David Murphy is a PhD student at Cornell’s Dyson School of Applied Economics and Management.
A recent blog post described how farmers in the developing world form perceptions about soil fertility, and how those perceptions correspond with high-resolution interpolated data and actual on-farm soil testing. They demonstrate, perhaps unsurprisingly, that farmer perceptions are primarily driven by past crop yields, a finding also observed by Marenya, Barrett, and Gulick (2008). Past yields offer a lagged information signal to farmers, but farmers are not necessarily able to perceive which—if any—particular nutrients are deficient in their soil. This is especially important for resource-constrained farmers, as they must determine which inputs are best for their soils based on this insufficient information. For example, not all inputs are appropriate for every soil type: nitrogen fertilizers are generally ineffective when applied to soils with low organic carbon. Low carbon soils may instead require additions of manure or crop residues to improve soil fertility (Vanlauwe et al. 2002; Marenya and Barrett 2009a,b). The resulting uncertainty and lack of an accurate measure of farmer’s soil type and nutrient levels can lead to inefficient adoption or use of fertilizer. Continue reading