Clay mineralogical properties of brown forest soils in northern Kyoto with special reference to their pedogenetic process

Abstract

Clay mineralogical properties of brown forest soils and podzolic soils under natural beech and/or cryptomeria forests were studied. B horizons in both profiles had 2:1:1-2:1 intergrade as a dominant clay mineral. This intergrade, which was formed from dioctahedral clay mica in the weathering process, changed to smectite or high charge smectite via vermiculite in the pedogenetic process.

The distribution pattern of exchangeable Al in the profiles was closely related to the mineralogical changes, which may enable to distinguish the brown forest soil from the podzolic soil, since the amount of Al increased toward the surface from the subsurface horizon in the brown forest soils whereas it showed a maximum value at A3 or BI horizon in the podzolic soils.

Key Words:

• exchangeable Al
• podzolization
• smectite
• 2:1:1-2:1 intergrade