The research was conducted to study the effect of liquid organic fertilizer on the yield, productivity elements, and grain quality of zoned soybean varieties. The work was carried out in the dark gray forest soil of the Oryol region in 2022–2024. The reaction of the Leader 1 and Mezenka varieties to pre-sowing seed treatment and double spraying of the crops in the 1…3 trifoliate leaf and budding phases was studied according to the following scheme: water treatment without fertilizer application (control); Bioklad – 1.0 lt and 1.0 l/ha; Bioklad – 2.0 lt and 2.0 l/ha. With the use of organic fertilizer, the mass of nodules on the root system in the flowering phase of soybean plants and their number increased by an average of 183.7 and 505.3 %, respectively, compared to the control, across varieties and experimental variants. In addition to the treatment of seeds and plants, the effect of Bioklad on the legume–rhizobia symbiosis was also manifested in an increase in nitrogenase activity in the Leader 1 variety by 114.6…136.2 %, and in the Mezenka variety by 102.9…109.1 %. Depending on the variety, fertilizers increased grain yield by 0.23…0.42 t/ha (10.1…17.7 %) relative to the control, the number of seeds per bean by 0.04…0.59 (1.6…27.6 %), and the weight of 1,000 seeds by 4.85…10.4 g (3.0…7.2 %). The quality of soybean grain improved significantly: the protein content increased by 0.2…0.68 %. In this experiment, the highest efficiency was observed when using liquid organic fertilizer at a dose of 2.0 liters on the determinate variety Leader 1 and 1.0 liters on the indeterminate variety Mezenka. The maximum grain yield increase over the years of research was observed in the Leader 1 variety at 0.42 t/ha and in the Mezenka variety at 0.27 t/ha. The highest protein yield per unit of cultivated area was 1178 and 1040.9 kg/ha, respectively.
V.I. Zotikov (Wed,) studied this question.