Published in Scientific Papers. Series A. Agronomy, Vol. LXIII, Issue 1
Written by Ivan VELINOV, Zhivko TODOROV, Svetla KOSTADINOVA
The response of nitrogen, phosphorus and potassium concentration of grain sorghum to nitrogen fertilization in rates 0, 60, 120, 180, 240 and 300 kg N∙ha-1 was studied in the experimental field of Agricultural University of Plovdiv, Bulgaria in 2017-2019 under non-irrigated conditions. It was established proven effect of nitrogen fertilization on the concentration of nitrogen, phosphorus and potassium in the sorghum straw. The average grain nitrogen concentration ranged from 1.96% N at N0 to 2.35% at N300. The applying of higher N180-300 rates proven increased the concentration of grain nitrogen. The increase of grain phosphorus concentration was up to N120 and higher nitrogen rates decreased its value. The hydro-thermal conditions during the sorghum vegetation slightly affected the concentration of nitrogen and phosphorus in plant parts, but the drought conditions in 2017 significantly decreased the grain potassium concentration.
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