Published in Scientific Papers. Series A. Agronomy, Vol. LXVIII, Issue 2
Written by Stefka STEFANOVA-DOBREVA, Angelina MUHOVA
The long-term 33-year study was aimed at clarifying the impact of mineral fertilizers under the influence of different weather conditions. The experiment was conducted at the Field Crops Institute, Chirpan, Bulgaria. The data presented in this article are for the period 1990-2022 (33 consecutive years). The following nitrogen (N) and phosphorus (P) rates were applied: 40, 80, 120 and 160 kg ha-1. Each fertilizer rate was introduced alone and in combinations (25 variants). All fertilization rates were compared to non-fertilized variant (N0P0). The results showed that the conditions of the year (47.87% of the total variation) and fertilization (33.40% of the total variation) have a significant influence on the productivity of durum wheat. Furthermore, we reported that nitrogen fertilization had a stronger effect than phosphorus, but combined fertilization at the N120P120 rate had the highest grain yield. The correlation coefficient (R=0.897) and the coefficient of determination (R2=0.805) were proven. Through second-order polynomial equations, it was found that the optimum fertilization rate was in the range of 120-130 kg N ha-1.
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