Substantial amounts of organic carbon are buried in an ancient layer of soil found in parts of the Central Great Plains of the US, reports a paper published this week in Nature Geoscience. Much of this carbon is in forms that could decompose to carbon dioxide if exposed to the atmosphere by land disturbance.
Erika Marin-Spiotta assessed the carbon chemistry of an ancient layer of soil known as the Brady soil, which formed between 10,000 and 12,000 years ago in parts of present-day Kansas and Nebraska, and was subsequently buried by metres of wind-blown sediments. From their analysis, Marin-Spiotta and colleagues found that some of the carbon is in the form of black carbon left over from biomass burning. They also found intact plant material that was saved from decomposition by rapid burial.
In an accompanying News and Views article, William C. Johnson writes that “ongoing and expanding anthropogenic land disturbances are increasing the risk that these buried reservoirs of reactive carbon could be exposed to decomposition, releasing carbon to the atmosphere.”