Frunze N. Microbiological features of fertility black soil of the Republic of Moldova

The agroecological features of the composition, properties and functions of the living component of anthropogenically transformed black soil of the Republic of Moldova – microbial communities – are established in the dissertation. For the first time in Moldova, monitoring of the microbiological state of black soil involved in long-term agricultural land use, with the establishment of regularities in the formation and functioning of microbial communities. The peculiarities of the formation of biogenic properties on various succession-age stages of microbial communities and at different levels of the organization (biomolecule, cell, microbial community, biocenosis) have been demonstrated. It is proved that microorganisms in agrocenosis are in a stressful state. Conservation of microbial diversity and the soil’s humus state is possible with the longterm application of agricultural technology using plant residues, green manuring, mineral and organic fertilizers. Carbon microbial biomass is 0.95–8.14 %, and is reliably inferior to local analogues. The tendency in the functioning of living matter is negative. The structure of the microbial biomass consists of a eukaryotic component (62.78–79.45 %). The content of the metabolically active part of the microbial community of soils of the natural ecosystem is on average 29.1 %, and in arable analogues – 9.8–21.8 %. The amino acid pool is 197 to 317 mg N/kg soil. The formation of amino acids has a related nature, but in anthropogenic soil, it is synthesized by 3–7 % of biomolecules more than in soil of virgin land. Nitrogen pool, accounting for 0.2–0.3 %, like carbon, is decreasing. The largest fraction of total nitrogen belongs to amino acids (10–31 %). Long-term exploitation of soils has significantly altered the respiration of microorganisms. On average, basal breathing increases compared to the substrateinduced respiration by 10–21 %. Specific respiration (1.99–3.07 mg C-CO2/mg Cmic per hour) characterizes the state of microbial communities as stress full, and its difference with natural soil (13–54 %) indicates the degree of stress. Soil «health» indicators revealed that its main components – organic, mineral and living matter – underwent significant transformations. The content of nutrients in black soil is unsatisfactory, the phytopathogenic properties of micromycetes predominate over suppressor ones.