Soil quality and resilience characteristics determine productivity, sustainability, and risks of soil and environmental degradation. Soil surface management, comprising residue mulch and tillage methods, affects soil quality and resilience. Field experiments were conducted in western Nigeria on soils prone to erosion and degradation to evaluate the effects of mulch rates on runoff, soil erosion and crop yield. Effects of five mulch rates (4, 3, 2, 1 and 0 Mg/ha/season of rice straw mulch) with notill on crop response were compared with that of plow till treatment on field runoff plots for four consecutive years from 1981 to 1984. Runoff and soil erosion effects of different mulch rates were measured for only 1981 and 1984. Maize grain yield was significantly affected by mulching in 1 out of 3 seasons, and was the highest at 5.4 Mg/ha for 4 Mg/ha mulch rate and the lowest at 3.5 Mg/ha for 1 Mg/ha mulch rate, a difference of 54%. Soybean grain yield was significantly higher at 1.4 Mg/ha for 4 Mg/ha mulch rate than 0.8 Mg/ha for 1 Mg/ha mulch rate, a difference of 62.5%. Mean cowpea yield was the highest at about 1 Mg/ha for 4 Mg/ha mulch rate and the lowest at 0.7 Mg/ha for unmulched plots. Runoff and soil erosion were lower in 1981 than in 1984, with higher losses generally for the plow till treatment. The index of relative mean annual soil erosion was in the order 100 (plow till), 35.1 (0 Mg/ha mulch rate), 25.0 (1 Mg/ha mulch rate), 30.9 (2 Mg/ha mulch rate), 20.8 (3 Mg/ha mulch rate), and 16.1 (4 Mg/ha mulch rate). Reductions in soil erosion by mulching were due both to decreased runoff and to lower sediment concentration in runoff. The data show that the desirable mulch rate for soil and water conservation is about 4 Mg/ha/season for these soils.
