Answer to Question #117987 in Microbiology for Meek

Question

Isomorphous substitution is a mechanism for the creation of charges on soil minerals. Explain.

Answer 1

Isomorphous substitution is the process that substitutes one atom for another in the structure of clay minerals at the time clay minerals form. This leads to net negative charge in the mineral. Examples are the substitution of Al³⁺ for Si⁴⁺ in tetrahedra and Mg²⁺, Fe²⁺, Fe³⁺ and others for Al³⁺ in octahedra within clay minerals. Importance of isomorphous substitution is that it produces a net negative charge in clays. This charge must be balanced by positive charged ions from solution. This is important for retention of plant nutrients (soil fertility) and the retention of charged pollutants.

Thus, isomorphous substitution is a mechanism for the creation of charges on soil minerals.