Reduced nitrogen rate sustains malt barley yield and quality in malt barley-pea rotation

Rotational benefit of pea (Pisum sativum L.) may reduce N fertilization rate and sustain malt barley (Hordeum vulgare L.) yield and quality in the malt barley-pea rotation. This study examined the effect of cover crop [oat (Avena sativa L.) cover crop vs. none] and N fertilization rate (0, 40, 50, 60, 70, and 80 kg N ha⁻¹) on malt barley growth, yield, and quality in the malt barley-pea rotation from 2012 to 2019 in the northern Great Plains. Cover crop biomass yield and N accumulation were greater in 2016 than other years. Compared to fallow, malt barley plant density with cover crop was 9%–13% lower from 2013 to 2015, but 10% greater in 2017. Malt barley straw yield was 38% greater in 2017 and grain yield 15%–39% greater in 2017 and 2018, but grain plumpness was 5%–10% lower in 2014 and 2017 with than without cover crop. Increasing N fertilization rate linearly increased grain yield and N uptake, but reduced grain test weight and plumpness in most years. Straw N concentration and uptake and grain protein concentration varied by year. Because of the similar grain yield, protein concentration, plumpness, and test weight between 60 and 80 kg N ha⁻¹, 60 kg N ha⁻¹ can be recommended to sustain malt barley yield and quality in the malt barley-pea rotation, regardless of cover crops. This helps to reduce N fertilization rate by 20 kg N ha⁻¹ for malt barley in dryland cropping systems of the US northern Great Plains.