Agrogenic transformation of the common black soil under long-term irrigation with mineralized waters

Abstract

We studied the influence of irrigation with saline water on the properties of ordinary chernozem depending on the duration of irrigation. An increase of the degree of adverse changes in the physical, physical-chemical, chemical and biological properties of the soil accordingly increasing duration of irrigation is shown. The processes of salinization, alkalinization and soil compaction enhance mineralogy and grain size distribution of soil changes. Irrigation with saline water for 20 years has led to an increase in the total content of water-soluble salts in soil’s layer 0–25 cm from 0.07% to 0.14%. After 50 years of irrigation salts concentration increased to 0.23%. Density of subsoil increased from 1.23 g/cm3 to 1.43 g/cm3 . Long-term irrigation with saline water has adverse effect not only on chemical and physical properties of ordinary chernozem but also on the size and functioning of the soil microbial cenosis and soil enzymatic activity. Irrigation with saline water for 20 years in the vegetable and fodder crop rotation resulted in a decrease in the number of microorganisms by 16–37 %, irrigation for a period of 50 years has reduced the number of microorganisms belonging to main ecological and functional groups by 26–47%.