Index >> Microbes and Lithosphere>>Soil Colloids

Soil Colloids
Most of the inorganic and organic matter in soil is in the form of minute particles, with a diameter of about 0.00002 mm and can remain suspended in water for a long period. They have an enormous surface area and are negatively charged, hence they repel each other in the suspension. These inorganic and organic particles in soil are called soil colloids (colla meaning glue-like).

Soil colloids are of two kinds:
Inorganic colloids which exist mostly as silicate clay found in less weathered soils in the temperate regions and as hydrous oxides of iron and aluminium clay in the extremely weathered soils in the tropics.

Organic colloids which are represented by humus.