Enhancing crop response to fertilization in northern Ghana: The role of inherent soil fertility and crop management

Governments in West Africa’s savannah agroecological zone and their international partners have been making mineral fertilizers available to farmers to improve crop yields. However, research has convincingly shown that the efficiency of applied fertilizers is low in northern Ghana, suggesting there are other factors that are impeding the ability of crops to take up and/or utilize nutrients in applied mineral fertilizers. In this thesis, I analyzed how targeted crop production measures, aimed at alleviating constraints in crop cover, sulfur availability and use, crop rooting depth, and soil moisture availability and use, drive crop yield responses to nitrogen (N), phosphorus (P), and potassium (K) fertilization in northern Ghana. I found that increased sowing density, sulfur fertilization, ridging, and mulching, represent alternative pathways through which crop yields could be improved when NPK is applied, in northern Ghana. However, mulching and possibly ridging seem not fit the existing farming context of smallholder farmers.