booklet aceh barat.pdf - Balai Penelitian Tanah

2.3. Soil
Based on the Soil Taxonomy (Soil Survey Staff, 2003), soils in the study
area can be distinguished into orders of Entisols, Inceptisols, Histosols, Ultisols and
Mollisols.
Entisols in this district are located under the permanently water saturated
environment. Inceptisols are formed on the drier environment with the ground water
table depth of more than 40 cm which facilitates weathering process (oxidation and
soil structure development).
Histosols, on the other hand, formed from organic deposits under water
saturated condition in the concave areas. Thickness ranges from 0.5-6 m and in
some places around the centre of the dome it reached > 9 m thick. Peat maturity
ranges from immature (fibric) from which peat the structure of plant fibre can still be
observed, somewhat mature (hemic) from which the plant fibre has disappeared and
mature (sapric) from which there is no more sign of plant fibre left.
Ultisols, formed from claystone underlain by sandstone, were located in the
undulating to rolling uplifted ancient marine sediment, which are situated behind the
alluvial and/or peat dome groups.
Dominant soil in the hilly to mountainous areas are Hapludults and
Dystrudepts. More than 60% of these regions falls into protection forest areas.
Hilly to mountainous topography of dykes (volcanic group) are dominated by
Hupludults and Dystrudepts, they are shallow soil (lithic sub-grup and associated
with rock out crops). Karst group (limestone) are dominated by shallow soil of
Haprendolls, Dystrudepts associated with rock outcrops. Dominant soils, their
properties and major land uses by physiographic groups in Aceh Barat District are
listed in Table 3 and spatially depicted in Figure 1. Area of each land use is provided
in Table 4.
17