Sardak A. Justification of the parameters of the subsurface drip irrigation system

In the dissertation, the task of parameters justification of the subsurface drip irrigation system (SSDI), namely the depth of the irrigation pipeline (IP) and the distance between them, is solved. Field research was carried out at research sites during 2018-2021, located on the lands of the State Enterprise "Experimental Farm "Brylivske" IWPLR NAAS in the Pryvitne village of Kherson district of the Kherson region and the State Enterprise "Experimental Farm "Velyki Klyny" IWPLR NAAS in the Velykyi Klyn village of Skadovsk district of the Kherson region. Laboratory studies were conducted to determine the water-physical parameters and characteristics of the main granulometric composition of the soils of Ukraine. Mathematical modeling of the substantiation of the main design parameters of the SSDI was carried out by solving the boundary value problem of moisture transfer based on the two-dimensional Richards equation in terms of pressures using experimentally determined hydrophysical parameters of the main granulometric composition of the soils of Ukraine. The scientific novelty of the obtained results. The dissertation is completed personal scientific research, in which, based on experimental studies and mathematical modeling of the patterns of soil wetting zones formation, the scientific and practical task of determining the design parameters and water supply regime at the SSDI was solved. According to the results of scientific research, for the first time: regularities of the formation of soil moistening zones using subsurface drip irrigation systems for soils of Ukraine of different granulometric composition, depending on the structural parameters of the system (depth of irrigation pipelines, distances between them, flow rates of drip water discharges) were determined by methods of mathematical modeling of moisture transfer; the influence of the structural parameters of the subsurface drip irrigation system, namely the depth of the irrigation pipeline (IP) placement and the distance between them, on the patterns of growth, development, and formation of the corn on soils of light mechanical composition was determined; a method of determining the main structural parameters of the subsurface drip irrigation system and forming the water supply regime based on the solution of the optimization problem of moisture transfer in the soils of the aeration zone was developed. Improved the method of determining the lowest moisture content of soils. Received further development: the method of determining the range of optimal moisture supply using the main hydrophysical characteristics of soils; assessment of the economic efficiency of the use of subsurface drip irrigation systems depending on the period of operation. Practical significance of the obtained results. The method of determining the main structural parameters of subsurface drip irrigation systems makes it possible to create subsurface drip irrigation systems adapted to soil conditions, the use of which makes it possible to form scientifically based regimes of soil moistening and obtain crop yields close to their potential. The method of the water supply regime allows for the formation of an irrigation regime, the implementation of which during the operation of the SSDI ensures the minimization of irrigation water consumption for infiltration. The methods of determining the lowest soil moisture capacity and the optimal range of soil moisture supply make it possible to determine the maximum permissible irrigation rates when forming irrigation regimes, the use of which completely excludes or reduces to a minimum the selection of irrigation water for infiltration.