Question

2. Describe specifically one way that charge is generated on soil clays. Identify the ions involved and the location of the substitution

Answer 1

As a result of negative charge developed by soil colloids ions are absorbed on the surfaces of these colloids in soils.

The ions absorbed are include Ca⁺², Mg⁺², K⁺, Al⁺³ and Na⁺

In humid regions Ca⁺² , Al⁺³ and H+ are by far the most numerous cations absorbed.

Al⁺³ and H+ tend to dominate in humid regions.

In semi and regions ca+2 , Mg+2 , K= and Na+ tend to dominate.

The main source of charge on clay minerals is isomorphous substitution which confers permanent charge on the surface of most layer silicates.

Displacent of one cation by another results in the process called exchange.