Effectiveness of pre-sowing treatment of red clover seeds with biological preparations

The study of the biological fixation of atmospheric nitrogen by legumes and the increase in its utilization are among the most important problems in the development of agricultural production. The purpose of the research was to establish the effect of various strains of nodule bacteria on the symbiotic nitrogen fixation and productivity of red clover in the subtaiga zone of Western Siberia. The nitrogen fraction fixed from the atmosphere and used for the formation of red clover biomass - the nitrogen fixation coefficient (Cf) - was determined by comparison with a non-leguminous plant - awnless brome. It was proved that in order to improve growth, increase nitrogen fixation and productivity of red clover, an effective method is the pre-sowing seed inoculation with biological preparations based on rhizotorfin. Biological preparations contribute to the good formation of a dense grass stand and a decrease in the content of weed vegetation in it, an improvement in the growth of the root system and an increase in the photosynthetic activity of red clover. The height of clover before harvesting was 68-72 cm, which exceeded the control sample by 8-12 cm. The weeding rate of clover sowing during years of use of grass was reduced from an average degree in the control sample to weak one (4.0-4.6%) when using biological preparations. In the third year of life, the mass of clover roots in the 0-30 cm soil layer was 6.4-6.5 t/ha, or exceeded the control by 0.6-0.7 t/ha. The area of leaves when using biological preparations exceeded the control sample by 3.000-3.300 m²/ha, while AF and NPF increased, reaching the maximum values of 4.1-4.2 million m² day/ha and 11.2-11.5 g/m² day. The inoculation of red clover seeds is best done with strains of nodule bacteria Kt-1 and K-2. The fixation of biological nitrogen by clover on gray forest soil is 62-67 kg/ha, the yield of green mass is on average 31.3-31.7 t/ha or increases by 13.0-14.9% compared to the control sample, Kf amounts to 0.56-0.58.