Electric charges on soil colloids arise from principally three sources:from isomorphous substitution of one ion by another of different valency within the clay mineral structure. This gives rise to mainly negative charges. The charges are permanent and do not change with change in pH of the exte...
The term isomorphous refers to the capability to crystallize in a form similar to another compound or mineral. This term is used specifically for substances that are closely related to each other and are able to form end members of a series of solid solutions. A good example of isomorphous is...