Carbon management index of tropical peat soil planted with various crops

Tropical peatland constitutes over 80% of the global area and can stores up to 20% of global peatland carbon. In Malaysia, there are about 2.3-2.7 million ha of peatland area and about 1.7 million ha is found in Sarawak. The carbon sink of a peatland is labile and sensitive to disturbance in environmental conditions. This study was conducted to investigate the changes in labile carbon of different land use on peat thus to establish the Carbon Management Index. The lability of soil carbon as a measure of sustainability which is proposed in this research is based on the degree of oxidation of organic carbon by potassium permanganate. Thus technique allows monitoring of small, short term changes in soil carbon which cannot be detected using total carbon measurements and the Carbon Management Index as a tool to monitor differences in soil carbon dynamics. The study sites were located in Mukah Dalat area, Sarawak and in Simpang Renggam, Johor. Peat samples from peat swamp forest were collected as a reference site for Carbon Management Index calculation. Top soil sample (0-15 cm) was used in this study. Means we compared to the reference (forest) using Dunnett`s test. In Mukah, the labile carbon content for sago (24.9 µg C/g soil), oil palm (237.1 µg C/g soil) and pineapple (214.7 µg C/g soil) are higher compared to the forest (177.4 µg C/g soil). There is a significant difference for sago and oil palm ecosystems compared to the forest. Meanwhile in Simpang Renggam, the forest (190.0 µg C/g soil) shows the highest content of labile carbon compared to oil palm (89.7 µg C/g soil) and pineapple (134.8 µg C/g soil) ecosystems. There is a significant difference for oil palm and pineapple ecosystems compared to the forest. Mukah forest ecosystems shows the lowest CMI value while that in Simpang Renggam, the highest CMI. It is believed that the differences in results among these two sites may be due to the use of different secondary forest asa reference site. Besides, the history of both plantations should also be considered because the age gap between these two plantation sites which is about 30-40 years old may have caused these differences. The older plantation has been exposed to a long term oxidation, subsidence etc. thereby having less labile C compared to the younger plantation. There is a possibility of using Carbon Management Index to monitor the soil carbon changes on peatland after conversation from forest to agriculture land.