KOSTADINOVA, S. and G. PANAYOTOVA, 2002. Energetical efficiency of durum wheat fertilization. Bulg. J. Agric. Sci., 8: 555–560
The investigation was carried out on the testing field of the Cotton and Durum Wheat Institute, Chirpan in a long-term trial at cotton-durum wheat crop rotation under non-irigated conditions. The rates of fertilization for N and P2O5 were 0, 6, 12 and 18 kg.da–1, and for K2O – 0, 6 and 12 kg.da–1. This study includes a selected number of variants. Nitrogen as NH4NO3 was applied two times – 1/3 pre-sowing and 2/3 as early spring dressing. Phosphorus and potassium were applied as pre-sowing treatment.
The aim of this study was to determine the energetical efficiency of diverse levels of fertilization at Zagorka durum wheat variety, grown under conditions of a long-term field trial. To realize our goal we had to solve the following problems: (i) to establish the Zagorka durum wheat variety productivity in dependence of fertilization; (ii) to investigate energetical efficiency of fertilization; and (iii) to study the retrievable efficiency of nitrogen and phosphorus fertilization.
It was found that nitrogen fertilizing afforded the main effect on the grain yield of durum wheat. It may be recommended an optimal nitrogen rate 12 kg.da–1. The annual applying of 6 kg P2O5.da–1 was economically effective. Under specific soil conditions potassium fertilizing may be temporarily eliminated. The amount of applied nitrogen determines the energetic efficiency of mineral fertilization of durum wheat variety Zagorka. From energetical viewpoint the most efficient rates were N6 and N6P6. At these rates the coefficient of energetical efficiency of the fertilizers used (η) was twofold higher compared to N18. The highest retrievable efficiency of nitrogen fertilizing was obtained at applying of 6 kg N.da–1. Fertilization N12P6 effectively increased grain recovery of nitrogen and phosphorus.