Precipitation and nitrogen management are key drivers of cropping system productivity in the Canadian prairies

Abstract

The performance of cropping systems is a function of crop and management practice interaction in a given growing environment. However, the critical factors affecting productivity remains unclear under varying climate conditions. We conducted a 5 year study at six sites in western Canada to identify the critical factors affecting the productivity, standardized as protein-based yield (PBY), and quantify the relationships between yield and critical factors. We tested six crop rotations, including conventional system (Control), pulse-or oilseed-intensified system (Intensified), diversified system (Diversified), market-driven system (Market-driven), high-risk and potentially high reward system (High-risk), and soil-health enhanced system (Soil-health). The importance index and structural equation modeling were used to identify key factors and explore the underlying relationships among them. Results showed that Market-driven and Diversified rotations outperformed the Control by 2%–6% in PBY, while Soil-health and High-risk yielded 23%–26% lower than the Control. Relative to the Control, all rotations showed an increase trend in PBY over time, with Diversified rotations increasing 13%–28% faster than Market-driven and Intensified rotations. Precipitation and nitrogen (N) management are the primary factors affecting cropping system productivity, explaining 25% and 21% yield variations, respectively. Structural equation modeling analysis revealed that precipitation had a significant indirect effect on yield through affecting biological N fixation of pulse crops, in addition to a significant direct effect. Increasing pulse frequency and rotation complexity mitigated PBY loss by 10%–24% during low rainfall seasons. We recommend integrating pulse crops into cropping systems to enhance N management and mitigate yield loss in low precipitation regions.