Elevation of soybean productivity and grain quality due to intensification of nitrogen fixation

Usage of the biopreparations beneficial to symbiotic nitrogen fixation are regarded as an effective and environmentally friendly technology, allowing elevation of the fodder crop yield and quality, and ensuring sustainable and low-energy consuming development of fodder production under the local climatic conditions. During the field trials in the Middle-Russian forest-steppe zone, the yield and grain quality parameters were examined in Mageva, an ultra-early ripening soybean variety, inoculated with Bradiorhizobium japonicum and Glomus intraradices under different levels of mineral N, P, and K. The number and the weight of nodules, the nitrogenase activity, and the N 2-fixation were estimated. A combination of nitrogen fixing and phosphate mobilizing microorganisms, being used with or without P and K fertilizers, was found to elevate the symbiotic activity in soybean plants (the nodulation at 94.5-98.6 %), to increase the nitrogen fixation (up to 115-161 kg/ha) and crop yield, and also to improve the fodder quality. When P and K fertilizers were applied separately from biopreparations, the nodulation made 68.6 % and was higher enough to cause 3-fold nitrogen fixation. When no fertilizer was used, the inoculation with Bradiorhizobium japonicum and Glomus intraradices resulted in the increase of soybean yield by 7.3 centner/ha, and the protein content was 2.3 % higher. If the calculated doses of P and K fertilizers were applied together with the biopreparatins, the soybean yield increased by 48.0 %.