Estimating Returns to Soil and Water Conservation Investments - An Application to Crop Yield in Kenya
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 study
investigated 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 plots
without 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 returns
from 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 be
beneficial for those who have not.
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Date
2009-11-30Author
Nyangena, Wilfred
Köhlin, Gunnar
Keywords
Kenya
soil conservation
switching regression
rural households
yields
Publication type
report
ISSN
1403-2465
Series/Report no.
Working Papers in Economics
402
Language
eng