ABSTRACT
Assessment of the terrestrial soil organic carbon (SOC) pool for the U.S. requires an appreciation of the information available from soil survey. The reason is that soil survey deals with the areal quantification of land at a very pertinent scale. Relatedly, the amount of information in the soil survey is very large; some 70 to 80% of the U.S. has first generation soil surveys with a higher proportion for private than for public land. Soil survey systematics is discussed briefly. Both the estimates of SOC for areas of land (map unit components) and the laboratory data base of point samples of SOC are explored. Bulk density and rock fragment volume needed to calculate SOC on a volume basis are considered. Examples of areal expression of SOC are included. Standing biomass is briefly considered. Methods for successive estimates of organic carbon are discussed.
