ABSTRACT
World soils represent the third largest global C pool. Soils contain about 1550 Pg of soil organic carbon (SOC) and 750 Pg of soil inorganic carbon (SIC) (Batjes, 1996). The SOC pool is about 2.2 times the atmospheric pool (720 Pg) and 2.8 times the biotic pool (560 Pg). The geologic pool is estimated at 5000 Pg, comprising 4000 Pg of coal and 500 Pg each of gas and oil (Post et al., 1990). There is a direct linkage between the SOC pool and the atmospheric pool. Change in SOC pool by 1 Pg is equivalent to a 0.47 ppmv change in the atmospheric C 0 2 concentration. The atmospheric pool has steadily increased from a pre-industrial concentration of 280 ppmv around 1850 to 365 ppmv in 1995 (IPCC, 1996; Hansen et al., 1998). The atmospheric pool has increased at the expense of the soil, biotic and the geologic pools.
