Microbiological activity of irrigated meadow-alluvial soil in Bukhara depending on salinity level

¹ Bukhara State University, Bukhara City, M. Iqbol, 11, 200100, Bukhara, Uzbekistan
² Samarkand State University, Samarkand, Uzbekistan
³ Bukhara State Pedagogical Institute, Bukhara City, Piridastgir, 2, 200100, Uzbekistan

^* Corresponding author: o.r.umarov@buxdu.uz

Abstract

The article is devoted to the study of the effect of salinization of meadow-alluvial soils on the number of taxonomic and physiological groups of microorganisms. When the content of water soluble salts in the meadow-alluvial soil deteriorates the conditions for the reproduction of microorganisms, which is reflected in their numbers. The salt mode of meadow-alluvial soil changes greatly in medium and highly degrees of salinization. Therefore, the number of taxonomic and physiological groups of microorganisms was the smallest in the mean and highly salinization meadow-alluvial soils. On highly saline meadow-alluvial soils, the concentration of the soil solution reaches the greatest indicator that negatively acting on the number of microorganisms. Therefore, on highly saline meadow-alluvial soils, the number of bacteria, mushrooms, actinomycetes, nitrogen fixers, ammonifiers, nitrifers,nitrate reductants and cellulose-decomposing bacteria. The number of microorganisms was influenced by the depth of the horizons. Down the soil profile the number of microorganisms of all groups was significantly reduced in the deepest soil horizon (50-80 cm) was the smallest. This may be due to a decrease in the content of humus and oxygen as it deepens in the soil. The decrease in aerobic microorganisms in this direction was more sharp. The number of taxonomic and physiological groups of microorganisms is significantly affected by the seasons. In irrigated meadow-alluvial soils in the summer in agrocenosis of cotton and other cultures, the number of microorganisms was larger than in spring or autumn. In autumn, the soil salinity is enhanced and achieves the worst state. Therefore, in the middle and strong degrees of salinization in the fall, the number of microorganisms was the smallest.