Rooting for food security in Sub-Saharan Africa
This letter (PDF) in the journal Environmental Research Letters provides a quantitative assessment of the degree to which major agricultural countries in west and east Sub-Saharan Africa (SSA) can join the ranks of the world most productive crop producing regions. There is a persistent narrative about the potential of SSA to be a ‘grain breadbasket’ because of large gaps between current low yields and yield potential with good management, and vast land resources with adequate rainfall. However, rigorous evaluation of the extent to which soils can support high, stable yields has been limited by lack of data on rootable soil depth of sufficient quality and spatial resolution. This paper uses location-specific climate data, a robust spatial upscaling approach, and crop simulation to assess sensitivity of rainfed maize yields to root-zone water holding capacity. It is found that SSA could produce a modest maize surplus but only if rootable soil depth is comparable to that of other major breadbaskets, which is unlikely based on currently available information. Otherwise, producing surplus grain for export will depend on expansion of crop area with the challenge of directing this expansion to regions where soil depth and rainfall are supportive of high and consistent yields, and where negative impacts on biodiversity are minimal.