Application of zai and rock bunds in the northwest region of Burkina Faso: Study of its impact on household level by using a stochastic linear programming model

Agricultural production in the northwest region of Burkina Faso is seriously endangered by soil erosion and an overall decline in soil fertility. In the past 15 years various anti-erosion methods have been adopted in this region with quite some success. The widespread promotion of rock bunds is an important example. Land conservation methods alone without increased efforts to mantain (or to increase) soil fertility levels does not suffice in the long run. In this article we focus on the potential impact of a combination of rock bunds and zai, a local technology to improve water infiltration and efficiency of manure application. The analysis is carried out at farm level with a stochastic linear programming model. It includes sequential decision making to cope with rainfall risks. The study reveals the important potential of rock bunds and application of zai, and limitations due to labour and manure constraints. The techniques are largely applied on common fields. Changes in labour organizations and use of manure have to be introduced before women may profit from these techniques on their individual fields as well. The results show that the impact on farm-level food security is more limited than is sometimes supposed on the basis of a simple extrapolation of plot-level results.