Problem formulation. Ecological quality of soils and agricultural products depends on the level of irrigation water mineralization. The quality of mineralized irrigation water has a negative impact on soils, agricultural products and ecosystems. This is especially negative in the conditions of Southern Ukraine within the Black Sea territories where the formation of irrigation waters in the Ingulets river basin depends on the influence of the Kryvyi Rih iron ore basin located in the river basin. The aim of the article is to assess the impact of mineralized irrigation waters on soils and natural ecosystems. Materials and methods. Field sampling of water and dark chestnut saline soils and southern chernozem soils to determine the impact of mineralized water quality on soils and ecosystems, statistical analysis of the obtained data. Results. Discharges of highly mineralized mine waters into the river basin lead to a change in the flow velocity in the river from 4 m³/s to 20 m³/s, which negatively affects the flora and fauna living conditions. Depending on the chemical composition of the discharges, the mineralization of irrigation water varies from 1.393 g/dm³ to 1.7608 g/dm³, and sometimes reaches 4.349 g/dm³. In terms of chemical composition, irrigation water is formed as a hydrocarbonate-sulfate-chloride with almost the same content of sulfates and chlorides, calcium-magnesium-sodium with a significant advantage of sodium. The dynamics of irrigation water quality indicators during 2013-2021 testifies to an increase of the most dangerous indicators for soils: hydrogen index of soil solution (pH) from 7.7 to 8.4, chlorine ion content (Cl–) – from 9.52 to 10.77 meq/dm³ and sodium (Na+) from 9.52 to 13.33 meq/dm³. By means of correlation and regression analyzes, the regularities of water hydrochemical composition formation were revealed and a strong functional connection between mineralization and chlorine ions (r = 0.99) and sulfate ions (r = 0.99), between mineralization and hydrocarbonate ions was established (r = 0.47). As the mineralization of water increases, the content of chlorine ions and sulfate ions increases proportionally, and hydrocarbonate ions play a secondary role in the formation of the hydrochemical composition. To prevent the chlorine ions excess of more than 350 meq/dm³ and sulfate ions excess – 500 meq/dm³, irrigation water mineralization should not exceed 1500 mg/dm³, and to prevent the chlorine ions excess of more than 350 meq/dm³, water flow from the canal should be at least 9.0 m³/s. Scientific novelty. New mathematical models of the irrigation water mineralization, its anionic composition, its chloride content dependence on water consumption from the Ingulets river and the interdependence between mineralization and cationic composition of water are offered. Practical significance. The obtained results are of practical importance for the implementation of agro-ameliorative measures for soil and ecosystem conservation.

The aim of the research was to determine the productivity of the Ingulsky corn hybrid of the medium-ripening group of maturity depending on seed and plant treatment during the growing season when applying Regoplant and Vermystym biostimulants, as well as the effect of a plant density in different moisture conditions. Methods. The field laboratory and mathematical and statistical methods were used in the course of the research. Results. Irrigation provided an increase in the yield of silage mass by 1,4-2,2 times. Thus, on average, over three years, the highest productivity of corn for silage was observed when having a plant density of 90 thousand/ha without applying biostimulants – 48,6 t/ha and with applying biostimulants – 59,3-64,7 t/ha. The highest dry matter yield of 17,3-18,5 t/ha, feed unit yield of 16,1-17,4 t/ha and digestible protein content of 0,75-0,82 t/ha was obtained when biostimulants were applied when having a plant density of 90 thousand/ha. It was found that in non-irrigated conditions, the highest grain yield was 3,1-4,7 t/ha on the variant with a plant density of 30 thousand/ha. Applying Regoplant biostimulant provided an increase in grain yield by 1,6 t/ha, while applying Vermystym biostimulant provided an increase in grain yield by 1,2 t/ha, respectively. Conclusions. In non-irrigated conditions, it is necessary to apply Vermystym biostimulant with a sowing rate of 70 thousand/ha to obtain the highest yield of fodder units of 9,6 t/ha and 0,42 t/ha of digestible protein content from corn green mass. In irrigated conditions, the seeding rate should be increased to 90 thousand/ha and Regoplant biostimulant should be used to obtain the highest yield of feed units of 17,4 t/ha and 0,87 t/ha of digestible protein content. The cultivation of the Ingulsky hybrid corn for grain in non-irrigated conditions provided the highest yield of 4,7 t/ha with a plant density of 30 thousand/ha and applying Regoplant biostimulant. In irrigated conditions increasing a plant density to 70 thousand/ha and applying Regoplant biostimulant provided the maximum yield of 11,2 t/ha.

