Growth and yield response of grain legumes to different soil management practices after rainfed lowland rice

Field experiments were conducted over a 3-year period (1992–1995) in Sulawesi, East Java and the Philippines to investigate the response of post-rice (Oryza sativa L.) soil managements on growth and yield of legumes after lowland rice under rainfed conditions. Grain legume yields ranged from complete crop loss due to excessive rainfall after sowing to a maximum of 1.08 Mg ha−1 for mungbean (Vigna radiata (L.) Wilzek), 1.33 Mg ha−1 for soybean (Glycine max L. Merr.) and 2.3 Mg ha−1 for peanut (Aracis hypogaea L.). The response and magnitude of the effects from different management systems on legumes were closely related to the climatic conditions prevailing during the crop establishment phase. Correct timing of legume sowing was seen as the most important factor determining successful moderate crop production, followed by the availability of subsoil water reserves. Tillage was considered a potential method to improve yields because sowing could be carried out later during the dry season when rainfall was more predictable. Tillage, provided it is carried out at suitable soil water contents, could probably partially overcome the adverse soil physical condition induced during the rice phase. Fertiliser application tended to increase food legume in wetter areas showing that residual fertiliser effects from the previous rice crop could be limiting. In drier areas, fertiliser application had little effect on grain legume yields. Mulch as a soil amendment tended to increase yields in drier areas due to its water conservation effect. In wetter areas mulching was not necessary and could even lead to yield reduction if conditions were too wet.