The purpose of this work is to present the results of fi eld studies on the effectiveness of applying different primary tillage systems for soybean cultivation in the Forest-Steppe zone of Ukraine and the infl uence of agrometeorological conditions during the growing season on biological grain yield. Methods. The studies were conducted using four primary tillage systems: traditional (A1), conservative (A2), mulching (A3), and no-till (A4). Soybean cultivation technology in the experiments was traditional for the research area, except for the studied factors. The effectiveness of the tillage systems was determined by assessing the biological yield of soybean and its structure. Biological grain yield was determined from sample sheaves collected in triplicate for each variant. The main elements of yield structure for each variant were identifi ed during the analysis of the sample sheaves. Statistical data processing was performed using correlation analysis. Agrometeorological conditions during the soybean growing season were assessed using data from the Bila Tserkva weather station. Results. Among the studied primary tillage systems for soybean cultivation, the traditional system with plowing showed the highest biological grain yield. Replacing moldboard plowing (traditional system) and deep loosening (conservative system) with shallow tillage negatively affected the biological yield. The average biological soybean grain yield over the research years was 2.76 t/ha, ranging from a minimum of 1.82 t/ha (2018, no-till system) to a maximum of 3.88 t/ha (2021, traditional primary tillage system). During the research period, a signifi cant increase in average daily temperatures was observed in all summer months: June increased by 2.0 ºC, July by 1.1 ºC, and August by 2.0 ºC. Correlation analysis indicated that changes in average daily temperatures are refl ected in soybean biological grain yields. The strength of the relationship depends on the soybean growth and development phase and the primary tillage system used in the cultivation technology. Over the past ten years, the amount of atmospheric precipitation and its distribution have signifi cantly changed, especially in the summer months, as indicated by the trend line and comparison with actual data from the previous thirty years of observations: the average precipitation sum for June decreased by 23.2 mm, for July by 19.4 mm, and for August by 34.4 mm. Conclusions. The biological yield of soybean grain is related to the year’s conditions (r = 0.418) and the primary tillage system (r = 0.404): a decrease in tillage depth and the abandonment of moldboard plowing lead to a reduction in the biological grain yield formed by soybean phytocenoses. Changes in average daily temperatures are refl ected in soybean biological grain yields. The strength of the relationship depends on the soybean growth and development phase and the primary tillage system used in the cultivation technology. An increase in temperature in May (emergence – early branching phase) and August (grain fi lling – ripening phase) negatively affects the biological soybean grain yield, as evidenced by correlation coeffi cients of r = –0.370 and r = –0.303, respectively. There is a moderate direct correlation (r = 0.343) between biological yield and the average daily air temperature in June, and a weak direct correlation (r = 0.111) between biological soybean grain yield and the average daily air temperature in July. According to correlation analysis data, the amount of atmospheric precipitation during the vegetative development of soybean (May – June) practically does not affect the biological grain yield.
Novokhatskyi et al. (Sun,) studied this question.