Abstract Winter intercropping offers a promising strategy to enhance land use efficiency and crop productivity in temperate agroecosystems. This 5‐year field study evaluated the performance of winter pea ( Pisum sativum L.)–canola ( Brassica napus L.) intercrops (peaola) under reduced nitrogen fertilization and variable plant population densities in southwestern Ontario. Intercropping in alternate rows significantly improved pea yield, with sole pea crops averaging 1.2 Mg ha −1 compared to 1.8–2.4 Mg ha −1 in intercrops, depending on density and overwinter survival. Land equivalent ratio values ranged from 1.0 to 2.3, and transgressive overyielding index exceeded 1.0 in high‐survival years, indicating that intercrops outperformed the best‐yielding sole‐crop. Net‐effect ratios (NERs), weighted using observed spring species proportions, further revealed how winterkill‐driven shifts in relative density shaped intercrop performance: high net‐effect ratio weighted using observed spring species proportions values aligned with years of strong pea survival and high total spring relative density. Intercropping also altered canopy structure by elevating pea pod height from 49 cm in sole‐crops to 87 cm in intercrops, enhancing light capture during canola senescence. Canola yield declined by over 40% relative to the sole‐crop baseline in years of vigorous pea growth, reflecting competitive interactions, yet overall system productivity improved whenever both species survived winter and maintained adequate spring density. These findings highlight how winter intercropping can enhance land use efficiency and, in years with strong legume survival, deliver substantial yield gains through combined temporal and structural complementarity.
Page et al. (Fri,) studied this question.