Effects of grass vegetations on the processes of soil erosion over slope lands in simulated rainfalls
模拟降雨下草地植被调控坡面土壤侵蚀过程

The processes of running off and sedimentation over slope lands covered by ryegrass (Lolium perenne L.) and sainfoin (Onobrychis viciaefolia Scop.) in their different growing periods as well as by bare soil were studied in simulated rainfall conditions on the Loess Plateau. The contributions of the roots and canopies of ryegrass and sainfoin to reducing the runoff and sediment over the slope lands were compared, by means of cutting off the canopies of the two types of grasses over some experimental pans before a rainfall. The results showed that both ryegrass and sainfoin could control the soil erosion over the slope lands effectively. At the final period of the experiment, the runoff was decreased by 65% over the ryegrass lands and 45% over the sainfoin lands respectively; the sediment was reduced by over 93% on both lands. It was also indicated that the contributions of the roots and canopies to reducing the runoff and sediment were different for both ryegrass and sainfoin. The ryegrass canopies contributed more than the roots to reducing the runoff, by over 60% runoff decreased in most periods except for a 44.7% runoff reduction in the final period. On the contrary, the decreasing of runoff by the sainfoin over slope lands mainly relied on the roots. Meanwhile, the roots of the plants largely affected the controlling of soil erosion on the slope lands; from the first to the final period during the experiment, with the growth of the roots, the reduction of the sediment by the ryegrass was increased from 72% to 96%, and prominently increased from 16% to 93% by the sainfoin.