Grain yield and quality responses of durum wheat (Triticum turgium L. var. durum) to nitrogen and phosphorus rate in Yilmana Densa, Northwestern Ethiopia

Proper rate of fertilizer application is the major factor that affects yield and quality of durum wheat. Location specific fertilizer recommendation is lacking for durum wheat, therefore, ni-trogen (N) and phosphorus (P) field experiment on durum wheat was carried out on farmer's field in 2017 and 2018 cropping seasons at Yilmana Densa district, Northwestern Ethiopia. The objective was to examine the response of durum wheat to N and P application and determine the optimal rate of nitrogen (N) and phosphorus (P) for durum wheat production in the district and similar agro ecology areas. Factorial combinations of four N levels (0, 90, 180 and 270 kg ha-1) and four P levels (0, 17.5, 35 and 52.5 kg ha-1) were evaluated in a randomized complete block design with three replications per site, over two sites in each year. Results indicated that N significantly affected most of the crop parametrs including grain yield, plant height, total number of tillers and effective tillers, spike length and seeds per spike, and the maximum value of the parameters recorded at the highest rate of N while application of phosphorus affected grain yield, plant height and spile length. The interaction effect of N and P significantly affected grain yield, plant height and seeds per spike. Grain yield showed quadratic and linear response to N and P application, respectively. The maximum grain yield (5182 kg ha-1) was obtained from the highest rate 270/52.5 N/P kg ha-1. The economic analysis revealed application of 270/52.5 N/P kg ha-1 gave the highest net benefit of 169741 ETB ha-1 with marginal rate of return 1453% and full fills the standard for quality of durum wheat production and hence can be recommended in Yilmana Densa District and other similar agro-ecologies in Ethiopia. The study revealed the need to further investigation for optimal N and P rates for different durum wheat varieties as they differ in protein content under the same management practices.