Biological activity is primarily responsible for the water-transfer processes involved in rock and soil erosion and sedimentation. It is also involved in many of the chemical reactions contributing to weathering and erosion, although less conspicuously than physical and chemical agents.
Only a few or even a single trace of some ions or salts may be removed from the active layer, but such losses may be important at an ecological level, owing to their importance in various biochemical processes.
Burrowing and wedging by organisms like earthworms, termites, rodents etc., help in exposing the new surfaces to chemical attack and assists in the penetration of moisture and air.
Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water and minerals in the earth materials.
Decaying plant and animal matter help in the production of humic, carbonic and other acids which enhance decay and solubility of some elements. Plant roots exert a tremendous pressure on the earth materials mechanically breaking them apart.
