Mineralogical and charge properties of volcanic ash soils from West Sumatra Indonesia

Fiantis D., . and Van Ranst E., . and Shamshuddin Jusop, . (1997) Mineralogical and charge properties of volcanic ash soils from West Sumatra Indonesia. [Proceedings Paper]

Four volcanic ash soils from two toposequences along Mt. Marapi and Mt. Talamau West Sumatra were studied in order to characterise their mineralogical and charge properties. In all the soils the silt fraction is composed mainly of gibbsite cristobalite and feldspar while the clay fraction is composed mainly of cristobalite feldspar and halloysite. Gibbsite is only present in the clay fraction of the soils from Mt. Talamau while opal-A is only found in the clay of the soils from Mt. Marapi. Allophane contents computed from Si and Al extracted by ammonium oxalate and pyrophosphate are lower in the surface horizons than in the subsoil. This is related to higher amounts of organic matter in the topsoil. Due to higher rainfall the soils of the Mt. Talamau are more weathered than those of the Mt. Marapi. This is reflected by lower allophane and higher ferrihydrite contents in the soils of the Mt. Talamau. In all the soils the surface horizons have lower pHo value than the underlying B-horizons. The negative variable charge in the soils varies from 6 to 10 cmol/kg soil while the negative permanent charge varies from 0.42 to 7.4 cmoljkg soil. The AEC is higher in the subsoil than in the topsoil having values ranging from 0.3 to 1.1 cmoljkg soil.

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Abstract

Four volcanic ash soils from two toposequences along Mt. Marapi and Mt. Talamau West Sumatra were studied in order to characterise their mineralogical and charge properties. In all the soils the silt fraction is composed mainly of gibbsite cristobalite and feldspar while the clay fraction is composed mainly of cristobalite feldspar and halloysite. Gibbsite is only present in the clay fraction of the soils from Mt. Talamau while opal-A is only found in the clay of the soils from Mt. Marapi. Allophane contents computed from Si and Al extracted by ammonium oxalate and pyrophosphate are lower in the surface horizons than in the subsoil. This is related to higher amounts of organic matter in the topsoil. Due to higher rainfall the soils of the Mt. Talamau are more weathered than those of the Mt. Marapi. This is reflected by lower allophane and higher ferrihydrite contents in the soils of the Mt. Talamau. In all the soils the surface horizons have lower pHo value than the underlying B-horizons. The negative variable charge in the soils varies from 6 to 10 cmol/kg soil while the negative permanent charge varies from 0.42 to 7.4 cmoljkg soil. The AEC is higher in the subsoil than in the topsoil having values ranging from 0.3 to 1.1 cmoljkg soil.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. mal S 590.2 S683 1997 Call Number
AGROVOC Term:	Mineralogy
AGROVOC Term:	Volcanic ash soils
AGROVOC Term:	Feldspar
AGROVOC Term:	Clay
AGROVOC Term:	Allophane
AGROVOC Term:	Rainfall
AGROVOC Term:	Top soil
AGROVOC Term:	Volcanic areas
AGROVOC Term:	Soil physicochemical properties
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:14
URI:	http://webagris.upm.edu.my/id/eprint/12172

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