Symbiotic productivity of soybeans depending on inoculation and fertiliser in conditions of the Right-Bank Forest-Steppe

Given the high value of the biochemical composition of soybean seeds and the versatility of using this crop, the need for it will continue to grow, which makes it necessary to improve existing and develop new technologies for its cultivation, considering local agroclimatic resources. Therefore, this study, aiming to investigate the agroecological foundations of the use of chemical and biological techniques in modern technologies for growing soybeans, is relevant. The purpose of the study was to identify the features of the formation of symbiotic productivity of soybeans under the influence of bacterial and mineral fertiliser in the conditions of the Right-Bank Forest-Steppe of Ukraine. A field method was laid down according to the developed scheme to achieve this goal. The positive effect of mineral fertiliser and inoculation on the formation of the symbiotic apparatus of soy and its productivity was established. The smallest increase in the number of root nodules was noted for the introduction of N45P60K60 – 24.7-27.3%, depending on the variety. Small initial doses of nitrogen were more effective – within the limits of N15–30 – they provided an increase in the number of active bulbs by 51.2-106.9%. Bacterisation of seeds with the complex bacterial preparation Phosphonitragine increased the number of active nodules on soybean roots by 106.8-138.6%, depending on the variety. The interaction of technological methods of mineral fertilisation and inoculation contributed to an increase in both the number of nodules with leghemoglobin – by 128.5-198.6%, and their mass – by 111.1-147.6%. The soy symbiotic apparatus was maximally developed by interacting seed inoculation factors with a bacterial preparation containing Br. japonicum and B. Mucilaginosus strains and applying N30P60K60 +N15 in the budding phase. This technological model of crop cultivation provided the highest productivity of legume-rhizobial symbiosis of soybean plants in terms of the volume of accumulation of symbiotically fixed nitrogen – in the early-ripening soybean variety Vilshanka – 124.2 kg/ha, in the medium-ripening variety Suziriia – 130.3 kg/ha. The practical importance of the obtained results is in the improvement of varietal technologies for growing soybeans based on the complex application of seed inoculation with a bacterial preparation and the introduction of nitrogen fertilisers in retail against the background of phosphorus-potassium fertiliser