State of decomposition of tropical peat soil under cultivated and fire damaged peatland
2002
Kurnain, A. (Universitas Lambung Mangkurat, Banjarmasin (Indonesia))) | Notohadikusumo, T. | Radjagukguk, B. | Hastuti, S.
The state of decomposition of tropical peat soils and changes in peat soil properties as affected by agricultural practices and fire damage were studied. Peat soils were sampled on a 10 x 15 km2 area in Central Kalimantan that represents four different land use systems, namely pristine peat swamp forest, burnt peat forest, clear cut peat forest, and peatland cultivated with maize, pineapple and rubber. Decomposition degree of tropical peat soil was indirectly measured by combined methods of fibre content and optical density of alkaline peat extract. Other peat soil properties relevant to the combined methods of fibre content and optical density could be applied to quantify the state of peat decomposition as affected by agricultural practices and damage. The fibre content and optical density of the peat extract expressed as E4/E6 significantly decreased with agricultural practices and fire damage, signifying that the peat substrates were more decomposed, especially in the top layer which is the most important for agricultural development. Compared to pristine peat swamp forest, the E4/E6 value and fibre content were 0.4 to 0.8 times lower for the cultivated and fire damaged peatland. The accelerated peat decomposition has led to an increase in ash content and bulk density and to a decrease in fibre content, organic C content, field moisture content, and specific volume of the peat soil. Shrinkage of the peat soil was substantially caused by dewatering and can be predicted by a simple straight-line model as obtained in this study
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