On Wilbourne Farm in Virginia, a carbon-removal experiment is underway. First a tractor sprays nearly 20 tonnes of gray crushed basalt over one field. Then the farmer makes several more passes spreading other material in different combinations: bone-white limestone dust, rich black biochar and chicken litter compost that reeks of ammonia. Each of these materials can boost both crop yields and the amount of carbon stored in soil. And Wilbourne Farm will help reveal whether these different ways of removing carbon from the atmosphere can be even more more effective in combination.
