ABSTRACT
The soil C pool is 2,400 Pg (1 Pg = 1015 g = 1 billion Mg), four and three times higher than the vegetation and atmospheric pools, respectively (Eswaran et al., 1993; Lal, 2003). The soil organic carbon (SOC) pool represents the largest reservoir in interaction with the atmosphere and is estimated at about 1,500 Pg C to 1 m depth and about 2,456 Pg C to 2 m depth. The soil inorganic C (SIC) pool comprises about 950 Pg and occurs in more stable forms. Vegetation (560 Pg) and the atmosphere (760 Pg) store considerably less C than soils do (Lal, 2004).
