USEFULNESS OF THE C-13 TRACER TECHNIQUE FOR CHARACTERIZING TERRESTRIAL CARBON POOLS

Application of the carbon-13 (C-13) tracer technique to soil organic c arbon emission is relatively new to many researchers and only a few re sults have been reported to date. This mini-review paper cites some we ll-documented research in organic carbon pool studies using the C-13 t racer technique. The C-13 abundance in soil usually remains at a stabl e level under a set of natural conditions. Variations in C-13 reflect different sources and types of organic components from natural environ ments. An important feature of C-13 discrimination in the soil C pool has permitted researchers to assess the dynamic nature of the pool. Th is discrimination may reflect a selective preference at early stage of residue decomposition by soil microbes. Crop rotation and residue inp ut to humic substances can change the C-13 abundance, which is a possi ble way to estimate soil C emission. However, the dynamic relationship between C-13 abundance in the soil C pool and C emission is still in an early stage of development. Restrictions due to requirement of long -term experiments and duration of vegetation changes may affect its wi de-spread adoptions in C emission studies.