Optimal nitrogen and phosphorus fertilizer rates for bread wheat production in the Northwestern Ethiopian highlands
摘要
Nitrogen (N) and phosphorus (P) are the major nutrients limiting bread wheat yield in Ethiopia, yet their optimal application rates remain uncertain in the Debark and Wogera districts of the North Gondar zone, Amhara Region, Ethiopia. This study was conducted to determine the optimum N and P rates for bread wheat production, along with their agronomic efficiency and economic feasibility. The experiment was carried out during the 2023/24 main rainy season using the Alidoro wheat variety in a randomized complete block design (RCBD + control) with three replications across two farmers’ fields. Treatments consisted of four N rates (115, 161, 207, and 253 kg ha⁻1), three P₂O₅ rates (46, 69, and 92 kg ha⁻1), and one control (0N–0P₂O₅). Data on phenology, growth, yield, and yield components were analyzed using SAS software. Nitrogen application significantly (p < 0.05) influenced grain yield, straw yield, nutrient uptake, and agronomic efficiency, whereas P application had limited effects, mainly enhancing biomass yield. Aboveground dry biomass and tiller number were significantly affected by the interaction between N and P₂O₅ rates. The highest grain yield (4,952 kg ha⁻1), representing a 125.5% increase over the control, was achieved at 161 kg N ha⁻1, while the maximum biomass yield (14.98 t ha⁻1) was obtained with the combined application of 161 kg N ha⁻1 and 46 kg P₂O₅ ha⁻1. Economic analysis revealed that this combination provided the greatest net benefit (313,460 ETB ha⁻1) and an acceptable marginal rate of return. Therefore, the combined application of 161 kg N ha⁻1 and 46 kg P₂O₅ ha⁻1 is both biologically effective and economically viable, and is recommended for bread wheat production in Debark, Wogera, and similar agro-ecologies.