Interrelation Study Of Soil Water And Thermal Parameters In Heavy Metal Contaminated Area

As four important soil physical features of soil,soil texture,infiltration rate,soil water content and thermal conductivity are meaningful for soil organic matter accumulation,chemical reaction rate,water-saving irrigation and efficient use of water resources,etc.Monitoring the above parameters is a fundamental work for the agricultural research.The relationship of soil water and heat parameters is meaningful for coupled transfer of water and heat and solute transport.In this paper,the computer software for rapid recognition of soil texture was developed,and the soil water infiltration process was measured directly.At the same time,the interrelation between soil water content and thermal conductivity was analyzed.The main results were as follows:(1)Soil infiltration capacity was higher in the study area,and the infiltration rate was faster and the cumulative infiltration was larger.In the infiltration process,the effect of disc diameters on infiltration was not significant.In the same period of time,the cumulative infiltration capacity of Dongchuan silty soil was larger than that of Chengong loam.As the negative pressure increased,the infiltration rate decreased,and the cumulative infiltration capacity was less in the same period of time.Different land use types had a greater effect on the saturated hydraulic conductivity of the soil,that is shrub land>grassland>farmland>bare land.(2)There was a strong spatial relationship(C0/(C0+C)<0.192)between soil watercontent and thermal conductivity in all depths of soil layer.However,in the experiment,the spatial correlation range caused by random factors is relatively low(C0<0.540).It was obvious that the boundary effect of the shallow soil water content distribution in the test plot.The connectivity of the pores in the deep soil contributed greatly to the spatial distribution of soil water content.The difference of soil water content in different depths of soil layer was caused by evaporation intensity and tillage activity.Soil water content dominated the spatial distribution of thermal conductivity,which made the spatial distribution of the two have higher similarity.(3)When the soil water content varies between 17%and 28%,the result of the regression fitting showed a linear positive correlation,under the condition of different depth soil layers and different land use types.According to the principle of spatial spectrum analysis,the soil water content as distance sequence,thermal conductivity as a variable sequence,then the Fourier transform is conducted.The result of spectrum analysis shows thermal conductivity has a long-term negative correlation in a sequence of soil water content.The research results are intended to provide assistance for precision agriculture field management;provide theoretical reference for local water-saving irrigation and efficient water use;provide a reference for similar research in different regions.