Total Water Consumption and Evaporation of Winter Wheat in the Irrigation Zone of Southern Ukraine

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 grai