Additional information

Rapeseed crops are susceptible to insect damage and weed competition. Research by INRA (France’s National Institute for Agricultural Research) showed that growing winter rapeseed crops together with companion legumes could be a more sustainable alternative to using synthetic herbicides - reducing weed pressure while maintaining the crop yields.



A winning combination

Sown at the same time at the end of summer, the winter rapeseed crop and its companion plants grow together during autumn - until the winter frosts naturally kill off the legumes.

During the autumn growth phase, the rapeseed crop and companion plants, but also weeds, compete for nutrients and light. The rapeseed crop is less affected by this competition when the companion plants are legumes because the latter compete less for nitrogen due to their ability to fix atmospheric nitrogen.

At the start of winter, the presence of companion plants caused a reduction in weed biomass of between 38% and 52%. Field bean (Vicia faba), lentil (Lens culinaris) or a mixture of the two also allows a reduction of nitrate inputs up to 25% (30-40 kg/hectare) without diminishing the crop yield significantly.

The project results showed that the cultivation of rapeseed crops in the presence of non-harvested companion legumes is a promising practice, particularly on nitrogen-poor soils. Field beans alone or mixed with lentil display the best overall performance.

Further studies need to be done to further evaluate the socioeconomic and environmental value of using companion plants and to prove the sustainability of this practice.