Over the past 15-20 years, agricultural production in Ukraine has been reoriented to the cultivation of more profitable, highly liquid, as well as drought-resistant crops, in particular – chickpeas and sunflowers. Simultaneously, the technology of growing these crops is quite energy-consuming, especially under irrigation conditions. Therefore, research on the impact of micro-irrigation system designs on the energy parameters of chickpea and sunflower cultivation is relevant. The purpose of the scientific work is to perform an energy assessment of chickpea and sunflower cultivation depending on the construction of micro-irrigation systems and the method of water supply. Research methods: short-term field experiments, and analytical and statistical methods for processing experimental data. The scheme of field experiments provided for various options for laying irrigation pipelines (IP) of micro-irrigation systems (in the horizontal and vertical planes) and the implementation of a pulsed water supply mode (standard). The control was the variant without irrigation. Based on the results of experimental studies, it was found that the method of laying irrigation pipelines (the design of micro-irrigation systems) reliably affects the yield of field crops. Thus, a higher yield was recorded with a shorter distances between the IP (0,7 and 1,0 m), regardless of the depth of the pipelines. It has been proven, that the higher yield level of both chickpeas (4,28 t/ha) and sunflower (4,50 t/ha) was obtained when implementing the pulse water supply mode, however, such an increase was within the error of the field experiment. At the same time, the introduction of subsoil drip irrigation is more appropriate than the cultivation of chickpeas and sunflowers in terms of the total energy costs of the technology. An analysis of energy efficiency in terms of the energy efficiency coefficient (EEC) indicates a high level of energy efficiency in chickpea and sunflower cultivation under both surface and subsurface drip irrigation (EEC = 2,03-2,23 and 2,32-2,50, respectively). The most effective was the cultivation of these crops with a pulsed water supply: EEC was 2,44 for growing of chickpeas and 2,61 for growing of sunflowers. The research materials are of practical value for farmers in the matter of energy management in chickpea and sunflower micro-irrigation technologies.

Мета. Вивчення впливу конструкцій систем мікрозрошення та способу водоподачі на ростові процеси і продуктивність рослин нуту і соняшнику. Методи. Короткотерміновий польовий дослід, аналітичні і статистичні методи обробки експериментальних даних. Результати досліджень. Сучасні способи мікрозрошення розглянуто як ключовий фактор інтенсифікації технологій вирощування нуту і соняшнику у ланці сівозміни. Польові експериментальні дослідження проведено на землях Брилівського дослідного поля ІВПіМ НААН протягом 2020-2022 рр. Отримані результати підтверджують, що конструкції систем мікрозрошення та спосіб водоподачі достовірно впливають на формування основних біометричних параметрів, структурні елементи врожаю та врожайність нуту і соняшнику. Встановлено, що максимальні параметри ростових процесів та продуктивність культур забезпечує імпульсний режим водоподачі з внутрішньоґрунтовим укладанням поливних трубопроводів. Достовірно нижчі та близькі за значеннями показники визначено для умов підґрунтового краплинного зрошення та краплинного зрошення із наземним укладанням поливних трубопроводів, а найнижчі параметри продуктивності отримано в умовах природнього зволоження. Врожайність нуту за краплинного зрошення отримано на рівні 3,76-4,17 т/га, за підґрунтового укладання поливних трубопроводів – 3,69-4,00 т/га, за реалізації імпульсного режиму водоподачі – 4,28 т/га. За вирощування соняшнику в умовах краплинного зрошення отримано врожайність 3,91-4,41 т/га, за підґрунтового укладання поливних трубопроводів – 3,69-4,09 т/га, за реалізації імпульсного режиму водоподачі – 4,28 т/га На варіанті контролю (без зрошення) у середньому за три роки отримано найнижчий рівень врожайності – 1,63 т/га нуту та 1,66 т/га соняшнику, що підтверджує значні ризики за вирощування цих культур в умовах Степу без зрошення. Висновки. За результатами досліджень визначено особливості формування основних біометричних параметрів та продуктивності рослин нуту і соняшнику залежно від конструкцій систем мікрозрошення та способу водоподачі. Найбільш доцільним за вирощування цих культур у ланці сівозміни є впровадження підґрунтового краплинного зрошення та реалізація імпульсного режиму водоподачі.

