Azotovit and Phosphatovit influence on the potato tubers yield and quality in the Russian Federation northwest

The aim of the study is to investigate the effect of using new bacterial preparations Azotovit and Phosphatovit against the background of mineral fertilizers on sod-podzolic soil, which increase the productivity and quality of early potato tubers in the Novgorod Region. The paper presents the results of a single-factor field experiment on the production of early potatoes of the Colombo variety for 2021-2023 to study the effect of three methods of using microbiological preparations Azotovit and Phosphatovit (treatment of tubers before planting, spraying of vegetative plants in the tuber formation phase and their double application) against the background of mineral fertilizers N50P130K130 on sod-podzolic soil (84 % of the arable land area in the region). The use of three methods of biofertilizers increased the yield of potato tubers by 28; 23 and 40 % compared to the background, respectively. We obtained potato tubers with a starch content higher than 15 % and a nitrate level in raw products lower than 85 mg/kg in all years of the studies. The use of Azotovita and Phosphatovit in technological operations twice (dressing potato tubers at 0.5 l/t of each preparation and foliar spraying of plants in the tuber formation phase at 1 l/ha of each preparation) and the introduction of mineral fertilizers under cultivation at a dose of N50P130K130 ensured high potato productivity - more than 35 t/ha. In this variant, high tuber quality indicators were obtained (marketability - 96.0 %, starchiness - 15.5 %) with a nitrate content in raw mass of 73.0 mg/kg, which is more than three times lower than the maximum permissible concentration of 250 mg/kg. The use of Azotovit and Phosphatovit twice in the cultivation technology of the Colombo potato variety against the background of mineral fertilizers provided an increase in yield of 10.2 t/ha (40 % in relation to the background) with high quality tubers. The value of the payback of costs and conditional income from additional products amounted to 14 rubles/rub. and 297 thousand rubles/ha in 2021 prices.