Properties and classification of andisols developed from volcanic ash in the Tondano area, North Sulawesi
1999
Hikmatullah | Subagyo, H. | Prasetyo, B.H. (Pusat Penelitian Tanah dan Agroklimat, Bogor (Indonesia))
There are a large distribution of Andisols in the Tondano area, North Sulawesi. This type of soil are very fertile for production of food and horticultural crops, but studies on these soils in the area are still very limited. Morphological, physico-chemical properties, mineralogical composition and classification of six Andisol pedons developed from volcanic ash, at elevation between 530 and 700 m above sea level, were studied. The results showed that all pedons met with the definition of andic soil properties and thus properly classified as an Andisol order. Soils had thick solum and dark color, granular structure, friable, and smeary. Texture ranged from sandy to loamy and clay. Bulk density at 33 kPa, tension varied from 0.57 to 1.20 g/cm3, phosphate retention from 44 to 97 percent, (Al + 0.5 Fe) content from 0.96 to 5.78 percent, volcanic glass content from 16 to 52 percent, and 1,500 kPa water retention ranged from 9.1 to 32.5 percent. The total sand fractions were dominated by volcanic glasses and rock fragments, whereas the heavy minerals were dominated by augite-hypersthene-olivine association which reflect an andesitic to basaltic soil parent materials. The clay mineral showed hydrated halloysite and amorphous materials (allophane), and a few disordered kaolinite, reflecting soils with young profile development. Five pedons belonged to an amorphic mineralogical class. The Andisols with high clay content showing clay illuviation are classified as alfic Hapludands, medial, amorphic, isohyperthermic. The others having sandy to loamy texture were classified as Humic Udivitrands, ashy, amorphic, isothermic; Typic Hapludands, ashy, amorphic, isothermic
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