Optimizing yield, quality, and nutrient uptake of bread wheat in response to N and P on Vertisols of North Central Highlands of Ethiopia

Abstract

Ethiopia is intensifying efforts to boost wheat production with effective nitrogen (N) and phosphorus (P) management. However, low soil fertility and the lack of recommendations on optimal N and P application rates remain major constraints limiting wheat production. The effects of different N and P nutrient rates on the yield of bread wheat were evaluated on Vertisols of Moretina Jiru District, North Shewa Zone, Amhara Region, Ethiopia. The study was conducted using a factorial arrangement of treatments in Randomized Complete Block Design (RCBD) with three replications. The treatments were five N rates (69, 115, 161, 207, and 253 kg ha−1), three phosphorus rates in the form of P2O5 (46, 69, and 92 kg ha−1), and one control (0N–0P2O5) treatment. Data on growth, yield parameters, and soil properties were collected and analyzed using R statistical software. The results showed that wheat grain yield was highly significantly affected by N rates (p < 0.001) and significantly (p < 0.05) by P rates, with the highest grain yield being five times greater than the control. Applying N or P alone significantly increased wheat grain yield, but their interaction did not affect the grain yield. The highest grain yield (4891 kg ha−1) was achieved with 253 kg N ha−1, resulting in a 101% increase over the control. This N rate also significantly improved straw yield, nutrient uptake, and protein content compared to other N rates. The optimum P2O5 rate was 69 kg P2O5 ha−1 which resulted in the highest grain (3869 kg ha−1) and straw yields (5210 kg ha−1). Moreover, the economic analysis revealed that the combined application of 253 kg N ha−1 and 69 kg P2O5 ha−1 resulted in the highest benefit–cost ratio (3.60), indicating a profitable investment for farmers by maximizing returns relative to input costs. Therefore, combined application of 253 kg N ha−1 and 69 kg P2O5 ha−1 was the optimum rate and recommended for wheat production on Vertisols of Moretina Jiru district and similar agroecologies and moisture domains until further N rate is determined based on multilocation studies.