Experimental Study On Soil Wind Erosion And Using Conservation Tillage To Reduce Wind Storm Disaster

Through field observation and wind tunnel experiment, combined with basic theory and method of ecology , natural geography, sandstorm physics, the research and analysis in doctor program are listed as follow.1.A systematic field observation experiment is set up. This experiment takes tradition tillage farmland, conservation tillage farmland, lawn and sandlot as the generating bottom surface of soil wind erosion and sand storm. The results show that conservation tillage farmland and lawn have strongly ability to prevent erosion. Comparing with tradition tillage farmland and sandlot, the soil water content, residue cover and surface roughness are high in conservation tillage farmland and lawn, thus conservation tillage farmland and lawn can effectively against the soil erosion and reduce the loss of soil nutrient and organism. Based on the research, the quantity of sandlot's dust samples is concentrated in 150cm height below, and primarily are the middle and lager particles, so sandlot's transmission of small particles is less than the other three surfaces in 150cm height above. The happening of soil erosion and sand storm is the outcome of special weather and bottom surface, it has close relation to crop residue covering, composition of soil and the way of cultivation. Different surface experiments show that the dust particles of wind erosion mainly come from tradition tillage farmland and deteriorative lawn.2.The effects and mechanism of conservation tillage on soil wind erosion is studied in the paper and firstly developing some important working parameters of conservation tillage preventing soil wind erosion and farmland dust moving. Soil erosion will gradually reduce as the increment of stalk residue's height, moreover, it will evidently reduce beyond 30cm heights and evidently increment below 30cm heights. Soil erosion will gradually reduce as the increment of residue covering, furthermore, the farmland that residue covering is 32.24% can reduce the soil erosion by 60.06% comparing cover rate of 20.56%, reduce 79.35% comparing cover rate of 9.68%. The surface roughness will power rise as the increment of stalk residue height and residue covering. The average value of exponent's absolute value which is between roughness and height is 0.42116, comparably the value between roughness and residue covering, is 0.39943. So it is clear that the surface roughness is more sensitive to stalk residue's height. Tillage destroys the structure of soil surface and makes the topsoil breakage. The results show that if the rate of topsoil breakage beyond 35%, the speed of soil erosion and desertification will be reduced effectively; if the rate of topsoil breakage above 35%, the speed of soil erosion and desertification will be accelerated.3.Based on further study on domestic and international soil erosion model, employing the method of PLS, two models are established. Model one can adapt to soil erosion of local experimental area, model two is a forecast model of conservation tillage practices on prevention of soil erosion. Two models are validated by experimental datum. They take different surfaces and the height of stalk residue as the variable of affecting soil erosion. The validity results of model show that the forecast value is basical consistent with measured value. It proves that the soil erosion forecast model can predict and estimate soil erosion of local experimental area and different soil erosion's condition under conservation tillage, providing information to help in forecasting and selecting of effective measures to reduce soilerosion.