Beyond fertilizer for closing yield gaps in sub-Saharan Africa

Numerous factors interact and result in the yield gaps in sub-Saharan Africa, although none have been studied more than mineral fertilizer13, particularly N-based fertilizer, from the micro to landscape scales. In the quest to close yield gaps, recommended fertilizer application rates are often informed by fertilizer response trials or simulation models based on these. However, this is not the only information farmers need. Farmers function in complex worlds, where information needs to be contextualized by considering the total cost of fertilizer application (purchase, transportation and labour) and how this cost relates to increased yields and crop prices. In this context, recommended fertilizer rates may render crop production unprofitable. What is viable and possible is quite different in the real world, especially for resource-poor small-scale farmers.