive methods of data generation for precision fertilization.

Validation of methodologies for estimating economically optimum fertilization rates for yields of specific crops, while reducing GHG emissions.

Tailoring of leading GHG footprinting tools to coffee, tea, cocoa farming systems.

Practical guidance and means to enable farmers to estimate inter-plot N demands.

Pruning/organic residue management

Research to develop a more predictive understanding of C and nutrient mineralization from organic residues and from residue or residue/inorganic fertilizer mixtures is needed.

Soil x residue quality interactions on C and N mineralization, especially long-term effects.

Shade trees Additional research to contrast and compare the carbon sequestration potential of various types of shade systems (e.g. windbreaks, boundary plantings, simple shade, complex agroforestry) for coffee, cocoa and tea.

Long-term trade-offs between crop yields, reduced chemical inputs, and use of shade.


Development of a more precise methodology for measuring C storage in shade systems, especially C dynamics of roots.

Windbreak arrangement effects on drought mitigation and yields.

Development of practical guides to enable farmers to identify best shade species given local farm characteristics (e.g. the World Agroforestry Centre’s Agroforestry Tree Database: http://www.worldagroforestrycentre.org/sea/Products/AFDbases/AF/index.asp)

Erosion control Measurement of GHG emissions due to erosion.

Enhanced understanding of impacts of cover crops, shade trees, and pruning mulch on C loss and GHG emissions in coffee, cocoa, and tea, and correlation to / quantification of those impacts on soil erosion.

Irrigation alternatives Effects of alternative fuel sources for water pumping on GHG emissions in coffee, tea, and cocoa farming.

Effects of shade density on system total evapotranspiration.

Assessment of trade-offs of investment in drought mitigation practices vs. investments in alternative adaptation strategies.

Weed control Plot level and well as system-wide accounting of effects of herbicides on GHG emissions, including indirect effects on GHGs and C stocks of substitution of herbicides by cover crops, shade trees, and mulch.

Appropriate combinations of weed control practices for specific crops.

Further research to determine the site-specific benefits and drawbacks of using weeds as a soil cover.

IPM Effects of shade trees and density on pests.

Cost-benefit analyses of IPM interventions vs. business-as-usual pest management strategies.

Trade-offs between implementation of IPM and productivity/yield.

Identification of main pests and traditional use of plant extracts as replacements for pesticides of coffee, tea, cocoa farms in East and West Africa and Southeast Asia.

On-farm processing Effects of alternative fuel sources and drying methods on GHG emissions.

Cost-benefit analysis demonstrating the cost of the shift from diesel fuel to natural gas amongst Ghanaian cocoa farmers (for example) and costs of developing a fuel wood lot vs. traditional energy sources for Kenya tea farmers.

Solid waste processing Improved quantification of GHG emissions associated with coffee, cocoa and tea wastes across various common processing systems.

Wastewater processing More on the GHG emissions associated with fermentation and treatment of residues coffee, tea, and cacao, since methane and N2O emissions in fermentation processes are complex and depend very much on local circumstances.

Quantification of reductions in GHG emissions tied to waste reduction (compost, methane biofuel generations, reuse of water).

Fuel wood extraction Assessment of the effects of using fuel wood lots, prunings, and use of improved fallows as fuel sources on GHG emissions/carbon sequestration.

Degraded land reclamation

Site-specific methodologies for enrichment plantings or tree plantations are needed.

Long-term data on tree growth, C sequestration in soil and vegetation, and costs are necessary to assess the effectiveness of strategies.

Interactions of degree of site degradation vs. restoration of C stocks.

Mechanisms for reducing financial burden on farmers of up-front costs of reforestation.

Household energy use Further research on the comparison of emissions impacts of transitioning from fuel wood and charcoal to fossil fuels or other energy sources by rural farmers.

Comparative assessment (cost, impacts on deforestation, local access, etc.) on the benefits/drawbacks of kerosene, LPG, and electricity in the context of emissions reductions.

