Hairy Vetch Seedbank Persistence and Implications for Cover Crop Management

Abstract

Hairy vetch (Vicia villosa Roth) is a fast‐growing, winter‐hardy annual legume that is well suited for summer annual grain rotations because it fixes N2, reduces erosion, and suppresses weeds. Utilization of hairy vetch as a cover crop has been limited due to producer concerns regarding its potential to become a weed in subsequent crops. Hairy vetch weediness is attributed to its hard seed, a physical dormancy trait common to Vicia species. A 2‐yr field experiment was conducted in Pennsylvania and Maryland to characterize the effects of mechanical scarification and burial depth on seedbank dynamics using two cultivars. Field and laboratory measurements were conducted to determine seedbank fate: seedling emergence, seedbank persistence, and seedbank loss. Hairy vetch emergence and persistence in the soil seedbank varied considerably across cultivars, years, and study locations. Scarification completely eliminated seedbank persistence 6 mo after burial but probably reduced viability and stand establishment in some cases. Among unscarified seed treatments, seedbank persistence ranged from <1 to 7% 6 mo after burial. Burial of seed at 15 cm resulted in decreased seedling emergence and increased seedbank loss in comparison to the 3‐cm burial depth. Among treatments, seedling emergence ranged from 36 to 84% at the 3‐cm depth and 7 to 46% at the 15‐cm depth. These results indicate that mechanical scarification is a potential strategy for managing hairy vetch seedbank persistence and warrants further investigation. Tillage may also be effective for decreasing hairy vetch seedbanks when coupled with other management tactics.