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The relevance of the study lies in the need to maintain optimal levels of mobile phosphorus in carbonate soils to support healthy plant growth and development, as it can be converted into less mobile forms in such soils. The purpose of the study was to assess the impact of various long-term fertilisation strategies on the content of various forms of phosphorus in the soil to improve this availability. The research was conducted in 2019-2022 as a stationary experiment in a separate division of the National University of Life and Environmental Sciences of Ukraine “Agronomic Experimental Station” in Kyiv Oblast on meadow chernozem carbonate low-humus coarse-sawn light loamy soil in a five-field crop rotation, where the influence of different levels of fertiliser saturation (no fertiliser, minimum, average, and optimal) on soil phosphate status and yield of Etana winter wheat variety and Sumiko sunflower hybrid was investigated. Soil samples were taken from the 0-20 and 20-40 cm layers, and the group and fractional composition of phosphates was determined using the Chang-Jackson method and the content of mobile phosphates using the Chirikov and Machigin methods. According to the analysis of the group and fractional composition of soil phosphates, it was found that in meadow chernozem carbonate low-humus coarse-sawn light loamy soil, the content of iron phosphates prevails among all fractions during long-term fertilisation. The results showed an increase in the content of aluminium phosphates in the 0-20 cm surface layer of the soil of two variants with long-term fertilisation, and an increase in the content of the second fraction of soluble calcium phosphates (Ca-PII), with the minimum saturation (N27P18K20) with the highest available phosphate fraction for plants (Ca-PI) is observed. The content of mobile phosphates was maximal at optimal fertiliser saturation (N81P54K62) and was 4.8 and 8.5 mg/100 g of soil, the aftereffect of organic fertilisers positively affected the accumulation of mobile phosphates in the soil. The highest yield of winter wheat (7.55 t/ha) and sunflower (4.28 t/ha) was obtained with optimal fertiliser saturation, the lowest – without the use of fertilisers, where it was 4.45 t/ha for winter wheat and 2.23 t/ha for sunflower. The results of the study can be used to develop more sustainable and effective strategies for using phosphorus in soils, which can help preserve soil resources and prevent possible contamination of water sources due to excessive phosphorus intake

The research relevance is predetermined by the need to study strains of Bacillus subtilis bacteria that have a positive effect on plant growth and development and exhibit a stimulating effect at optimal bacterial loads. The research is of great importance for agriculture, ecology, and sustainable development. The research aims to determine the effect of new strains of B. subtilis (H3, H10, H13, H36, H38, H40, H43, H45) on the development of winter wheat (Triticum aestivum L.) seedlings when inoculated with inoculated crops. Laboratory, vegetation, and mathematical and statistical methods were used in the study: deep cultivation of strains, roll method of germination of test plant seeds, and data processing using Statistica 8.0 and MS Excel. The results of the model experiment on the effect of culture liquids of B. subtilis strains under different technological forms and dilutions on the growth and development of wheat test plants are summarised. It has been established that at dilutions of 1:10, 1:50, 1:100, and 1:500, the stimulating effect of bioagents is observed, and the maximum effect is achieved at a dilution of 1:100. It has been shown that the greatest positive effect on wheat seed germination was observed for B. subtilis inoculants applied to seeds in mature technological forms (spore culture, 2.0 x 107 cells per seed). The germination energy of Triticum aestivum L. seeds increased by 96.5% when interacting with B. subtilis inoculants, and the raw weight of seedlings increased by 84.0-109.6% depending on the experiment variant compared to the control, which indicates the growth-stimulating properties of the new strains. It was proved that the use of mature cultures of B. subtilis H38, H40 and H45 resulted in an increase in root weight by 4.8-11.3% compared to the control without bacterisation. When treated with culture fluids of B. subtilis H3, H10, H13, H36, and H43 in the form of vegetative cells, the root mass decreased by 11.8-44.0% compared to the control. The use of the studied strains of B. subtilis effectively affects the development of winter wheat and is a promising inoculant with a growth-stimulating effect. The practical significance of the study is to understand and determine the potential benefits of using Bacillus subtilis bacterial strains to enhance the growth and development of plants, in particular winter wheat (Triticum aestivum L.)

