Yield of soybean varieties and their quality depending on the dose of seedbed dressing on leached chernozem of the Western Ciscaucasia

The aim of the research was to evaluate the soybean variety specificity based on their response to dif-ferent levels of mineral nutrition of plants. In 2021–2023, new and promising varieties from different maturity groups: very early Vita, Puma, Kora, Parus, early Selena, Chara, Olympia, Irbis and mid-early Bars and Zara, were studied in field experiments at V.S. Pustovoit All-Russian Research Institute of Oil Crops (Krasnodar). The seedbed dressing doses were N6P26 and N12P52; the results were compared with the control variant without fertilization. We used a complex compound mineral fertilizer ammophos (brand 12 : 52), which was applied as seedbed dressing at sowing with a row spacing of 70 cm using the local strip method with deep embedding (12–14 cm). The soil of the experimental plot was leached low-humus extra-heavy loamy chernozem with humus content in the arable layer of 3.3–3.7%, mobile phosphorus of 16–18 mg/kg, exchange-able potassium of 320–485 mg/kg, pHKCl of 5.1–5.5. Soy-bean yield and the specificity of response to seedbed dress-ing at sowing depended on varietal characteristics and weather conditions of the growing season. The highest yield, due to relatively uniform distribution of precipitation during the generative phases, was obtained in 2022 – on average for all varieties and variants 2.68–2.81 t/ha, which is higher than in 2021 and 2023 by 1.03 and 0.91 t/ha (59.9 and 49.5%), respectively. When mineral fertilizer was ap-plied, the highest yield increase, compared to the control, was observed in the variety Selena, with a three-year aver-age of 0.21 t/ha (9%), with no significant difference be-tween the doses of N6P26 and N12P52.The average yield in-crease from fertilization at sowing with the doses of N6P26 and N12P52 was at the same level and equal 0.07 t/ha (3.2%) and 0.08 t/ha (3.7%), respectively. The highest seed protein content was found in Irbis (45.3%), Zara (44.1%), and Puma (44.0%) varieties. The seed oil content confirmed the inherent soybean pattern of an inverse rela-tionship between this trait and protein content. On average over three years, the lowest seed oil content was found in the variety Irbis (19.7%) and the highest – in the varieties Vita and Selena (23.1%). Seedbed dressing in the doses of N6P26 and N12P52 had little effect on the content of protein and oil in the seeds of the varieties.