Influence of agricultural systems and basic tillage on soil microorganisms number under winter wheat crops of the Right- bank Forest-Dteppe of Ukraine

National University of Life and Environmental Sciences of Ukraine, 15 Heroiv Oborony St, 03041, Kyiv, Ukraine Sumy National Agrarian University, 160 Herasym Kondratiev St, 40021, Sumy, Ukraine Ukrainian Laboratory of Quality and Safety of Agricultural Products, National University of Life and Environmental Sciences of Ukraine 7 Mashynobudivnykiv St, 08162, Сhabany, Ukraine 4 National Scientific Centre “Institute of Agriculture of the National Academy of Agrarian Science of Ukraine”, 2b Mashynobudivnykiv St, 08162, Сhabany, Ukraine Corresponding author E-mail: andb201727@ukr.net Received: 27.09.2020. Accepted: 27.10.2020


Introduction
Soil is a very complex substance in which, depending on the technology of growing crops, selection of these crops in crop rotation and many other factors, specific agrophysical, agrochemical and biological conditions are formed Mishchenko et al., 2019;Karbivska et al., 2020). In turn, these conditions affect the species, numerical composition and living conditions of different ecological and trophic groups of microorganisms (Aristovskaya, 1980;Karpenko, 2015;Vekirchik, 2001). The influence of various industrial chemical elements, which are used during the growing season of crops as fertilizers and means of protection against pests, is especially actively (Kolisnyk et al., 2019;Tsyhanskyi et al., 2019). The results of research by many scientists shown that the species and quantitative composition of the microflora changes significantly with increasing or decreasing the depth of tillage, replacement of moldboard plowing on boardless tillage, application of different types of fertilizers, their ratio and quality composition (Zvyagintsev, 1987;Karpenko et al., 2019;Radchenko et al., 2018;Mishchenko et al., 2017). Based on the above, the development of efficient and environmentally balanced cultivation technologies and the entire agricultural system in specific conditions in general is closely related to the study of rational integration of one of its most important parts -tillage of soil and fertilization of crops (Iutinskaya, 2006;Pyrog, 2004). However, such a comprehensive approach in terms of its impact on soil microflora has not been sufficiently studied. This issue is especially relevant today, as there is a problem of obtaining environmentally friendly products (Litvinov et al., 2019;Karbivska et al., 2019a;Butenko et al., 2019). Thus, the aim of our research was to establish the impact of agricultural systems on the species composition of microorganisms and its change during the growing season of winter wheat against the background of various measures of basic tillage and farming systems in Separated subdivision of NULES of Ukraine "Agronomic Research Station". The research was performed in a ten-field crop rotation, which is part of a long-term stationary experiment of the Department of Agriculture and Herbology of the National University of Life and Environmental Sciences of Ukraine.

Materials and Methods
The research was carried out in the field of winter wheat after peas in the typical for the Forest-Steppe Zone grain-beet crop rotation with the following crop rotation: clover -winter wheat, oil radish (for green manure) -sugar beet -corn for silagewinter wheat, winter wheat for green manure) -corn for grain -peas -winter wheat, green radish oil -sugar beets -barley with sowing of clover. The soil of the experimental plot is represented by black-soil typical low-humus medium loam coarsedust with a humus content in the arable layer of 4.34-4.68% (according to Tyurin), a total nitrogen content of 0.27 -0.31% (according to Keldal), mobile phosphorus 4.5-5.5 mg/100 g of soil (according to Machigin), exchangeable potassium -9.8-10.3 mg/100 g of soil (according to Maslova). The industrial system of agriculture (control) to restore soil fertility provided application 300 kg mineral fertilizers (N92P180K108) and 12 tons of organic matter per 1 ha of crop rotation area with intensive application of pesticides. Under the ecological system was applied 24 t of organic matter, consisting of 12 t/ha of manure, 6 t/ha of by-products and 6 t/ha of crop green manure, as well as 150 kg of mineral fertilizers (N46P49K55) with standard application of pesticides. Biological system included the use of only natural organic fertilizers 24 t/ha to reproduce soil fertility without the introduction of industrial agrochemicals, as well as biological products to optimize plant nutrition and biological means of crop protection against pests. The measures of the main tillage were the differentiated tillage (control) provides for one flat-cut loosening under barley, two surface tillage with disc implements for winter wheat (predecessor -peas for grain) and includes six various-deeps of moldboard tillage under other cultures; moldboard-boardless tillage in crop rotation involves deep plowing for sugar beets by 28-30 cm and for other crops -subsurface and surface tillage(for the above field of winter wheat); 3. surface tillage is to carry out disking for all crops by 8-10 cm. Laboratory tests were carried out on the basis of Ukrainian Laboratory of Quality and safety of Agricultural products National University of Life and Environmental Sciences of Ukraine according to generally accepted current methods and standards. Soil samples were taken in the development phase of winter wheat -exit to the tube and earing. The moisture content in the soil was determined by thermostatic-weight method. Mathematical processing of the obtained experimental data was carried out according to B. Dospekhov (1985).

