The stable material formed from decomposed plants and microbes. This material is called humus, and is broken down very slowly. Organic matter affects both chemical and physical properties of the soil. If CEC is increased, the soil can hold more nutrients and release them for plant growth. To increase CEC, you have to increase organic matter.
Organic matter loosens the soil, which increases the amount of pore space.
This has several important effects. This means that the sand, silt and clay particles in the soil stick together, forming aggregates or crumbs. Because there is more pore space, the soil is able to hold more water and more air. Plants grown on healthy soils won t be as stressed by drought or excess water. Water also flows into the soil from the surface more quickly.