Carbon isotopes also record drought, Springer added, because drier soils slow biological activity. This causes the soil to “breathe less, changing the mix of light and heavy carbon atoms in it,” he said.

http://news.research.ohiou.edu/news/index.php?item=503

Despite the other implications from this article,

...here is a key to understanding how to measure CO2 sequestration in soil.

~ more later, I hope.

Pyrolysis creates reduced carbon! ...Time for the next step in our evolutionary symbiosis with fire.