秸秆覆盖对坡耕地细沟侵蚀过程阻控机制研究

Straw mulching is one of the effective methods for controlling water and soil loss in slope lands, and plays an important role in the occurrence and development of soil erosion. According to the result of stimulated rainfall experiment in the laboratory and field monitoring, this program would study the mechanism and processes of rill erosion on the slope land under different forms of straw mulching, unravel the effect of different forms of straw mulching on hydraulic and soil anti-erodibility on the slope land, thereby reveal the relationship between soil erosion and rill development under straw mulching. This study would clarify the mechanism of effect of different forms of straw mulching on rill erosion, and also find out the crucial factors of straw mulching which affected the development of rill on the slope land, model the process of erosion on the slope land under straw mulching, and finally raise the optimal model in conservation tillage under straw mulching. This program would systematically study the mechanism of straw mulching acting on the occurrence and development of rill erosion. Based on revealing the mechanism of distraction, denudation, sediment and transport of soil, this program would probe thoroughly into the effect of straw mulching on the development of rill on the slope land, and unraveled the important role of straw mulching in the economical and effective treatment of soil erosion, perfection and popularization of conservation tillage, and maintenance of the arability and productivity level of the slope land. The results of these studies would provide the practical guidance for enhancing anti-water erosion ability of soil on the slope land as well as the control of water and soil loss.

秸秆覆盖是防治坡耕地水土流失最有效的措施之一，对坡耕地土壤侵蚀发生发展有重要影响。本项目通过室内模拟降雨和野外小区监测，研究秸秆覆盖条件下坡耕地细沟侵蚀发育过程和机理，阐明坡面细沟水动力学参数和土壤抗蚀性变化对不同秸秆覆盖的响应机制，探索秸秆覆盖下土壤侵蚀变化及其与细沟发育的关系。揭示不同秸秆覆盖对细沟发育的阻控机理，辨识不同秸秆覆盖对细沟发育的主要控制因素，模拟秸秆覆盖下坡面侵蚀过程，并提出秸秆覆盖保护性耕作的优化模式。本项目从揭示坡面径流分散、剥蚀、沉积和输移过程机理出发，深入探索秸秆覆盖在坡耕地细沟发育过程中所起的作用，阐明秸秆覆盖对细沟侵蚀过程的阻控机制，为侵蚀模型的应用和改进提供参考，对于进一步完善坡面土壤侵蚀理论和经济、高效地防治坡耕地土壤侵蚀有重要的科学意义，并为黄土区坡耕地水土流失治理提供理论指导。

项目基于人工模拟降雨试验和人工模拟放水冲刷试验等方法，对不同秸秆覆盖方式、秸秆覆盖量及秸秆长度条件下坡面土壤侵蚀过程及水动力学特征进行了系统分析，阐明了不同秸秆覆盖条件下坡面土壤侵蚀的发生发展过程及动力学机制，揭示了秸秆覆盖对坡面土壤侵蚀的影响机理，并提出不同覆盖方式下小麦秸秆的最佳覆盖模式。结果表明秸秆覆盖可深刻影响坡面的土壤侵蚀过程，使坡面产流产沙量得到有效降低。秸秆表土覆盖模式下，随着秸秆覆盖量增加，坡面土壤产流产沙量显著降低；随秸秆长度增加，坡面产流产沙量呈增加趋势；浅耕半固定混合式覆盖模式下，坡面产流产沙量随秸秆覆盖量及秸秆长度增加均呈现先降低后增加的趋势。浅耕半固定混合式覆盖减蚀效果优于秸秆表土覆盖模式，但秸秆表土覆盖模式更利于降雨入渗。基于以上研究结果，提出秸秆表土覆盖模式下宜采用短秸秆覆盖，浅耕半固定混合式覆盖模式下宜采用长秸秆覆盖，两种秸秆覆盖模式下当秸秆量为3.0t/ha时可达到稳定较好的防蚀作用。