Domestic wastewater Quantification of GHG emissions from domestic wastewater use in rural areas.

http://www.worldagroforestrycentre.org/sea/Products/AFDbases/AF/index.asp


Biochar More exploratory research is needed on biomass sources, soils and climate regions before broader generalizations can be drawn (Verheijen et al. 2009).

The effects of biochar additions to the soil on GHG emissions need to be quantified (Laird 2008) and effective rates and placement methods better defined.

Gas emissions and nutrient losses during combustion are needed in order to better define biochar´s overall benefits.

Trade-offs between using land for the production of biochar vs. crops as well as the costs and benefits involved in biochar collection.


9. Common Barriers to Adoption of CFPs This section presents a preliminary evaluation of the common barriers to adoption of the CFP alternatives proposed in this review. This assessment, seen in Table 24s based on conclusions drawn from scientific literature and is complemented by the Rainforest Alliance’s anecdotal experiences working directly with thousands of tropical farmers to facilitate their implementation of improved management practices.

Table 24. Potential barriers to adoption of proposed CFP alternatives. Proposed CFP Alternatives Principal adoption barriers

Short-term improved fallows Land availability, seed availability.

Long-term improved fallows Land availability, seed availability. Insect pests can be a problem when fallowing with trees (Albrecht and Kanji 2003).

Reduced tillage Labor and cash for herbicide applications. Availability/access to specialized tools.

Cover crops Labor, seed availability.

More efficient use of inorganic fertilizer (Product;Rate; Timing; Placement; Integration

Farmer knowledge, availability of appropriate and effective technologies, information on optimum application, N inhibitors not readily available.

Pruning mulch Labor, availability of other alternatives

Other organic residue mulch Labor, knowledge

Shade trees, simple arrangements Labor (Palm et al 2004); tree competition with crops; potential pests problems; risk of fire enhanced; secure rights and markets for tree products; delayed benefits (Beer, 1987, Beer et al 1988; Palm et al 2004, Hunt and Baum, 2009)

Shade trees, complex arrangements Labor, knowledge, tree competition with crops, potential pests problems, risk of natural disasters (e.g. fire), secure rights and markets for tree products (Albrecht and Kandji, 2003, Isaac et al 2007)

Weed control via litter Labor, litter availability

Weed control via shade Labor, knowledge

IPM Knowledge, labor, appropriate technologies, availability of biological control agents, local specificity

Drip irrigation Capital, knowledge

Drought mitigation via reduced evapotranspiration, increased moisture retention via cover crops, shade trees

See cover crops, shade trees

Solar drying crop processing Investment capital, knowledge, access to technologies

More energy efficient drying Investment capital, knowledge, access to appropriate technologies

Fuel wood lots Land availability, seed availability


10. Reflections on CFPs Identified In light of the sections above, and in the context of facilitating farmer adoption of CFPs that enhance carbon storage, reduce emissions and can build adaptive capacity, the following take-home points are put forth:

Globally, soil carbon sequestration activities have tremendous potential to mitigate climate change. Yet, in the context of perennial cropping practices, the ultimate impacts on carbon sequestration and GHG emissions reductions of adoption of reduced tillage and improved fallow alternatives is relatively low. Considering also that the implementation of such practices often require additional labor inputs and utilization of specialized farming implements (which may not be readily accessible to many Sub-saharan African farmers, in particular) and that the net economic benefits of implementation via enhanced productivity and yield are often not evidenced for at least 5 years after adoption, and often longer for perennial cropping systems, other CFP alternatives may be considered as higher priorities for adoption.

