Study On Spatial Distribution Heterogeneity Of Soil Heat Conduction Parameters Based On Multifractal

Soil thermal conductivity is one of the important parameters of soil physical characteristics.The effective sampling and monitoring of soil thermal conductivity is beneficial to the development of fine agricultural.Therefore,it is very important to measure the sampling scale of soil thermal conductivity parameters and the reasonable selection of different sampling distances.The study of spatial variability and spatial heterogeneity of soil thermal conductivity will help guide the rational planting,differential irrigation and fertilization in agricultural production.This paper first analyzes the main factors affecting soil thermal conductivity,and then through the field survey and sampling of different small scale,the soil thermal conductivity parameters on the spatial distribution and the autocorrelation,multi fractal spectrum function are calculated on different scales of soil thermal conductivity and physical properties of soil,and the soil thermal conductivity with the physical characteristics of soil in multiple proportion value analysis,we get the following results:(1)Under the same bulk density,soil thermal conductivity increased with the increase of soil volumetric water content,and soil volumetric water content showed a strong power function relationship with soil thermal conductivity.The thermal conductivity of soil increases with the increase of bulk density in different land use types in different test areas.(2)The three small scales(50*50 m(H),10*10 m(M),2*2 m(L)),50*50 m sampling scale variable coefficient of soil thermal conductivity is highest,the thermal conductivity of various scales have strong spatial dependence,but the soil thermal conductivity in 3 kinds of small scale spatial autocorrelation has very big difference,spatial autocorrelation and confidence level decreases with the the scale decreases,in the actual field sampling can be based on the purpose of the study on the degree of confidence on the selection of suitable sampling interval appropriate,determine the number of sampling points,the purpose of the study and Research on reducing cost.(3)Multifractal width and delta alpha can quantitatively describe the spatial distribution characteristics of soil thermal conductivity.Under three sampling scales(80*80 m(H1),40*40 m(M1),20*20m(L1)),soil thermal conductivity of different depths has multifractal characteristics.The distribution of thermal conductivity of 80*80 m(M1)soil is the most uneven,and the distribution of thermal conductivity in deep soil is even more uniform under the same sampling scale.The spatial distribution regularity of soil thermal conductivity in different depth soil layers at various scales is also different.(4)The multifractal spectral function of 80*80 m(H1)soil physical properties is calculated.The distribution law of saturated moisture content is the most uneven and has strong spatial heterogeneity.The spatial distribution of bulk density is more uniform and the space isomerism is the smallest.There is spatial correlation between soil thermal conductivity and soil moisture content,soil bulk density and soil sand content under the same sampling point.The correlation between soil thermal conductivity and soil moisture content is strong,the soil bulk density is second,and the correlation of sand content is lessness.(5)The multi fractal method can better reflect the local singularity of the spatial distribution of soil thermal conductivity,and characterize the distribution characteristics of the data value of the soil thermal conductivity measurement.