The article presents the results of long-term experimental studies on the effect of different methods of main tillage on soil fertility and crop productivity when applying different degrees of fertilization. Field research was conducted during 2013-2020 on the lands of the Poltava Research Station of the Institute of Pig Breeding and Agro-Industrial Production of the National Academy of Agricultural Sciences. It has been established that the systematic use of organic and organic and-mineral fertilization systems improves the nutrient regime of typical black soil with differentiation of the arable layer by the amount of phosphorus and potassium when applying long-term minimal loosening. There is a tendency towards an increase in density in the layers of 20-40 and 40-60 cm when applying systematic shallow tillage, where this indicator exceeds the upper limit of the optimal range of 1,0-1,3 g/cm3. Application of manure and mineral fertilizers compared to surface loosening makes it possible to additionally annually sequester 0,3-0,4 t/ha of carbon, which is equivalent to 1,2-1,6 t of carbon dioxide. By the average multi-year yield of corn per silage, shallow loosening is inferior to combined tillage by an average of 10%. Tendencies to a decrease in the average long-term productivity of soybean, spring barley, and pea crops when using minimal tillage compared to the combined one are manifested only in certain fertilizer options. Under optimal conditions of heat and moisture supply, the ratio of grain and straw in soybeans decreases. On winter wheat, after peas, there is a tendency towards the preference of shallow loosening. The ratio of wheat grain to straw increases significantly under favorable conditions. Corn responds better to the combined tillage system, which prevails shallow loosening in terms of grain yield by the fertilizer options by 6-10%. Under favorable conditions, the ratio of stems to grain increases significantly, especially on fertilized grounds. From the studied crops, the productivity of sugar beets fluctuates to a greater extent to the conditions of the year, and to a lesser extent - winter wheat, grown after peas and corn for grain. By the average long-term crop productivity, shallow tillage is inferior to combined tillage by 4-8% having a confidence level of 5%. When applying manure, it is advisable to use a combined system of soil tillage, for plant-oriented agrarian production, it is economically advisable to use surface loosening for all crops.

Irrigation with saline water is a challenging yet necessary practice for maintaining sustainable crop production in arid and semi-arid regions, particularly under conditions of climate change and freshwater scarcity. Given the potentially harmful effects of saline water on soil properties, particularly fertility, the primary aim of this study was to determine the extent of impact effects on dark chestnut soils in southern Ukraine, resulting from continuous irrigation of croplands with mineralised water from the Inhulets irrigation system. The Inhulets irrigation water is characterised by a high sodium content (10.49-21.63 me/L), elevated levels of toxic ions (11.83 21.97 me/L), and a high total dissolved solids content (1489-2280 mg/L). The research was conducted between 2003 and 2018 in the Bilozerka District of the Kherson Region. Soil fertility was assessed using the following indicators: humus content and nitrogen, phosphorus, and potassium concentrations. Changes in soil traits were evaluated for statistical significance at P < 0.05 using the MannKendall trend test and cumulative sums of change methods. The findings revealed a statistically significant trend towards a decline in soil humus content (-0.73%; Z-statistic: 2.0381). Conversely, slight but statistically insignificant increasing trends were observed in nitrogen, phosphorus, and potassium concentrations (+9, +2, and +65 mg/kg, respectively; Z-statistics: 0.6794, 0, and 0, respectively). Notably, positive changes were primarily observed after 2013, whereas the earlier period was predominantly characterised by declining soil fertility across all studied indicators. The study’s outcomes hold significant practical value as they highlight the longterm effects of continuous irrigation with mineralised water on soil fertility. These findings provide crucial insights into land reclamation and agrochemical measures necessary to mitigate soil degradation and ensure sustainable agricultural practices in vulnerable agroecosystems

