Soil loss: Effect of plant litter incorporation rate under simulated rainfall conditions

Abstract

AbstractPlant litter can control land degradation by increasing soil organic matter and decreasing soil erosion by covering the soil surface or being incorporated into topsoil. However, the effect of litter incorporation on soil erosion is not clear. This study aimed to investigate the effect of litter incorporation into topsoil on interrill erosion. The poorly decomposed litter was collected from the field and incorporated into topsoil (5 cm) at six rates (ranging from 0 to 0.5 kg m−2). Laboratory rainfall (80 mm hr−1) experiments were conducted under five slope gradients (ranging from 9% to 47%). The results showed that the soil loss rates declined exponentially with increase in litter incorporation rate on slope gradients between 9% and 36%. However, on slope gradient of 47%, litter incorporation caused an increase in the soil loss rate. The efficiency of litter incorporation in controlling soil loss varied from −21.7% to 40.5% with a mean of 10.8%. It decreased linearly with the slope gradient (R2 = 0.34). The decrease can be explained by two simultaneous but opposite effects: the effect of preventing erosion and that of promoting erosion. The former was induced by decreases in the effective erosive force of raindrop and overland flow exerted on soil, and soil erodibility, along with increases in sediment interception. The latter was caused by rapid saturation of the surface soil and concentrated overland flow. The results demonstrate the complexity of the effect of litter incorporation on soil erosion and can improve our understanding of litter in soil loss control.