Effect of preceding crop and nitrogen application on malting barley quality

As legume crops fix nitrogen (N) from the atmosphere, there is concern that soil residual N from legumes grown in rotation with malting barley may result in unacceptably high protein content and have negative effects on quality. However, little research has been conducted to investigate this. Field pea, lentil, faba bean [as seed or as a green manure (GM) crop], canola, and wheat were grown in 2009, canola in 2010, and malting barley in 2011. The objective was to determine the effects of crops grown in 2009 on the quality of barley grown in 2011. Crops were direct-seeded at Lacombe (Alberta), Swift Current (Saskatchewan), and Brandon (Manitoba). Fertilizer N (urea) was applied in 2010 and 2011 at 0, 30, 60, 90, and 120 kg ha-1. The legumes had few negative effects on barley quality compared with canola or wheat. Exceptions occurred at Lacombe where the lentil and faba bean GM crops increased protein and decreased kernel plumpness. This was not evident at other locations. Increasing N fertilizer rate negatively affected almost all malt quality parameters at all locations. The results indicate that growing legume crops prior to malting barley is less likely to reduce malting barley quality than applying fertilizer N.