Australia is currently the world leader in the recognition of the soil carbon opportunity, and the development of carbon markets that include soil carbon.
In the United States, the current carbon market at the Chicago Climate Exchange buys offsets or "pollution credits" as some have called them. The amount of carbon sequestration purchased is directly related to emissions of carbon into the atmosphere by industries, for example. As the trading price of carbon offsets increases, presumably emissions will go down, but then so will the purchase of offsets.