Influence of methods and terms of application of mineral fertilizers on the yield of oilseed flax on ordinary chernozem in the conditions of the Rostov region

Field experiments were conducted in 2020-2023 on black soil in the Azov zone of the Rostov region. The aim of the research was to establish optimal doses, methods and timing of the use of mineral fertilizers on the yield of flax oilseeds. They cultivated a variety of Heavenly oilseed flax. The predecessor is winter wheat. The following types of mineral fertilizers were used in the experiment: ammonium nitrate (34.4% N), ammophos (12-52), potassium chloride (K2O65). The use of mineral fertilizers was carried out in the autumn period for plowing the soil, in the spring for continuous cultivation and when sowing oilseed flax. In 2021, the highest yield of flax oilseeds was obtained on the variant by the application of nitrogen-phosphorus fertilizers at a dose of N30P30. The increase in control reached 0.74 t/ha or 42.8%. In 2022, with a lack of soil moisture against the background of sufficient provision of the soil with mobile phosphorus, the method and period of application of fertilizers did not have a decisive effect on the yield of flax oil seed. The highest yield of flax was obtained when nitrogen-phosphorus fertilizers were applied at a dose of N60P60. The increases to the control amounted to 0.82-0.87 t/ha or 73.2-77.7%. In 2023, with abundant moistening of the soil, the use of nitrogen-phosphorus fertilizers in spring for continuous cultivation was also effective. The yield increased by 0.47 t/ha or by 34.3% compared to the control variant. On average, in 2020-2023, the maximum increase from the use of fertilizers was achieved on the variant with the introduction of nitrogen-phosphorus fertilizers at a dose of N60P60 for continuous cultivation. The increase in the yield of flax oilseeds was 0.74 t/ha or 51.7% compared to the control variant.