Effect of nitrogen fertilization on grain yield and quality of winter wheat variety Skipetr

Abstract

The effectiveness of nitrogen fertilization of winter wheat of Skipetr variety depends on the weather conditions during spring growth and tillering, and the distribution of precipitation during the growing season. In 2022, base fertilizer N₈₁P₄₆K₄₆S₇₂ was applied in the form of ammonium sulfate and compound NPK fertilizer (diammophoska) under favorable hydrothermal conditions of spring, rainfall deficit and windstorm during harvesting; the grain yield of 3.42 t ha was obtained; and with fertilization with ammonium nitrate and ammonium sulfate the yield was 3.5-3.91 t ha, and decreased in the variant of fertilization with ammonium sulfate N₃₀ at tillering. Higher yields were formed with fertilization at tillering (N₃₅) with ammonium nitrate - 3.91 t ha, and two-fold fertilization (N₃₀ and N₃₅) at first with ammonium sulfate and then with ammonium nitrate - 3.89 t ha; gluten content increased from 37.9% to 37-39.4% and protein content - from 12.6% to 14.8-15.7%. In 2023, the base fertilizer N₁₀P₂₆K₂₆ (compound NPK fertilizer at sowing) under unfavorable hydrothermal conditions of the first half of the growing season with good overwintering ensured the yield of 5.9 t ha, and with fertilization with ammonium sulfate and ammonium nitrate in different rates and combinations, the yield increased to 6.2-6.67 t ha except for fertilization with ammonium nitrate at rate of N₇₀ at tillering where 5.67 t ha was obtained. Decreased yield was due to abundant growth of aerial part and larger ratio of straw to grain - 1:1.25 compared to 1:1.03-1:1.14 in other variants. The yield gain of 13.05% was obtained by the combination of twofold fertilizations with ammonium sulfate and ammonium nitrate. The grain in this variant contained 14.6% of protein and 25.8% of gluten. The highest quality indices were obtained by twofold fertilization with ammonium nitrate with the yield of 6.2 t ha. Two-year long experiments with different backgrounds of the base fertilizer and fertilization showed that high rates of nitrogen applied before sowing improved nutrition at the first development stages - tillering and earing with subsequent nitrogen deficiency. Fertilizations enhance nutrition, but the yields remain at the level of 3.5-3.9 t ha. At the same time, pre-sowing application of the starting rate of N₁₀P₂₆K₂₆ and fertilization with nitrogen fertilizers increase yields, and to a large extent the content of protein and gluten. The greatest effect was obtained from ammonium nitrate and twofold fertilization when combined with ammonium sulfate.