Spodosols podzols

Spodosols (podzols) contain separate horizons from which material has been both removed and deposited (Fig. 4.24). However, spodosols form under very 

Mild weathering, various conditions Inceptisols (beginning of B horizon development) 

High base status, high CEC clays smectite, dry season 

Semi-arid to moist grasslands, 0.6% SOM in thick upper horizon 

tropical forest, extreme weathering, low activity clays, Fe, Al oxides 

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Fig. 4.24 Schematic diagram of a spodosol (podzol) with an explanation of horizon formation. The resulting horizons are comparable to those in Plate 4.2(b). The master horizons are typically centimetres to tens of centimetres thick.

In the study of soil science, most attention has historically been paid to the aluminosilicate clays, which dominate the properties of temperate soils, the first to be scientifically studied. More recently, the importance of the amorphous aluminosilicates has been shown in young soils, in soils derived from volcanic ash and in leached, acidic soil (e.g. podzols or spodosols). The hydrous oxides are especially important components of old, highly weathered soils, such as those found in the tropics (e.g. oxisols). This is an important distinction as the charge on the aluminosilicate clays is predominantly a permanent negative charge, while the amorphous aluminosilicates and hydrous oxides have a variable,... 

Podzol. A soil consisting of a whitish-grey, highly leached A horizon (Podzolic), developed in cool-temperate to temperate, humid climates, under coniferous or mixed coniferous and deciduous forests. In the current soil taxonomic system, most Podzol soils (an older classification) are Spodosols. 

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