Soil quality and fertilizer use rates among smallholder farmers in western Kenya

Low fertilizer use perpetuates the slow yield growth in Sub Saharan Africa (in comparison to Asia and Latin America) as well as subsequent rates of hunger and malnutrition. Current models use primarily market-level factors in their analyses on fertilizer input use. However, increasing research indicates that nonmarket factors are also important determinants. The purpose of this study is to validate the accuracy of a soil carbon content (SCC) threshold in a switching regression model to determine fertilizer use in 260 farm households in Kenya. The model revealed that, in addition to market factors, fertilizer use was dependent upon SCC, and improved market level factors were less likely to increase its use in low SCC households. These results suggest that SCC improvement and favorable fertilizer market conditions must occur in tandem.