Millet (Pennisetum typhoides) yield and selected soil attributes as influenced by some tree types of the semi-arid tropics of Sudan

Two experiments were conducted in southern Kordofan State to determine the influence of Acacia senegal L., Balanites aegyptiaca L. and Azadirachta indica L. on millet (Pennisetum typhoides) yield, soil quality and to monitor decomposition and nutrients release from tree litters. Yield under A. indica (174.83 kg ha−1) and B. aegyptiaca (173.09 kg ha−1) were significantly higher than the control (121.43 kg ha−1). The lowest yield (111.04 kg ha−1) was recorded under A. senegal. Straw dry matter under B. aegyptiaca (1161.5 kg ha−1) and A. indica (857.8 kg ha−1) was significantly higher than both under A. senegal (321.8 kg ha−1) and the control (454.8 kg ha−1). Trees varied in their capacity to induce changes in soil properties whereas effects on soil N were not substantial. A. indica had a decomposition rate (0.6283 week−1) 2.0 times higher than that of B. aegyptiaca (0.2057 week−1) and A. senegal (0.267 week−1). The highest rate of P and K release from A. indica and B. aegyptiaca litters has resulted in significant accumulation in the soil indicating these tree litters are potential sources for these elements. The capacity of trees to improve soil fertility could offer an alternative management system for improved cultivation of field crops.