Stevia rebaudiana plants produce sweet tasting compounds, steviosides, which are 300 times sweeter as sugar and can be used as natural sweeteners. Moreover, stevia leaves contain high amount of antioxidants. The use of plant compounds as components of functional nutrition and nutraceuticals is extremely relevant today. The purpose of this study was to investigate the effect of increased nitrogen and saccharose supply on growth and accumulation of steviosides and anthocyanins as well as antioxidative activity in fast-growing shoot cultures of S. rebaudiana. The morphological changes of the leaves, the accumulation of steviosides and anthocyanins, and the antioxidant properties of the extracts were determined. It was shown that during three weeks of in vitro cultivation of shoots on MS medium with double concentration of nitrogen, the biomass increased by 71.0%, after application of double concentration of saccharose – by 133%, and after increasing nitrogen in combination with saccharose supply – by 162.0% compared to the control. Sucrose stimulated the accumulation of biomass. Anti-oxidative potential after nitrogen application was 2.4 times higher than the control, and with saccharose supply it increased 2.7 times. Shoots treated with increased nitrogen and saccharose concentration contained 50.7 and 57.8 mg/g-1 steviosides, respectively. However, the combination of nitrogen and saccharose led to accumulation of 73.4 1 mg/g-1 steviosides. Shoots grown on MS medium culture had 26.0 mg/g-1 of steviosides. The content of anthocyanins was 1.7 times greater under added nitrogen supply, and 2.3 times greater after the application of nitrogen and saccharose. Optimum cultivation media developed individually for each in vitro culture increase the production of valuable plant secondary metabolites up to 3 times

In organic potato cultivation technologies, various biopreparations are used, which have a considerable impact on both the growth and development of crops, and on soil fertility indicators, which is especially important for sod-podzolic soils characterised by low potential fertility. The purpose of the study is to establish the changes in humus content and mineral nitrogen in sod-mediumpodzolic loam soil under the influence of biopreparations for the decomposition of white mustard as a cover crop and for the treatment of potato tubers and vegetative potato plants. In a two-factor experiment, the following factors were examined: factor 1: control without a destructor and “Ecostern” destructor at a dosage of 1.2 litres per hectare; factor 2: nine options of biopreparations application, including Agat, Regoplant, Mycohelp, Phytohelp, and Stimpо. Soil samples were collected from the 0-30 cm layer of sod-medium-podzolic sandy loam soil on water-glacial deposits. In them, the total humus content was established by the Tyurin method, and the mineral nitrogen content was calculated as the sum of ammonium and nitrate nitrogen determined potentiometrically. The application of the destructor on the green biomass of the cover crop contributed to an increase in the humus content in the 0-30 cm soil layer, where it ranged from 1.135% to 1.24%, compared to 1.025% to 1.15% in the options without the use of the bio-destructor. A reverse dependence was observed in terms of mineral nitrogen content. In the options with the use of the Ecostern destructor, the mineral nitrogen content was on average 2.09 mg/kg lower compared to the options without the application of the destructor. The highest humus content was observed in option 8, which involved the use of “Phytohelp” for treating potato tubers at a dosage of 1.0 litre per ton and three-fold treatment by “Phytohelp” at a dosage of 1.0 litre per hectare during the vegetation period. In the option without the destructor, the humus content was 1.15% and 1.24% with the application of the Ecostern bio-destructor. It slightly lagged behind option 9 with the “Phytohelp” biopreparations. The materials presented in the study may have practical value for agricultural enterprises engaged in growing organic potatoes to ensure the preservation and reproduction of organic matter in soils

