The use of biological products to increase the nitrogen-fixing capability and productivity of alfalfa on gray forest soil in Western Siberia

In many countries, interest in the problem of biological nitrogen is currently increasing, since it allows, along with mineral nitrogen, to better meet the needs of crops in nitrogen, to obtain products rich in high-grade protein, enriches the soil with nitrogen and does not pollute the environment. Legumes, in particular alfalfa, are an important supplier of biological nitrogen. An effective method of enhancing the process of atmospheric nitrogen fixation by legumes is pre-sowing inoculation of the seeds with biological preparations. The purpose of the research is to identify the most effective biological preparations that contribute to the increase of symbiotic nitrogen fixation and productivity of alfalfa in the conditions of the subtaiga zone of Western Siberia. The amount of nitrogen fixed from the atmosphere and used for the formation of alfalfa biomass - coefficient of nitrogen fixation (Cf) - it was determined by the method of comparison with a non-leguminous plant - awnless brome. It has been established that when cultivating alfalfa on soils where it has not been sown before, pre-sowing inoculation of seeds with biological preparations containing specific strains of nitrogen-fixing bacteria for it is an effective method to increase the nitrogen-fixing ability and productivity of the crop. In the subtaiga zone of Western Siberia, on gray forest soil, the greatest effect in the inoculation of alfalfa seeds is exerted by nodule bacteria with associative strains based on rhizotorphin - strains 912 and 913. Fixation of biological nitrogen by alfalfa on average over the years of herbage use is 142-147 kg/ha, the coefficient of nitrogen fixation reaches 0.75, the yield of green mass is 27.6-29.9 t/ha or increases by 11.3-20.6% compared to the control.