保护性耕作对地表径流及土壤侵蚀的影响

采用人工模拟降雨方法对陇中黄土高原连续实施5a的4种耕作措施：传统耕作（T），传统耕作结合秸秆还田（TS），免耕（NT），免耕加秸秆覆盖（NTS）下豌豆地收获后的径流起始时间、径流量、土壤侵蚀量进行了研究。结果表明，在降雨强度为85mm／h的条件下，NTS可以延缓径流，减小径流强度。与NT，TS，T这3种处理比较，NTS的径流量分别降低了2．4％，12．1％，34．7％。入渗量分别增加了2．7％，13．6％，38．6％。径流出现时间分别延迟1．17，0．83，3．83min。土壤侵蚀量减少了0．3％，17．7％，62．4％。可见，免耕秸秆覆盖的水土保持效应最为明显，传统耕作的方式极易发生土壤侵蚀。

Runoff and Quantity of Soil Erosion Uunder Conservation Tillage System by Simulated Rainfall

Four tillage treatments were carried out for five years by simulated rainfall in the middle area of the Loess Plateau: traditional tillage(T), traditional tillage with straw incorporated(TS), no-tillage(NT), and no tillage with straw cover(NTS).Runoff starting time, amount of runoff, and amount of soil erosion were measured af ter harvest of pea.Under rainfall intensity of 85 mm/h, ru noff process was alleviated and the amou nt of ru noff was red uced using NTS.Compared to NT, TS, and T, the amounts of runoff under NTS were red uced by 2.4%, 12.1%, and 34.7%, respectively; infiltration rates were increased by 2.7%,13.6%, and 38.6%; runoff starting times were slowed down 1.17, 0.83, and 3.83 min; the amounts of soil erosion were red uced by 0.3%, 17.7%, and 62.4%.Therefore, the effects of soil and water conservation under NTS are most obvious and soil erosion is easily to take place u nder traditional tillage.