State-Conditional Fertilizer Yield Response on Western Kenyan Farms

45 Pages Posted: 26 Jun 2008

See all articles by Paswel Marenya

Paswel Marenya

Cornell University

Christopher B. Barrett

Cornell University - Charles H. Dyson School of Applied Economics & Management

Multiple version iconThere are 2 versions of this paper

Date Written: April 2007

Abstract

Serious declines in agricultural soil quality in sub-Saharan Africa presently command high profile attention in development circles, with much emphasis placed on stimulating increased use of fertilizers to increase agricultural productivity and sustain soils. This paper explores whether inherent biophysical complementarities among soil nutrient stocks might limit incentives for nitrogen fertilizer application on more degraded farms. The prioritization of fertilizer interventions in contemporary poverty reduction programming in Africa is based, implicitly or explicitly, on the assumption that the marginal returns to fertilizer are high and that resolving institutional or market failures that restrict fertilizer uptake will generate big gains. Using a unique survey design and soils data from plots operated by small farmers in western Kenya, we find von Liebig-type complementarities among soil nutrients, with maize yield response to nitrogen fertilizer application that is strongly and statistically significantly S-shaped with respect to soil organic carbon stocks. On a large minority of plots, degraded soils limit the marginal productivity of fertilizer such that it becomes unprofitable at prevailing prices. This suggests that in certain cases ex ante soil conditions will matter to the return on investments in fertilizer policies.

Suggested Citation

Marenya, Paswel and Barrett, Christopher B., State-Conditional Fertilizer Yield Response on Western Kenyan Farms (April 2007). Available at SSRN: https://ssrn.com/abstract=1141937 or http://dx.doi.org/10.2139/ssrn.1141937

Paswel Marenya

Cornell University ( email )

Ithaca, NY 14853
United States

Christopher B. Barrett (Contact Author)

Cornell University - Charles H. Dyson School of Applied Economics & Management ( email )

315 Warren Hall
Ithaca, NY 14853-7801
United States
607-255-4489 (Phone)
607-255-9984 (Fax)

HOME PAGE: http://aem.cornell.edu/faculty_sites/cbb2/

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