北方农牧交错带土壤风蚀沙化影响因子的风洞试验研究

土壤风蚀沙化是北方农牧交错带农牧业生产与发展的主要限制因子,通过室内风洞实验研究,定量分析了土壤风蚀率(风蚀强度)与风速及土壤水分的相关关系、土壤风蚀输沙量的空间分布规律以及翻耕后土壤风蚀的动态变化。结果表明:风蚀率与风速变化成正相关,随着风速增大,风蚀率相应增加,18m/s风速是风蚀由轻变重的一个转折点;土壤水分与风蚀率呈负相关,水分含量越高,风蚀率越小,6%含水量水平是土壤风蚀由重变轻的一个转折点。通过曲线拟合表明,风蚀率与风速成幂函数的关系,与土壤水分含量成对数函数关系。土壤风蚀空间不同高度输沙量呈单峰曲线的变化趋势,在距地面2～4cm范围内集沙量最多,80%左右的沙量集中在近地面10cm范围内。土地翻耕是加重土壤风蚀的重要因素,对于天然草场,翻耕后风蚀强度是未翻耕的66～306倍,对于旱作农田,留茬覆盖可以有效控制土壤风蚀,翻耕马铃薯地风蚀强度是留茬地的25～108倍。

Study on Some Factors Influencing Soil Erosion by Wind Tunnel Experiment in North Ecotone Between Agriculture and Pasture

Some factors influencing wind erosion are quantitatively studied by the wind tunnel experiment. The results show that the rate of wind erosion positively interrelates with the wind speed. The rate of wind erosion increases with the increasing of wind velocity. The wind velocity of 18 m/s is significance point to aggravate the wind erosion. The rate of wind erosion decreases with the increasing of soil moisture, 6% of soil moisture content is a turning point. The spatial distributing trend of eroded sand takes on a single-peak curve. The maximum quantity of collecting sand is within 2~4 cm high above ground, 80 percents of the eroded sand distributes within 10 cm high. Unreasonable tillage and over-reclamation are the important factors to aggravate the wind erosion.The rate of wind erosion of tilled grassland is 66~306 times than the untilled.The rate of wind erosion for tilled farmland is 25~108 times than the untilled.