VOLUME 3 Issue 4/3

 DOI: 10.32636/agroscience.2024-(3)-4-3

FACTORS AND PATTERNS OF THE FORMATION OF SOY GRAIN PRODUCTIVITY ON THE SOD CLAY SOIL OF THE MALЕ POLISSIA

Bohdan KOTSYUBA, PhD candidate Lviv National University of Nature Management

The article highlights the impact of forms of nitrogen fertilizers and rates of application, the effectiveness of using the N-LoсkTM inhibitor and seed inoculation on the conditions of formation of soybean productivity in Male Polissia in the West of Ukraine. The description of the properties of the sod clay sandy light-loamy soil of the experimental field is given. The hydrothermal conditions of 2022-2024 are described. May, June and July 2023 were the wettest, warm enough, so that year provided the maximum soy productivity in the experiment – 4.12 t/ha. From January to September including, 538 mm of precipitation fell in 2022, 604 mm in 2023, and 525 mm in 2024. Depending on the change in hydrothermal conditions, soy development phases shifted, plant parameters and crop structure were formed. Applying nitrogen before sowing at the rate of N30 increased available nitrogen reserves by 7.1-12.1 mg/kg of soil in the seedling phase, compared to the unfertilized background (121.0 mg/kg). The use of nitrapyrin after the application of ammonium sulfate significantly, and ammonium nitrate less significantly, reduced the formation of nitrate ions in the soil layer. Close connections (r±) of nitrogen application rates with the content of soil forms of nitrogen, as well as рНsaline solution, and soy grain yield were revealed. The close relationship between application rates and changes in nitrogen reserves in the soil is shown on a planar 3D-model, which is described by a regression polynomial equation: Nnitr., mg/kg = 23.8079+0.0065×Nnorm+0.2244×Nhydr. The soy fertilization system using a nitrate stabilizer and bacterial inoculants provided a significant limitation of nitrate accumulation in the arable and subsoil horizons of the soil (by 21.1% compared to the control N30P60K60 (ammonium sulfate). The N30 (ammonium sulfate) nitrogen fertilization system on the background of P60K60 with the use of nitrogen-fixing inoculant provided the highest yield in three years and the maximum grain yield in 2023, which is 0.40 t/ha more than the average for 2022-2024. When using N-LoсkTM nitrogen stabilizer (1.7 l/ha before sowing) on the background of N30+30P60K60 soy provided a yield of 3.90 t/ha, which is 0.36 t/ha higher than the N30 (ammonium sulfate) option on the background of P60K60, which is considered traditional.

Keywords: soy, nitrogen fertilizer, nitrapyrin, inoculant, nitrate nitrogen, correlation, regression