Returns to fertiliser use: Does it pay enough? Some new evidence from Sub-Saharan Africa
研究布基纳法索农民化肥使用率低的原因，发现化肥盈利性并非主因，而供应不足和信贷限制可能是关键障碍。
The low level of modern inputs adoption by African farmers is considered to be a major impediment to food security and poverty reduction in Sub-Saharan Africa. The government of Burkina Faso, following the example of a number of other countries in the region, launched a subsidy program in 2008 to encourage farmers’ uptake of chemical fertilizers and foster cereal production. This article explores the importance of fertilizer profitability in explaining the relative, apparent low use of chemical fertilizers by farmers in Burkina Faso. Using largescale plot data, we estimate maize yield response to nitrogen to be 19 kg/ha on average and to vary with soil characteristics. Profitability, which we measure through the calculation of a marginal value cost ratio, is estimated at 1.4 on those plots which received fertilizers, with significant variations across regions. For those plots on which fertilizers were not applied, we predict that fertilizers should have been profitable in most cases under the current level of subsidized fertilizer prices. These findings suggest that the low uptake of chemical fertilizers might have been driven by factors other than profitability, including insufficient supply of subsidized fertilizers to farmers in need. Our results also call for increasing the availability of credit to farmers in order to encourage adoption of chemical fertilizers. Finally, our results also show that not taking into account the endogeneity of nitrogen use in the yield equation may produce biased estimates of the maize yield response to nitrogen.