To assess the ability of soils to self-repair and self-rehabilitation, it is important to monitor the indicators of soil microbiological activity. In conditions of manure deficiency, the restoration of organic matter of soils is provided by using non-commercial share of the crop and growing green manure crops, which is especially important for zonal soils of Ukrainian Polissia. The purpose of the study was to estimate the number of various physiological groups of microorganisms in sod-medium podzolic soil under the influence of various fertiliser systems. Field, laboratory, and statistical methods were used in the study. Field method: an experiment was conducted in a field of the Chernihiv Institute of Agricultural Microbiology and Agroindustrial Production of the NAAS with an area of sown plots of 102 m2 on sod-medium podzolic light loamy soil with a humus content of 0.9-1.1% in 0-30 cm layer. The number of different groups of microorganisms that transform carbon and nitrogen compounds was determined in soil samples. Statistical methods – system analysis, mathematical and statistical analysis. Sowing of green manure such as lupine and oilseed radish had a positive effect on the number of ammonifiers (4.3-13.2 million CFU), which is 44-180% more than in the control. The mineral fertiliser system for potatoes also increased the number of ammonifiers by 15-50% compared to the option without fertilisers. The mineralisation-immobilisation coefficient was calculated as the ratio of the number of microorganisms that immobilise mineral forms of nitrogen to the number of organotrophs, and the pedotrophicity coefficient by the ratio of the number of microorganisms on soil agar to the number of microorganisms that grew on meat-peptone agar. It was established that the cultivation of green manure on sod-podzolic soil has a positive effect on the development of physiological groups of microorganisms and the microbiological processes tend to accumulate humus. The materials of the study are of practical value for agricultural producers who are engaged in growing potatoes on sod-podzolic soils in the possibility of replacing manure and mineral fertilisers in the fertiliser system of agricultural crops with green manure (lupine, oilseed radish)

In the present-day world, the demand for organic products is growing, but there is an insufficient number of studies on the impact of biological preparations on soil fertility parameters. Indicators of microbiological activity are not the same for different soil types, which is why it is necessary to investigate them in detail in specific soil and climatic conditions, especially on zonal soils, which are sod-podzolic soils in Polissia. Research on the impact of various biological preparations on soil fertility indicators for the cultivation of one of the most popular crops in Ukraine – food potatoes – is relevant. The purpose of this study was to establish the effect of treatment of potato tuber seeds with biological preparations and introduction of a biodestructor for better decomposition of siderate on the focus of microbiological processes in the soil. The study was carried out in an experiment at the Volyn State Agricultural Research Station of the Institute of Potato Growing of the National Academy of Agrarian Sciences of Ukraine. The soil of the experimental site was sod-medium-podzolic sandy soil on water-glacial deposits. The stationary experiment included variants with the addition of siderate to the soil without a destructor (Background 1) and with the addition of the Ecostern destructor to the siderate (Background 2). The effectiveness of the following biological preparations was also investigated: Mycohelp, Agat, Regoplant, Fitohelp, Stimpo. Soil analysis for microbiological indicators was carried out in samples taken from the 0-20 cm layer. The focus of microbiological processes in the soil was found by the corresponding coefficients. It was found that the oligotrophicity coefficient was less than one on the variants using the Ecostern biodestructor during the growing season of potatoes, which indicates a good supply of easily digestible organic substances to the soil microbiota, while on the variants without Ecostern during the ripening phase, the oligotrophicity coefficients exceeded one. The coefficient of pedotrophicity changed more during the growing season than according to the variants of the experiment. In the seedling and flowering phase of potatoes, mineralisationimmobilisation coefficients were low in all variants of the experiment, which indicates the predominance of synthesis of organic matter. The materials of this paper are of practical value for farmers and producers of organic crop production in the issue of plant residue management for the use of biodestructors in the technology of growing food potatoes

