Vertical Change of the Soil Structure Parameters and the Soil Thermodynamic Para meters in the Gobi Deserts in Arid Areas

This paper analyzes the vertical distribution characteristics of the parameters of soil structure, such as the soil constituent, soil bulk density, soil moisture content and soil porosity, and of the soil thermodynamic parameters, such as the soil thermal conductivity, soil heat capacity, soil specific heat and soil diffusivity, by using the laboratory-measured results of the soil samples sampled from the soil profiles of 80 cm in depth in the Dunhuang Gobi Desert in northwest China on October 27, 2000. The results show that the change of soil bulk density with depth is obviously affected by the soil porosity, and it conversely correlative with the soil porosity; but the effect of the soil moisture content on it is not so obvious. The vertical change of the soil thermodynamic parameters, such as the soil thermal conductivity, soil heat capacity, soil specific heat and soil diffusivity, is related to the change of the parameters of soil structure, such as the soil bulk density and soil porosity, it is positively correlative with the soil bulk density and conversely correlative with the soil porosity; but the relationship between it and the soil moisture content is not so obvious. These reveal that the soil thermodynamic parameters are mainly affected by the soil bulk density and soil porosity. The laboratory-measured results of the soil thermodynamic parameters are close to the field observation data, and it is verified that the field observation data are reliable.