Agromeliorative assessment of the conditions of the dark-chestnut soil in the seven-field crop rotation at different fertilization systems under irrigation with mineralized water

Abstract

Purpose. Studying agromeliorative conditions of the irrigated dark-chestnut soil in the seven-field crop rotation in the zone of the Ingulets irrigation system at different fertilization systems for the development of measures for soil fertility preservation and degradation prevention in the context of climate change. Methods. Field and laboratorian trials as well as calculation of the data were carried out with accordance to current requirements and standards of scientific research in agronomy and agriculture. Water and soil samples were analyzed with accordance to current standards of agrochemical and meliorative analysis. Results. The water of the Ingulets irrigation system for the whole period of the study (2006-2020) belonged to the second class of the quality by agronomical criteria. Prolonged irrigation with such a water with increased sodium content resulted in degradation processes, namely: salt content increased in arable and meter soil layers, especially at the expense of toxic ones –1.4-1.8 times in arable, and 1.2-1.6 times in meter layer; inversion of calcium-sodium relationship in the soil was observed because of replacement of calcium with sodium in the soil absorbing complex; chemical content of the soil solution of the dark-chestnut soil changed because of prolonged irrigation with the Ingulets irrigation water from hydro carbonate-sulphate sodium-calcium type to hydro carbonate-sulphate calcium-sodium type; 50-year period of the mineralized water impact resulted in the decrease in agronomically valuable aggregates, increase in the clogging by 3.99%, and decrease in the coefficient of structure from 1.80 to 1.34. Conclusions. Prolonged irrigation with the mineralized water of the Ingulets irrigation system with unfavorable cation-anion content significantly affected on the agromeliorative conditions of the dark-chestnut soil in the seven-field irrigated crop rotation that is evident through degradation processes of secondary salinization, accumulation of toxic salts in the soil, increased risks of alkalization and deterioration of structure and physicmechanical soil properties of the soil. Fertilization system had no significant impact on the studied soil parameters.