Soil CO2 Fluxes from Different Ages of Oil Palm in Tropical Peatland of Sarawak, Malaysia

Conversion of tropical peatland into oil palm plantation in Southeast Asia has been alleged to have increased the decomposition process via peat oxidation due to drainage and water management, raising the emission of soil CO2. This is postulated to increase with age of oil palm cultivation. However, management also plays a role in soil CO2 emissions from oil palm plantations. The objective of this study was to determine the controlling factors influencing soil CO2 fluxes in different ages of oil palm on tropical peatland. The soil CO2 fluxes were measured for 24 months from three palm ages (1, 5 and 7 years palm; S1, S2, S3) in tropical peatland of Sarawak, Malaysia using a closed-chamber method. The highest mean soil CO2 flux was recorded in S3 (221 mg C m(-2) h(-1)) followed by S2 (195 mg C m(-2) h(-1)) and S1 (178 mg C m(-2) h(-1)) palms. The cumulative soil CO2 fluxes for S1, S2 and S3 were 14.7, 16.4 and 18.5 t C ha(-1) year(-1), respectively. Water table was found to have no correlation with soil CO2 fluxes but water-filled pores space (WFPS) correlated negatively with soil CO2 fluxes in all three different ages of oil palm. The increase in soil CO2 flux with palm age was consistent with higher root biomass, suggesting that root respiration and microbial activity were associated with root exudates as major component of soil respiration in tropical peatland under oil palm.