Split Application of Nitrogen Fertilizer for Optimum Yield of Durum Wheat (Triticum turgidum L. var. Durum) at Central Ethiopia

Nitrogen (N) plays an essential role in durum wheat production since it affects yield and quality. However, applied nitrogen is liable to losses through denitrification, volatilization, leaching and runoff. Thus, it is important to apply the recommended amount in splits based on crop requirement and critical growth stages. A field experiment was carried out to evaluate the effect of time of N fertilizer application on yield of Durum wheat at Adaa and Minjar during 2016 and 2017 cropping season. The experiment was laid out in a randomized complete block design (RCBD) with three replications. The treatments consisted of a factorial combination of two Durum wheat varieties (Mangudo and Ude) and eight times of split N application (0-0-0-0 N (control), full dose at tillering, 1/3 at planting + 2/3 at tillering), 1/2 at planting + 1/4 at tillering +1/4 at flag leaf, 1/2 at tillering +1/4 at flag leaf + 1/4 at heading, 1/2 at tillering +1/3 at flag leaf + 1/6 at heading, 1/2 at planting + 1/4 at tillering + 1/8 at flag leaf + 1/8 at heading, and 1/2 at planting+ 1/6 at tillering +1/6 at flag leaf + 1/6 at heading). The fixed rate of N (92 kg/ha) was used. The results showed that variety and time of N applications had a significant effect on growth parameters and grain yield at both locations. The highest grain yield (5579 kg/ha) was obtained when N was applied 1/3 at planting + 2/3 at tillering at Adaa, while the maximum yield (3154 kg/ha) was recorded for 1/2 at planting+ 1/4 at tillering + 1/8 at flag leaf + 1/8 at heading stage at Minjar. The partial budget analysis also confirmed that the highest net benefit (115190 and 78147 Ethiopian birr) and Marginal rate of return (MRR) (7267and 3615) were obtained in 1/3 at planting + 2/3 at tillering at Adaa and 1/2 at planting+ 1/4 at tillering + 1/8 at flag leaf + 1/8 at heading at Minjar, respectively. Therefore, two times (1/3 at planting + 2/3 at tillering) and four times (1/2 at planting+ 1/4 at tillering + 1/8 at flag leaf + 1/8 at heading) split application of the recommended N rate would be advisable to attain higher yields of durum wheat at Adaa and Minjar, respectively.