Improving the productivity and stability of oilseed cropping systems through crop diversification

Diversifying cropping systems is essential to enhance oilseed production resiliency in a changing climate. Here, we determined the productivity and stability of five oilseed crops under different crop stubble management strategies over all nine environments. A 2-year cropping sequence study was conducted at nine environ-sites (3 sites×3 independent 2-yr cropping sequence phases). Crops in year 1 consisted of chemical fallow, lentil (Lens culinaris L.)and spring wheat (Triticum aestivum L.), which resulted in fallow, lentil and wheat stubbles for the following year crops. Crops in year 2 were five oilseed crops: canola (Brassica napus L.), Ethiopian mustard (Brassica carinata L.), oriental mustard (Brassica juncea L.), yellow mustard (Sinapis alba L.), and camelina (Camelina sativa L.). Over all nine environ-sites, B. juncea had high yield and low yield variation, making it a good substitute for B. napus, the primary oilseed crop in acreage on the Canadian Prairies. Lentil and wheat stubbles reduced oilseed crop yields by 4% and 5% compared with chemical fallow, respectively; however, at the 2-yr cropping sequence level, lentil-oilseed sequence increased system production, expressed by annualized canola equivalent yield, by 33% compared with wheat–oilseed sequence and by 112% compared with fallow–oilseed system. The lentil-oilseed sequence had the lowest variation in production and was most suitable for high-yielding environments compared with fallow- and wheat–oilseed sequences, while B. juncea- and B. napus-based cropping sequences were most stable based on the static and dynamic stabilities among all five oilseed-based cropping sequences. Crops explained more variation in system production than weather (40% vs 5%)because of a dramatic difference of cropping sequences with and without fallow. Under changing climatic conditions, diversifying conventional wheat- or fallow-based canola systems using lentil and B. juncea will enhance system productivity and yield stability across different environments.