Mixtures of plant species greatly increase weed suppression

What is it about?

Across 31 sites in Europe and Canada weed suppression by mixtures of plant species was investigated under agricultural conditions. At each site the study compared weed yield in 11 mixtures of plant species with weed yield where each species was grown by itself (monocultures). Each of the 11mixtures consisted of different proportions of two grass and two legume species and each of the four species was also grown in monoculture. Average weed yield in mixture over the whole experiment was 52% less than in the best (least weedy) monoculture. This effect persisted over 3 years. Weed yield for all mixtures was consistently low and relatively similar across all years. From a scientific perspective this study showed a strong and robust effect of diversity (multiple species) on weed suppression, while the consistency of the effect across mixtures and time are important from an agricultural viewpoint.

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