Irrigated malt barley nitrogen management: Insights from historical and modern cultivars

Abstract Barley ( Hordeum vulgare L.) is the primary grain used for malting and brewing in the United States. Idaho accounts for upward of 40% of US production with the largest share grown under irrigation in the Snake River Plain. Cultivar and agronomic advancements occurred in the past century but, N‐supply research has lagged behind. We addressed this with N‐response trials of historical and modern malt barley cultivars from 2015 to 2019. Six N‐supplies (applied fertilizer‐N + soil inorganic‐N) were tested, allowing critical nitrogen supply (CNS) determination, that is, N‐supply at yield plateau. Site‐by‐site analysis of variance (ANOVA) and linear plateau (LP) models were used to determine ANOVA CNS, which ranged from 110 to 149 kg N ha −1 . At ANOVA CNS, modern barley yields were 10%–20% greater than historical cultivars. Combined‐site LP and quadratic plateau (QP) models resulted in CNS ranges of 117–152 kg N ha −1 for historical cultivars and 141–170 kg N ha −1 for modern cultivars; both model results are below the current maximum recommendation of 235 kg N ha −1 . Grain yields for Klages were 20%–35% greater than reported from research in the 1970s and 1980s; however, CNS were similar. Grain protein was more negatively affected by N‐supply for Klages, but all cultivars remained below malting thresholds across their CNS ranges. Our data support lower fertilizer‐N applications and expenditures compared to current recommendations and evidence the importance of synergistic enhancement of malt barley production through breeding and agronomic advancement to optimize crop and farm business performance.