Abstract
Problem statement: Peatlands are natural sequesters of carbon and nitrogen. Once they are disturbed the tendency to lose carbon and nitrogen to the environment is very high. This study investigated the effect of converting peat land forest into oil palm plantation on soil chemical properties with particular emphasis on carbon and nitrogen storage. Approach: Soil samples were collected randomly at depths 0-25 and 25-50 cm from a secondary forest and from four different ages of oil palm plantations at woodman oil palm plantation located in Sarawak, Malaysia. Soil pH in water and KCl, Organic Matter (OM), Organic Carbon (OC), Total Nitrogen (TN), Organic Nitrogen (ON), ammonium, nitrate, available phosphorous, carbon to nitrogen ratio, carbon to phosphorous ratio and bulk density were determined using standard procedures. The bulk density method was used to quantify Carbon (C), Nitrogen (N), ammonium, nitrate and available phosphorous storage on per hectare basis. Results: Statistical analysis showed that the OC content was statistically similar for all soil depths and vegetation types (forest or plantation). The TN content was statistically higher for secondary forest. Conclusion: Regardless of depth, C sequestration was not altered due to land use change but the secondary forest had higher stores of soil N.
Highlights
Peat is defined as the accumulation of purely one hundred percent organic matter and the distinction between soil and vegetative accumulation is not clear[1]
Soil Organic Matter (SOM) was determined by the wet oxidation using sulfuric acid and digestion catalyst (K2SO4, CuSO4 and SeO: ratio 100:10:1)
The pH values of this study were typical of tropical peat soils[3]
Summary
Peat is defined as the accumulation of purely one hundred percent organic matter and the distinction between soil and vegetative accumulation is not clear[1]. The soil division of Sarawak, Malaysia adopted a more recent definition which is based on soil partition, i.e. soils that have 50 cm or more Soil Organic Matter (SOM) within 100 cm or more than twice that of mineral soil materials overlying bedrock within 50 cm[2]. Peat soils form generally in large basin swamps which are dome-shaped. Organic soil deposits occupying the central portion of the dome, generally known as ‘ombrogenous peat’, comprises mainly of disaggregated tree trunks, branches, leaves, roots and fruits. Occurrence of peat soil around the globe is about 423.7 million ha. The occurrence of peat soil in Sarawak, Malaysia is estimated to be about 1.8 million ha which is the largest hectarage for any of the Malaysian states[3]
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