Preliminary studies were conducted in 1990 wet and 1991 dry seasons to evaluate 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-humid area of south-western Nigeria. Soil moisture retention in the 30-cm top layer was in the order (P < 0.01) NT > RT > MT. Air-filled pore spaces of the same depth zone was in the reverse order (P < 0.01). Total N content at first planting and final harvest was 0.11 and 0.20%, 0.24 and 0.19%, and 0.04 and 0.19% at N0 in IV1, IV2, and IV3, respectively. In the 1990 wet season, MT significantly (P < 0.01) produced higher yields than NT and RT in green 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 increases in crop yields in valley bottom soils.