Experimental Study On Influence Factors Of Soil Water Evaporation In Gavel-mulched Land In Xiangshan Area Of Ningxia

Aiming at the problem that the law of water transport in the process of soil evaporation of sandy compacted land in northwest arid region is not clear,this paper takes sandy compacted land in central Ningxia arid zone Zhongwei Xiangshan area as the research object,aiming at reducing soil moisture evaporation and inhibiting steaming and conserving moisture.Field experiments were conducted to study the effects of rainfall,sand mixing ratio and sand cover thickness on soil moisture evaporation in compacted sandy land using three factors and five levels orthogonal design method.By collecting data and combining with the actual monitoring results under the specific conditions of the experiment,this paper makes a comprehensive analysis of the law of water transport in the process of soil evaporation in this area,and draws the following main conclusions:(1)Through the study and analysis of the cumulative evaporation with time under the conditions of different rainfall,sand-soil mixing ratio and sand cover thickness in the test area,it is found that the cumulative evaporation of soil increases with time.Within the specific range of this test,the cumulative evaporation of high rainfall corresponds to larger cumulative evaporation,and the growth rate of cumulative evaporation decreases with the increase of sand-soil mixing ratio,while the cumulative evaporation of sand-soil cover The greater the thickness,the smaller the cumulative evaporation.(2)Through monitoring the moisture content of the test area under different rainfall,sand mixing ratio and sand cover thickness during soil evaporation,the dynamic change characteristics of soil moisture were obtained.In the process of water redistribution,there is an obvious demarcation point in the soil profile.The soil volume water content above the demarcation point decreases with the increase of time,but it is opposite below the demarcation point The greater the rainfall,the deeper the boundary point is.The larger the sand mixing ratio and the thickness of sand cover,the shallower the boundary point is,the more soil moisture can be continuously moved downward.(3)Least squares method was used to fit and analyze the variation process of soil evaporation with time under different rainfall,sand mixing ratio and sand cover thickness.It was found that the relationship between soil evaporation and time under different influencing factors could be described by two-order polynomial,and the correlation coefficient R2 was greater than 0.95.(4)The threshold of soil moisture evaporation increases with the increase of rainfall,sand mixing ratio and sand cover thickness.Polynomial function can be used to express the relations hip between soil moisture evaporation threshold and it.Its correlation coefficients R2 are 0.9705、0.8967 and 0.8527 respectively.The goodness of fit was high and reached a significant level.This study is of great significance for understanding the dynamic changes of soil moisture in the process of evaporation of sand-compacted land,providing data support for perfecting the theory of soil evaporation under water control,and providing data support and theoretical basis for objective evaluation of soil water carrying capacity,water allocation,ecological environment maintenance and restoration of sand-compacted land and efficient utilization of water resources in ecologically fragile areas of Northwest China.