Energy efficiency of growing crops under different fertilizer systems on gray forest soil

Goal. To conduct a bioenergetic assessment of crop fertilizer systems on gray forest soil under the conditions of a stationary experiment. Methods. General scientific (field, morphogenetic, comparative analytical, agro-analytical, laboratory) and special methods (methodology of bioenergetic assessment of farming systems according to Yu.O. Tarariko) were used. Results. It was established that the long-term use of mineral fertilizers with limestone ameliorants as a background on the gray forest soil contributed to a significant increase in the content of humus in the arable layer. The agronomic and energy efficiency of growing crops in the chain of crop rotation was determined, and the energy content of the main and secondary products, anthropogenic energy costs, the energy potential of organic matter of the arable layer as well as the indicator of biological energy accumulation were calculated. Conclusions. Among the fertilizer options, the highest content of humus in the arable layer — 1.21% — ensured the application of a double dose of mineral fertilizer while neutralizing excessive acidity. Calculations of the energy potential of the organic matter of the arable layer of the gray forest soil showed that it was the lowest with the application of a double dose of mineral fertilizer on the background of liming — 752 GJ/ha, and the maximum on the fallow — 1739 GJ/ha, which was approximately 2.5 times more than in the variant of the stationary experiment. The coefficient of energy efficiency in the chain of crop rotation was minimal in the case of application of a single dose of mineral fertilizer — 7.5, on the background of liming with the application of a single or double dose of mineral fertilizer, it reached 8.8, and the maximum value was in the option "siderates + 1.0 Ng of CaCO3" — 9.4. In general, the value of this coefficient significantly depended on the culture of the crop rotation. Its lowest values were observed in the case of growing soybeans — 6.6–7.8; for the cultivation of spring barley, they increased to 9.4–10.0 and reached the maximum values for the cultivation of buckwheat — 9.0–11.2. The lowest values of biological energy accumulation (BEA) were characteristic of options with the introduction of a single dose of mineral fertilizer and siderates on the background of liming — 71–76 GJ/ha, in the case of applying lime and a double dose of mineral fertilizer, they reached a maximum — 170 GJ/ha.