Keywords: mineral nitrogen, fertilizers, ¹³⁷Cs, accumulation, peaty-gley soil, perennial grasses

Мелиорация.– 2026. – №1 (115). – P 20–28

At the beginning of the spring growing season of perennial grasses, nitrate nitrogen predominates in the mineral nitrogen composition of the soil, accounting for
an average of 53.5%. During the first grass cutting period, ammonium nitrogen accounts for the majority of the mineral nitrogen content across all  experimental variants, accounting for 64.9-72.4%. A significant correlation (r = 0.50-0.66) was found between the Nmin content in the soil in early spring and  after the first cutting and the ¹³⁷Cs activity in the hay of perennial grasses from the first and second cuttings. Strong correlations were found between mineral nitrogen content in the soil in early spring and after the first grass cutting and hay yields from the first and second cuttings. The correlation coefficients (r)  were 0.83 and 0.73, respectively. With increasing N_min reserves in the soil, a significant increase in productivity was observed.