Stoichiometry of arable black soil on the Ukrainian Western forest steppe.

Luvic Greyzemic Phaeozems have been farmed for centuries in Western Ukraine. We investigate their stocks of major nutrients and stoichiometry under arable crops receiving conventional NPK fertilisation and an unfertilised control. Total carbon stocks increase only with parallel increases in total N, P, Ca and Mg. Likewise, total N increases along with parallel increases in total Ca and Mg, P and Ca, P and C. Under winter barley, application of the background fertilisation (N₂₃P₆₀K₆₀) + N₉₇ (urea) before sowing, with or without nitrapyrin as a nitrogen stabiliser, improved the status of C, N, Ca and Mg to P in the 0–20 cm soil layer. The best ratio of total C, N, Ca and Mg to P and the best C:N, C:P, N:P, and Ca:N ratios were achieved with the background fertilisation plus nitrapyrin and urea or ammonium nitrate. The system cannot hold onto nutrients, nitrogen in particular, applied in excess of the harmonic stoichiometry. [ABSTRACT FROM AUTHOR]