Scientists are increasingly being challenged to provide policy makers with information on the trade-offs between environmental and economic development goals. There is a need for new approaches for assessing potential impacts of interventions that combine scientific knowledge with empirical information on constraints of land users. In this paper we use a custom-built, economic-ecological simulation model to examine the impact of existing and proposed soil management strategies on farm productivity, profitability, and sustainability for smallholder farmers in western Kenya. The model is applied to three representative farm types, which were developed using wealth ranking and other participatory techniques to reflect the differences in resource endowments and constraints faced by farmers in Vihiga District of western Kenya. The model is first used to examine the impact of existing soil management strategies. Results show the importance of differentiating farm types by important characteristics that impact opportunities and management. The current soil management practices of high resource endowment farms are productive, profitable, and ecologically sustainable. Low and medium resource endowment farms, on the other hand, use techniques with much lower levels of productivity and profitability that result in a declining soil resource base. The model is then applied to analyze the potential impacts of improved soil fertility management, using various sources of phosphorous (P) and nitrogen (N). Results indicate that high resource endowment farmers are already using near optimal management practices, and new management techniques have little impact on yields or other indicators. Low and medium resource endowment farmers, on the other hand, can greatly improve farm profitability and sustainability through improved management of p and N, but low land and capital resources constrain the adoption of the improved practices. Targeting interventions to low and medium resource endowments will, therefore, have much larger payoffs. Model results-as well as extensive discussions with farmers during the participatory data collection exercises-suggest that most farmers are aware of better soil fertility management practices but are not able to apply them due to lack of resources. When cash is available, investment in soil fertility must compete with other needs and investments such as education. It is likely that high resource endowment farmers only began to invest in soil fertility when other needs and higher-return investments (such as educating children) were already satisfied.

English

0310|AGRIS 0301|AL-Economics Program|R01PROCE

Juan Carlos Mendieta

CIMMYT Publications Collection