Effect of Nitrogen Levels on Grain Yield and Protein Content of Malt Barley (Hordeum Vulgare L.) Varieties in Digalu-Tijo District, Southeastern Ethiopia

Nitrogen is the most important plant nutrient for crop production and grain quality of malt barley improvement; but the yield and quality of malt barely produced in Ethiopia is very low due to nutrients diminished from the soil. A field experiment was conducted at Digelu–Tijo District, Southeastern Ethiopia to evaluate the effect of different rates of nitrogen on yield and protein content of two malt barley varieties in 2015/16 cropping season. Factorial arrangements of the two malt barley varieties (Grace and Traveler) and six nitrogen rates (0, 19.0, 30.5, 42.0, 53.5 and 65.0 kg N ha -1 ) were laid out in a randomized complete block design with three replications. Nitrogen rate had significant (P<0.05) effect on days to physiological maturity, plant height, tiller number, grain per spike, spike length, grain yield, biological yield, straw yield, harvest index and grain protein content. Variety had significant (P<0.05) influence on days to physiological maturity, plant height, spike length, grain per spike and thousand kernel weights. Their interaction showed significant (P<0.05) influences only on grain per spike and harvest index. When nitrogen fertilizer rate increased from 0 to 65 kg ha -1 , the growth, yield and quality components were significantly increased with corresponding increase of grain yield from 17.8 to 58.8 quintals. The responses of malt barley varieties to applied nitrogen fertilizer rate increased with respect to growth, grain yield and yield components. Thus, irrespective of varieties, the highest net benefit of 38481.55 Birr ha -1 with acceptable protein content (11.3%) was recorded at nitrogen fertilizer rate of 65 kg ha -1 in the study area. Generally, from the study result, it can be concluded that the farmer in the study area can produce optimum grain yield and quality of malt barley varieties at the application rate of 65 kg ha -1 of nitrogen fertilizer in the study area. However, further studies should be done using more levels of nitrogen at different seasons and locations through integrating with other fertilizer types to reach at dependable conclusion.