Tumbleweed Mitigation through Biochar Production

Russian Thistle (Salsola tragus), which turns into “tumbleweed” when it dries, is an invasive species and poses a threat to surrounding native vegetation and ecosystems. Though originating from the Russian steppe, tumbleweed has adapted to the American southwest readily. This pest is almost impossible to kill; the seeds are viable for 2-3 years and only need a few hours of moisture to germinate. Each plant, when mature, can grow to be the size of a small car and can release up to 200,000 seeds. In addition to competing with native plants, tumbleweed creates fire hazards, dramatically reduces crop yields, promotes wind erosion of soil, and causes allergies when flowering. There have been numerous control measures, including biocontrols, tested but these have yet to give satisfactory results. Pyrolysis, a thermochemical process that transforms biomass through heating under limited-oxygen conditions, can be used to make tumbleweed into biochar and renewable energy. Biochar has the potential to sequester carbon, enrich soils, and increase water retention.