Efficiency of nitrogen fertilization of winter rapeseed in the Steppe of Ukraine

Abstract

The current problem is to determine the optimal rates and timing of nitrogen fertilizer application in the conditions of the Steppe of Ukraine, which is key to obtaining high yields of winter rapeseed and economic efficiency of production. Purpose. To determine the effects of rates and timing of nitrogen fertilization on the growth, development, formation of yield structure components, and productivity of winter rapeseed hybrid Temptation (DSV, Germany) under the agro-climatic conditions of the northern Steppe of Ukraine, as well as to evaluate the economic efficiency of the applied fertilization systems. Methods. The study was conducted in 2022–2025 at LLC “DVK” (village Slavhorod, Synelnykove district, Dnipropetrovsk region) using a randomized block design with four replications. The experimental plot area was 20 m2, and the seeding rate was 0.7 million viable seeds per hectare. Phosphorus-potassium nutrition was standardized (P60K80), while nitrogen fertilizers (urea) were applied in spring as top-dressings at rates N60, N90, N90 + N30, N90 + N60, N90 + N90. Parameters measured included seed yield, number of pods, number of seeds per pod, thousand-seed weight, seed protein and oil content, as well as economic indicators. Statistical analysis was performed using Statistica 10.0 software, including factorial analysis and comparison at LSD0.05. Results. Nitrogen fertilization significantly increased winter rapeseed yield: without nitro- gen – 2.47 t/he, with two applications of N150 (N90 + N60) – 4.17 t/hе, an increase of 1.70 t/he (68.8 %). Two applications of N150 optimized leaf area development, promoted intensive branching, increased pod number, and improved thousand-seed weight. Seed protein content increased up to 22.1 %, while oil content remained high, ensuring maximum protein and oil yield per hectare. Economic efficiency was highest with N150: net profit – 56.7 thousand UAH/hе, profitability – 152.7 %. Further increasing nitrogen above 150 kg/ha did not result in substantial yield gains or economic benefit. Conclusions. Optimization of nitrogen fertilization of winter rapeseed within 120–150 kg/hе with split applications is recommended for establishing high-yielding, resource-efficient agrocenoses in the Steppe of Ukraine. This approach ensures maximum seed yield, improves seed quality, and provides economic efficiency of production.