Diversification with minor oilseeds: Effects on system productivity and nitrogen use efficiency in semi‐arid Canadian prairies

Abstract Diversified cropping systems in the semi‐arid Canadian prairies comprise major cereal, oilseed, and pulse crops. Further diversification with minor oilseeds, such as oriental ( Brassica juncea ), industrial ( Brassica carinata L.), and yellow ( Sinapis alba L.) mustard, camelina [ Camelina sativa (L.) Crantz], and flax ( Linum usitatissimum L.) could enhance productivity and sustainability. This 5‐year (2018–2022) study, conducted at four sites (Brooks and Lethbridge, Alberta, and Scott and Swift Current, Saskatchewan), compared system productivity, expressed as annualized canola ( Brassica napus L.) equivalent yield (CEY), and nitrogen use efficiency (NUE) of 14 cropping sequences, and examined the effect of stubbles, particularly minor oilseeds, on subsequent crop yields and the influence of soil and environmental driving factors. Averaged across sites, CEY was significantly higher for cropping sequences with minor oilseeds and pulses compared to continuous spring wheat ( Triticum aestivum L.) or wheat with fallow. However, there were no significant differences in CEY among sequences with oilseeds and between sequences with oilseeds and field pea ( Pisum sativum L.) versus lentil ( Lens culinaris Medikus). While CEY and NUE were similar between sequences with minor oilseeds and canola, NUE (grain yield based) was significantly higher for the conventional (spring wheat, canola, and pulse) than diversified sequence with minor oilseeds. Furthermore, the minor oilseeds had no adverse effect on subsequent pulse grain yields. Growing season and July mean air temperature most significantly impacted productivity and NUE. Our findings reveal that diversifying existing cropping systems with minor oilseeds can sustain productivity while enhancing NUE in the semi‐arid Canadian prairies.