Increasing tree cover on-farm through adoption/more robust implementation of agroforestry practices offers one of the most comprehensive opportunities to transition tree-crop, based, perennial cropping systems such as coffee, tea and cocoa towards a more climate smart management regime. Yet, attention should be paid to the type of agroforestry implemented, as the preferred options will vary considerably with local context, capital, and system type, and these will have corresponding impacts on sequestration potential. A tiered approach culminating in the implementation of complex agroforestry practices could be explored, through which a farmer utilizing minimal (1-2) shade trees intercropped with coffee, cocoa, or tea at intervals, could explore gradually increasing density, creating hedgerows or windbreaks, and, as appropriate, exploring diversification of tree species planted towards a more complex productive shade/robust agroforestry system. However, this must be done with an understanding of the trade-offs between shade percentage, crop yields and incidence of diseases.

Nitrogen fertilizer use is a major emissions source. Optimized use of inorganic fertilizers, in conjunction with organic amendments, offers a near-immediate and potentially (depending on scale and rigor of adoption) very significant source of emissions reductions.

On-farm processing represents a large source of emissions for well-resourced plantations. While significant capital outlays to change these, these plantations may have the financial resources to fund the up-front investment, which presumably would be repaid through continual improvements in resource use efficiency for many years to come.

In general, more attention/research should be conducted to understand the trade-offs and opportunity costs of implementing these practices.

In the context of smallholders, climate-friendly practices can only realistically be considered for adoption when they contribute tangible economic benefits to the farm economy, through reducing input costs, enhancing yields, etc. Climate-friendly farming should be coordinated with improved land management for enhanced economic livelihoods.


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http://www.agr.hokudai.ac.jp/env/ctc_siberia/bibliography/pdf/Yanai2007.pdf Zake, J .Y. K. (1993). Tillage systems and soil properties in east Africa. Soil and Tillage Research, 27(1-4), 95-104.

http://www.agr.hokudai.ac.jp/env/ctc_siberia/bibliography/pdf/Yanai2007.pdf


12. Annexes The following annexes are categorized by the practice(s) they relate to, and are composed primarily of graphical tabular data that indicates very specific and local-context oriented information that can be utilized to make specific and targeted CFP recommendations.

Annex 1. Leguminous species recommended as short-duration improved fallows in Western Kenya (adapted from Amadalo et al. 2003)

Type Scientific Name Common Name

Woody species

Cajanus cajan Pigeon pea

Calliandra calothyrsus Calliandra

Crotalaria grahamiana Crotalaria

Crotalaria mucronata N/A

Crotalaria paulina N/A

Crotalaria striata N/A

Desmodium uncinatum Desmodium

Gliricidia sepium Mexican lilac

Sesbania sesban Sesbania

Tephrosia candida Tephrosia or fish poison

Tephrosia vogelii N/A

Herbaceous species

Canavalia ensiformis N/A

Colopogonium mucunoides Mucuna

Dolichos lablab Lab lab bean

Macroptilium atropurpureum Siratro


Annex 2. Impact of different fallow practices on constraints to crop production

A ranking of fallows processes, listed in decreasing order of importance, for overcoming constraints to crop production in the humid tropics High base status, N deficient soil

High base status, N and P deficient soil Low base status, high Al soil

Constraint/process

Potential of fallow Constraint/process

Potential of fallow

Constraint/process

Potential of fallow

1 N supply 1 N supply 1 N supply

N2 fixation High

N2 fixation High N2 fixation High

Retrieval from subsoil High

Retrieval from subsoil High

Retrieval from subsoil Low, ?

Capture of subsurface lateral flow ?

Capture of subsurface lateral flow ?

Capture of subsurface lateral flow Low, ?

2 Weeds 2 P supply 2 P supply

Fool propagules ?, *

Chemical transformations Low

Chemical transformations Low

Reduce seed pools, germination High

Reduce P complexation Low

Reduce P complexation High

Reduce weed vigor High

Special acquisition mechanisms ?

Special acquisition mechanisms ?

3 Soil structure Low, ? 3 Weeds 3 Cation supply

4 Soil pests ?

Fool Propagules ?

Retrieval from subsoil Low, ?

* may be locally important


AI-organic acid interactions

Intermediate, ?


CEC of soil organic matter High, ?

