Three-dimensional quantification of soil pore structure in wind-deposited loess under different vegetation types using industrial X-ray computed tomography

Abstract

Quantifying the soil pore structure is critical for understanding plant growth and water/solute movements in the soil. However, most previous studies quantified the soil pore structure in a shallow layer by using low resolution medical computed tomography (CT), whereas few have quantified the soil pore structure in deep soil layers with high resolution CT. In this study, we quantified the soil pore structure of wind-deposited loess under different vegetation types (wheat, weeds, apple orchard, and Robinia pseudoacacia) at depths from 0 to 4.5 m by industrial CT. The results showed that the soil pore number and porosity tended to decreased with depth, but there were no significance differences below 2 m among all vegetation types. For different depths and vegetation types, the number of pores measuring 0–100 μm was highest, followed by those measuring.100–500 μm, and lowest for those measuring > 1000 μm. The contribution of pores measuring 100–500 μm to the total pore volume was highest. The variations in the connectivity and surface area density were also focused mainly within the depth down to 2 m, and the variations were minor below 2 m. There were no significant differences in the bulk density and soil pore characteristics under different vegetation types, except for weeds. The results obtained in this study provide insights into the interactions between vegetation and soil water, as well as the hydrological processes for the wind-deposited loess.