CHANGE OF SOIL PROPERTIES OF COMPLEX COVER OF SEMI-DESERT ZONE INFLUENCED BY IRRIGATION

Abstract

Purpose: to determine a change in the soil properties of a complex cover influenced by irrigation for developing the appropriate measures to prevent their further degradation. Materials and methods. The object of research is brown semi-desert soils in combination with solonetzes located in the region of the Caspian lowland. Soil samples and data assessment analysis was carried out according to generally accepted methods. Mathematical data processing was carried out according to B. A. Dospekhov. Results. Irrigation carried out regularly with fresh water for 6 years with an average irrigation rate of about 5400 cubic meters per hectare contributed to the leaching of water-soluble salts in the soil layer of a complex cover of 0–40 cm. The decrease in the total salt content in this layer was 13 %, in solonetzes – 46 %, and in the layer of 40–60 cm, on the contrary, their accumulation is observed in the amount of 9 and 18 %, respectively. At the same time irrigation with water of class II by hazard degree of sodium alkalinity increased the content of exchangeable sodium and magnesium in the soil adsorption complex in the 0–40 cm layer of brown soils by 50 and 26 %, respectively, and in solonetzes by 60 and 21 % (in the meter layer, respectively, 25 and 9; 25 and 11 %). The number of water-resistant aggregates in the layer of 0–40 cm in both soils decreased by 20 %, and the soils became denser. As a result, water permeability from brown soils surface decreased by 33 % and in solonetzes – by 27 %. The humus content in the 0–40 cm layer of brown soils decreased by 10 % and on solonetzes – by 20 % of the initial content. After 6 years of irrigation, its amount was 90 and 80 %, respectively, which indicates the presence of weak and medium dehumification. Conclusions. The detected changes in properties of the soils studied indicate the need for chemical reclamation, which eliminates the salinity and compaction as well as the development of appropriate measures that contribute to the humus accumulation.

Keywords

• soil properties
• complex cover
• brown semi-desert soils
• irrigation
• land reclamation