Effect of preparations on microbiological activity of soil and yield of spring wheat depending on weather conditions

The aim of the study was to investigate the effect of various preparations on the microbiological activity of the soil and the yield of spring wheat under unstable weather conditions. Spring wheat was grown on sod-podzolic light loamy soil. The years of the study differed in moisture supply, taking into account the values of the hydrothermal coefficient: 2020 – excessively moistened, 2021 – dry, 2022 – optimal. A humic preparation (HP) and a microbial biopreparation (BP) were used for pre-sowing seed treatment (at the rate of 20 l of a working solution of HP or BP of 1% concentration per 1 ton of seeds), for double foliar treatment of plants in the tillering and heading phases (HP – at the rate of 1 l / ha, BP – 3 l / ha, the consumption rate of working solutions is 300 l / ha) and when combining the above methods. During the tillering phase, a statistically significant increase in the number of dominant microorganisms was observed in the variants with seed treatment with preparations: in 2020 – by 25.4 and 53.3% in the case of using HP and BP, respectively, in 2022 – by 51.8 and 43.9%. During the heading phase, the effect was weaker – 21.6 and 23.5%. On average, over three years, the maximum effect from the use of HP was observed in the dry year of 2021: an increase in the number of microorganisms amounted to 59.3–94.2%, and the yield increase was 13.0% and 13.9%, respectively, for variants with pre-sowing seed treatment and foliar treatment of plants, the greatest increase was obtained from combining these methods – 17.3%. BP was most effective in the year of excess moisture – the number of microorganisms increased by 50.8–84.7%, and the maximum increase in wheat yield (15%) was obtained from combining seed and plant treatment methods.