4 Soil structure High 4 Weeds

5 Soil pests ? Fool propagules *, ?



5 Soil structure High

6 Soil pests ?


Annex 3. Above- and below-ground biomass (Mg ha-1) in some improved fallow trials in western Kenya (from Albrecht and Kandji, 2003)

Fallow Species Above-ground biomass Below-ground biomass

Fine root biomass R/S

12-month-old fallows

Calliandra grahamiana 8.5 2.7 - 0.32

Calliandra calothyrus 21.0 7.0 - 0.33

Cajanus cajan 8.5 3.9 - 0.46

Senna spectabilis 7.0 4.8 - 0.69

S. sesban 14.2 7.3 - 0.51

Tephrosia vogelii 10.8 4.0 - 0.37


C. grahamiana 24.7 10.9 6.4 0.44

Calliandra paulina 19.8 13.6 3.7 0.69

Tephrosia candida 31.0 33.2 3.6 1.07


C. calothyrsus 27.0 15.5 2.8 0.57

S. sesban 36.9 10.8 2.4 0.29

Grevillia robusta 32.6 17.7 2.8 0.54

Eucalyptus saligna 43.4 19.1 2.4 0.44

Annex 4. Common cover crops used in East and West Africa and/or SE Asia, with coffee, tea and/or cocoa (adapted from Baligar and Fageria, 2007)

Cover Crop Name Description

Pigeon pea (Pennisetum glaucum L.)

Grain legume. Grown in Africa, but is native to India. Used as a cover or nurse crop for cacao seedlings. Tolerates high temperature and drought, can be grown on low fertility soils, has few diseases or insect pests. Is sensitive to waterlogging. Optimal growing temperature between 29 – 36 C.

Hairy indigo (Indigofera hirsuta L.)

Cover crop native to Africa and Asia, is mainly grown with tea and coffee. Requires at least 900 mm of rainfall; optimal temperature range is 15 – 28o C.

Sunhemp (Crotolaria juncea L)

Grown as a cover crop for coffee throughout the tropics, but is used mainly in Brazil. Useful for controlling erosion, fixing nitrogen (as much as 300 kg N ha-1) and reducing weeds. Grows best at 10 to 30 C and is drought resistant, but susceptible to water logging and some insects and diseases

Crotolaria (Crotalaria pallida)

Native to tropical Africa, but is now grown in Indonesia and throughout South-east Asia. Used as a cover crop in cacao, tea, and coffee plantations. Successful on variety of soil types, from sandy loam to clay, and over a temperature range of 16 – 27 C and 850 - 3000 mm of rainfall.

White tephrosia (Tephrosia candida)

Originally from India, but is grown as a cover crop with coffee and tea throughout the tropics. Can reduce erosion and increase soil fertility of degraded lands. Requires 700 - 2500 mm of rainfall and temperatures between 8 – 30 C.

Vogel teprosia (Tephrosia vogelii J.)

Native to tropical Africa, is grown as a cover crop with coffee and tea in Africa and Indonesia, in conditions where annual rainfall is 850 - 2650 mm and temperatures range from 13 – 27 C. Susceptible to fungal diseases and nematodes.

Sesbania (Sesbania bisbinosa)

Grown throughout tropical regions as a cover crop with tea. It grows best in a temperature range of 20 – 30 C, and 570 - 2210 mm of rainfall. Fixes N in the soil. Susceptible to nematodes.


Annex 5. Desirable characteristics for perennial crop shade trees (adapted from Beer, 1987)

Crop compatibility; little competition for water, nutrients, and space Tolerance for pruning

Strong rooting systems, to prevent wind throw High biomass production and decomposition, through leaf litter and pruning

Rooting ability of stakes Rapid flushing of new leaves for deciduous trees

Ability to extract nutrients, not in competition with crop Low disease and insect susceptibility

Nitrogen fixation Small leaf size

A light grown that produces mottled light, not a uniform shadow of poor quality light No allelopathic properties

