Agrogenic changes in the physicochemical properties and health of chornozem soils under the long-term influence of irrigation

Abstract

Goal. To assess the long-term impact of irrigation using water of different quality on indicators of salt composition, the composition of exchangeable cations of the soil absorption complex as indicators of the health of chornozem soils for sustainable management of their quality and fertility. Methods. Field — for conducting long-term research in a field experiment; laboratory-analytical — for determination of the chemical composition of irrigation water, the salt composition of the soil, the composition of exchangeable cations of the soil absorbing complex (SAC); analysis, theoretical generalization, synthesis — for assessing the long-term impact of irrigation on the properties of irrigated soils depending on the quality of irrigation water, analyzing time trends in changes in the content of water-soluble salts in the studied soils; statistical — for variance analysis using the STATISTICA software. The research was conducted at 2 stationary facilities located in different soil-climatic zones (Forest Steppe and Steppe) and differing in the level of anthropogenic load. Results. Based on the analysis of long-term trends in the content of water-soluble salts and exchangeable cations in irrigated chornozems (typical and ordinary) at the use of suitable and unsuitable water for irrigation, it was established that with an increase in the duration of irrigation, further gradual transformation of the composition of water-soluble salts and the composition of the soil absorption complex, the degree of which was determined by the chemical composition of irrigation water, irrigation standards, duration of irrigation, and farming culture. During irrigation with fresh water of the 1st quality class, the total content and content of toxic salts did not change, but there was a transformation of the composition of salts. The water-soluble Ca:Na ratio in the 0–50 cm soil profile decreased from 5.43–4.14:1 to 2.50–1.42:1. When irrigating ordinary chornozem with mineralized unsuitable water, the changes in the values of this indicator were more significant (from 5.20–2.61:1 to 0.55–0.71:1), which indicated a degradation transformation of soil properties. Conclusions. It was found that with the increase in the irrigation period, the trends were preserved regarding changes in the salt composition and the composition of exchangeable cations of ordinary and typical chernozems, which were determined by the quality of irrigation water, the irrigation period, the level of application of chemical soil reclamation measures, and the culture of agriculture. The degree of agrogenic transformation of the salt composition and the composition of exchangeable cations during long-term systematic irrigation using fresh and mineralized water was determined. It was proven that one of the informative indicators of the health of irrigated soil was the degree of salinity and salinity, which determined its quality, fertility, and the performance of ecosystem services and functions.