Analysis of changes in hydrothermal conditions of growing crops in the forest steppe zone of Ukraine over a period of 2004–2016 showed that by the average monthly air temperature more than a half of the years under study and by rainfall nearly a third of the researched period differed significantly from the average long-term value and were close to extreme weather. Statistical analysis of long-term indicators of the air temperature regime is evidence of a steady trend towards an increase in average annual air temperature with significant fluctuations in indices in separate periods from 7.9 ± 2.9 to 10.0 ± 2.5oС and a decrease in the amount and instability of natural moisture entry. The influence of weather conditions on the formation of productivity of spiked cereals (winter and spring wheat, spring barley) and maize was assessed at the current agrometeorological risks in the forest steppe of Ukraine. Based on the correlation-regression analysis, mathematical models were created that reproduce the dependence of grain yields upon the complex weather conditions of the growing season, the impact of which reached 60–70%. The conditions of eight years (2006–2008, 2011–2014 and 2016), when the hydrothermal index for the vegetation period was 1.13–1.76, turned out to be optimal by hydrothermal indicators to harvest maize yield at 5.83–9.47 t/ha. However, the years of 2005, 2009–2010 and 2015 were unfavorable as they received precipitation by 120 mm lower than a norm or 36% of the norm. The rainfall by 37–61% lower than a norm in June–July and grain yield 3.12–6.51 t/ha were also characteristic of the years mentioned above.

In the results of research are presented the regularities of the formation of cenoses of segetal vegetation in field crops, in particular, corn for grain and soybeans, with adaptive tillage systems in the Forest-Steppe zone of Ukraine in order to develop effective, environmentally safe, resource-and energy-saving agrotechnological measures to control the level of contamination of agricultural land. The research was carried out during 2016-2020 in a stationary two – factor field experiment, which includes 5 alternative tillage systems (plowing, flat – cutting processing, differentiated – chiseling, shallow and surface – disking) and 3 fertilizer systems (without fertilizers; earning in the soil by – products of the predecessor; by-products + mineral fertilizers) in a short-term grain crop rotation (winter wheat-corn for grain-spring barley-soy) on gray large-sawn-light loamy forest soils.It was found that in agrocenoses of corn for grain and soybeans during the growing season, a small-year type of contamination is formed with a predominance of representatives of the Poaceae family, the monocotyledonous class, in particular Echinochloa crus-galli L. and Setaria glauca L.The best results in controlling of the development of segetal vegetation on experimental variants were provided by varieties of deep tillage (plow, flat-cut or chisel) against the background of an organic-mineral fertilizer system with the introduction of by-products of the predecessor into the soil and the introduction of mineral fertilizers. Such fertilizer systems decreased the contamination of crops by 38.9%.When cultivating the soil without turning the soil chunk – flat-cut and disking, against the background without fertilizers, the development of segetal vegetation was poorly controlled.Systems of minimized–shallow and surface disk treatments significantly (up to 88%) increased the abundance and (up to 91%) weight indicators of crop weed contamination in the pre-harvest period compared to multi-depth plowing and differentiated system of basic soil tilling.

The purpose of the research is to establish the effectiveness of the use of alternative sources of organic fertilizers in short-rotation grain crop rotations, the influence of the volume of by-products and root residues in combination with the application of mineral fertilizers on the formation of the nutritional regime of gray forest soil. To analyze the impact of different crop rotations saturated with leguminous and grain ear crops on the amount of plant biomass input as an alternative organic fertilizer, to determine the effectiveness of the complex application of by-products and mineral fertilizers. Methods. Research methods are field, laboratory, measuring-weighing, comparative-calculating. The research was carried out in the conditions of the Forest Steppe of Ukraine in a long-term stationary experiment of the Department of Soil Tillage and Segetal Vegetation Control of the NSC «IZ NAAN» on gray forest soil in two short-rotational crop rotations. Results. Based on the results of the research, data were obtained on the influence of different tillage systems, the use of plant by-products in the organo-mineral fertilization system of short-rotation crops on the change in the nutrient regime of gray forest light loamy soil. The level of supply of nutrients in the crop rotation depended on the method of the main tillage, the yield level of the crops of the crop rotation, the amount of plant residues and the content of the main nutrients in them. It was noted that with the long-term use of tillage, the active and loosened 0–10 cm layer of the soil is the most saturated with nutrients, both due to the mineralization of crop residues and due to the localization of the main part of the applied mineral fertilizers, while the lower, 10–40 cm layer was characterized by low security level. Conclusions. Earning by-products of crops by carrying out shelf cultivation of the soil, both in 4 and in 5 field crop rotations, contributes to the differentiation of the 0-40 cm soil layer by the content of humus and biogenic nutrients. With the combined use of by-products with mineral fertilizers, the differentiation of the treated soil layer is more pronounced, which led to an increase in the productivity of crop rotations. The use of leaf-stem mass and root residues of corn as an organic fertilizer has a significant effect on improving soil fertility, due to which the largest reserves of humus are formed in 0-40 cm of soil and recirculation of nutrients occurs.

