Suitability of Image Analysis in Evaluating Air and Water Permeability of Soil

Abstract

A comprehensive understanding of the water and air permeability of soil is necessary for modelling the transport properties which depend on soil structure. We aimed to evaluate the suitability of image analysis to estimate gas and liquid transport in soil using resin-impregnated soil blocks. The soil texture, TOC, density, porosity, air capacity (VV), air permeability (logAP), and the saturated hydraulic conductivity (logKS) of a Cambisol developed from loess were measured. To characterise the pores, using the soil structure images, we determined the macroporosity (AA), index of soil pore-network growth rate, percolation number (lognPER), length of pore path/unit area (PLA), and relative volume of pores overlapping top and/or bottom edge of the image (VTB). logKS and logAP related to morphometric parameters of soil structure derived from the image analysis. The main factor controlling the soil’s infiltration was the total volume of soil pores (VV and AA). AA, PLA, VTB, and lognPER were equally useful for characterising the soil pore system. These results will contribute to more accurate estimations of gas and liquid transport in soils and allow to obtain historical hydraulic properties and model long-term trends in the soil water regime based on the existing collections of thin sections and polished blocks.