If shade species is to be used as timber, the species should have wind resistance, should not reduce light levels to insufficient quantities, and should not risk crop damage when the tree is harvested Smooth bark, no thorns

Non-brittle branches and stem Valuable wood or fruit

Rapid growth Lack of host suitability for crop pests or diseases

Self-pruning, development of straight stems Lack of ability of shade tree to become a weed

Annex 6. Annual litter and litter nutrient inputs in agroforestry systems with Coffea Arabica and Theobroma cacao (Beer 1988)

Coffea arabica:

Shade species

Crop (plants/ha)

Shade (trees/ha)

Tree pruning frequency (prunings/yr)

Inputs from litterfall (kg/ha/yr; dry weight) References

Organic material

N P K Ca Mg

Erythrina poeppigiana 3,700 238 3 17,200* 366* 30* 264* 243* 48*

Glover and Beer, 1986

E. poeppigiana & Cordia alliodora

3,700 238 3

15,800* 331* 22* 162* 328* 69* Glover and Beer, 1986 3,700 475 0

E. poeppigiana 5,000 555 2 20,000 461 35 259 243 76

Fassbender et al, 1985

C. alliodora 5,000 185 0 5,700 114 7 54 110 37 Fassbender et al, 1985

Mixed shade 6,460 1,930 0 11,200 189

No data

No data

No data

No data

Aranguren et al, 1982a

No shade 1,600 0 0 2,100 No data

No data

No data

No data

No data

Jimenez y Martinez, 1979a,b

Inga jinicuil 1,540 205 0 8,200 No data

No data

No data

No data

No data


I. leptoloba 1,560 225 0 6,900 No data

No data

No data

No data

No data



Mixed shade 1,475 217 0 6,000

No data

No data

No data

No data

No data


Mixed shade Variable Variable No data

4,700-13,100

No data

No data

No data

No data

No data

Suarez de Castro y Rodriguez, 1955

* Includes C. arabica pruning residues

Theobroma cacao:

Shade species

Crop (plants/ha)

Shade (trees/ha)

Tree pruning frequency (prunings/yr)

Inputs from Litterfall (kg/ha/yr; dry weight) References

Organic material

N P K Ca Mg

Erythrina poeppigiana 1,111 278 3 6,400* 116* 6* 40* 116* 41*

Alpizar et al, 1983

Cordia alliodora 1,111 278 0 5,900 95 11 57 108 43

Alpizar et al, 1983

E. poeppigiana

1,111 - 1,600 123 No data

5,200-8,850

No data

No data

No data

No data

No data

Granados, 1972

E.fusca 1,111 40 0 7,100 112 14 26 162 52

Santana and Cabala, 1985

Mixed shade 950 570 0 20,900 321

No data

No data

No data

No data

Aranguren et al, 1982b

Mixed shade No data No data No data 8,400 52 4 38 89 26

Boyer, 1973

Cocus nucifera 350 175 0 No data 62** 7** 31**

No data

No data Nair, 1979

* Natural litterfally only (pruning residues excluded) ** Assuming C. nucifera litter remains; husks not included.


Annex 7. Common pests in East African coffee systems (from Nyambo et al. 1996) Summary of the major insect pests and diseases of coffee in East Africa and methods of control. Pest Common Name Status Control Measures

Insects

CBB (Hypothenemus hampei)

Major in all countries

Insecticide sprays and cultural practices

Antestia bugs (Antestiopsis spp.)


Insecticide sprays and cultural practices (biocontrol Kenya)

Coffee leaf miner (Leucoptera meyricki)

Major in Kenya and Tanzania

Insecticide sprays

Coffee green scales (Coccus spp)

Major in Kenya Insecticide sprays and biocontrol

Coffee root mealybug (Planococcus ireneus de Lotto)

Major Uganda No control measures available

Fried egg scales (Aspidiotus, spp)

Major in Kenya Insecticide sprays

Berry moth (Prophantis smaragdina)

Major in Kenya Insecticide sprays

Giant looper (Ascotis selenaria reciprocaria)

Major in Kenya Insecticide sprays and *biocontrol

Coffee stem borer (Bixadus siericolla)

Major in Uganda

Stem banding with suitable insecticides

Coffee lacebug (Habrochilla spp.)

