DEVELOPMENT OF MICROORGANISMS AND TRENDS OF BIOLOGICAL PROCESSES IN LEACHED CHORNOZEM UNDER SIMULATION OF DEFICIENCY OF THE FRESH ORGANIC MATTER AND THE INFLUENCE OF MINERAL NITROGEN

Abstract

Objective. Study the peculiarities of the development of microorganisms and trends of biological processes in the soil under the influence of mineral nitrogen under the conditions of simulation of the deficiency of fresh organic matter.
 Methods. Microbiological, agrochemical, gas chromatographic, statistical.
 Results. In the conditions of the vegetative experiment under the simulation of the deficiency of fresh organic matter (preparation of soil in accordance with the method of determining the content of humus) in the leached chornozem, the effect of increasing doses of mineral nitrogen on the dynamics of the number of representatives of certain ecological trophic groups of microorganisms and the course of soil-biological processes that accompany the mineralization of humus was studied. Nitrogen fertilizers, under given conditions, stimulate the development of ammonifiers, microorganisms that mainly utilize mineral compounds of nitrogen, denitrifiers, cellulolytic bacteria, activates biological nitrogen and carbon dioxide emission processes. In this case, the need for carbon to provide metabolic processes of microorganisms can meet only at the expense of destruction of humus compounds. When the fresh organic matter is introduced in the soil in the form of straw chopped to sawdust, as well as under the growth of barley, the activity of biological denitrification is reduced. At the end of the experiment, the content of total carbon in the soil has a clear tendency to decrease with increasing doses of mineral nitrogen – according to the variants: without fertilizers, control – 2.97 %, 13 mg N/kg of soil – 2.91 %, 26 mg N/kg – 2.88 %, 39 mg N/kg – 2.85 %.
 Conclusion. Under the deficiency of fresh organic matter in leached chornozem, the depleted use of mineral nitrogen fertilizers, especially in large quantities, leads to the creation of a situation where microorganisms for the maintenance of metabolic needs use carbon-preservative organic compounds. The use of mineral nitrogen, not coordinated with the required amount of fresh organic matter, leads to the initiation of dehumidification processes. To prevent such effects, environmentally sound fertilizer systems for crops should include systematic entry of fresh organic matter into the soil.