Nature-based solutions like enhanced rock weathering and microbial enrichment could increase tree growth and boost carbon storage at the same time, according to a new analysis.
A study led by researchers at Imperial College London and science-based charity the Carbon Community claims the techniques could help boost carbon capture by up to 27% in young woodlands.
Enhanced rock weathering is a process that involves applying crushed silicate rock to the soil, which over time removes carbon dioxide from the atmosphere.
The addition of crushed silicate rock such as basalt to the soil can improve tree nutrition in two ways, either by stimulating tree growth via directly releasing nutrients into the soil, or by increasing soil PH.
While microbial enrichment is a method that introduces beneficial microorganisms from established forests to the soil.
The researchers found enhanced rock weathering increased above-ground carbon storage by up to 27% in native woodland plots after four years.
And the use of microbial enrichment tended to increase above-ground biomass in native broadleaf woodland areas by 13% after four years, with the greatest benefits seen in the first year after planting.
The study is the largest field trial of its kind in the world, with 72 individually managed research plots across 28 acres of hillsides in Wales, the equivalent to 18 football pitches.
Dr. Bonnie Waring, an associate professor at Imperial College London, said enhanced rock weathering is a naturally occurring chemical reaction, which already sequesters at least 350 million metric tons of carbon dioxide every year, in an interview.
Dr. Waring added by grinding up silicate rocks, which in many cases are byproducts of mining operations, and spreading it on the soil, the process can be speeded up.
She added research around enhanced rock weathering has focuses on agricultural land in the past, but the researchers were interested on its impact on woodlands.
“The only problem with tree planting as a climate mitigation tool is we just do not have enough space to plant all the trees that we need,” she told me.
“So, combining rock weathering and tree planting together can really maximize the amount of carbon we can pull out of the atmosphere.”
Dr. Waring said the researchers found while the rock dust dissolved in the woodland and captured carbon in the soil, it also had a secondary benefit by encouraging the trees to grow and capture more carbon themselves.
“We were getting the benefit of the extra carbon in the trees, which makes foresters happy and we get the benefit of the carbon removal via the rock itself.
“Enhanced rock weathering on its own might not be as fast as some models predict, but it’s still carbon dioxide removal, and we need to stabilize the climate, and remove nine gigatons of carbon dioxide per year.
“We are nowhere near reaching that, so we need to sequester every bit of carbon that we can.”
The project is the result of a long-term collaboration between the Carbon Community charity and researchers from Imperial College London, the Royal Botanic Gardens, Kew, and the University of Sheffield.
It also represents a remarkable success of citizen science, with over 200 volunteers working alongside professional researchers to collect vital data from 6,400 individually monitored trees annually as part of its ‘Big Tree Measure’.
Charles Nicholls, co-founder of the Carbon Community, said the study’s findings come at a critical time when we must rapidly invest in effective solutions that can tackle both the climate and biodiversity crises, in a statement.
Nicholls added these two simple, but promising nature-based interventions could help transform restoration efforts, improve tree survival and increase the amount of carbon captured by every tree planted.
“It’s a scientific breakthrough with significant practical implications for the U.K’s national carbon removal strategy,” he added.
