Due to the relatively high adsorption rate of aluminium to soil colloids, it will be taken out of the soil, hence the plant cannot be adversely affected by it.
12.
In high rainfall areas, soils tend to acidity as the basic cations are forced off the soil colloids by the mass action of hydrogen ions from the rain as those attach to the colloids.
13.
The addition of a small amount of lime, CaCO 3, will displace hydrogen ions from the soil colloids, causing the fixation of calcium to colloids and the evolution of CO 2 and water, with no permanent change in soil pH.
14.
Bioavailability is commonly a limiting factor in the production of crops ( due to solubility limitation or adsorption of plant nutrients to soil colloids ) and in the removal of toxic substances from the food chain by microorganisms ( due to sorption to or partitioning of otherwise degradable substances into inaccessible phases in the environment ).
