Dr Patrick Musinguzi1, Dr Peter Ebanyat1
1Makerere University, Kampala, Uganda
East African region is one of the regions with the lowest fertilizer use in world. This has curtailed optimum crop production subsequently resulting in food and income insecurity. Measures that can optimize fertilizer use in highly heterogeneous farming environment – typical of smallholder farming are critically vital. Soil organic carbon (SOC) is an important parameter believed to be a universal indicator of soil quality and crop productivity. Its contribution as a determinant factor in optimizing fertilizer use efficiency in East Africa remains debatable. An analysis of SOC in selected fields using the Partial Least Square models demonstrated that the contribution of SOC is more than a half (53-62%) of the soil factors in influencing crop yield variability. Quadratic plus models demonstrated evidences of moderate SOC (1.7-2.2%) influencing nutrient recovery efficiency that translated to highest nitrogen recovery efficiency (32-36% of the applied N) and optimal yield. Field with high and low SOC resulted in low nutrient recovery efficiency (21-27%) of the applied N. This suggested that SOC may be a reliable factor in understanding the state of soil quality, nutrient recovery efficiency, and crop responsiveness to applied fertilizer in smallholder farming systems. It is a dependable factor in contributing to understanding the conundrum of fertilizer use and for guiding field selection of responsive and less responsive fields in East Africa.