OBJECTIVES

• To exchange information and experiences on the use of cover crops by farmers

• To identify the major constraints on adoption of cover crops by smallholders

• To identify priority actions and research needs

OUTPUTS

• Technical and socio-economic descriptions of key cover crop managment options for specific environments

• An outline of a regional strategy for promoting production systems employing cover crops

RATIONALE

In the next decade, agricultural productivity in sub-Saharan Africa (SSA) must be increased substantially to avert a serious food crisis. Since the 1970s, food production across much of the region has not kept pace with population growth. The has lead to increased pressure on the land, a decline in soil fertility, and an acceleration of desertification. Any efforts to enhance food security in SSA, therefore, must include measures to effectively and sustainably regenerate soil productivity.

Reviving agricultural productivity means dealing with the degraded soils that are a sad reality in many parts of Africa. Decades of cropping without fallowing have decreased soil fertility, destroyed organic matter and acidified soils. In Southern Benin, for example, where the red ultisols of the Alada plateaux have been intensively farmed for 23 years, organic matter content has dropped from 2.6 % to 0.8 %, pH has fallen from 5.8 to 4.8, and maize yields have plummeted from an average of 1500 kg/ha to 400 kg/ha. Evidence suggests that cover cropping could help reverse this trend.

Empirical trials and theoretical considerations indicate that cover crops help to sustain intensive agricultural practices, while conserving the natural resource base, especially soil. Cover crops are efficient sources of Nitrogen (N). They improve soil structure and other properties, increase the soil's biological activity, and help to control pests and weeds. Cover crops can also be additional sources of food, feed and fuel for farm families.

Cover cropping, however, is not a stand alone solution to the problems of low soil productivity. Cover crops can help to maximize the benefits derived from other low cost external soil amendments, such as rock phosphate. Where fertilizers are expensive and their quantity is limited, cover crops along with moderate amounts of externally derived nutrients (e.g. mineral fertilizer) are a cost-effective means for increasing the nutrients available in the soil and thereby increasing its productivity.

Much of the recent experimentation with cover crops has come from traditional developing-world farmers in non-mechanized, manual farming systems. Of note is the experience of 10,000 Honduran farmers with velvetbean (Mucuna sp.), an aggressive Asian legume. Their success has motivated scientists in Latin America to initiate cover crop research and disseminate practical, farmer- tested information on their use. In the West African Republic of Benin, farmer supported research carried out by the RAMR project (Recherche Appliquée en Milieu Réel, in collaboration with IITA) resulted in a simple innovation to rehabilitate fields abandoned because of degraded soils or excessive spear grass infestation (the noxious weed Imperata cylindrica). The national extension service of the Republic of Benin and Sasakawa Global 2000 have distributed Mucuna seeds to about 10,000 farmers, who are now adapting it to a variety of agricultural systems.

Though most of these experiences have been in regions of high rainfall, there have also been successes in areas with a unimodal rainfall pattern. In arid regions such as Mali, northern Nigeria, Burkina Faso, and Senegal other leguminous species have been used: Dolichos lablab and Stylosanthes hamata to improve pasture, Aeschynomene histrix as a rotation crop for Striga control and for pasture improvement.

These farmer-led experiences have compelled numerous formal and informal organizations in Latin America, and a growing number in West Africa, to include cover crops among the technologies they research or promote.

Globally, the historical constraints on the use of cover crops has been modified by the collapse of many shifting cultivation systems and the high cost and unreliable supply of fertilizer. In cropping systems where labour productivity is low and declining due to weed invasion, cover crops can provide an effective alternative to chemical weed control and a net savings in labour costs. The large amount of biomass produced in situ by cover crops can also reduce the amount of time needed to restore agricultural productivity through fallowing and create on-farm incentives to control wildfires. Understanding the conditions under which cover crops can respond to farmer needs will be important to extending current experience to other regions.

Working with local farmers has challenged researchers and development workers alike to redefine their role and the role of farmers in the technology generation and diffusion process - this has been perhaps the most unexpected outcome of recent work with cover crops. Mesoamerican and Beninese farmers have been remarkably creative with cover crops and have developed and circulated a wide range of cropping practices. By raising the profile of farmer experience with cover crops and integrating these practices into existing soil productivity initiatives, an opportunity will be created to build the capacity of key institutions to develop agricultural technology with full farmer participation.

• Opening session and field visit to the Departments of Oueme, Atlantique and Mono (Participants divided into 3 small groups)

• Plenary reports of each group on the field visit (technical, socio-economic and institutional issues reviewed)

• Presentations by invited speakers on key experiences with cover crops

• Discussions in working groups focused on the constraints to adoption of cover crops in humid, sub-humid and semi-arid regions

• Plenary synthesis

• Conclusions and recommendations

• Closing session