The possibilities of composting Asian knotweed

Abstract

Many industrial platforms producing compost refuse organic waste from mowing or grubbing up knotweed in order to avoid marketing a product that might still contain living diaspores, there is in fact relatively little data on this risk. This risk was thus studied in a trial conducted by the Savoie department at the Grand-Chambéry platform. It consisted in massively integrating the different parts of the plant (rhizomes, seeds and stems) and studying their survival over a complete composting cycle. The results show that the process, as implemented on this platform, leads to the devitalization of the stems, seeds and rhizomes of Asian knotweed and that there is no risk of spreading the plant via the diffusion of the final compost. These results can be extended to composts produced under the same conditions of duration, temperature rise and frequency of turnings. On the other hand, observations made during the entire production period show that composts produced in a few weeks with a single turn may contain rhizomes or seeds of Asian knotweed that are still alive.