The influence of agrotechnical measures on the number of melanin-synthesizing microorganisms

Abstract

In connection with the growing scale of soil dehumification, studies of the patterns of synthesis of the precursors of humus molecules – melanins of bacterial origin – are becoming increasingly relevant. The purpose of this study was to establish the influence of the main factors of agricultural production on the spread of melaninsynthesizing microorganisms: the method of basic soil cultivation, mineral fertilizers, and the type of agricultural crop. Research methods: microbiological, laboratory-analytical, statistical, correlational. As a result, the study found for the first time that the main cultivation of the soil affects the number of melaninsynthesizing microorganisms: micromycetes, bacteria, аzotobacter. In the variant without the application of mineral fertilizers (control), the soil was characterized by the minimum amount of melanin-synthesizing bacteria using the No-till technology, 28.8% more – using disking, and 2.4 times more – using ploughing. The number of melaninsynthesizing micromycetes in the variant without fertilizers was also maximum upon ploughing, the average number was observed with No-till technologies, and the minimum number – using shallow disk tillage. Application of mineral fertilizers in a dose of N30P30K65 leads to an increase in the number of melanin-synthesizing bacteria in the ploughing option by 3.58 times, disking by 3.53 times, No-till technology by 2.28 times. An increase in the dose of mineral fertilizers to N150P100K120 contributes to an increase in the number of melanin-synthesizing bacteria by 5.04 times upon ploughing, 5.78 times upon disking, and 2.24 times upon no-till technologies. The medium-significant nature of the relationship between the content of humus and the number of melanin-synthesizing bacteria (r=0.528) and their share in the total number of microorganisms (r=0.470) suggested that in chernozem inherent in growing sunflowers, humus is formed mainly with the participation melanins of bacterial origin. Metabolites of polysaccharide-synthesizing bacteria take part in the formation of the resistance of humus molecules to microbial mineralization, the probability of the formation of colonies of which has a moderately significant relationship with the content of humus (r=0.532). The results of these studies can be used in the development of recommendations for regulating the content of humus in agricultural soils, preventing its excessive mineralization, which will allow preserving and increasing soil fertility