Corn is a highly productive crop of universal purpose, which is grown for food – 20–25 %, forage – 60–65 and technical purposes – 15–20 %. Increasing its yield is possible due to the improvement of the elements of the technology of cultivation taking into account biological characteristics. The growth and development of corn, the production of high yields, as well as the improvement of the quality of the main products are determined by factors of anthropogenic origin and weather conditions. Hydrothermal conditions of Ukraine have already begun to change significantly during the last decades, which resulted in a shift in the climatic seasons, changes in the vegetation period duration (depending on the zone and the biological features of the crops it can either decrease or expand), the decrease in the duration of a stable snow cover, changes in water resources of local drainage. The period 2005–2016 was analyzed for the reliable estimation of the typicality of weather conditions and their influence on the corn productivity under the following basic cultivation methods: ploughing at the depth of 28–30 cm (control), flat-cut tilling at the depth of 28–30 сm, chisel ploughing at the depth of 43–45 cm and disking at the depth of 10–12 cm. The dynamics of precipitation in the northern part of the Right Bank Forest Steppe during the corn vegetation period for the last 2005–2016 testifies to the noticeable tendency of increasing the amount of precipitation in May-June and their sharp decrease in July-August. It was determined that the conditions for eight years – 2006–2008, 2011–2014 and 2016 were optimal for their hydrothermal indices for the production of corn yields at the level of 5.83–9.47 t/ha. The hydrothermal coefficient for vegetation was 1.13–1.76. Weather conditions were unfavorable in 2005, 2009–2010, and 2015 with the amount of precipitation for vegetation of 120–288 mm, which is below the long-term amount by 120 mm, or 36 %. The peculiarity of these years was 37–61 % lower precipitation level in June–July with the grain yield of 3.12–6.51 t/ha. The mathematical-statistical analysis allows to characterize features and typicality of weather conditions of 2005–2016 and to estimate the influence of hydrothermal years and separate months on corn crops productivity. It has been established that there is the following correlation between weather conditions in July and the yield of corn: high correlation for disk soil cultivation (r=0.75–0.86), the average – for ploughing and chyzel loosening (r=0.49–0.53). Thus, the formation of a deep layer of soil with the best water–physical characteristics and fertility in these cultivation modes reduced the dependence of the elements of yield formation from the adverse weather conditions and provided a higher yield of corn by 6.0–8.0 %. Key words: hydrothermal conditions, hydrothermal coefficient (HTC), vegetation period, corn yield.

The research aims to establish the eff ectiveness of granular chalk use produced by «Slavuta-Calcium» Ltd. under growing Poliska–90 winter wheat variety, changing the physicochemical properties of grey forest soil and the wheat productivity. It also aims to establish optimal dosis of «Slavuta-Calcium» granular chalk as the meliorant and mineral fertilizer for grey forest soil in the system of winter wheat fertilization. In the temporary fi eld studies, various doses of nutrients N60–90–120P30–45–60K60–90–120 combined with «Slavuta–Calcium» granular chalk in a dose of Ca230–460–690 kg/ha of the active substance were studied against the background of secondary plowing of rotation products – soybean biomass that averaged 2.34 t/ha. Granular chalk is a modern complex highly eff ective meliorant with the content of Ca – 37.7 and Mg – 0.2 %, the mass fraction of carbonates (CaCO3 + MgCO3) makes at least 95 %. It is characterized by a high level of solubility when interacting with moisture in soil. It has a form of white granules, the mass fraction of 4.0–6.0 mm in size granules makes not less than 90 % and the one of 1.0 mm in size makes less than 5 %. Reactivity – 97 %. The granular chalk is advisable to apply on acidic soils, as a highly concentrated calcium-magnesium fertilizer, with the former as the dominant fertilizer, to optimize the physicochemical properties of the soil, as well as the plant nutrition system, in particular, increasing the availability of an element for assimilation by plants and as long-term ameliorants. The eff ectiveness of the use of mineral fertilizers, in particular acidic nitrogen on highly and medium acidic soils, after chemical reclamation is increased by 30–50 %, and slightly acidic by 15–20 %. The increase in productivity of crops from the combined eff ects of nutrients and chalk granulated is usually higher than when separately applied. The eff ectiveness of the integrated action of these elements is manifested in the growth of plant productivity and the quality of the resulting products, as well as the optimization of physical chemical properties and soil buff ering in the long term. In order to optimize the physicochemical properties of the arable layer of gray forest soil and the productive nutrition of agricultural crops, winter wheat, in particular, biogenic elements should be used in doses N60-90-120P30-45- 60K60-90-120 with granulated chalk «Slavuta-Calcium» in doses of Ca230-460-690 kg/ha of active substance. Granulated chalk obtained as a result of industrial grinding of solid sedimentary carbonate rocks of natural origin, subsequently under the infl uence of the granulation process of the starting material contains Ca and Mg carbonates of at least 95 %, dense granules which facilitates convenient mechanized application, as well as chalk suitable for accurate metered application on the quest map. Key words: granular chalk, gray forest soil, chemical reclamation, crop productivity.