Microbiological destruction of organic substance in agrocenoses

Abstract

Goal. To study the microbiological processes of straw transformation during introduction into agrocenoses of microorganisms — producers of cellulase enzyme complexes, which play an important role in the biodegradation of fresh organic matter. Methods. Field — to carry out field experiment, microbiological — to determine the quantity of cellulosolytic bacteria, biochemical — to determine the cellulase, peroxidase, and polyphenol oxidase activity of the soil, statistical — to identify differences between relevant indicators and assessment of the reliability of such differences. Results. In the conditions of a long-term field experiment on leached chornozem (short-term crop rotation: winter wheat — buckwheat — lupine), microbiological processes that occur during the mineralization of 4 t/ha of straw were studied. It was found that during the growing season buckwheat in the soil (the 1-st year after the introduction of winter wheat straw) and lupine (the 2-nd year after the introduction of organic residues) increased the number of cellulosolytic microorganisms. In buckwheat agrocenoses in the variant with Microbacterium sp. 6634 their quantity amounted to 25.6 million/g of soil with a value of 10.9 million/g of soil under control. The studied soil samples from lupine agrocenoses were also characterized by a significant number of cellulose-destructive microorganisms (17.7 million/g of soil under the action of Bacillus sp. 6658) compared to the control variant (9 million/g of soil). Under the action of bacterial destructors of organic matter, they observed increased enzymatic activity of soil (cellulase, peroxidase, and polyphenol oxidase). Cellulase activity at the use of Bacillus sp. 6658 and Pseudomonas sp. 6650 increased 1.5 times. Under the influence of microorganisms introduced into agrocenoses, an increase in the biochemical coefficient of humus accumulation according to Muromtsev’s methodology was observed. Conclusions. Introduction into the agrocenosis of bacteria — members of the genera Bacillus, Microbacterium, Pseudomonas promoted the development of leached chornozem microorganisms with cellulosolytic properties and increased cellulase, peroxidase, and polyphenol oxidase activity, which was a prerequisite for strengthening the mineralization of straw. The increase in the intensity of decomposition of fresh organic matter with the introduction of plant residues was confirmed by indicators of the biochemical coefficient of humus accumulation according to Muromtsev’s methodology. The studied bacteria are promising as bioagents of microbial preparations to optimize the processes of mineralization-immobilization using plant by-products.