Biomass productivity and weed suppression of diverse plant phenotypes in organic faba bean-pea intercropping

This study evaluated faba bean (Vicia faba L.) and pea (Pisum sativum L.) legume-legume intercropping for biomass productivity and weed suppression using varieties with a wide range of plant lengths and growth habits. Three years of field experiments were performed under organic management in Sweden. Ten pea varieties and three faba bean varieties were tested in a replacement design with different variety combinations and seeding ratios. The highest total biomass production (8–10 t ha−1) and weed suppression were obtained by intercropping long and vining pea landraces with faba bean. Intercrops often showed a higher biomass productivity compared to the corresponding pure stands with average LERtot of 1.14, 1.14, and 1.05 in the years 2021–2023, respectively, and pea was the more competitive species. Pea biomass and weed biomass correlated negatively, and a substantial difference in correlation was observed between pea and weed biomass in intercrops (−0.78) and pure stands (−0.34). Negative correlations were found between weed biomass and early ground cover (−0.47) and early pea height (−0.46) in intercrops. In conclusion, faba bean-pea intercropping with phenotypes present among traditional varieties can reduce weed biomass and produce crop biomass similar to or higher than pure stands of modern varieties of either species.