FIELD: agriculture.SUBSTANCE: invention relates to the field of agriculture. Aqueous samples are produced in the process that are extracted from a plurality of suction tubes placed at different depths in the soil substrate, including the operation zone of the root system of the plants in the soil substrate. Specified water samples are analyzed to determine the chemical composition of the water samples of the soil substrate. Moreover, this chemical composition includes the concentration of one or more marker ion in the said operation area of the root system. The efficiency of the nutrient use is determined with these types of plants, at least partially on the basis of the indicated concentrations of marker ions. The amount of additive to the irrigation water supplied to the soil substrate for adjusting the chemical composition of the soil substrate at least partially based on the determined efficiency of use of nutrients by these plants, is determined. In the method a suction tube is installed at the depth in the soil substrate. Hydraulic conductivity of aqueous solutions of the soil substrate is provided to the suction tube by applying a vacuum to the said suction tube. The aqueous sample is extracted from the suction tube after the application of vacuum for a certain period of time. The aqueous sample is analyzes to determine its chemical composition. The concentration of marker ions is determined at the depth of the soil substrate on the basis of the chemical composition of the said aqueous sample. The presence of soil leaching is determined, at least partially on the basis of the said marker ion concentrations at the depth below the surface.EFFECT: invention allows to improve the quality of the manufactured products and the losses due to soil leaching.23 cl, 7 dwg, 7 tblИзобретения относятся к области сельского хозяйства. В способе получают водные пробы, извлекаемые из множества всасывающих зондов, размещенных на различных глубинах в почвенном субстрате, включая
