OPTIMAL PARAMETERS OF SOIL WATER REGIME DURING CROPS CULTIVATION ON DRAINED LANDS

The results of the research on determining the optimal parameters of the soil water regime during cultivation of promising agricultural crops on drained lands under modern conditions of farm management and climate changes are presented. It was found that the weather conditions of the vegetation seasons of 2022, 2023, and 2024 on the drained lands of the reclamation system of the Sarny Research Station of IWP&LR of NAAS were very contrasting: periods with excessive precipitation alternated with their prolonged absence, and significant fluctuations in temperature indicators were noted. The assessment of the impact of water regime regulation on the yield of spring wheat, winter rapeseed, grain corn, and soybeans was carried out using an unified fertilization system, applying the same rates of mineral fertilizers, and with an identical plant protection system on the background of 3 options for regulating the groundwater level (GWL) - 75-80 cm, 85-100 cm, and 100-140 cm. On the background of the indicated options for regulating the GWL, the lowest moisture reserves were observed in the summer period, and in areas adjacent to the studied territory, where the GWL was not regulated, moisture reserves in the summer in the soil layer of 0-30 cm dropped to the critical values (8–9 mm). On the experimental plots during this period, thanks to timely sluicing, soil moisture reserves did not fall below 47-50 mm. Based on the analysis of the dynamics of dry mass of growth of spring wheat, winter rapeseed, grain corn, and soybeans according to the options for regulating the soil water regime, the optimal parameters of the soil water regime (GWL, moisture, and moisture reserves) were determined for the phenological phases of the studied crops. It was found that the highest yield increase due to the optimization of moisture supply was observed in spring wheat and soybeans. Spring wheat is the most sensitive to soil water regime and reacts more actively than other crops to a decrease in GWL. The regulation of the GWL contributed to an increase in the yield of spring wheat by 41.6%, winter rapeseed by 18.3%, grain corn by 32.5%, and soybeans by 44,8%.