This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Transitioning an aging perennial forage seed stand into annual cropping can be difficult, particularly when the original crop persists or weeds establish after termination. Preliminary Canadian research suggests cover crops could help by suppressing regrowth and weeds, retaining biomass and cycling nutrients.
The three-year study began in 2024 after a creeping red fescue stand was terminated with herbicide. Researchers compared five treatments containing combinations of hairy vetch, sweet clover, fall rye, tillage radish and field pea. No fertilizer was applied.
Cover crop competition provided the main weed suppression, with mowing used to prevent seed set. Residues were retained to decompose before canola was planted in 2025. Wheat will follow in 2026.
Hairy vetch produced the most first-year biomass at 7.5 tonnes of dry matter per hectare. Hairy vetch with sweet clover produced 7.0 t DM/ha, followed by hairy vetch with fall rye at 6.6 t DM/ha. These treatments formed dense canopies and showed the strongest potential to suppress weeds.
Field pea produced less biomass and was associated with greater weed pressure in the following season. These results highlight the importance of rapid establishment and canopy closure when choosing a cover crop to compete with weeds and regrowth. Severe drought affected canola establishment in 2025.
Biennial sweet clover was also planted instead of the intended annual type, while fall rye persisted into the second year. The economic results therefore need cautious interpretation. Sweet clover with tillage radish produced the highest canola-equivalent return, followed by hairy vetch with sweet clover.
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