Major in Uganda

Insecticide sprays

Diseases

CBD (Colletotrichum kahawae)


Broad-spectrum, copper-based and organic fungicides Resistant/tolerant varieties Sanitation

CLR (Hemileia vastratix) Major in all countries

Broad-spectrum, copper-based fungicides Triazoles Resistant/tolerant varieties

BBC (Pseudomonas syringue pv garcae)

Major in Kenya Copper-based bactericides

Red blister disease (Cercospora coffeicola)

Major in Uganda

No control measures developed as of publication

Root rot (Armillaria melea) Major in Uganda

Use of trenches to separate infected from healthy

Nematodes African coffee root-knot nematode (Meloidogyne spp.)

Major in Tanzania

Ring barking of trees when clearing new land Cultural, sanitation, clean seedlings and destruction of old coffee trees

*control measures experimental


Annex 8. Locally available species for pest control in sub-Saharan Africa (from Pretty 1995 cited in Coulibaly et al. 2002)

Selection of locally available species used for pest control in sub-Saharan Africa

Plant Country/Region Preparation Pests Controlled

Chili pepper (Capsicum frutescens) Kenya Stirred in water, left to stand and spray

Aphids and diarrhea for chickens

Custard apples sweets op (Annoma sp.) West Africa Water suspension of seeds Insect pests

Neem (Azardirachta indica) various Dried, sprayed roots add to stored products Weevils

Mexican marigold Kenya Cut and laid around livestock Repels safari ants

Simson weeds (Datura stratonium) Cameroon

Leaves, stems, flowers and seeds shredded and soaked in water, soap and kerosene solution

Leaf caterpillar and aphids

Castor oil (Ricinus communis) Cameroon

Seeds mashed and heated in water, soap and kerosene solution mixture - sifted, diluted and sprayed

Annex 9. Common pesticides and non-chemical alternatives for pest and disease control in coffee in Malawi (from Hillocks et al. 1999)

Pests and diseases Commercial chemical Alternative control measure (compatible with organic production)

White stem borer None since aldrin became unacceptable Wire picks, pheromones (under research), ratooning, botanicals.

Green scale Disulfoton, azinphos-methyl Botanicals

Leaf miner Chlorpyrifos, fenitrothion, disulfoton, deltamethryn, fenvalerate, fenthion

None

Tip (yellow) borer None Physical removal of larvae from affected branches

Antestia Fenitrothion, monocrotophos, chloryrifos Pruning to keep bush open, physical removal of bugs

Coffee berry disease Copper oxychloride, atrazine, chlorothalonil Removal of affected berries, use of resistant cultivars. e.g. ‘Catimor' hybrids

Leaf rust Copper oxychloride, propiconazole, triadimenol, Tridimefon

Pruning to keep canopy open, use of resistant cultivars

Fusarium bark disease Seed dressing chemicals Field sanitation - and burning of infected seedlings from nursery and bushes from the field.

Nematodes Aldicarb, carbofuran (nurseries) Ensure seedlings are grown in nematode-free soil and affected seedlings are not transplanted to the field.


Annex 10. Types of kilns utilized in Tanzania (from van Beukering et al. 2007)

Common kiln types and their energy use efficiency

Kiln Type Traditional Kiln

Improved Kiln

Efficiency (%)

Earth Pit Kiln X 10-15

Portable Steel Kiln X 20

Brick Kiln X 25-35

Cassamance Earth Mound Kiln

X 25-30

Earth Mount Kiln X 10-20

Basic Earth Mound Kiln

X 10-20

Improved Basic Earth Mount Kiln

X 15-25

Annex 11.Household energy usage - CO2 equivalent emissions from different cooking options (from Bhattacharya and Abdul Salam 2002)

