Discussion Paper

Estimating Returns to Soil and Water Conservation Investments: An Application to Crop Yield in Kenya

Oct 15, 2008 | Wilfred Nyangena, Gunnar Kohlin

This was created in partnership with Environment for Development .

Abstract

Productivity gains from soil and water conservation (SWC) have empirical support in research stations. Previous empirical results from on-farm adoption of SWC are, however, varied. This studyinvestigated the impact of soil conservation investment on farm productivity in three regions in Kenya. Using plot-level survey data, we focused on land productivity on plots with and without SWC. We tested the overall soil conservation hypothesis that increased SWC is beneficial for yield, as well as more specific hypotheses that SWC affects levels of inputs, returns from these inputs, and crop characteristics. The results showed a mixed picture where plots without SWC generally have higher yield values per hectare. However, plots with SWC are significantly steeper and more eroded than plotswithout SWC. A more careful analysis of a two-stage random effects–switching regression estimation comparing three SWC technologies to plots without SWC indicated that SWC increased the returnsfrom degraded plots and sometimes from other inputs. A simulation exercise based on these estimations also showed that, in most cases, adoption has been beneficial for those who have done it and would bebeneficial for those who have not.