Investigation of microbiological processes during long-term storage of grey forest soil samples
¹National Scientific Centre, Institute of Agriculture of NAAS of Ukraine, 2 b, Mashinobudivnikiv Str., Chabany vil., Kyiv- Svyatoshin Dist., UA08162 Kyiv Region, Ukraine
²National University of Life and Environmental Sciences of Ukraine,
15 Heroiv Oborony Str., UA03041 Kyiv, Ukraine
³Latvia University of Life Sciences and Technologies, Institute of Engineering and Energetics, Faculty of Engineering and Information Technologies, Ulbroka Research Centre, 1 Instituta Street, Ulbroka, Ropazu Region, Stopinu Municipality, LV2130 Latvia
*Correspondence: adolfs.rucins@lbtu.lv
Abstract:
Investigation of a decrease in the viability of microorganism cells in the soil samples, stored for a long time in an air-dry state, has both theoretical and practical significance since in agrochemistry and the soil science it is a custom to store the soil samples for many years and decades, taking it as an axiom that the properties of these samples remain unchanged. To find out what are the patterns of survival of microorganisms of various ecological-trophic, functional and systematic groups, their viability was studied in samples of gray forest soil, stored for 32 months in an air-dry state. It has been shown that the number of microorganisms of most groups decreases by 42–94 times, the number of polysaccharides-synthesizing microorganisms decreases maximum- by 3,993–18,210 times, depending on the agricultural practices, used in a stationary experiment. the number of spores and cysts decreases. The microorganisms which have the least decrease in the number of colony-forming units of micromycetes and Azotobacter as groups that have forms of surviving unfavourable conditions during storage are spores and cysts. In addition, the physiological and biochemical activity of micromycetes decreases significantly, compared to their activity in the original (initial) fresh soil. During storage the number and share in the total number of melanin-synthesizing micromycetes sharply decreases from 65.8–94.6% to 2.48–5.17%. When storing soil in an air-dry state, the rate of decline in the number of microorganisms depends on the functional affiliation of the group and on agrotechnical techniques that were previously used in the stationary experiments: liming, application of mineral fertilizers, ploughing in the by-products of the predecessor crop in the crop rotation, and the biomass of the sideral crop. The organic matter, ploughed into the soil, promotes the survival of ammonifiers, mineral nitrogen immobilizers, Azotobacter and polysaccharide-synthesizing microorganisms. Ploughing in of crop by-products reduce the number and proportion of melanin-synthesizing micromycetes. Verification of the obtained data, using long-term stored soil samples, is not permissible since microbiological processes occur in the soil during which the soil microbiota consumes the macro- and microelements, present in it, organic and organomineral complexes, including humus.
Key words:
ammonifiers, Azotobacter, micromycetes, number, physiological and biochemical activity, soil, storage