Effect of vegetative cover and slope on soil loss by erosion using rainfall simulator

Abstract

Top soil is very important for crop production but it is usually washed away in the tropical countries like Nigeria by erosion due to heavy rainfall with high intensity. In this study, a rainfall simulator was used to determine the quantity of soil loss (sediment load) from a bare soil and vegetative cover soil under different slopes. The slopes of the land for plots 1 to 5 for a bare soil varied from 5.20 to 9.7 % but for a vegetative cover soil (grown with grasses), the slopes varied from 2.8 to 3.2 %. The uniformity coefficient and drop velocity of the rainfall simulator used were 84.4 % and 8.156 m/s, respectively. The soil of the experimental site was sandy loam and the area of coverage by rainfall simulator was 3 by 3 m. Soil loss (sediment load) for a vegetative cover soil for slopes 2.8, 2.9, 3.0, 3.1 and 3.2 % were 0.252, 0.358, 0.350, 0.371 and 0.422 kg, respectively. Soil loss from a bared soil for slopes 5.2, 6.7, 9.0, 9.6 and 9.7 % were 1.045, 1.070, 1.100, 2.266 and 3.121 kg, respectively. Vegetative cover soil with grasses reduced the runoff volume and soil loss. Runoff volume and soil loss increased as slope of the land increases.

Keywords: erodibility, erosion, erosivity, rainfall simulator, soil loss