| 其他摘要 | Soil wind erosion is the important influence factor on land desertification and sand storm in arid, semi-arid and some semi-humid area, which is the primary environment problem of the most countries in the world. Conservation tillage could reduce soil wind erosion effectively. The effect of different conservation tillage treatments, which were straw mulch, stubble and ridge, on the factors of soil wind erosion under three kind of soil of the Loess Plateau was studied through sand wind tunnel. The results summed up as below:
1） Wheat straw mulch and stubble could reduce soil wind erosion rate compared to the control, the rate of soil wind erosion under stubble with 20cm high and straw mulch with 4210kg/hm2 were the lowest of all conservation treatments, and the reduction erosion rate were the highest. The ridge tillage could reduce rate of soil wind erosion in low wind velocity, which was in the vertical direction of wind, the rate of soil wind erosion under ridge tillage with the same direction as the wind is higher than other treatments, even exceed the control when the wind velocity is higher. In the same wind velocity the rate of soil wind erosion decreased with straw mulch weight increasing, while the height of stubble increasing, rate of soil wind erosion deceased.
2） Under conservation tillage treatments, the rate of soil wind erosion had a power function to wind velocity, while the soil wind erosion of the control had a significantly linear correlation to wind velocity. 3） In the height of 0~60cm, the total volume of sand transport under straw mulch with 4210kg/hm2 was the least, the second is stubble with 20cm high. In the same wind velocity the total volume of sand transport decreased with straw mulch weight increasing, while the height of stubble increasing, the total volume of sand transport deceased. The total volume of sand transport of ridge was more than the control when the wind velocity exceed 8 meter per second.
The volume of sand transport of ridge which was in the vertical direction of wind concentrate in the height of 45~60cm, the sand of other treatments including the control mostly concentrate in the height of 0~15cm. The sand transport percent in the 0~15cm increased with wind velocity increasing. It also decreased with height of stubble decreasing, while sand transport percent decreased with straw mulch increasing.
4） The magnitude order of soil wind erosion with three types of soil were as follow: aeolian sand soil > loessal soil > lou soil, and the order of reduction erosion rate with conservation treatments were as fellow: lou soil > loessal soil > aeolian soil, while the reduction erosion rate decreased with wind velocity increasing.
Under the straw mulch with 4210kg/hm2 treatments, the order of sediment transport rate in the height of 0~15cm were as follow: aeolian sand soil > loessal soil > lou soil, while the value of sediment transport was too lower to cause serious wind erosion harm. Under the stubble with 20cm high, the sand transport percent of aeolian sand soil in the 0~15cm decreased with wind velocity increasing. the order of sediment transport rate in the height of 0~15cm were as follow: loessal soil > aeolian sand soil > lou soil.
The order of soil wind erosion under ridge treatment with in the vertical direction of wind were as follow: aeolian sand soil > lou soil > loessal soil, the reduction erosion rate of loessal soil was higher than the others. The sediment transport rate of aeolian sand soil in 0~15cm was lower than others, result from the sand transport percent was lower than 45~60cm.
Key Words：conservation tillage; soil wind erosion; wind tunnel simulation |
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