Welsh forest study: crushed rock and soil microbes boost carbon capture in young woodlands by up to 27%

A field trial in Glandwr Forest, Carmarthenshire, found that adding crushed basalt rock to soil increased aboveground carbon storage in young native woodlands by 27% over four years. Applying beneficial soil microbes boosted carbon capture by 13%. The study, led by Imperial College London and The Carbon Community, is the largest of its kind with 72 plots across 28 acres and 200 volunteers monitoring 6,400 trees annually. The interventions work in different ways. Enhanced rock weathering releases calcium and raises soil pH, making nutrients more available to trees. Microbial enrichment helps tree establishment in the first year, especially for spruce and oak. If applied to the UK's target of 37,000 hectares of new woodland per year, these methods could remove an extra 45,000 to 106,000 tonnes of CO2 in the first four years alone. The results are peer-reviewed and published in Communications Sustainability. They offer practical, low-cost options for reforestation projects to increase carbon removal without needing more land. Further studies will measure belowground carbon storage.