Agrogenic transformation of the properties of irrigated chornozems and measures to preserve their fertility

Abstract

Goal. To study the orientation of agrogenic transformation of the properties of chornozems (typical and ordinary) at prolonged irrigation with water suitable and unsuitable for agronomic and environmental criteria, and to develop measures to increase their fertility. Methods. Field — for monitoring studies; remote sensing of the Earth — to assess the impact of hostilities on the state of soils of both types; laboratory analytical — to determine the chemical composition of water and indicators of soil properties; analysis — to determine the direction of agrogenic transformation of soil properties. Results. The prolonged irrigation contributed to the activation of salt processes and changes in the qualitative composition of chornozems (typical and ordinary), manifested in reducing the Ca/Na value from 5.43–4.14:1 to 2.50–1.42:1 (irrigation with suitable water) and from 5.20–2.1:1 to 0.53–0.64:1 (irrigation with unsuitable water). The typical chornozem of vegetable and fodder crop rotation, with controlled irrigation with suitable water and the use of agricultural reclamation measures, developed mainly according to the quasi-equilibrium vector. There was a gradual increase in the content of humus in the soil, an increase in Sha/Sfa (the ratio of the amount of humic acids to fulvic acids in humus) to 3.58–3.75 (soil layer — 0–30 cm), an increase in the content of agronomically valuable aggregates to 83.0–87.9%, especially in versions with organic, organic-mineral, biological systems. For long-term irrigation with unusable water, salting and contamination with heavy metals were significant. In ordinary chornozem, the content of mobile compounds of lead, cadmium, nickel, and chromium exceeded the background by 4–10 times. Conclusions. The degree of agrogenic transformation and vectors for the development of salt processes, the composition of exchange cations, the content of humus, the structural and aggregate composition, the density of the composition, and the pollution of soils of both types during prolonged irrigation were determined. Assessment of damage and identification of manifestations of mechanical and physical degradation of ordinary chornozem during combat operations were carried out. Priority measures to preserve and increase the fertility of irrigated chornozem were outlined.