||The results of studies of the influence of various norms, timing and methods of application of nitrogen fertilizers on the nutrient regime of the soil and the yield of spring spring seeds on chernozem podzolized Pravoberezhnaya Forest-steppe of Ukraine are presented. A high correlation dependence (0,73–0,86) between the reserves of mineral forms of nitrogen in soil layers 0–20 and 20–40 cm and the yield of false flax spring seeds was established.
On average, over three years of research, the nitrogen content of mineral compounds in the upper soil layer during the formation of the rosette of false flax spring on variants without fertilizer was 16,1 mg/kg and grew to 30,5 mg/kg in the variant of the experiment with the highest norm of nitrogen fertilizers (P60K60 + N120), and in the soil layer of 20–40 cm its content increased from 14,1 to 23,2 mg/kg, respectively.
During the vegetation period of false flax spring , the nitrogen content of mineral compounds in the soil decreased.
The highest yield of seeds was obtained for the application of full mineral fertilizer in a dose of N120P60K60 – 2,06 t/ha, which is 0,73 t/ha more control.
Between the stocks of various forms of nitrogen and yield, there is a high correlation in the soil layer 0–20 and 0–40 cm in all phases of growth and development of false flax spring plants. In order to diagnose the nutrition of false flax spring plants on chernozem podzolized during vegetation, we can confine ourselves to sampling the samples in the 0–20 cm layer. This is due to the fact that nitrogen fertilizers for this culture are usually introduced under pre-sowing cultivation or simultaneously with sowing. Therefore, fertilizer nitrogen is concentrated mainly in the 0–20 cm layer. In addition, only the nitrate form of nitrogen can be determined, because, as studies have shown, the ratio in this soil subtype between N–NO3– and N–NН4+ is usually 1 : 1.