Peat Soil Labile Carbon in Selected Agroecosytems and Its Use.

Tropical peatlands forms a large carbon (C) pool but their C sink is labile and sensitive to disturbance in environmental conditions. This disturbance will lead to emission of green house gases such as carbon dioxide to the atmosphere. Changes in soil carbon from natural state ecosystem (forest, reference site) to agriculture land such as oil palm, sago and pineapple ecosystems in Mukah, Sarawak, Malaysia were studied. The experimental area was about 12 years under cultivation. At all agriculture sites, the proportional changes in labile C were greater than the changes in total C as compared to the reference site (forest) which ranged from 7-32% and 1-5% respectively.  This is because labile C represents the C fraction that is more easily oxidized and lost. Oil palm and pineapple ecosystems showed an approximately 23% and 7% increase in labile C in the surface to 15 cm soil depth respectively, as compared to the reference site, thus higher in Carbon Management Index (CMI) values. In sago ecosystem, the decline in labile C was approximately 32% in the surface to 15 cm as compared to the reference site resulting in lower CMI value. Samples collected down to 60 cm depth for each ecosystem indicate a significant increase in labile carbon. The increase may be due to the inherent undecomposed materials that are found in peat soil as the soil depth increases. Labile C and the CMI can be used to monitor the rate of changes in soil C for different land use on peat.