The purpose of the research was to improve and substantiate the parameters of the drip irrigation regimes for crops in the Steppe of Ukraine. Field studies were carried out at the Kamyansko-Dniprovska experimental station (47046' N 34042' E), the Brylivska experimental station (46040' N 33012' E) and the Southern research station (46033' N 33059' E) from 2004 to 2021 on 11 crops. The research scheme assumed the implementation of a one-factor experiments’ series with different levels of soil humidification, the control was the variant without irrigation. At the first stage, the mathematical dependencies "Soil moisture level (SML) –Number of vegetation irrigations" and "SML–Irrigation rate" were obtained for all crops. The establishment of correlations between the evapotranspiration of crops and their productivity is the result of the work. Based on this, were built the dependencies (statistical models) "Evapotranspiration–Productivity" and the most optimal options for using water were determined in terms of its costs for the formation of products for the drip irrigation of the Steppe of Ukraine. The given dependencies are reaction curves for a one-factor experiment, they consist of three areas: limiting, stationary and excessive. Correlation coefficients r=0,92-0,98 indicate a close relationship between these parameters. Established relationships "Evapotranspiration–Yield" from an agro biological point of view are not stable since there are potential opportunities for increasing yields with the same evapotranspiration. It has been established that the optimal moisture range for drip irrigation of most crops is a narrow range of soil moisture suction pressure of -9 to -15 kPa. This involves irrigation with small rates (50-75 m3/ha) while reducing the inter-irrigation periods. Under such conditions, the ratio of actual transpiration (Тс) to potential (То) approaches 1 (≈ 0,83-0,87), which characterizes the water supply of plants as close to optimal.

The accuracy of calculation methods for determining the evapotranspiration (ET) of corn for grain under drip irrigation in the steppe of Ukraine was established. A comprehensive assessment of calculation methods for soil optimal water regime formation during different growth phases of maize plants was carried out. The accuracy of the estimated value of evapotranspiration was determined by the mean absolute percentage error (MAPE). It has been proven that the use of calculation methods without taking into account the climatic conditions of Southern Ukraine leads to a significant error in determining the actual evapotranspiration. By the Penman-Monteith method, the MAPE of 16.3-26.9% corresponds to the good and satisfactory accuracy of the chosen calculation model. Using the methods of A.M. and S.M. Alpatyev as well as D.A. Stoyko the MAPE increased to 22.2-39.7% and 20.8-29.1%, respectively, which proved their satisfactory accuracy. The calculation method of M.M. Ivanov ensured the MAPE of 48,7-76,8%; that is unsatisfactory calculation accuracy. Adapted crop coefficients Kc for the conditions of the South of Ukraine increased the accuracy of calculating ET by the Penman-Monteith method by an average of 2,2 times, D.A. Shtoyko and A.M. and S.M. Alpatiev by 1,9 and 2,2 times, and M.M. Ivanov by 4,4 times. An analysis of the MAPE using various calculation methods for determining the evapotranspiration of corn for grain under drip irrigation showed that the Penman-Monteith method provides the smallest error (MAPE = 9.1%), which corresponds to high prediction accuracy. In a wet year, the accuracy of ET determination decreases by all methods, which indicates an increase in the MAPE: by Penman-Monteith and D.A. Shtoyko - up to 11.9% and 18.7%, respectively, and the determination accuracy decreases to category “good”. When calculating using the methods of A.M. and S.M. Alpatiev and M.M. Ivanov the MAPE increased to 23,3% and 21,5%, respectively, and the accuracy of ET determination was satisfactory.

The article presents the results of experimental studies on the effect of micro-irrigation methods (drip irrigation with the surface laying of irrigation pipelines (IP) and subsoil drip irrigation with laying of IP at a depth of 30 cm) on the species and quantitative composition of weeds. The variant with a natural moisture supply (without irrigation) served as a reference area. Field research was conducted in the period 2020-2021 on the lands of the Brylivs’ke experimental field of the Institute of Water Problems and Land Reclamation of NAAS (Dry Steppe subzone) in sunflower and chickpea crops. Monitoring of the number and species composition of weeds was carried out by applying the recording framework by the method of the Institute of Plant Protection of NAAS during the third decade of May and the third decade of August. Based on the results of experimental research, it was proved that the irrigation methods (and hence the conditions of moisture supply) reliably influenced the degree of weed development in sunflower and chickpea crops. It was specified that the implementation of subsoil drip irrigation on average over the years of research reduced the degree of weed development in sunflower and chickpea crops by 1,65 and 1,55 times, respectively, compared to the typical surface laying of drip irrigation pipelines. Ultimately, that reduced the pesticide load on the field agro-ecosystem by reducing the number of herbicide treatments of crops by an average of 33-50 %. The species composition of weeds was not significantly affected by the method of irrigation. In addition, the researchers have shown that, regardless of the irrigation method, weed development in crops significantly reduced the productivity of the investigated crops: sunflower by 18,0-21,2 % and chickpea by 27,9-29,7 %. At the same time, in non-irrigated conditions, the degree of weed development had a greater impact on crop yield; thus, yield reduction in the reference variant without irrigation was 24,6 % for sunflower and 30,0 % for chickpeas.