У статті висвітлені результати експериментальних досліджень впливу різних способів і глибини основного обробітку ґрунту на фоні трьох систем удобрення у сівозміні на урожайність сільськогосподарських культур та енергетичну ефективність технологій їх вирощування. Метою статті було встановлення впливу мінімізованого основного обробітку й органічних і органо-мінеральних систем удобрення на формування агрофізичних властивостей, водного режиму ґрунту та продуктивності 4-пільної сівозміни в умовах зрошення півдня України. Методи: польовий, кількісно-ваговий, візуальний, лабораторний, розрахунково-порівняльний, математично-статистичний методи з використанням загальновизнаних в Україні методик і методичних рекомендацій. Система основного диференційованого обробітку, що базується на безполицевому мілкому обробітку, поєднаному з одним щілюванням за ротацію сівозміни на глибину 38–40 см, забезпечила зниження енергетичних витрат порівняно із різноглибинною оранкою на 53,5 % і сприяла оптимізації агрофізичних властивостей і водного режиму ґрунту, створивши умови для реалізації генетично обумовленого потенціалу продуктивності сортів і гібридів. У середньому за роки досліджень (2016–2020 рр.) встановлено, що найвищу урожайність культур сівозміни забезпечувало внесення добрив дозою N120P60 у розрахунку на один гектар сівозмінної площі, на фоні різноглибинної полицевої та диференційованої-1 систем основного обробітку. Так, урожайність зерна кукурудзи відповідно становила 14,44 та 14,82 т/га, сої – 4,31 і 4,34 т/га, пшениці озимої 6,81 та 6,90 т/га та сорго зернового – 7,09 і 7,70 т/га. Найнижчі технологічні витрати встановлені у варіанті з дисковим розпушуванням на 12–14 см у системі безполицевого мілкого одноглибинного основного обробітку ґрунту без внесення мінеральних добрив – 53,2 ГДж/га. Найвищу продуктивність 8,43 т/га зерна й енергомісткість врожаю сільськогосподарських культур сівозміни 159,5 ГДж забезпечила диференційована-1 система основного обробітку з одним щілюванням (38–40 см) за ротацію на фоні органо-мінеральної системи удобрення з використанням побічної продукції культур сівозміни та розрахункової дози мінеральних добрив N120P60 на гектар сівозмінної площі з окупністю енергетичних витрат 2,05.

The most important element in the development of the irrigation regime of agricultural crops is the total water consumption or/and the amount of water that plants need during the growing season to obtain the planned crop in specific natural conditions while optimising all technological processes. The purpose of the study is to determine the features of total water consumption and average daily evaporation of winter wheat plants depending on the natural moisture supply of growing years, irrigation regimes, and groundwater level in the irrigation zone of southern Ukraine. In the course of the study, generally accepted methods were used: system approach and systems analysis, monographic, analysis and synthesis, abstract-logical, historical, field research, statistical and economic-mathematical, etc. The highest indicators of total water consumption were observed in the average weather conditions and amounted to 4,263 m3 /ha in the 2-metre layer of soil, in wet years characterised by moderate temperatures, high humidity, and a considerable number of days with precipitation, the average water consumption from this soil layer was 3,993 m3 /ha. In dry years, which were characterised by hot weather with low humidity and low precipitation, the total water consumption was the lowest and amounted to 3685 m3 /ha. The reduction of the growing season occurs in late June – early July when high air temperatures and low humidity are observed, which is the main reason for the decrease in the total water consumption of irrigated winter wheat. Analysis of data on the use of moisture from different soil layers indicates that during the autumn growing season and during the wintering of plants water reserves in the deep layers are replenished. In general, during the growing season of winter wheat, considering the winter period, the field of this crop consumes an average of 5.2 thousand m³ of water during irrigation over 12 years. Observation of the average daily evaporation of winter wheat plants in conditions of natural and artificial irrigation indicates that it has the form of a parabola, the maximum mark of which falls on the interphase period of earing – the beginning of milky ripeness of grain