Three-phase and gel models of soils in the analysis of experimental results

It is common to consider the results of experiments in soil physics from the position of a three-phase soil model. Along with the three-phase, there is a gel model of soils. The models are based on different principles: in the three–phase model – the constancy of the solid phase and the mobility of the liquid, in the gel model – the ability of soil gels to swell, harden and reduce the mobility of water. The purpose of the work is to assess the applicability of using three–phase and gel soil models to analyze the results of studying some physical properties of soils. The studies were carried out on the soils of the zonal series: sod-podzolic, gray forest, chernozem, chestnut soil. The following methods were used in the work: vibration viscometry, laser diffractometry, electrical resistance of soils. When studying the physical properties of soils, unexpected results were obtained. Firstly, the curve of the influence of the samples moisture content on the viscosity of the pastes prepared from them reached a maximum in the area of the moisture content of the point of limited availability of water (PLAW). Secondly, with increased mechanical action on soil pastes, the particle size in them did not decrease, but increased. Thirdly, the dependence of the electrical resistance of soils on their humidity maintains a uniform course in the area of PLAW. Although at this humidity, the continuous framework of the liquid phase in soils disappears, providing moisture and electrical conductivity. Fourth, moist soils dry out in a desiccator over water. It is not possible to explain these results from the standpoint of the three-phase soil model generally accepted in soil science. Therefore, a gel model of soils was used to analyze the results, which made it possible to explain all the results obtained.