Efforts to improve the yields of staple cereal crops like maize and rice at scale in Africa remain seriously hampered by the effects of poor soil fertility. The lack of adequate information to base an effective fertilizer recommendation upon often results in inefficient nutrient use by crops and low crop yields. A root cause of poor crop response to applied nutrients is generalized fertilizer recommendations that fail to account for variability in factors such as the climate, soil properties, and water availability. As we improve our understanding of the range of underlying issues that interact to create variability, better solutions can be created for farmers, and confidence in fertilizer use will grow.