Study On The Effect Of Regulation Of Sandy Loam Soil Water And Salt Transport Under Different Mulching Models

The rainfall is rare,and the evaporation is strong in Northwest China,the soil moisture is easily lost through evaporatio n,it is easy to form saline soil for water is difficult to maintain.Soil surface cover can avoid the direct contact between the surface soil and air,which can effectively reduce the evaporation of soil moisture,change the physical and chemical properti es of the surface soil,thus affecting the process of soil moisture infiltration,evaporation and salt migration process.This paper studied the regularity of soil water and salt transport under different mulching models by indoor and outdoor simulation ex periment.The test set up five modes including,sand mulching(S),plastic film mulching and sand(MS),sand mulching and straw(SJ),plastic film mulching and straw(MJ)and bare land(CK),the main contents are as follows:(1)The effects of different mu lching models on soil water infiltration were studied by indoor soil column simulation experiment.The results showed that the soil surface mulching treatment affect ed the wetting front distance and cumulative infiltration,reduced soil water infiltration capacity,had barrier effect,The results showed that the plastic film mulching and sand was the strongest,followed by plastic film mulching and straw,followed by sand mulching and straw,and sand mulching was the weakest.At the same time,the relations hip between advancing distance of wetting front formed and time was described by a power function,with high coefficients of determination ranging from 0.9930 to 0.9991.The relationship between cumulative infiltration and time satisfied the Kostiakov mode l,with high coefficients of determination ranging from 0.9916 to 0.9980.The relationship between wetting-front displacement and cumulative infiltration could be characterized by a linear equation,with high coefficients of determination ranging from 0.9991 to 0.9999.(2)The effects of different mulching models on the water evaporation were studied by outdoor evaporation tank simulation experiment.The results showed that the change trend of soil water evaporation cover treatment was consistent with that of CK treatment,the change trend of soil water evaporation of CK treatment was more obvious than that of JS,JM,S and SM treatments.Meanwhile,cumulative evaporation cover treatment were less than less than CK,S,MS,SJ,MJ and CK of the cumulative evaporation were 450.6g,375.1g,712.2g,473.3g and 1823.6g,compared with CK,the cumulative evaporation mulching treatments were reduced by 75.3%,79.4%,60.9%,74%,showed that the surface of the soil mulching on soil moisture evaporation will produce inhi bition.The relationship between the soil water evaporation and time could be described by a logarithmic function,with the coefficients of determination ranging from 0.9243 to 0.9800.(3)This paper studied the effect of soil water and salt transport und er different mulching models by outdoor simulation experiment,conducted in the 5 square block area of 1m2,and indoor soil column simulation experiment.The results showed that the soil surface with different mulching treatment has obvious effect of water conservation,the water conservation effect for MS>SJ>S>MJ.Meanwhile,the mulching treatment can effectively control the accumulation of soil salt to the surface layer,and has an effect on the vertical migration of soil salinity.The soil salinity migration with mulching treatment mainly occurs in the range of 0~20 cm,and the migration of soil salt without mulching treatment occurred mainly in the range of 0~35 cm.It is of great significance to improve the salinization of soil and control the secondary salinization of soil.(4)The effect of different mulching treatments on soil water infiltration,evaporation and salt transport were contrastively analyzed,by indoor and outdoor simulation experiment,and taking into account the climatic characteristic s of the test area and the characteristics of the sand resources in the area,it was concluded that the method of sand and gravel mulch was more suitable for the Northwest area.