From an agrocoenosis of winter wheat (Triticum aestivum L.; phylloplane and rhizosphere of the root system; typical chernozem, soil column measuring up to 40 cm), using the classical microbiological methods, we had isolated soil bacteria and characterized them according to the morphological features as representatives of Gram-positive and spore-forming bacteria of Bacillus sp. genus. In the earing-swelling phase of grain, the screening studies found non-pigmented forms of colonies of bacterial isolates, 19 of which were classified to colonial-morphological diversity of R-type with the diameter of 7 to 13 mm. The analysis of physiological condition of cells of populations of soil isolates revealed technologic specificity according to parameters of spore formation in different conditions and incubation time (up to 48–72 h). We observed 90.0% of free spores in axenic cultures as early as after 72 h of cultivation and no more than 10.0% of prospores in the studied monoisolates with stable morphologic traits. Isolates Н10 and Н45 demonstrated the ability to grow in higher cultivation temperatures (+37…+40 °С). According to environmental рН, isolates were able to grow in рН ranging 4.5–8.0. Differential diagnostic testing revealed that as the source of carbon, with formation of acid, soil isolates used arabinose, xylose, mannitol, glucose, galactose, fructose, maltose, sorbitol, glycerin, dextrin, starch, rhamnose and dulcite (with development of alkaline). There was observed active use of mineral forms of nitrogen: ammonium salt and nitrates, aminoacids and proteins. The isolates hydrolyzed casein, gelatin, starch, and litmus was being reduced in the young during growth in milk with litmus. They also exerted catalase activity and were oxidase-positive. Biochemical testing using API test system determined that the studied isolated bacteria differed by a range of fermentation carbohydrates, reduction of nitrates. In the conditions of submerged fermentation, isolates Н38 and Н40 grew in heightened temperature ranges of cultivation (40 °С) for 48 h (according to fact of spore development). Therefore, according to the key morphologic and biochemical traits, strains Н3, Н10, Н13, Н36, Н38, Н40, Н43, Н45 were similar to such of reference strain B. subtilis 8A, and were identified to Bacillus sp., species B. subtilis.

In agroecosystems, microorganisms are the main factor in the soil formation process, plant nutrition and phytosanitary condition of the soil. All measures aimed at restoring soil fertility and increasing productivity, environmental safety of agricultural production, are closely related to the activity of microorganisms. Increased local activity, biomass and diversity of microbiota are one of the most important characteristics that distinguish the rhizosphere from the total soil volume. The purpose of the research was to study the number and composition of the microbial complex of the rhizosphere of grain crops (winter wheat of different varieties of domestic selection) in the process of ontogenesis. To conduct a set of microbiological studies, soil samples (typical chernozem) were selected and prepared in compliance with standard requirements for sample preparation and storage in laboratory conditions. Analysis of rhizosphere soil samples was carried out on variants of different varieties of winter wheat of domestic selection. The number of soil microorganisms was determined by seeding suspensions on nutrient media according to generally accepted methods in microbiology. The determination of the total microbial biomass in the soil was carried out by the rehydration method, and the intensity of soil “breathing”, in terms of CO2 release and O2 absorption, was determined by the manometric method (Warburg apparatus). It was found that winter wheat varieties affected the formation of the microbiome of typical chernozem. The number and composition of the microbial complex of the rhizosphere of winter wheat in the process of ontogenesis changes significantly, especially in terms of the ratio of the number of spore-forming and non-spore forms of microorganisms under the same conditions of agricultural technology for growing crops. The rhizosphere's total pool of saprotrophic microorganisms shows biomass variability and changes in favour of ecoplastic bacilli. An increase in the number of spore-forming bacteria to 4.2 x 107 CFU/g was found in the variants of cultivation of certain varieties. Cultivation of different varieties of winter wheat demonstrates stable indicators of CO2 emission intensity – from 5.2 to 7.0. A similar trend can be traced in the absorption rate of O2 (no more than 5.3-6.8)

Microorganisms play an important role in shaping soil fertility, maintaining its performance as a bio-inert matter, and are an indicator of qualitative changes in the soil. As a result of anthropogenic impact on the soil, the number and species composition of the microbiota is decreasing. The purpose of the study was to assess the number of different physiological groups of microorganisms on meadow chernozem carbonate soil under different pea fertilisation systems. The number of different groups of soil microorganisms was estimated according to the method of D. H. Zvyagintsev by sowing soil suspension on solid culture media. It was found that the most favourable indicators of micro biocenosis and the highest yield of peas of the Tsarevych variety were formed by the residual effect of organic fertilisers and N45P45K45. The variant without fertilisers induces the development of organic matter mineralisation processes in meadow chernozem carbonate soil by the content of pedotrophic and humate-decomposing organisms and formed the lowest pea yield. The introduction of only mineral fertilizers for pea cultivation formed a high rate of humus accumulation at the level of Kac.= 1,6-1,9