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    保护性耕作对土壤风蚀的影响

    Impact of conservation tillage on soil wind erosion

    • 摘要: 保护性耕作能够有效减少农田土壤风蚀。通过室内风洞模拟试验,研究秸秆覆盖、留茬和垄作3种保护性耕作措施对黄土高原北部农田土壤风蚀的影响。结果表明:1)秸秆覆盖和留茬能有效降低土壤风蚀速率,秸秆覆盖量为4210kg/hm2时土壤风蚀速率最小,与对照相比减少62.8%;垄作在低风速下能够降低土壤风蚀率,垄向与风向垂直时降低土壤风蚀,垄向与风向平行甚至加剧土壤风蚀;土壤风蚀速率随着覆盖量的增加而降低,随着留茬高度的增加而降低。2)采取保护性耕作措施时,土壤风蚀速率与风速呈显著幂函数关系。3)秸秆覆盖处理0~60cm总输沙量最小,垄作方式总输沙量最大;垄向与风向垂直的垄作方式0~60cm输沙量主要集中在45~60cm,其他耕作方式下0~60cm输沙量主要集中在0~15cm。0~15cm输沙量比例随风速的增加而升高,风速一定时则随留茬高度的降低而降低,随秸秆覆盖量的增加而降低。因此,为减少该地区的土壤风蚀,宜采用秸秆覆盖、留茬20cm以及二者结合的保护性耕作措施来降低土壤风蚀量。

       

      Abstract: Conservation tillage could reduce soil wind erosion effectively on farmland. An experiment of soil wind erosion on farmland in northern Loess Plateau was designed with wind tunnel tests under different conservation treatments including straw mulch, stubble and ridge tillage. The results indicated that straw mulch and stubble could reduce the soil wind erosion rate, and the soil wind erosion rate under straw mulch with 4210kg/hm2 was decreased by 62.8% compared with CK(no conservation treatment), which was less than that under other conservation tillage. The ridge tillage which was perpendicular to the wind could reduce soil wind erosion rate in low wind velocity, the direction of ridge also affected soil wind erosion, and the soil wind erosion rate under ridge tillage with the same direction as the wind was more than others. With increasing straw mulch and height of stubble, the soil wind erosion rate decreased in the same velocity. The soil wind erosion rate had a significant power function to wind velocity under conservation tillage treatments. In the height of 0-60cm, the total volume of sediment discharge under straw mulch was the least, while the largest under ridge tillage. The most of sand concentrate in the height of 45-60cm under ridge tillage that direction was perpendicular to the wind, and concentrate in the height of 0-15cm under other treatments. The sediment discharge percent in the height of 0-15cm increased with increasing wind speed. The sediment discharge percent decreased with decreasing height of stubble and with the increasing amount of straw mulching. It is suggested that the straw mulching 20cm and both of them should be suitable for preventing soil wind erosion.

       

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