The Contribution of Astragalus adsurgens Roots and Canopy to Water Erosion Control in the Water-Wind Crisscrossed Erosion Region of the Loess Plateau, China

Simulated rainfall experiments were conducted to investigate the effect of Astragalus adsurgens roots and canopy on water erosion yield, erosion processes and soil resistance to erosion. Experiments were conducted on grass, root and bare slopes, with sandy soil from a water-wind crisscrossed erosion region of the Loess Plateau, China. A. adsurgens coverage on grass slopes was approximately 40%. There were three rainfall intensities of 30, 60 and 90mmh(-1) and four slope gradients of 3, 6, 9 and 12 degrees. A. adsurgens had a significant effect on soil erosion control; soil loss was reduced by similar to 70% on slopes with the grass compared with bare slopes. The grass roots reduced soil loss more than its canopy, particularly in high-intensity rainfall, which reduced soil loss by 82%. The presence of the grass and its roots changed the soil erosion process, reducing soil erodibility (K-r) and increasing the critical shear stress ((c)). The soil erosion rate on the bare slope increased steadily over time; on the grass and root slopes, its rate initially increased, then decreased and then finally stabilized. K-r on the grass and root slopes was reduced by 96% and 89%, respectively, compared with the bare slope, while the corresponding (c) increased by 92% and 195% respectively. These results provide insights into the mechanisms of grass on soil and water conservation and may help to improve vegetation construction in water-wind crisscrossed erosion regions of the Loess Plateau. Copyright (c) 2016 John Wiley & Sons, Ltd.