Soil Loss as Affected by Different Combinations of Surface Litter and Rock

Abstract

AbstractThe effects of various surface cover types, their combinations, and bare ground on soil loss from a clay loam topsoil were studied on small plots in the laboratory using a rotating boom rainfall simulator. A total of 105 plots with various types and amounts of surface cover were exposed to simulated rainfall at 100 mm/h for 30 min. Cover treatments included herbaceous litter of sedges (Carex spp.) and bluegrass (Poa spp.), shrub litter of willows (Salix spp.), small rocks, and mixtures of these cover types at several levels of cover (0, 25, 50, 75, 100%) and bare ground (control). Experimental data for high intensity storm were used to develop an equation to quantify soil loss and surface cover relationships for a clay loam soil. Regression analysis indicated high correlation (R2 = 0.86) between soil loss and types and amounts of surface cover. Soil loss from bare plots was about 13 000 kg/ha. A surface cover proportion of about 0.60 for vegetation litter, and 0.85 for rock, would reduce soil loss to about 5000 kg/ha. Rocks were not as effective as vegetation litter in our experiment in protecting the soil from erosion. However, surface coverage of 100% with combinations of vegetation litter and rocks offered the best protection of the soil against erosion. This combination was better than either 100% vegetation litter cover or 100% rock cover alone. Rock in combination with vegetation litter may have increased roughness and allowed deposition of sediment.