From the Carnegie Institution  Climate change and the soil

Climate warming may not drive net losses of soil carbon from tropical forests

Washington, DC — The planet’s soil releases about 60 billion tons of carbon into the atmosphere each year, which is far more than that released by burning fossil fuels. This happens through a process called soil respiration. This enormous release of carbon is balanced by carbon coming into the soil system from falling leaves and other plant matter, as well as by the underground activities of plant roots.