Present stage of the development of water-economic complex as a part of agricultural sector has rather ambitious objective on creating fundamentally new technologies for utilizing water resources in different technological schemes of agricultural production. Proceeding from the unity of natural transforming processes in the environments (atmosphere, hydrosphere, upper layers of lithosphere) forming water resources (surface and subsurface runoff) in the spatial limits of watershed geo-systems and technological processes of water use and consumption in structural elements of agricultural sector, the conceptual bases for creating nature-looking technical systems “environment – object(s) of activity – human” focused on using water resources in agricultural production, especially for creating complexes of irrigation systems, taking into account the law of diminishing returns, were considered. Water regime in root-inhabited soil layer can be managed and create the opportunity for handling the processes of interrelation and interaction between the consumption of required quantity of water by plants and the technology of conveying water to the active soil layer. The main condition for increasing the efficacy of irrigation water use in systemic understanding is concordance of water regime with the basic factors of vital functions of plants, what is conditioned by the known law of operating factors equivalence and irreplaceability of one by another. The tendency for optimizing water regime in active soil layer as a final water consumer is reached by scientific substantiation of irrigation regimes taking into account the condition of moisturizing soil layer to the depth where the main mass of root system of the given crop is situated. It should be noted that water regime of plants was interrelated systemically with the content of moisture in ambient natural environments: surface layers of atmosphere and soil cover. Changes of water content in natural environments determine the regulating process for water regime of plants at irrigated site.
Keywords: technology, system, principle, nature-technical system, moisture availability, law of diminishing returns, irrigation requirement.
