LABORATORY DIAGNOSTIC SYSTEM FOR WATER-PHYSICAL SOIL PROPERTIES
Abstract
Actuality of the problem. Irrigation has become a determining factor in the formation of bioproduction processes of new agricultural crop varieties and hybrids due to global climate change for all soil-climatic zones of Ukraine. Moreover, irrigation efficiency is determined to a significant degree by the reliability of the soil water-physical properties. The purpose of comprehensive hydrophysical studies was to determine the basic soil water-physical properties and constants necessary to create favorable soil regimes of reclaimed lands, and to do the mathematical modeling of the soil water regime. Complex laboratory hydrophysical tests of soil samples of undisturbed structure make it possible to determine hydrophysical functions for each soil sample: water holding capacity, water conductivity and water-physical constants of full and minimum moisture capacity, wilting moisture and maximum hygroscopic moisture, which can be determined on the same soil sample located on the same soil desorption curve from full moisture capacity to maximum hygroscopic humidity. The primary saturation of the soil sample under vacuum to full moisture capacity provides a single curve of water retention capacity taking into account structural macroporosity, which is the main feature of this technique. The resulting capillary hysteresis loop has the algorithm: fast nonequilibrium desorption from full moisture capacity and slow equilibrium sorption enables to build a differential curve of the distribution of pore volume over radii, characterizing the structure of the soil pore space. These structural characteristics are sensitive to soil processes, which determine the direction of epigenetic changes in the structure of the soil pore space and the direction of evolution of the soil matrix. The threshold of structural soil macroporosity formation is established from the loop of capillary hysteresis by the ratio of meniscus radii exceeding . Conclusions. The proposed system of soil laboratory diagnostics has advantages over the existing diagnostic methods and significantly increases the information content of complex hydrophysical tests, provides qualitatively new information on soils and provides mathematical modeling with the necessary parameters of mass transfer processes in moisture-saturated soils of the aeration zone.
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