Vestnik of the Mari State University. Chapter ?Agriculture. Economics?

Introduction. Nitrogen nutrition of oat plants is a key component in the formation of grain yield, the sig-nificance of which depends on crop moisture supply. Early sowing is the main agricultural technique that allows crops in Belarus to efficiently use soil moisture. The aim of the research was to study the effectiveness of differ-ent doses of nitrogen fertilizers at different periods of oat sowing, when soil moisture decreases. Materials and methods. Determination of field germination, survival and preservation of oat plants for harvesting, soil moisture of the arable horizon, as well as structural elements and grain yield was carried out according to generally accepted methods. Indicators of photosynthetic activity processes are according to A. A. Nichiporovich. Research results, discussions. The highest field germination rate (88.9 %) and the survival rate of oat plants to harvest (73.2 %) were observed in early-term crops compared to sowing after 7 and 14 days, while their persistence was lower (82.5 %). The maximum photosynthetic potential is 2451 thousand m2 / ha x days at this time of sowing with the introduction of nitrogen N90+30. An increase in the level of nitrogen nutrition from N60 to N90 before sowing and the use of N30 in the tillering stage on these backgrounds contributed to the growth of yield structure elements, sowing the crop 7 and 14 days later than the early sowing period led to their decrease. Conclusions. The highest yield of oat grain is formed at an early sowing period (the onset of physical ripeness of the soil). With a seeding rate of 5.0 million / ha of germinating seeds, the optimal nitrogen dose is N90 once for pre-sowing tillage or fractionally ? N60 for pre-sowing treatment and N30 during the tillering stage.