Irrigated Malt Barley Nitrogen Management: Insights from Historical and Modern Cultivars

Authors: Rogers, Christopher; PRAMANIK, CHANCHAL - University Of Idaho; HU, GONGSHE - US Department Of Agriculture (USDA); MARSHALL, JULIET - University Of Idaho; Tarkalson, David; HATZENBUEHLER, PATRICK - University Of Idaho; EVANS, CHRIS - US Department Of Agriculture (USDA)

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2025
Publication Date: 9/1/2025
Citation: Rogers, C.W., Pramanik, C., Hu, G., Marshall, J.M., Tarkalson, D.D., Hatzenbuehler, P., Evans, C. 2025. Irrigated Malt Barley Nitrogen Management: Insights from Historical and Modern Cultivars. Soil Science Society of America Journal. https://doi.org/10.1002/saj2.70124.
DOI: https://doi.org/10.1002/saj2.70124

Interpretive Summary: Most U.S. barley is for malting and brewing, where Idaho produces 40% of the crop, largely in irrigated areas. Over the past 100 years, barley has been improved through breeding and better farming practices. However, research in the region on nitrogen fertilization has lagged behind, particularly determination of the point where crop yields stop increasing, or the critical nitrogen supply (CNS). We addressed this from 2015-2019 using older and modern barley in nitrogen rate response trials. We estimated CNS ranged from 117 to 152 kg N/ha for older lower-yield barley and from 141 to 170 kg N/ha for the modern higher-yield types, both below the current rate of 235 kg N/ha. No barley exceeded the protein level required for malting at their CNS. Our study provides a path towards more efficient farming practices that would reduce fertilizer use and save between $8-14 million annually without sacrificing yield or quality.

Technical Abstract: Barley (Hordeum vulgare L.) is the primary grain used for malting and brewing with production concentrated in the Great Plains and Western US. Idaho accounts for upwards of 40% of US production with the largest share grown around the Snake River Plain under irrigation. Cultivar and agronomic advancement occurred in the past century but, nitrogen-supply (N-supply) research has remained limited despite its importance. To address this, we researched historical and modern malt barley cultivars from 2015-2019. Six N-supplies (applied fertilizer-N + soil inorganic-N) were tested, allowing critical N-Supply (CNS, N-supply at yield plateau) determination. Site-by-site analysis used ANOVA and linear-plateau models to determine CNS, which ranged from 109-149 kg N ha-1 for the historical cultivar Klages and modern cultivar Moravian 69 (M69), respectively. At ANOVA CNS, modern cultivar yields were upwards of 20% greater than Klages. Combined-site response was assessed using linear- and quadratic-plateaus models. This resulted in CNS ranges of 117-152 kg N ha-1 for historical and 141-170 kg N ha-1 for modern cultivars, below the recommended maximum of 235 kg N ha-1. Yields for Klages were 20-35% greater reported from 1970s and 80s research; however, CNS were similar. Grain protein was more negatively affected by N-supply for Klages, but all cultivars remained below malt targets at their CNS. Our data would support lower fertilizer-N applications, and thus, increased economic returns compared to current recommendations. Results evidence the importance of synergistic enhancement of malt barley production through breeding efforts alongside improved agronomics to optimize crop performance and farm economies.