Anti-Erosion Influences of Surface Roughness on Sloping Agricultural Land in the Loess Plateau, Northwest China

Abstract

The roughness of surface soil and the benefits produced by tillage for slope runoff and sediment reduction have attracted considerable interest; however, there are inconsistencies in existing research results. In this study, we have studied the anti-erosion influences of several typical tillage practices on both runoff and sediment generation in areas of sloping farmland in the Loess Plateau of northwest China. Rough surfaces were prepared manually, according to the surface microtopography of the plateau’s sloping farmland, using four tillage practices; a smooth surface was used as a control. Rainfall simulation experiments were performed using three rainfall intensities and five slope gradients. A path analysis was used to analyze the interactive effects of the slope gradient, rainfall intensity, and the surface roughness on the sediment yield and runoff volume. According to our findings, the gradient of a slope and the intensity of the rainfall both had a positive effect, while the surface roughness had a negative effect; the rate of 40.8% and 21.0% was lower than the values under CK on sediment yield and runoff volume. The interaction between the rainfall intensity and surface roughness always had a runoff reduction effect. Conversely, there was a critical slope gradient between 5° and 10° for sediment yield. The interaction between the slope gradient and surface roughness also had a runoff reduction effect, which was diminished by increasing the rainfall intensity. However, their interactive influence on sediment yield was inconsistent, with a critical slope gradient between 10° and 15°. Based on the comprehensive interactive effects among all three factors, we concluded that rainfall intensity, slope gradient, and surface roughness collectively played a crucial role in promoting runoff and sediment generation under tillage. The results support soil and water conservation by tillage on the sloping farmlands of the Loess Plateau.