"Organic carbon" refers to the carbon found in living or once-living organisms, such as plants, animals, and microorganisms. It is a critical component of the biological cycle and is essential for life on Earth. Full definition
There are at least ~ 1500 billion tons of organic carbon in permafrost zone soils, almost twice as much as currently exists in the atmosphere. (searcharcticscience.org)
The results showed that mature forest stands stored significantly more soil organic carbon in strongly mineral - bound and stable carbon pools than did soils from cut stands. (sciencedaily.com)
Also, there has not been a uniform definition of soil organic carbon sequestration among researchers. (en.wikipedia.org)