The relative importance of pedogenic processes in deep sandy regolith in Western Australia
There have been no detailed pedological studies on the extensive tract of sandy regolith that characterises the geomorphology of the Victoria Plateau, Western Australia. We report the results of physical and chemical analyses of 15 Arenosols from the plateau. Three classes of earthy sand profiles are recognised on the basis of the distribution of sand and clay down the profiles. All are dominated by quartz with a very low heavy mineral fraction. Low to very low levels of exchangeable cations and sesquioxides accord with the dominance of siliceous sand and kaolinite as the only clay mineral present. The high sand content, acidic upper profile and low base status of most of the profiles favour leaching as a soil forming process. Concentration of mobile constituents such as Na, Mg and Ca are generally higher at depth, particularly when associated with clay-rich sections. However pedogenic alteration in the profiles is limited and the chemical and physical variation that does occur is more likely to be related to variability of the substrate than leaching. Minor amounts of organic matter are incorporated to shallow depth but there is no evidence of bleaching within the profiles. Indications of leaching, in general do not occur. While some profiles do have higher clay content at the base than closer to the surface, this is not invariable and there is a lack of consistent down-profile increase in Feox, Alox, Fep and Alp. The location of these profiles in a low rainfall area which has been in this situation for at least hundreds of thousands of years, the low productivity of the covering vegetation and rapid oxidation of any organic material derived from litter means that conditions conducive to leaching very rarely occur. This has led to a situation where, unlike much younger sand sequences in the more mesic south of Western Australia, there is little evidence of soil profile development, such as podsolization, in the earthy sands of the Victoria Plateau.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Environmental Science|
|Publisher:||Gebruder Borntraeger Verlagsbuchhandlung|
|Copyright:||© 2003 Gebrüder Borntraeger|
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