The malt industry has specific requirements for malting barley (Hordeum vulgare L.) grain protein concentration (from 9.5 to 13%) and size (>85%), which could be affected by nitrogen (N) fertilization. We aimed to (a) define and explain the economic optimum nitrogen rate (EONR) for grain yield in feed (EONRf) and malting barley (EONRm), and (b) analyze if grain quality requirements are reached at the EONRm. We evaluated six N rates (0, 40, 80, 120, 160, and 200 kg N ha⁻¹) in field experiments (14 site-years). At each site-year, the EONR was calculated using two fertilizer cost to grain price ratios, 6:1 for feed and 4:1 for malting barley. On average, maximum yield and protein response to N were 1,681 kg ha⁻¹ and 2%, respectively. There was no consistent effect of N fertilization on grain size. The EONRf was explained by N availability and maximum yield response to N (y = 130 – 0.37N availability + 0.03N response, r² = .89), and EONRm was explained solely by N availability (y = 320 – 0.93N availability, r² = .75). The overall EONRm was 134 kg N ha⁻¹. At sites with low soil N availability and high yield response to N, an average N rate of 69 kg ha⁻¹ greater than the EONRm was necessary to reach 9.5% protein. Otherwise, the EONRf could be used (106 kg N ha⁻¹) and grains be sold as feed barley. These results are useful to adjust N fertilizer recommendations to satisfy the malting industry demand while reducing the economic and environmental impacts of fertilization.

中文翻译：

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饲料和麦芽大麦的经济最佳施氮量分析

麦芽行业对麦芽大麦 ( Hordeum vulgare L.) 谷物蛋白质浓度（9.5% 至 13%）和大小（>85%）有特定要求，这可能会受到氮 (N) 施肥的影响。我们的目标是 (a) 定义和解释饲料中谷物产量 (EONRf) 和麦芽大麦 (EONRm) 的经济最佳氮肥用量 (EONR)，以及 (b) 分析在 EONRm 下谷物质量是否达到要求。我们在现场实验（14 个场地年）中评估了六种 N 速率（0、40、80、120、160 和 200 kg N ha ^-1）。在每个站点年，EONR 使用两种肥料成本与谷物价格比率计算，饲料为 6:1，大麦麦芽为 4:1。平均而言，最大产量和蛋白质对 N 的响应为 1,681 kg ha ^-1和 2%，分别。施氮肥对籽粒大小没有一致的影响。EONRf 由 N 可用性和对 N 的最大产量响应（y = 130 – 0.37N 可用性 + 0.03N 响应，r ² = .89）解释，EONRm 仅由 N 可用性（y = 320 – 0.93N 可用性，r ² = .75)。总EONRm为134 kg N ha ^-1。在土壤氮含量低且对氮的产量响应高的地点，平均氮含量比 EONRm 高69 kg ha ^{-1是达到 9.5% 蛋白质所必需的。}否则，可以使用 EONRf (106 kg N ha ^-1) 和谷物作为饲料大麦出售。这些结果有助于调整氮肥建议以满足麦芽行业的需求，同时减少施肥对经济和环境的影响。