INFLUENCE OF REGIMES OF USE AND FERTILIZATION OF SPONTANEOUSLY RENEWABLE SWARD ON THE COURSE OF SOIL MICROBIOLOGICAL PROCESSES

Objective. To study the state of the soil microbiocenosis of spontaneously renewable phytocoenosis of the 21st year of self-growth after the application of mineral fertilizers at the dose of N90P40K70 and the two-mow regime. Methods. Experimental-field, laboratory-analytical, microbiological, statistical. Results. Optimization of mineral nutrition of renewable phytocoenosis contributes to an increase in the number of microorganisms: ammonifiers 2.24 times, mineral nitrogen immobilizers — 1.39, denitrifiers — 3.19, nitrifiers — 1.71, cellulose-destructive — 1.64, actinomycetes — 1.17, micromycetes — 1.20, organophosphate mobilizers — 1.33 times. As a result of twomow regime of the use grass cenoses, the number of microorganisms in most of the studied groups does not change, except for denitrifiers, cellulose-destroying bacteria, micromycetes and organophosphate mobilizers. The use of mineral fertilizers leads to a slowdown of mineralization processes in the soil: pedotrophicity index decreases by 2.28 times, the coefficient of mineralization of nitrogen compounds — by 1.60 time, oligotrophicity — by 2.25 times, the activity of humus mineralization — by 1.65 times. Alienation of plant biomass has a negligible effect on the course of microbiological processes in the soil: pedotrophicity index increases by 18.2 %, oligotrophicity coefficient — by 3.63 %, nitrogen mineralization coefficient decreases by 6.6 %, humus mineralization activity — by 6.2 %. Conclusion. Lack of mineral elements in the soil of the fallow provokes the intensification of mineralization processes, and the optimization of mineral nutrition of phytocoenosis plants contributes to their slowing down. The decrease in the total biological activity and the increase in the phytotoxicity of the soil with the two-mow use of sward indicate the beginning of the processes of soil depletion.