Jackson-Sherman soil weathering stages

▪ Table

      Jackson-Sherman soil weathering stages

 

      characteristic minerals in soil clay fraction

      characteristic chemical and physical conditions of soil

      characteristic soil profile features

early stage

      gypsum, carbonates, olivine/pyroxene/ amphibole, Fe²⁺-bearing micas, and feldspars

      low water and humus content, limited leaching, reducing environments, and limited time for weathering

      minimally weathered soils all over the world, though mainly in arid regions, where low rainfall keeps weathering to a minimum

intermediate stage

      quartz, mica/illite, vermiculite/chlorite, and smectite

      retention of Na, K, Ca, Mg, Fe²⁺, and silica; alkalinity

and ineffective leaching; igneous rock rich in Ca, Mg, and Fe²⁺ but no Fe²⁺ oxides; easily hydrolyzed silicates; and transport of silica into 

the weathering zone

      soils of temperate regions developed under grass or

trees—i.e., the major agricultural soils of the 

world

advanced stage

      kaolin, aluminum and 

iron oxides, and titanium oxides

      removal of Na, K, Ca, Mg, Fe²⁺, and silica; effective leaching by fresh water; low pH; and dispersion of silica

      intensely weathered soils of the humid tropics, frequently characterized by acidity and low fertility

See as table:

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