Study On The Soil Wind Erosion Process Under Ridge Tillage

Soil wind erosion is the process of wind erosion,transportation and accumulation of surface soil,and it is a process of interaction between wind and surface particles.Wind erosion destroys the surface,which results in the loss of soil fine particulate and soil nutrients,resulting in desertification.Wind erosion is particularly serious in arid,semi-arid and semi humid regions,and it has been one of the most important research areas both at home and abroad.But at present,most of the research focuses on the bare soil,and soil wind erosion under vegetation cover,soil wind erosion under ridge tillage is still rare.Therefore,the article selected the Zhenglan Banner Area of Inner Mongolia Autonomous Region as the typical area,collected the grasslandy aeolian sandy soil as the research object,and designed five different spacing of soil ridge.This paper based on the wind tunnel simulation test of five friction velocity,studied the relationship between total transport sediment and soil ridge spacing,wind speed,and analyzed sand flow characteristic of vertical structure,the rule of wind erosion sediment grain size variation.Main results are the following:(1)Ridge tillage can change the surface micro topography and increase surface roughness,effectively inhibit soil erosion.The weakening effect of different height and spacing ridge is different.(2)Wind erosion was mainly concentrated in 0-30cm of the sand collecting instrument,which showed that the sand drift movement was a kind of the material handing process of closing to the surface.(3)Analysis of the relationship between total sediment load and impact factor showed that the wind speed and soil ridge spacing had a great influence on the total amount of sediment.The same row spacing with the increasing of friction velocity,the total sediment amount increased gradually.When the friction velocity changed from 0.34m/s to 0.42m/s,which was low wind speed,the change of total sediment transport volume was not obvious.The experimental sample is almost no sediment spacing in 5H,10H ridge,while the total sediment is rare spacing in 15H,20H,25H ridge.When the wind speed reached 0.51m/s and above,total variation of sediment transport under 5h,10h was still not too obvious,and the total sediment load under 15h,20h,25h soil ridge spacing increased rapidly.Through fitting the relationship of grasslandy aeolian sandy soil in total sediment and wind speed change trend,we found that the best fitting formula spacing in 5H,10H ridge was exponential function,another best fitting formula was power function spacing in15H,20H,25H ridge.Besides the correlation coefficient was relatively high.Under the same wind speed,with the increase of soil ridge spacing,the total sediment of experimental samples volume also gradually increased,which with the total sediment and wind speed change were basically same.When the friction velocity changed from 0.34m/s to 0.42m/s,although soil ridge spacing increased gradually,total transport sediment was still little change;when the wind speed reached 0.51m/s,with the increase of soil ridge spacing,total sediment volume increased to a lesser extent;target speed was 0.59m/s to 0.68m/s,total transport sand amount began greatly increased.With the increase of soil ridge spacing,total sediment volume increased with the exponential function law,the correlation coefficient(R~2)was between the 0.50 and 0.99.The correlation is better.(4)Because the friction velocity 0.34m/s was too small,the change of sediment transport quantity was not obvious and could not fit the function,so the wind blown sand flow structure of 0.42m/s-0.68m/s was analyzed,the results showed that:with the increase of both the friction velocity and soil ridge,the erosion sand collector stroke saltation height all increased;When five kinds of soil ridge spacing and the friction velocity was 0.51m/s,sand saltation height almost reached 50-60cm;While with the increase of friction velocity,the total sediment amount in all height increased gradually,but the range of different soil ridge was different.In the friction velocity of the 0.42 to 0.68m/s,with the increase of the height,the sand content of the experimental samples decreased with the logarithm function.(5)Due to the sediment was largely concentrated in the 0-30cm height,so we only analyzed the relationship of the mean particle size and wind speed in the 0-30cm height.The results showed that:under the same soil ridge spacing,with the increase of wind speed,the sand average particle size in the same height increased,but the rules were not too obvious.Under the same wind speed,with the increase of soil ridge spacing,the average particle size of all height was increased.In the same conditions under the ridge distance and wind speed,average particle size of the erosion in overall vertical height distribution generally showed a decreasing trend;When the average particle size was above 30cm,most of the experimental samples increased first and then decreased.This showed that the average particle size increased with height was not in strict accordance with the law of diminishing,which was different from the previous conclusions that average particle size decreased with the exponential function.