27.5 Soil Characteristics
27.5.1 Physical Properties
Peat in Thailand is mostly composed of slightly decomposed to semi-decomposed
organic soil materials with very dark gray to dark reddish brown (5YR 2-3/1-2)
color. If the coarse woody fragments are taken out, the soil materials as evaluated by
determining the fiber content and the color of the sodium pyrophosphate extract
mainly consist of fibric soil materials. Commonly, the fiber contents are above 75%.
However, in the drained swamps, the surface tier (beneath the fibrous mat of few
inches on the top) appears to be more decomposed and some of them can be
identified as humic soil material. Consequently, the bulk density of these soils is
very low ranging from 0.1 to 0.32 gm/cc. The hydraulic conductivity, on the
contrary, varies from 0.001 to 0.032 cm/s, due to the heterogeneity of the soil matrix.
In order to analyze the heterogeneous morphological characteristics of peat in
Thailand, Yonebayashi (1992) dug three long trenches in Narathiwat peat swamps
and illustrated the woody peat profile in Fig. 27.9.
Fig. 27.8 Formation of Bacho swamp and To Daeng swamp
27 Sustainable Management of Peatland in Thailand
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