Influence of nitrogen fertilizers and reserves of soil mobile phosphorus on soybean productivity in the conditions of the forest-steppe of the Southern Trans-Urals

Abstract. The purpose is to study the effect of nitrogen fertilizers on the yield and quality of soybean grain in the conditions of the forest-steppe of the Southern Trans-Urals. Methods. The object of the study is the early-ripening soybean variety Cheremshanka of the Omsk Agrarian Scientific Centre zoned in the Ural region. The studies were carried out in a stationary experiment included in the register of long-term experiments of the Geonetwork of the Russian Federation. Soybean was cultivated in a grain-grass crop rotation, the predecessor was winter rye. Nitrogen fertilizers are spread into the soil for pre-sowing cultivation. Factorial scheme of experience – 0, N1, N2, N3, P1, P2, P3, all combinations (4 × 4). Doses of fertilizers in the crop rotation for soybeans and peas – N20–60. The effectiveness of nitrogen fertilizers was studied against the background of the aftereffect of phosphorus fertilizers. The spatial implementation of the scheme was carried out in two blocks. The repetition of the fields is fourfold. The total area of an elementary plot is 240 m2, the accounting area is 114 m2. The following methods were used in the studies: common humus according to Tyurin; the sum of absorbed bases according to Kappen – Gelkovitz; pH potentiometrically; mobile phosphorus and exchangeable potassium according to Chirikov; protein in grains of peas and soybeans according to Kjeldahl; fat by the Soxhlet method. Results. Studies have established that soybeans in crop rotation are not inferior to peas in terms of productivity, and due to the oil yield, the soybean rotation even surpasses the similar crop rotation with peas. The protein content in soybean seeds increases with an increase in the dose of nitrogen fertilizer, while the fat content decreases. Scientific novelty. The responsiveness of soybeans to the doses of nitrogen fertilizers against the background of different availability of mobile phosphorus in the soil in the conditions of the forest-steppe of the Southern Trans-Urals was revealed.