免耕条件下农田休闲期直立作物残茬对土壤风蚀的影响

Effect of standing crop stubble on soil erosion by wind under no-tillage

为了探讨直立作物残茬防治农田土壤风蚀发生的机理,该文利用风洞试验和野外观测相结合的方法,分析土壤免耕条件下直立作物残茬对农田土壤风蚀的影响。风洞试验研究表明:翻耕土壤地表风速、土壤风蚀侵蚀率均比免耕土壤高,而地表粗糙度免耕明显高于翻耕。在同样风速条件下,翻耕地土壤风蚀侵蚀率是免耕地的3～8.2倍,且随免耕年限的增加,土壤风蚀侵蚀率呈现递减的趋势。留有不同直立作物残茬免耕土壤地表粗糙度草谷子>草玉米>莜麦>油菜,土壤风蚀侵蚀率呈现相反的趋势,地表粗糙度越大,风蚀侵蚀率越小。野外观测结果表明,不同直立作物残茬对裸露农田的保护作用草谷子>莜麦>草玉米>油菜。风洞试验与野外观测具有相似的试验结论,因此,风洞试验方法可作为测定农田土壤抗风蚀能力的重要工具。

To discuss the mechanism of controlling soil erosion by wind with standing crop stubble, combined the wind tunnel experiment with field experiment, the influence of soil erosion by wind on standing crop stubble under no-tillage practices was analyzed. The wind tunnel test results show that surface soil velocity and wind erosion modulus in the farmland under plow tillage are larger than that under no-tillage with standing crop stubble, while surface roughness under plow tillage is smaller than that under no-tillage with standing crop stubble. At the same surface soil velocity, the wind erosion modules under plough tillage are 3-8.2 times of those under no-tillage. And the wind erosion modules decrease with the increase of years of no-tillage. The order of surface roughness under no-tillage with different standing crop stubbles is millet forage 〉 maize forage 〉 oats 〉 rape, while the order of the soil wind erosion modules is rape 〉 oats 〉maize forage〉millet forage. The larger the soil wind erosion modules are, the smaller the surface roughness is. The field experimental results show that the order of the capabilities of protection for uncovered farmland by standing crop stubble are millet forage〉oats〉maize forage〉rape. The experimental results of wind tunnel are similar to that of observation result. Therefore, the wind tunnel technique may become an important experiment tools for controlling wind erosion in the farmland.