What impact does soil organic matter have on cation exchange capacity?

Soil organic matter plays a crucial role in enhancing cation exchange capacity (CEC). When organic matter is present in the soil, it contributes a significant number of negatively charged sites that can attract and hold positively charged ions, known as cations (such as calcium, magnesium, potassium, and sodium).

The components of organic matter, such as humus, have a complex molecular structure that creates many functional groups capable of ion exchange. This means that as the quantity of soil organic matter increases, the soil's ability to retain and supply cations for plant uptake also increases.

The capacity to exchange cations is vital for overall soil fertility, as it directly affects nutrient availability and the soil's ability to retain essential minerals, particularly in sandy soils that normally have lower CEC. Thus, an increase in soil organic matter results in a higher cation exchange capacity, allowing for better nutrient retention and higher agricultural productivity.