土壤翻耕对坡地水分转化与产流产沙特征的影响

坡耕地严重的水土流失是导致黄土高原土壤质量退化与生态环境恶化的重要原因。采用模拟降雨的方法研究了翻耕与压实对休闲黄绵土坡耕地水分转化与产流产沙特征的影响。结果表明，(1)与压实相比，土壤翻耕导致入渗率下降40%～60%，产流强度增加1至3倍，降雨向土壤水分的转化率降低50％以上。(2)翻耕条件下流失径流的平均含沙量增加近70％，坡地产沙量增加3倍，径流流失量增加1倍，因此对坡地实行免耕休闲可以有效减轻水土流失、遏制坡地土壤质量退化的态势。(3)降雨过程中，随着产流时间的延长，坡地产沙量呈加速增加的趋势，而且增加速度显著快于坡面径流，因此采取适当措施延长初始产流时间、减少产流量以及提高降雨向土壤水分的转化率均可有效减少坡地土壤流失量。

Impact of tillage on water transformation and runoff-sediment-yielding characteristics on slope land

Serious soil and water loss from slope land was the main causes for soil degradation and eco environmental degradation on the Loess Plateau. Experiments were conducted on soil water transformation and runoff sediment yielding characteristics on loessial soil slope land for tillage and compaction under simulated rainfall conditions. Results showed that: (1) comparing soil tillage with compaction, the infiltration rate decreased by 40%~60%, runoff yielding intensities increased by one to three times, and the transforming ratio from rainfall to soil water decreased by over 50%; (2) Under tillage conditions, the average sediment concentration in lost runoff increased by 70%, sediment yielding amount increased by three times, and runoff volume doubled. So the application of no till fallow could reduce the loss of soil and water and even control soil quality degradation on slope land. (3) With the extension of runoff yielding time during the rainfall process, the sediment loss from slope tended to accelerate more rapidly than runoff volume increased. So the applications of suitable measures to prolong the initial runoff yielding time, reduce runoff yielding volume, and increase the transformation ratio from rainfall to soil water will be effective in reducing soil loss from slope land.