Burozems in the South of the Vitim Plateau: Humus Pockets, Morphology, Properties, and Microbiome

The purpose of this work is to study the structure of microbial communities, the physicochemical characteristics of the burozems’ profiles, and the soil material infilling the humus pockets. Burozems (Cambisols) in the south of the Vitim Plateau are characterized by specific morphological features: presence of frost cracks, which form wedge-shaped humus pockets, sharply narrowing down the profile. Humus pockets are filled with dark brown humus-enriched material with black stripes that are sharply contrasting in color and properties with the enclosing soil. Compared to the profile of burozems at corresponding depths, the soil mass from humus pockets is less compacted. An increase in total porosity results in greater water permeability of the soil material in the frost cracks. Specific features of the microbial cenosis structure and of the microbial biomass carbon in the soil profile and in the soil material of pockets were revealed. The organic carbon and the absorbed bases are rather evenly distributed in the soil material of the pockets and their contents sharply decrease down the soil profile. The experimental data obtained during the study will replenish the database of the properties and status of microbial cenosis in burozems and in the soil material of their humus pockets in the south of the Vitim Plateau.