Soil fertility decline poses a major threat to food security in the African Sahelian region. Historically, soil fertility in the region has been maintained through shifting cultivation with long natural fallow, however, increasing population pressure has shortened fallow periods. As a result, nutrient lost through crop yields are not replaced due to unavailability and high cost of inorganic fertilizers1. Curbing this problem has led to the promotion of green manure from various agroforestry practices such as alleycropping, improved fallows, border tree plantings and woodlots. The ability of green manure to release nutrients into the soil is based on type of green manure (leguminous or non-leguminous) and the season of harvest and application (dry or rainy). Considering these factors, our study sought to compare the seasonal variation in green manure nutrient concentration and decomposition rate based on green manure type.