Features of the Soil Cover of the Semi-Desert Ecotone in the South of the Volga Upland

The semi-desert ecotone of the south of the Volga Upland is part of the zonal macroecotone bordering the Eastern European steppes from the southeast. Under strained hydrothermal conditions, the microrelief plays a decisive role in the redistribution of atmospheric moisture. This article contains materials from 10-year studies of the soil and landscape cover of the contact zone of the south of the Volga Upland and the northern end of Ergeni. The so-called three-membered complex described 100 years ago by N.A. Dimo and B.A. Keller is not traced in the soil cover. The methodology of landscape-catenary sections was used by laying soil-geomorphological profiles and drilling wells with subsequent sampling of soils at 5 test sites. The soil cover of the watersheds of the sites is represented by complexes of light chestnut low-humic weakly alkalinized medium- and heavy-loam soils. A smaller area is occupied by meadow-chestnut soils of cavities and solonets. The structure of the soil cover of the slopes includes combinations and variations that transform into mesocatenes. In the mesocatene of balkas, zonal light chestnut turn into metamorphosed meadow-chestnut soils or drift dark-colored soils of the bottom of balkas. The semi-desert ecotone is almost completely located within the boundaries of the spread of light chestnut soils in Volgograd region. The structure of the soil cover of the ecotone is dominated by a twofold complex, where zonal light chestnut soils in combination with meadow-chestnut soils of cavities and solonets.