Experimental Study On Protective Tillage Measures For Wind Erosion Prevention And Control Of Farmland Soils In Beijing

The ecological environment in Beijing and its surrounding areas is fragile,the farming techniques are simple and extensive,the farmland is covered with no vegetation,and the surface is bare.Coupled with the influence of spring and winter winds,the wind erosion of farmland soil is very serious.Aiming at this problem,this paper takes the farmland soil in Yanqing,Beijing as the research object,and uses the combination of field investigation and indoor wind tunnel experiment to analyze the coverage,stubble and three protective tillage measures on the farmland through orthogonal experiments.The control effect of soil wind erosion dust.The main conclusions drawn are(1)The law of soil water content change is:compared with traditional cultivated land,the soil moisture growth rate of the top layer is 28.7%,25.1%and 8.3%,respectively;For stubble>stubble+cover>cover>traditional cultivated land;the particle size and volume content of each measure showed the largest proportion of powder particles,all reached more than 49%,and the soil particle content of traditional cultivated land susceptible to wind erosion was 96.68%,accounting for 96.68%.Than the biggest.(2)The relationship between wind erosion rate and wind speed is exponential function,12m/s is the turning point of wind erosion intensity sharply increasing;when the wind speed is 4m/s and the coverage is more than 40%,or when the wind speed is 8m/s and the coverage is greater than At 60%,the wind erosion rate is extremely small(less than 0.83 g·m-2·min-1).The wind erosion intensity will decrease with the increase of coverage,and the negative index relationship will decrease.When the coverage reaches 60%,the soil erosion resistance efficiency will reach the maximum(more than 78%).The wind erosion rate decreases with the increase of the height of the stubble,and the quadratic polynomial decreases.When the density of the radon is greater than 14cmx43.2cm and the height of the crucible is more than 36cm,the wind erosion resistance is the best,and the wind erosion rate is less than 1.49 g·m-2·min-1.The wind erosion resistance effect of the stubble and covering combination measures is greater than the single measure.When the wind speed is less than 12m/s and the coverage is greater than 40%,and the height is greater than 21.6cm,the wind erosion rate is less than 1.5 g·m-2·min-1.(3)There is an exponential function relationship between dust emission and wind speed,and a negative exponential function relationship between coverage and coverage;when the coverage is greater than 60%,the dust emission basically reaches the minimum value,and at this time,the dust is in the wind erosion.The proportion of dust in the wind erosion is 3.73%when the wind speed reaches 16m/s.As the wind speed increases further,the proportion of dust in the wind erosion tends to be stable.