Optimization of nitrogen fertilizer of the dark-gray soldized soil of the western forest steppe for using nitrification inhibitor

Abstract

Nitrogen is a key element for the growth and yield of all crops. Increased doses of nitrogen do not give the expected return, create a danger of leaching of nitrates, activate the emission of nitrous oxide. These problems make it necessary to solve the urgent issue of optimizing nitrogen nutrition using the nitrogen stabilizer nitrapyrin. The purpose of our research under conditions of sufficient moisture in the Western Forest Steppe was to find out the effect of the urease inhibitor on the agrochemical parameters of the dark gray forest podzolized light loam soil, as well as the effect on the yield of winter barley. We conducted field experiments at the Lviv National University of Nature Management. We used traditional methods of field research and standardized methods of laboratory analysis. A positive effect of the use of the nitrogen stabilizer nitrapyrin on the funds of nitrogen, phosphorus and potassium available for nutrition, as well as on the reduction of soil acidity, was established. The highest content of easily hydrolyzable nitrogen was achieved when applying N23P60K60 in autumn + N97 in the phase of vegetation recovery with nitrapyrin – 132 mg/kg of soil. This was 28 mg/kg more than the traditional fertilization system without nitrapyrin (N60P60K60). Application of 120 kg/ha of nitrogen in the form of urea created a reserve 3.3 times higher, and ammonium nitrate created a reserve 3.6 times higher than the unfertilized version. Nitrapyrin, a stabilizer of nitrates, made it possible to limit their formation with the introduction of urea by 3 5%, ammonium nitrate by 10 %. The nitrogen application rate of N120 kg/ha per year led to the annual emission of nitrous oxide in the amount of 121.5 kg/ha. Nitrapyrin limited the amount of nitrous oxide emission by 3.3–7.2 kg/ha, depending on the amount of nitrogen application rate. The use of ammonium nitrate at the rate of N120 when applied in the spring caused the highest level of nitrogen oxide emissions (29.5 kg/ha of soil). However, the application of this fertilizer and inhibitor reduced gaseous nitrogen losses to 25.9 kg/ha when applied to restore vegetation. The introduction of N97 (ammonium nitrate) + N-Lok Max under winter barley during the restoration of vegetation on the background of N23P60K60 under plowing gave the highest average yield in the experiment for 2020–2022 – 7.65 t/ha, for 2022 – 7.90 t/ha. The 3D regression model of winter barley grain yield under the influence of the synergistic effect of both forms of nitrogen illustrates the importance of balancing the funds of forms of this nutrient element in the soil.