Seed germination of the weed Rumex obtusifolius after on-farm conventional, biodynamic and vermicomposting of cattle manure

This study investigated whether composting methods differ in their impact on seed germination of Rumex obtusifolius (broad‐leaved dock). Weed seeds were buried in windrows of cattle farmyard manure, removed at monthly intervals and germinated during the course of 7 months. Composting methods differed in the maximum temperatures reached (63°C for conventional and biodynamic composting and 35°C for vermicomposting), the addition of 1000 m^?2 earthworms (Eisenia fetida) for vermicomposting and the inoculation of biodynamic preparations for biodynamic composting. After 1 month in windrows, germination rate of Rumex seeds was significantly higher in vermicompost (48%) than in conventional (28%) or biodynamic compost (18%). After 2 months in windrows, 26% of the seeds germinated in vermicomposting windrows, while those inserted in conventional and biodynamic windrows showed a negligible germination (0% and 2%, respectively). After 3 and 4 months, only seeds under vermicomposting germinated (22% and 3%, respectively). No germination was determined when seeds were inserted for longer than 4 months in any of the treatments. Seeds stored at room temperature germinated at 89% over the course of the experiment. Results suggest that the maximum temperature reached in windrows is not the single main factor reducing weed seed germination during composting.