This experiment assessed the feasibility of using leaf prunings ofCalliandra calothyrsusandLeucaena leucocephalafor soil fertility improvement in alley cropping and sole cropping systems. The experiment, conducted at the National Agroforestry Research site at the Kenya Agricultural Research Institutes's (KARI's) Regional Research Centre, Embu, was a randomised block design with four alley cropping treatments namely: (1)C. calothyrsuswith primings incorporated; (2)L. leucocephalawith prunings incorporated; (3)C. calothyrsuswith prunings removed to (5); (4)L. leucocephalawith prunings removed to (6); and six sole cropped treatments namely (5)C. calothyrsusprunings imported from (3); (6)L. leucocephalaprunings imported from (4); (7)C. calothyrsusprunings plus fertilizer 25 kg N and P/ha; (8)L. leucocephalaprunings plus fertilizer at 25 kg N and P/ha; (9) Fertilizer at 50 kg N and P/ha, and (10) Control-no fertilizer and no prunings. Biomass production decreased from an average of 6.5 t/ha during the 1993 Long Rainy season (first cutting) to an average of 1.7 t/ha during the 1994 Long Rainy season. This resulted to small amounts of nutrients supplied to the soil by incorporated leaf prunings and could have limited crop growth thus giving low crop yields during 1994 LR. Alley cropped treatments yielded less maize and bean grain than sole cropped treatments during the 1993/94 Short Rainy season; thus was attributed to competition for growth resources. Improvement of crop yields in alley cropping systems through green manuring may be limited by low biomass production and competition. In a sole cropping system, use of green manure to boost crop yields seems feasible with high biomass applications or fertiliser supplementation.