Optimizing seeding ratios of field pea–brown mustard intercrops in Atlantic Canada

Abstract Intercropping is a promising approach for ecological intensification that can enhance productivity and agroecosystem services. This study evaluated the agroecological performance of field pea ( Pisum sativum ) and brown mustard ( Brassica juncea ) intercropping across seeding ratios (0.5×, 1.0×, and 1.5× the recommended rates; 100 seeds m −2 recommended seeding rate for each crop) at 4‐site years in Atlantic Canada: Canning, NS (2020); Harrington, PEI (2021); New Glasgow, PEI (2022); and Truro, NS (2024). Treatments were arranged in a randomized completed block design at each site‐year. Measurement for seed yield, land equivalent ratio (LER), and weed suppression were taken. Recommended or higher seeding rates (1.0× and 1.5×) achieved greater yields and higher LER (1.48–1.78) than sole crops (LER of 1), while the lowest seeding rate (0.5×) reduced pea yield by 38% and reduced mustard yield by 33%. Across site‐years, pea yield averaged 2507 kg ha −1 at 1.0× (100 seeds m −2 ) or 1.5× (150 seeds m −2 ) compared to 1547 kg ha −1 at 0.5× ( p < 0.001). Brown mustard showed a similar trend, yielding an average of 476 kg ha −1 at 1.0× (100 seeds m −2 ) or 1.5× (150 seeds m −2 ) versus 320 kg ha −1 at 0.5× (50 seeds m −2 ). Weed biomass declined significantly under intercropping, with the greatest suppression (62%) observed at the 1.5×:1.5× ratio at Truro (2024). Although combined site‐year data provide general trends, significant site‐year × treatment interactions suggest environmental and management factors influenced outcomes. Overall, pea‐mustard intercropping at recommended or higher seeding rates improves land‐use efficiency and weed control, supporting its potential as a component in diversified and sustainable cropping systems.