Quantifying Soil Structure Based On Solid, Liquid and Gas Components.

Soil is a three-component system comprised of solid, liquid and gas phases distributed in a complex geometry that gives rise to large solid-liquid, liquid-gas and gas-solid interfacial areas. These interfaces affect, to a significant extent, the physical, chemical and biological properties of soils. Finally soil conditions controlling many dynamic processes such as root growth, heat and water flow and crop yield, are determined by compositing and regulating these three soil phases. A generalized soil structure index (GSSI) was developed to predict the structure properties based on solid, liquid, and gas phases for dry land soil utilizing diminishing marginal productivity in the Cobb-Douglas production function for reference. GSSI is defined as GSS I = [ ( X_S - A ) X_L X_G ] ^k, where A and K are the constants for dry land soil, the subscripts S, L and G denote solid, liquid and gas phases, respectively. The objective of this paper was to test the sensitive of GSSI to soil properties and then apply GSSI to quantify the influence of soil management on soil condition by comparing selected credible methods of soil structural characterization. Results showed that GSSI was sensitive to soil texture and soil water potential. Furthermore, GSSI had a significant linear relationship with selected soil properties, such as bulk density, oxygen diffusion rate, redox potential and grain yield. GSSI, which utilizes three soil phases (solids, liquids, and gas) rather than focusing on solids alone was a useful method to characterize and evaluate the effect of management practices on soil condition.