ChileanJAR

Some properties and the genetic relationship of three Andosols of the Lake Region, southern Chile, are described. The parent materials are andesitic-basaltic ashes, that include two mineral associations: one of volcanic and the other of metamorphic origin. Clay minerals are represented by allophane and imogolite, except in soil Osorno, which contains either traces of imogolite or none in the clay fraction. The formation and transformation of clay minerals has been controlled by the soil environment, particularly by the supply of silica, associated to the amount of rain,deposition of fresh ashes and organic matter, and the age of the soils or the rate of weathering. It is assumed that the relative age of the soils follows the chronose quence represented by: Corte > Osorno > Puyehue, according with the amount of residual glasses, iron oxides and metahalloysite, associated with the non-crystalline or paracrystalline minerals. Differences observed in the determination of organic carbon and CEC by different methods are explained.