This is a mapping project for measured changes in soil carbon content over time (as well as Soil Carbon Challenge entries, in yellow). The purpose is not to aggregate "offsets" or to make broad predictions, but to show what's possible as verified by actual measurements. When the purpose is to show what is possible, rather than to generate a broad-scale prediction or quantify carbon offsets, questions of statistical reliability are less troubling.
In the Sacramento Delta of California, a freshwater tidal marsh thick with tules and other marsh vegetation formed carbon-rich peat soils 60 feet deep in places. In the 1870s, farmers began to build dikes, drain the marshes, burn the tules, and farm the peat soils.