Terradot, a carbon removal company, is using “enhanced rock weathering” to sequester carbon by spreading crushed volcanic rock over farmland.STATE OF SÃO PAULO, Brazil — Across vast stretches of farmland in southern Brazil, researchers at a carbon removal company are attempting to accelerate a natural process that normally unfolds over thousands or millions of years. The company, Terradot, is spreading tons of volcanic rock crushed into a fine dust over land where soybeans, sugar cane and other crops are grown. As rain percolates through the soil, chemical reactions pull carbon from the air and convert it into bicarbonate ions that...