Relationship between soil rheological properties and water retention curves

Abstract

The interdependence between the rheological properties and the water retention curve was determined on the example of typical chernozems of Kursk region. The strength of the aggregates of humus horizons of a virgin chernozem, an arable chernozem, and aggregates of Bca horizon in a wide range of water content was investigated by the conical Rebinder’s plastometer. It was shown that the strength of the aggregates depends on water content. The dependence of aggregates strength on moisture is exponential. Comparison of virgin and arable soils revealed a positive effect of organic matter on the structural state of the soil. At high water content, aggregates of the virgin soil are more stable than aggregates of the arable soil and ones of the lower horizons Bca. In air-dry conditions, the strength of aggregates from the arable soil significantly exceeds the aggregates’ strength from the virgin soil, which indicates degradation processes in the arable soil, a decrease of organic matter content leads to an increase of interparticle interaction and an increase in a block-like structure. These experimentally obtained data confirmed the existence of a close relationship between logarithm’s values of the soil moisture full potentials’ moduli and the strength of soil aggregates and the presence of an appropriate linear regression dependence. Voronin’s structural-functional concept is confirmed by the fact that hydrophysical, mechanical and rheological properties of soils are functions of the soil structure.