Abstract
Barley (Hordeum vulgare L.) is used mainly for malting, brewing, and animal feed. In antiquity, barley was a major calorie source for humans and has recently become of increased interest as consumers seek healthier options. Hull-less barley plays a key role in this resurgence as the need to process barley through pearling is removed and modern cultivars have high fiber content. To our knowledge, no work has established fertilizer-nitrogen (N) recommendations for hull-less food barley under high-yielding irrigated conditions common in the semi-arid western United States. Research was conducted in the major irrigated production area of southern Idaho over 11 site-years of replicated N response trial data (similar to 5 fertilizer-N rates) from 2019 to 2023 for the cultivars Goldenhart and Julie. N-supply is reported and is the sum of applied fertilizer-N and soil inorganic-N to 60 cm. Analysis of variance (ANOVA) critical N-supply (CNS) was calculated site-by-site as the lowest yield that did not differ from the maximum. The average ANOVA CNS was 194 kg N ha-1 across all site-years. A yield-based approach and corresponding nitrogen requirements (Nr) from the ANOVA CNS resulted in an N-supply range from 200 to 224 kg N ha-1. A 95% relative grain yield (RGY) was used for linear- and quadratic-plateau models which determined CNS of 194 and 234 kg N ha-1, respectively. Protein increased slightly but was poorly explained by N-supply. A static-N range from 194 to 234 kg N ha-1 is suitable for irrigated hull-less barley production.