ABSTRACT
Potassium required in plant nutrition is usually obtained by the depletion of interlayer K+ ions from illites or micas, whether as separate phases or in mixtures with other layers. Pores, responsible for the transport, uptake and release of water for plant uptake, are formed both within and between components of the hierarchy of aggregates in soils dominated by 2:1 minerals. Soils which display a hierarchical structure of aggregates as a result of the action of organic materials, whether dead, processed or alive, also have a hierarchy of pores. The strength of the soil quality index proposed by A. R. Dexter is that it is able to separate structural porosity from textural porosity. The variability of the geologic substrata producing soil clays is then fundamental in the production of ceramics, and identification of these materials is used by archaeologists to determine the provenance of the ceramic products.
