Keywords: water balance soil, biothermal coefficients, evapotranspiration, field experiment error, standard deviations

// Мелиорация.– 2021. – №1(95) – P 5–18

Plant water consumption depends on soil and climatic conditions and culture physiology and, as an element of water balance, includes plant transpiration and evaporation from the soil surface. Water consumption is difficult to measure, so it is usually calculated using indirect indexes.
The most accurate as indicated by numerous research, is the bioclimatic method for calculating water consumption, when calculations are based on a rather stable correlation of moisture consumption on an agricultural field with one of the meteorological indicators, for example, with a deficit of air humidity, daily average or maximum air temperature. In this regard, the biological component is taken into account through the so-called bioclimatic (biothermal) coefficients. In our calculations, plant water consumption was linked to the maximum air temperature per day, using biothermal coefficients. Comparative analysis of measured in the field and calculated soil moisture reserves showed that the accuracy of calculating the soil water balance to a great extent depends on the method of establishing the biothermal coefficients of water consumption of crops.