Effects of Inorganic and Organic Amendments on Soil Carbon and Nitrogen Dynamics in Four Agro-Ecosystems of Ghana.

Due to inherent low soil fertility, limited access to costly fertilizers, and widespread promotion of generic fertilizer recommendations in Sub-Saharan Africa, local soil analysis-based fertilizer recommendations are critically needed.  Previous research exploring the effect of different rates of mineral and organic amendments on soil nutrients have found mixed results due to variations in geography and cropping systems. In 2014, soils from four agro-ecosystems of Ghana were analyzed for the soil fertility response to varying rates of phosphorus, nitrogen, and compost in a continuous maize cropping system. The study was arranged in a completely randomized split-plot design with three replications. Phosphorus was the main plot at 0, 20 and 40 kg ha^-1, nitrogen and compost were randomly assigned to the subplot at a rate of 0, 70, and 140 kg ha^-1 and 0, 3000, and 6000 kg ha^-1, respectively. In agro-ecosystems with ample precipitation, it is expected that a high rate of compost and N in conjunction with high P will result in the most significant soil nutrient gains. In rainfall scarce regions of Ghana, greatest soil fertility is expected from plots treated with high P and N alone.