Cooking Options Efficiency values (%)

Emissions factor values Estimated CO2 equivalent emissions

CO2 (kg TJ-1

) CH4 (kg TJ-1

) N2O (kg TJ-1

) g CO2-eq MJ-1

g CO2-eq MJ-

1useful

Traditional stoves (wood)

11 - 519.6 3.74 12.1 109.7

Traditional stoves (residues)

10.2 - 300 4 7.5 73.9

Traditional stoves (charcoal)

19 - 253.6 1 5.6 29.7

Traditional stoves (dung)

10.6 - 300 4 7.5 71.1

Improved stoves (wood)

24 - 408 4.83 10.1 41.9

Improved stoves (residues)

21 - 131.8 4 4.0 19.1

Improved stoves (charcoal)

27 - 200 1 4.5 16.7

Improved stoves (dung)

19 - 300 4 7.5 39.7

Biogas stoves 55 - 57.8 5.2 2.8 5.1

Gasifier stoves 27 - - 1.48 0.46 1.7

Natural Gas 55 90402 21.11 1.84 91.4 166.2

LPG 55 106900 28.05 1.88 107.9 196.2

Kerosene 45 155500 4.81 157.4 349.7


Annex 12. Benefits, complementarity and compatibility of agroforestry (AF) and conservation agriculture (CA) (Sims et al., 2009)

Concept Constituents Potential of AF and CA

Efficiency of natural

resource use

Soil nutrients Trees promote nutrient cycling and N fixation. Compare this benefit with the cycling capacity of rotating main and cover crops with different rooting depths in CA systems. Leguminous cover crops also fix N.

Solar energy Multi-storied cropping systems intercept and use sunlight at all levels. Although this is a benefit better illustrated by AF systems, crop associations in CA demonstrate similar efficiency.

Water Both AF and CA reduce runoff while increasing water infiltration and holding capacity in the soil.

Favorable environment for sustained

production

Shade AF (and some CA) systems can provide filtered shade which conserves water and reduces evapotranspiration, keeps topsoil cool and helps maintain healthy soil biota activity.

Wind protection

Tree wind breaks protect crops from wind damage and soils from wind erosion and drying. Wind breaks combined with CA give more complete protection.

Soil conservation

Undisturbed tree, crop and cover crop roots and mycorrhizal systems reduce nutrient leaching, bind soil and prevent erosion. Tree leaf litter and CA soil cover enhance soil physical, chemical and biological conditions making soils more resilient to erosive forces.

Nutrient cycling

Through nutrient uptake from deep soil layers and N fixing species, trees, bushes and cover crops promote more closed nutrient cycling and more efficient use of nutrients.

Habitat diversity

Both CA and AF, but more especially in association, provide habitats for diverse biota that help to enhance biodiversity and pest-predator balance in the system.

More profitable

systems

Reduced costs

Through nutrient cycling cover crops and trees reduce the need for purchased fertilizers. Fuel and labor costs may be reduced in CA systems versus plough-based agriculture.

Diversified products

Mixed cropping systems typically have more economic products. For example, tree fruits and timber in AF, leguminous seeds in CA.

Continuous flow of products

With multiple cropping in both AF and CA, there can be a more even supply of products throughout the year.

Greater self- reliance

AF and CA can reduce the farm family's dependence on purchased products as well as reducing vulnerability to changing market conditions, especially for mono-cropping systems.

Environmental improvement

Reduced pressure on natural forests

This is particularly an advantage for AF systems, which may reduce pressure for forest products.

Species diversity

Both AF and CA provide enhanced habitat and support biodiversity for macro and micro fauna.

Resource conservation

AF and CA contribute to the conservation of soil, nutrients and water in the landscape.

Carbon sequestration

Trees, and especially soils, store C.

Decreased pollution

Nutrient cycling can reduce the need to use inorganic fertilizers and reduced erosion and runoff mean that nutrient loss may be minimized.

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