THE REASONS FOR SECONDARY SALINATION OF THE SHIRVAN STEPPE LANDS IN AZERBAIJAN AND MEASURES FOR ITS PREVENTION

Abstract

Purpose: to determine the causes of secondary salinization of irrigated lands for the development of specific measures for its prevention and combating the phenomenon of salinization. Materials and Methods. The processes of salinization and desalinization of the Shirvan steppe soils were studied by salt surveying. At the points of salt surveys soil samples were taken every 20 cm on the layer, which were subjected to complete chemical and granulometric analysis. The formation of top water has been studied by pressures developed in piezometric wells. Results: long-term studies showd that the cause of the soil secondary salinization is the formation of top water under the arable top layer due to the low filtration capacity of soil and unsatisfactory operation of existing collector-drainage networks. The soils of the Shirvan steppe are practically watertight, their filtration coefficient varies from 0.001 to 0.19 m per day, in rare cases, its value reaches 2.5 m per day. During irrigation and heavy rainfall, water seeps freely under the arable layer and due to the low filtration ability of the lower horizons of the soil, a top water forms there. Under a hot climate conditions (in the Shirvan steppe the air temperature reaches 47 °C), a high evaporation of the top water occurs, as a result of which salts dissolved in water accumulate in the upper layer of the soil, and thereby secondary salinization of the land occurs. It has been determined that the soil salt regime and the crops productivity are interconnected, so, with an increase in the salt soil content the yield of crops decreases, and with a decrease in the soil salinity the yield increases. Conclusions: to prevent secondary salinization of soil and to combat it, a complex of land reclamation measures is required: deep plowing, installation of mole drains with further topwater withdrawal and performing water-charging irrigation in autumn-winter period.

Keywords

• soil
• secondary salinization
• topwater
• filtration capacity
• collector-drainage network
• prevention
• measure