Preliminary evaluation of tillage systems on poorly-drained inland valley bottom soils

Preliminary studies were conducted in 1990 wet and 1991 dry seasons to eval uate the effects of mound-tillage (MT), ridge-tillage (RT), and no-tillage (NT) planting systems on soil properties and yield of maize in the sub-humi d area of south-western Nigeria. Soil moisture retention in the 30-cm top l ayer was in the order (P < 0.01) NT > RT > MT. Air-filled pore spaces of th e same depth zone was in the reverse order (P < 0.01). Total N content at f irst planting and final harvest was 0.11 and 0.20%, 0.24 and 0.19%, and 0.0 4 and 0.19% at No in IV1, IV2, and IV3, respectively. In the 1990 wet seaso n, MT significantly (P < 0.01) produced higher yields than NT and RT in gre en maize in IV2 and IV3, whether fertilized or not. In the 1991 dry season, the differences were also highly significant (P < 0.01) in IV3, where the fertilized MT and RT plots produced more green maize than the NT plot. The study demonstrated that MT with fertilizer would lead to sustainable increa ses in crop yields in valley bottom soils.