Anthropogenic Impact on Solonetz Soils Development in the Desert–Steppe Zone

Abstract

A study of soils of winter pastures with different intensities of grazing in the north of the Terek-Kuma Lowland was conducted. Based on the results of a survey of the soil cover of three key areas located at different distances from the watering hole, it was established that, in the zone of intensive cattle traffic, the proportion of solonetz soils increases in the structure of the soil cover. The largest proportion of solonetz soils is found in the 200-meter zone. Solonetz soils are associated with cattle trails and elongated micro-depressions of erosional origin. No salt licks were found at a distance of 500 m from the watering place. It has been shown that the development of the solonetz process under the influence of cattle grazing is a consequence of the reduction of vegetation cover and soil compaction. This leads to a decrease in desiccation and intense heating of open areas, resulting in an increase in the salt content in the middle part of the profile. Subsequently, with periodic moistening and drying of the upper horizons, sodium salts enter them with capillary-suspended solutions and the share of exchangeable sodium increases to 20–30% of the cation exchange capacity. Subsequent evolutionary transformations of solonetz soils are associated with a reduction in the thickness of the SEL horizon up to its complete loss as a result of erosion and deflation and the complete destruction of the vegetation cover. The desiccative–exudative water regime is replaced periodically by an exudative one; degradation of solonetzic features occurs due to surface salinization. Thus, there is a pasture evolution of chestnut soils into solonetz and then into post-solonetz salt marsh abrazems, which form large areas of “badlands” near farms and watering places.