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Fertilizer and grain prices constrain food production in sub-Saharan Africa


Crop yields across sub-Saharan Africa are much lower than what is attainable given the environmental conditions and available technologies. Closing this ‘ecological yield gap’ is considered an important food security and rural welfare goal. It is not clear, however, whether it is economically sensible for farmers to substantially increase crop yields. Here we estimate the local yield response of maize to fertilizer across sub-Saharan Africa with an empirical machine-learning model based on 12,081 trial observations and with a mechanistic model. We show that the average ‘economic yield gap’—the difference between current yield and profit-maximizing yield—is about one-quarter of the ecological yield gap. Furthermore, although maize yields could be profitably doubled, the economic incentives to do so may be weak. Our findings suggest that agricultural intensification in sub-Saharan Africa could be supported by complementary agronomic approaches to improve soil fertility, lowering the fertilizer cost, and by spatial targeting of fertilizer recommendations.

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Fig. 1: Estimated maize yield and nitrogen use efficiency in SSA.
Fig. 2: Spatial variation in prices in SSA.
Fig. 3: Maximum profitability of fertilizer use and maize yield in SSA.
Fig. 4: Economic and relative yield gaps for maize production in SSA.
Fig. 5: Cumulative proportion of the economic and ecological yield gaps, maximum profitability of fertilizer use and the VCR for the most profitable fertilizer use for maize production in SSA.

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Funding for this project was provided by the Feed the Future Sustainable Intensification Innovation Lab (SIIL) through USAID (grant number AID-OOA-L-14-00006) (R.J.H.), by the Bill and Melinda Gates Foundation through the Taking Maize Agronomy to Scale in Africa (TAMASA) project (investment number INV-008260) (J.C.) and by the MAIZE CGIAR Research Program led by the International Maize and Wheat Improvement Center (CIMMYT) (J.C.).

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C.B.-C., J.C. and R.J.H. conceived the research. C.B.-C. performed the data acquisition and processing. C.B.-C. and R.J.H. analysed the data. C.B.-C., J.C. and R.J.H. wrote the manuscript.

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Correspondence to Camila Bonilla-Cedrez.

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Peer review information Nature Food thanks Andrew Nelson, Liangzhi You and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Bonilla-Cedrez, C., Chamberlin, J. & Hijmans, R.J. Fertilizer and grain prices constrain food production in sub-Saharan Africa. Nat Food 2, 766–772 (2021).

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