In the article presented the features of application and adaptation of the calculation method for determination of evapotranspiration Penman–Monteith. With the purpose of effective use of this method in the practice of a drip irrigation in the steppe zone of Ukraine, on the base of the field’s experiments results were conducted correlation of Kc with a taking into account deviations from standard conditions (on the example of grain corn).

Microirrigation is by far the most progressive irrigation method, with efficiencies reaching 92-98 %. According to the International Commission on Irrigation and Drainage, the world's agricultural land, which is irrigated through micro-irrigation systems, is constantly growing and now stands at over 20 million hectares. By the "Irrigation and drainage strategy in Ukraine until 2030" micro-irrigation methods are defined as one of the strategic directions of the state policy of the branch. Research on the direction of "micro-irrigation of crops" in Ukraine began from the late 60's of the last century. The historical aspect of the development of research in this area is thoroughly covered in previous scientific papers. Therefore, the purpose of this study is a comprehensive analysis of the basic fundamental and applied results of research of the scientific school on micro irrigation IWPaLR NAAS in the early XXI century and substantiation of perspective directions of their development. Using theoretical methods of scientific research (analysis and synthesis, comparison, classification and generalization), the authors systematized the most significant scientific results in terms of normative, methodological, technical and technological components. The list of normative and methodological documents prepared by IWPaLR NAAS in the direction of microirrigation is given. The results of developments in the technological component are detailed according to the research objects: water regime and processes of water consumption of crops, fertigation, pestigation, the influence of local moistening, fertilizers and water of different quality on the soil-plant-technical means of irrigation system, the formation of soil moisture zones, methods of appointment timing of vegetation irrigation and irrigation management systems. The key scientific results of the irrigation facilities’ testing laboratory are highlighted. The list of developed and implemented by the IWPaLR NAAS technical means of microirrigation systems is given. The strategic directions of further scientific research are substantiated, which should meet the global trend for environmentally friendly irrigation, as well as resource and energy conservation. The need of Ukraine in the systems of microirrigation of agricultural crops for the period up to 2030, the role of current and future developments of the scientific school of micro irrigation IWPaLR NAAS on their implementation are determined.

The purpose. To study features and to adapt rated method of determination of total evaporation «PenmanMonteith» for conditions of drip irrigation of Steppe of Ukraine. Methods. Field short-term experiments, conventional analytical research techniques; dispersion, correlation, regression and variation analysis. Results. With the use of modern tooling (Internet-meteorological station iMetos®, station of soil moisture iMetos® SM/ECHO/TNS/ECOD2) they determined specific benchmark ETo, rated and actual values of total evaporation ETc. On the basis of results of field experiment they adjusted quotient of crop Kc according to phases of growth of plants of corn with the use of deflexions from reference conditions. Conclusions. It is fixed that value of actual quotient of crop Kc for grain corn in conditions of drip irrigation of Steppe of Ukraine differs from standard Kc (FAO). Considering precise correlation between Kc (FАО) and Kc (cor.) for determination of actual evapotranspiration (ETc) of plants of corn they recommend to use corrected values of Kc.Key words: evapotranspiration, quotient of crop, irrigation requirement, drip irrigation, corn for grain. Problem statement and literature reviewThe biological basis of irrigation's mode is a total water consumption of plants or evapotranspiration (ETc). Under the ET S we understand the total volume of water that evaporates during the vegetative period by plants and soil surface (physical evaporation -K e ) infiltrate into the lower soil's horizons and spends by plants on transpiration (K cb ).Determining factors that influence the value of the ETc are the climate of zone and weather conditions of current or calculated growing season of their cultivation.Determination of agricultural crops' water consumption is a key issue from the solution of which depends the values of irrigation's rates, efficiency and ecological consequences of irrigation.In the practice of irrigated agriculture water consumption is calculated using different methods: by the data of special experiments, by the coefficients of transpiration and water consumption, on the base of water balance's equations and so on.At present there are many methods by which evapotranspiration has determined on the basis of meteorological parameters and biological characteristics of agricultural crops. At the irrigated conditions of the Steppe zone of Ukraine at different times practically applicated the following methods: bioclimatic method of A.M. Alpatyeva (1954) [1], and later it was improved by S.M. Alpatyev (1965) [2] and V.P. Ostapchykom (1989) In the world for a long time been widespread methods of Penman (1956) [6] and Blaney-Criddle (1950) [7]. Taking into account a certain inexactness of these methods in the 1990 council of experts in FAO had recommended approving of the combined method of «Penman-Monteith» as the standard for calculation of an etalon total evapotranspiration (ETo).The method predicts determination of ETo of a hypothetical culture with a height of 0,12 m, the surface resistance of 70 cm ...

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.

No abstract