Comparative Characteristics of Recent and Buried Soil Associations in the Desert-Steppe Zone on the Volga-Don Interfluve

Abstract

We studied ancient (27th–26th centuries BC) and recent soil associations of the desert-steppe zone on low and high terraces of the Dzhurak-Sal River and in the interfluve area within the Sal-Manych Ridge (southeast of the East European Plain). Morphological, chemical, and microbiological soil analyses were performed. It has been found out that soil associations formed in the Bronze Age were the most contrast on low terraces and the least contrast in the interfluve areas. Microbial communities in buried and recent soil associations weakly depended on the solonetz process. The total number of three groups of microorganisms–(a) growing on soil agar and using nutrients from a dispersed state, (b) growing on nitrite agar and consuming humus, and (c) growing on a rich medium and decomposing plant residues–is approximately the same within the test plot, but their proportions differ significantly in soils on various landforms. At the same time, the ratios between microorganisms of different trophic groups, corresponding to ancient and present-day climatic conditions, are preserved both in light chestnut soils (Eutric Cambisols (Loamic, Protocalcic)) and in solonetzes (Haplic Solonetz (Loamic, Cutanic, Ochric),