ABSTRACT
Carbon in soils exists in both organic and inorganic forms. Carbonate, in a variety of forms,
makes up the inorganic component of total carbon (TC), whereas a range of organic moieties
make up the organic carbon (OC) component. The terms OC or organic matter associated
with soil have been defined in various ways. Stevenson (1994) and Baldock and Nelson
(1998) defined OC as the total of all organic materials existing within and on soil, whereas
Oades (1988) excluded charcoal and charred materials and MacCarthy et al. (1990) excluded
nondecayed plant and animal tissues, their partial decomposition products, and the living soil
biomass. In reality, however, the methods used to determine both TC and OC do not
discriminate between the various fractions described above, and consequently, the all
encompassing definition of OC used by Stevenson (1994) and Baldock and Nelson (1998)
is also used in this chapter.
