ТРАНСФОРМАЦИЯ ЧЕРНОЗЕМА ОБЫКНОВЕННОГО ПРИ ДЛИТЕЛЬНОМ ОРОШЕНИИ СЛАБОМИНЕРАЛИЗОВАННОЙ ВОДОЙ СУЛЬФАТНО-НАТРИЕВОГО СОСТАВА

Abstract

Purpose: to determine the impact of low-mineralized sulfate-sodium water on ordinary chernozem properties in the Miusskaya irrigation system under various conditions of land reclamation. Materials and methods. The studies were carried out in Neklinovsky district Rostov region on ordinary chernozems. Three plots have been selected: non-irrigated, irrigated grain fodder crop rotation with annual irrigation rates of 1500–2500 m³/ha and irrigated vegetable crop rotation with annual irrigation rates of 3000–4000 m³/ha. Irrigation of these crop rotations has been carried out for more than 20 years. Irrigation source is the Miussky liman. Soil samples were taken in autumn, and the composition of water-soluble salts, pH of water extract, absorbed bases, aggregate water resistance, and humus were determined in them. The selection of soil samples, their analysis and evaluation were carried out according to generally accepted methods. Results. Long-term irrigation with low-mineralized (1.3–1.7 g/dm³) sulfate-sodium water adversely affects the ordinary chernozem properties (the chemistry of salinity from sulfate transforms into chloride-sulfate). According to the degree of salinity, chernozems remain non-saline, but the amount of salts increases by almost 2 times over the entire soil profile due to their washing deep into the autumn-winter precipitation. Non salt soils are transformed into solonetsous ones with varying degrees of absorbed sodium content in the 0–60 cm layer: 5 % (grain forage crop rotation) and 7–12 % of the total soil absorption complex (vegetable crop rotation). Calcium loss in the 0–60 cm layer is from 14 to 18–22 %, respectively. Conclusions. The alkalinity of chernozem, which occurs during long-term irrigation with low-mineralized sulfate-sodium water, generally affects soil fertility. This is evidenced by the close relationship between humus and the amount of exchangeable sodium in soil (R² = 0.84), between the aggregate water resistance and the amount of exchangeable sodium in soil (R² = 0.89).