Nutrient and productivity status of corn-indigenous legume rotation schemes in upland alley cropping systems

The different crop rotations did not alter N, P, and K organic matter and cation exchange capacity (CEC) at 0-15 cm layer with and without alley, although, these soil properties decreased over time. The significantly high reduction in percentage N and organic matter with alley indicates that more nutrients are taken by corn plants. The utilization of winged beans and lima beans as rotation crops resulted to a decreased exchangeable K. The decrease, however, was higher with than without alley. The Gliricidia prunings contributed to the soil K content and not to the organic matter, N, P, and CEC. Corn grain yield and its components were not significantly affected by the different crop rotations with and without alley. However, the high crop growth rates contributed to the high corn grain yield and its components with alley. The harvest index was not altered by the different crop rotations, but was higher with than without alley. The stover yield did not significantly vary with the different crop rotations. With alley, stover yield was slightly higher compared to without alley. Stover yield was positively correlated with crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD) and net assimilation rate (NAR). The total dry matter (TDM) was significanty affected by the different crop rotations and growth stages with and without alley. The CGR, LAI, and NAR were not significantly affected by the different crop rotations, with and without alley. With alley, the increased LAI and NAR increased CGR. Soil loss and surface runoff were significantly affected by the different crop rotations. Corn-fallow-corn and corn/winged beans (relay)-corn had lower soil loss and surface runoff values than corn-winged beans-corn and corn-lima beans-corn. The thick biomass and high percentage crop cover of corn-fallow-corn and corn/winged beans (relay)-corn reduced soil loss and surface runoff. Based on the nutrient balance, N, P, K decreased in the different crop rotations with and without alley. With alley, the decrease in N, P, and K increased plant uptake, soil loss and surface runoff. Corn-fallow-corn had low nutrient loss, soil loss and surface runoff. The depletion of nutrients was minimal without alley. The corn grain yield under alley cropping system was affected by agronomic and physiological characteristics. The high nutrient uptake of corn in alley cropping increased crop growth at vegetative stage and thus, increased grain yield. The utilization of winged beans and lima beans as rotation crops did not affect corn productivity and nutrient status over a short period. The corn-fallow-corn had positive effect on both soil nitrogen, organic matter, soil loss and surface runoff