An ecological and economic analysis of phosphorus replenishment for VihigaDivision, western Kenya

Soil scientists have identified phosphorus deficiency as a major constraint to improved maize and bean yields in the highland areas of western Kenya. This study evaluated the economic costs and benefits as well as ecological impacts of different phosphorus replenishment strategies from both a farm-l evel and a regional perspective using an economic-ecological simulation mod el. The study associated soil properties with representative farm types and showed how the impact of soil fertility replenishment depends on initial s oil conditions as well as the resource endowment level of the farmer. Two h undred and ten different strategies for phosphorus replenishment with diffe rent sources of phosphorus applied at various levels were analyzed for seve n farm types. The farm-level analysis showed that phosphorus replenishment was generally profitable for farms with low and medium pH (4.9-6.2) soils, but not for farms with high pH (6.2-7.0) soils. A regional analysis showed that benefits were higher when phosphorus replenishment was targeted to far mers with low and medium resource endowments on low and medium pH soils rat her than spread evenly across all soil and farm types. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.