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CHEMICAL PROPERTIES AND THE STATE OF THE MICROBIAL COMMUNITIES OF THE BURIED SOILS IN THE LOESS OF THE EASTERN CISCAUCASIA

K. S. Dushchanova

Abstract

The physicochemical properties and the state of the microbial communities of the buried soils of the loess strata of the Khasavyurt plain (Eastern Ciscaucasia, Russia) were studied. The thickness of loess deposits was about 50 m. An exposed surface dark chestnut soil (Kastanozem) had a thickness of about 0.5 m, the next 3-3.5 m were almost pure light yellow loess. Buried soils were observed in the upper part of the loess. Palaeosol 1 at a depth of 5-10 m and a thickness of about 2 m was morphologically similar to chernozem-like soil. It was dated back to 10,850 yrs BP. Palaeosol 2 dated back to 19,425 yrs BP was well pronounced at a depth of 15-20 m, intensely colored on the top, and was also of a chernozem-like type. The lower part of the loess stratum (10?15 m) was complicated by several horizons with obvious traces of soil formation processes (palaeosol 3). These horizons reflect the dynamics of erosion-accumulative processes during the loess accumulation and redistribution likely in the end of the Eopleistocene. Living microbial biomass was determined from the content of soil phospholipids. In the upper 10 cm soil layer, it was about 290 ?g C / g. In the loess layers, it was 12?42% of that in the upper soil layer. The highest biomass was detected in the upper and closest to the surface loess layer, which was probably affected by current soil formation processes. In the palaeosols, the content of living microbial biomass varied from 20% to 28% of the level in the upper soil layer. Compared to the adjacent loess layers, the living microbial biomass was reliably higher.

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