M.T. Kuprichenkov, N.N. Shapovalova, E.P. Shustikova
Stavropol Research Institute on Agriculture of Russian Academy of Agrarian Sciences, Russia, Stavropol region, Shpakovsky district, Mikhaylovsk city, Nikonova Str., 49
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Summary. The long-term annual effect of applying different types and doses of fertilizers on agro-ecological conditions of the upper layer (0 ... 60 cm) of ordinary black soil in central Caucasus region based on the analysis of soil reaction (pH), total content of humus, its mobile part and indicators of enzymatic activity. The studies were performed in 2012-2013 on the basis of the stationary field experiment, established in 1975, where over a period of studying from 630 to 3780 kg-ha of nitrogen and phosphorus were applied in pure form and in background 1800 kg-ha of potassium. Influence of agrochemicals on soil ecosystem was caused by the type of fertilizers. Phosphate fertilizers contributed to the increase in the layer of 0...60 cm amount of organic matter (within 0, 43...0, 65%) and, in 4 – 7 times – invertase activity that ferment is involved in the hydrolysis of complex carbohydrates of plant residues. Applying mineral nitrogen on ordinary black soil had no significant effect on the total content of organic matter, however, along with more intense acidification of topsoil (0,48...0,79 units PH) caused increasing the share of its movable part (up to 17%) and oxidation of organic matter and its potential losses. Nitrogen fertilizers helped to increase by 1,6 times in the layer 0...60 cm urease activity that responsible for the release of ammonia nitrogen by hydrolytic cleavage of urea, and in 1,9-3,2 times in the layer 0...40 cm – phosphatase activity accelerating decomposition of organophosphorus compounds to simple substances. The results showed different influence of the fertilizers on the ecosystem of black soil that allows running the enzymatic activity of the soil by casting of their types.
Keywords: nitrogen, phosphorus, total humus and mobile, catalase, urease, phosphatase, invertase, stabilization, balance.