Simulation of Bulk Density Changes with Soil Water Content for Several Soils

Taking the yellow brown soil,red soil,chao soil,rice soil in Hubei area as studying soil,the soil bulk density change with soil water content of variable bulk density soils is studied and simulated.The results show that with the decrease of the weight water content(θg),the soil bulk density(B)increases gradually for all the tested soils,the change relationship between soil bulk density and soil water content can be described with the exponential model B=a e-b θg for high precision.The a-value and b-value are different in model for different soils.For general soil,the clay content and the expandable minerals content is high,the organic matter content is small,the water-stable aggregate content is small in the undisturbed soil.This will lead to the bigger a-value and b-value in soil contraction curve.The size of a-value and b-value for different soils are decided by integrated influencing effects of these factors.