Results and Discussion
Studies have shown a different effect of different farming systems and measures of basic tillage on the number of microorganisms and individual ecological-trophic and taxonomic groups (Table 1), the analysis of which shows that the phase of exit to the tube under surface tillage is formed more microorganisms of all studied groups than under differentiated and moldboard-boardless tillage. Among agricultural systems, the advantage is ecological one. Our research confirms the opinion of many scientists on the activation of microorganisms under surface treatment of soil (Grodzinsky, 1973;Beresteckiy, 1987;Butenko et al., 2020). The biological system of agriculture does not involve the use of chemicals to restore soil fertility, which could adversely affect the number of microorganisms in it. Ecological system involves their use in much smaller quantities, and the industrial system of agriculture due to the influence of mineral fertilizers, herbicides and other plant protection products cannot provide conditions for the maximum number of microorganisms of different ecological-trophic groups. For a more detailed analysis of the processes occurring in the soil, it is necessary to pay attention to the number of non-spore and ammonifying bacteria, pedotrophic myxomycetes. These indicators increased significantly during the earing phase. The ecological system of agriculture provided the best conditions for nitrogen mineralization and the total number of microorganisms. In the industrial system of agriculture, the total activity is lower compared to the ecological and the salinity ratio is 0.68-1.2. In particular, with surface tillage, the oligotrophic coefficient is 2.27, which indicates the creation of deficient conditions for nutrition crops ( Table 2). The coefficient of mineralization in the phase of exit to the tube was the highest in the ecological system of agriculture under the conditions of moldboard-boardless tillage (1.25), and under industrial (1.14), which indicates the intensity of mineralization processes. The biological system has the lowest coefficient of nitrogen mineralization, which indicates its lack in the soil and in general the number of microorganisms was smaller. Thus, we can conclude that the biological system of agriculture uses the natural fertility of the soil. Obviously, the amount of organic fertilizers and post-harvest residues used in the experiment is low and does not provide extended reproduction of soil fertility (Table 3). The coefficient of mineralization in the phase of exit to the

Influence of agricultural systems
Ukrainian Journal of Ecology, 10(5), 2020 tube was the highest in the ecological system of agriculture under the conditions of moldboard-boardless tillage (1.25), and under industrial (1.14), which indicates the intensity of mineralization processes. The biological system has the lowest coefficient of nitrogen mineralization, which indicates its lack in the soil and in general the number of microorganisms was smaller. Thus, we can conclude that the biological system of agriculture uses the natural fertility of the soil. Obviously, the amount of organic fertilizers and post-harvest residues used in the experiment is low and does not provide extended reproduction of soil fertility (Table 3). During the earing phase, the nature of microbiological activity changed somewhat, but under the biological system the advantage remained relative to the coefficient of mineralization immobilization of nitrogen (1.32) against the background of moldboard-boardless tillage (Table 4). During the decomposition of plant residues in the soil, as a result of the activity of microorganisms, free organic substances accumulate, which create a certain allopathic potential of the root environment (Iutinskaya, 2006;2004;Karbivska et al., 2019b;Litvinov et al., 2020). The method of direct biotesting allows to observe the content of physiologically active substances in the soil. We conducted a study of root growth cress-salad (%) under different farming systems and measures of basic tillage in winter wheat crops. The study of the influence of different farming systems and measures of basic tillage showed that in the phase of exit to the tube of winter wheat (Table 5) stimulation of cress-salad`s roots was observed, while in the earing phase it decreases against the background of increasing microorganisms, especially myxomycetes. As can be seen from the table, in winter wheat crops differentiated tillage showed almost the same effect on soil phytotoxicity regardless of the farming system, while under the surface tillage system differed slightly. The largest increase in cress-salad roots was under the ecological system of agriculture. This is due to the fact that organic matter was in the upper layer of the soil, and a balanced combination of organic matter and mineral fertilizers stimulates the development of soil microflora, as well as reduces the phytotoxicity of the soil

Conclusion
The dynamics of microbiological activity of the soil is an indicator of its fertility and indicates changes in its properties. The biological system of agriculture has the lowest coefficient of nitrogen mineralization, which indicates a decrease in natural soil fertility. Therefore, it is believed that the amount of organic matter that is provided, in this case today, was very small.
The coefficient of mineralization is the highest under the ecological system of agriculture, under the conditions of moldboardboardless tillage (1.25), and -industrial (1.14), which indicates the intensity of mineralization processes due to natural fertility. In the industrial system of agriculture the general microbiological activity is lower, in comparison with ecological and the coefficient of mineralization is 0.68-1.2, therefore for effective improvement of soils and reception of ecologically safe production it is necessary to introduce under winter wheat (predecessor peas for grain) ecological system of agriculture using surface tillageas the main.