Аннотация:The rising cost of N in western Canada has created interest in alternative sources of N fertilizer. Legumes have the ability to fix N supply for subsequent crops, but knowledge of the effects of legumes on subsequent canola or barley is limited. A multi‐location study was conducted from 2009 to 2011 in western Canada to evaluate the economic effects of various preceding crops (P) and N rate on subsequent canola and barley in a P–canola–barley rotation. Six preceding crops (field pea, lentil, faba bean, canola, wheat, and green manure [GRM] legume [faba bean]) were grown in factorial combination with five N rates (0, 30, 60, 90, and 120 kg ha −1 ) at seven sites in Alberta, Saskatchewan, and Manitoba. When the preceding crop was GRM, the net revenue (NR) of canola or canola–barley was highest but insufficient to compensate for negative NR during the GRM year (2009). Canola as a preceding crop yielded the least NR for the canola and canola–barley phases of the rotation. The quadratic responses of NR for canola and barley to optimal N indicated that N applied could be reduced below 120 kg ha −1 without diminishing yield at some locations in western Canada. Over the entire 3‐yr crop sequence, legume preceding crops (lentil or field pea) grown for seed provided the greatest returns. The GRM improved the yield of the following crops considerably but the increased canola and barley yields were not able to alleviate the lost NR during the preceding crop phase.
