Effects Of Different Protective Measures On Soil Erosion And Physical Properties Of Sandy Farmland In Sprinkler Irrigation Circle

In recent years,the cultivated land in the circle of sprinkler irrigation is a kind of cultivated land with the center pivot sprinkler as the sprinkler irrigation method.This kind of cultivated land is relatively flat and homogeneous,and the cultivated land area of a single sprinkler irrigation circle is large,the common area is 20hm~2per circle,the maximum can reach 80hm~2,and most of the lack of shelter forest protection,coupled with the cultivation and harvest process of potato cultivated land need a large degree of soil turning,resulting in dry and loose soil,this type of cultivated land has become a typical source of wind sand in the wind season.In this thesis,the potato sprinkling farmland in the northeastern margin of Kubuqi Desert was selected as the research object,and the differences of soil wind erosion and soil physical properties in the sprinkling farmland protected by oat planting,clay mixing and without any protective measures after harvest were compared,so as to reveal the change law of soil wind erosion in the potato sprinkling farmland in the sandy area during the wind erosion period.And explore the prevention and control measures of potato sprinkler irrigation circle farmland in sandy area to provide theoretical basis for soil wind erosion prevention in sandy area.The main research conclusions are as follows:(1)The sand transport of different protected farmland showed a power function attenuation trend with the height,and the wind-blown sand activities of cultivated land were mainly concentrated in the height range of 0～20cm.The wind-blown erosion of cultivated land was not significantly reduced by oat protection measures,but significantly reduced by clay protection measures in the potato sprinkler irrigation circle,with a decrease of 47.97%.The grain size of the erosion particles in the sprinkler irrigation circle in the sand area is 0～500μm,and the main erosion particles are 0～250μm.The main erosion particles are 100～250μm in the height range of 0～20 cm,and 50～250μm in the height range of 30～60 cm.In the range of 70～100cm height,the main erosion particle size is 0～100μm.The average particle size of wind erosion was decreased by clay mixing,and the particle size of>50μm in the airflow was significantly decreased,while the grain size of wind erosion protection of oat planting was not significantly changed.(2)In the wind season,the wind erosion of potato irrigation circle farmland was severe,and the wind erosion of oat protected farmland,clay protected farmland and unprotected farmland were 346.80t/hm~2,206.86t/hm~2and 396.41t/hm~2,respectively.Both of the two protective measures can reduce soil wind erosion to a certain extent.The effect of clay mixing protective measures is better,and the wind erosion is reduced by 47.82%compared with that of unprotected cultivated land,and the protection of oat planting is reduced by 12.51%.The micro-topography of cultivated land was gradually flattened during the wind-sand activity.The surface roughness index of unprotected cultivated land,oat protected cultivated land and clay protected cultivated land decreased by 11.01%,3.7%and 3.5%,respectively.(3)The soil water retention capacity of sandy cultivated land is weak and the water loss rate is fast.In the wind season,the average soil moisture content of the unprotected farmland,the oat protected farmland and the clay protected farmland was 1.32%,1.28%and 1.91%,respectively,and the soil moisture content decreased by 82.24%,62.08%and79.55%,respectively.The water retention capacity of clay-protected cultivated land was significantly improved after the improvement of guest soil.The average soil bulk density of unprotected cultivated land,oat protected cultivated land and clay protected cultivated land was 1.58g/cm~3,1.56 g/cm~3and 1.54 g/cm~3,respectively.The surface soil bulk density of unprotected farmland and oat protected farmland increased significantly by 14.70%and11.37%during wind erosion,while the soil bulk density of clay protected farmland did not change significantly.The soil structure stability was the strongest during wind erosion.The average non-capillary porosity of unprotected,oat protected and clay protected farmland was 9.94%,6.35%and 7.20%,respectively,and the average capillary porosity of soil was29.18%,30.58%and 30.26%,respectively.The soil structure was improved by clay mixing,which decreased the non-capillary porosity and increased the capillary porosity.The surface soil particle size of unprotected cultivated land,oat protected cultivated land and clay protected cultivated land mainly distributed in the range of 60～350μm,60～350μm and 60～600μm.The soil particle size of sandy cultivated land increased due to clay mixing.In the process of wind erosion,the surface soil fine particles were lost and the average particle size of soil particles increased.Both oat and clay protective measures reduced the coarsening degree of sandy cultivated land during the wind erosion cycle,and reduced the loss of surface fine particles.