Nitrogen Rate and Variety Effects on Yield and Nitrogen Use Efficiency of Malt Barley in Horro Highland, Ethiopia

Enhancing nitrogen fertilization while reducing environmental and economic trade‐offs is crucial for achieving sustainable malt barley production in the Ethiopian highlands. This study investigated the interactive effects of nitrogen rates and malt barley varieties on grain yield and nitrogen use efficiency (NUE) indices—quantitative measures of how effectively crops absorb, recover, and convert applied nitrogen into grain yield. The research was conducted under the agroecological conditions of Horro and Jimma Gannati districts over two consecutive cropping seasons (2023 and 2024). A factorial experiment was conducted using five nitrogen rates (0, 23, 46, 69, and 92 kg N ha −1 ) and three malt barley varieties (IBON‐174/03, Holker, and Traveler), arranged in a randomized complete block design. Results showed that nitrogen rate, variety, and location had significant effects ( p < 0.05) on grain yield and total biomass. The highest grain (5469.83 kg ha −1 ) and straw (11,090 kg ha −1 ) yields were obtained at the highest nitrogen rate (92 kg N ha −1 ) from the Holker and IBON‐174/03 varieties in Jimma Gannati and Horro, respectively. However, no significant differences were observed between 69 and 92 kg N ha −1 , suggesting a yield plateau at higher N levels. Notably, NUE indices declined with peak values recorded at 46 kg N ha −1 across varieties and sites. Economically, the highest marginal rate of return was achieved by IBON‐174/03 at 46 kg N ha −1 , followed by Holker, indicating superior agronomic performance and profitability under moderate N input. From an environment prospective, reducing nitrogen application to 46 kg N ha −1 minimizes nitrate leaching, lowers nitrous oxide (N 2 O) emissions, reduces soil acidification risk, and decreases the energy footprint associated with fertilizer production and transport. This study fills a critical research gap by providing site‐specific recommendations for the Horro highlands, where farmers traditionally rely on blanket applications. Applying 46 kg N ha −1 and selecting high‐performing varieties such as IBON‐174/03 and Holker optimize the balance among productivity, profitability, and environmental sustainability.