Activity of Extracellular Enzymes Hydrolyzing the Carbohydrates in Irrigated Soil

Abstract

The irrigated lands of Uzbekistan in semiarid zone with low humus content (0.8-0.5% Ctot) are subjected to risk of dehumification. Abundance of microbes provides the high enzymatic mineralization of soil organic matter (SOM) and nutrients which are contained in it. The use of mineral fertilizers in irrigated soils contributes repeatedly increases of microbial growth rate, metabolism, respiration, energy, etc., and brings to the regrouping of microbe communities and their enzyme status. Therefore, all new agricultural chemicals should be tested for their impact on soil biological activity. For agriculture the chemicals or fertilizers, which have no significant stimulating effect on the soil hydrolytic enzymes are more preferable. The purpose of our studies was to investigate the new phosphorus fertilizer’s effect on activity of carbohydrate enzymes in typical sierozem under cotton. During 3-year field experiment three types of phosphorous fertilizers - bacterial (PhBF), organic (OMF) and mineral (MF) were studied. We compared the impact of these fertilizers on the four extracellular carbohydrate enzymes: cellulase (Cel), xylanase (Xyl), chitinase (Chit) and glucosidase (Glu). The results have shown that application of the such new fertilizers as PhBF, OMF and MF leads to decrease in activity of carbohydrates enzymes (from slight to strong effect) and to possible positive C- balance under the regular use of fertilizers.