A research agenda to explore the role of conservation agriculture in African smallholder farming systems

Abstract

Controversy surrounds the promotion of conservation agriculture (CA) in smallholder farming systems in sub-Saharan Africa. The introduction of CA is a profound change in farm management. Benefits in reduced erosion and stabilized crop production may be obtained, but technical performance at field level is but one of the determinants of adoption. For various reasons, all of the CA principles are not always fully implemented by farmers and results not as favourable as expected. As with other approaches to increasing agricultural productivity, the production constraints, farmers' objectives, and the expected benefits and costs of implementing CA are important aspects that influence adoption. At farm and village levels, trade-offs in the allocation of resources become important in determining how CA may fit into a given farming system. At a regional level, factors such as the market conditions, interactions among stakeholders and other institutional and political dimensions become important. At each level, opportunities or difficulties emerge that enhance or impede development, adaptation and adoption of CA. The ex-ante identification of situations for where CA (and which form of CA) is appropriate demands research from a multi-stakeholder, multi-level, and interdisciplinary perspective. Recommendations are made where research is required to address key knowledge gaps. (Résumé d'auteur

Conservation agriculture for small holder rainfed farming: Opportunities and constraints of new mechanized seeding systems

“…However, for small holder, resource-constrained farmers various bottlenecks to adoption of CA remain, as elaborated by Giller et al, 2009 andGiller et al, 2011, despite the recent emergence of suitable minimum tillage implements. A particular challenge is development of integrated weed management strategies that will at least compensate the weed control afforded by conventional tillage.…”

“…In view of often suboptimal soil moisture levels in rainfed environments, it would be particularly instructive to quantify the effect of CA components on soil moisture availability to crops. Giller et al, 2009 andGiller et al, 2011 have questioned the universal suitability of CA practices.…”

“…They reduce the risk involved in such farming and are likely to remain integral to small holder farming into the future. Therefore, it is necessary to establish a compromise between crop residues used for retention on the field and for feed (Mueller et al, 2001 andGiller et al, 2011). Crop residues are also in demand as fuel and building material particularly in South Asia.…”

Infiltration and runoff losses under fallowing and conservation agriculture practices on contrasting soils, Zimbabwe

“…Increasing temperatures will directly affect water availability, through increased evaporation. Thus, there is a need for farmers use land management practices that increase water use efficiency by increasing infiltration rates and reducing evaporation (Marongwe et al, 2011) Conservation agriculture (CA) practices that minimise soil disturbance and which involve the spreading of crop residues on the soil surface are viable options for increasing water use efficiency because they reduce erosion (Giller et al, 2011) and increase water infiltration and storage in soil (Nyagumbo, 2002;Mzezewa and Van Rensburg, 2011). Some of the benefits of CA are immediate, e.g., improved infiltration rates and reduced soil loss (Thierfelder and Wall, 2009).…”

Strategies for improving water use efficiency of livestock production in rain-fed systems

“…However, there is a limit: keeping large numbers of animals on limited natural resource base will result in overexploitation of natural resources through excessive removal of vegetation through grazing. Likewise, allocation of higher amounts of crop residue to livestock feed exerts a competitive pressure on alternative uses of crop residues such as for soil mulching, roofing and fuel (Williams et al, 2000;Giller et al, 2011b). Alternatively, high volumes of beneficial outputs and services can be achieved by keeping few productive animals, improved feeding and better healthcare.…”