Japanese knotweed has a pretty villainous reputation, but what if there was a way to positively harness its ability to scavenge atmospheric carbon and use it to help fight climate change?

That might sound ambitious but we’ve been looking for more environmentally friendly ways of dealing with Japanese knotweed waste for a number of years and following field trials at our research facility in Surrey we believe we’re onto something.

Excavation of knotweed has grown in popularity in recent years as an alternative to traditional herbicide treatments, which can damage the local environment. Currently the vast majority of plant waste removed from the ground ends up in landfill where it rots, producing damaging landfill gases such as carbon dioxide and methane.

We’ve been looking for ways to produce something useful from this leftover plant material and a few weeks ago we filed a patent for the methods and apparatus used in converting Japanese knotweed waste into biochar, a charcoal based soil amendment.

By heating the Japanese knotweed rhizome, roots and canes in the absence of oxygen, a method otherwise known as pyrolysis, it’s possible to remove the naturally occurring tars to leave biochar, a honeycomb like structure made almost entirely from carbon that can be charged up with additives such as liquid organic fertiliser, improving soil health and structure. The carbon remains sequestered in the ground for hundreds if not thousands of years.

By utilising Japanese knotweed waste in this way, we have the potential to eliminate the need for landfill altogether. We’ll be carrying out further research in the months ahead to improve the scalability and efficiency of this process, but ultimately we believe all knotweed material can be transformed from a biologically active pest, to an atmospheric-carbon scavenger, and finally to carbon gold.

To learn more about Environet’s Research & Development programme please contact us today.