OPTIMIZATION OF NITROGEN MINERAL FERTILIZATION OF AGRICULTURAL CULTURES BY THE PARAMETERS OF THE INTENSITY OF THE NITROGEN FIXATION AND DENITRIFICATION PROCESSES

Abstract

Objective. Investigate the performance of the nitrogen fixation and process of N-N2O loss un-der the cultivation of potatoes and peas on the leached chornozem under various mineral agrarian backgrounds and the use of microbial preparations and to determine the ecological compromise normal rate of mineral nitrogen, under which the emission losses of nitrogen compounds will not exceed the intake of “biological” nitrogen in agrocenoses. Methods. Field experiment, gas chroma-tographic. Results. Studies of the activity of nitrogen fixation and N2O emission in situ in potato and pea agrocenoses using different rates of mineral fertilizers and microbial preparations, with subsequent calculations of the parameters of intake of the “biological” nitrogen and emission loss-es of the element indicate the possibility of determining the conditions (doses of mineral nitrogen) for which equality between profit and non-productive expenditure of the nitrogen balance is achieved. This amount of mineral nitrogen can be considered environmentally permissible, its ex-cess is undesirable due to a decrease in the intake of “biological” nitrogen and increased activity of the denitrification process. For potatoes grown on leached chornozem, environmentally permis-sible nitrogen fertilizer rate should be considered as 80 kg/ha, for peas — 60 kg/ha. The use of mi-crobial preparations in the cultivation of crops promotes an increase in the range of environmen-tally permissible normal rates of mineral nitrogen due to the formation of conditions under which the bacterization of plants require more nitrogen compounds to ensure a constructive metabolism, which additionally to increased nitrogen fixation activity is accompanied by an increase in the level of consumption of mineral nitrogen in the soil. At the same time, the activity of biological denitrifi-cation becomes reduced. Based on the obtained parameters, a model of optimization of nitrogen mineral fertilization of agricultural cultures was developed. Conclusion. It is advisable to deter-mine the ecologically permissible normal rates of mineral nitrogen fertilization of crops by the per-formance indices of the nitrogen fixation process and N-N2O losses. In this case, the emission losses of nitrogen compounds should not exceed the levels of intake of biologically bound nitrogen in ag-rocenoses.