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Podzolic Soils |
  
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Podzolic Soils |
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In quartzitic materials the concentration of humic substances from decomposing vegetation exceeds the capacity of clay to adsorb them and they migrate downwards, within the soil profile and through the landscape, complexing metals (chiefly Al and Fe) and precipitating once a solubility threshold of metal saturation is reached (a gradient in soil pH is probably also involved).
The result is a spectacular chromatogram in which a darker subsoil horizon, sometimes cemented, forms beneath a bleached E or Ae horizon. High rainfall and certain types of vegetation are more conducive to podzolization. Nutrient deficiencies are common, especially in shallow-rooted plants (Soil forms: Tsitsikamma, Lamotte, Concordia, Houwhoek, Jonkersberg, Witfontein, Pinegrove, Groenkop).
Source: http://www.sydneyolympicpark.com.au |
