Between the crown of the grass plant and the soil lies a thatch layer. This is basically the dead and/or dying parts of the plant (not the clippings though). This layer will progressively get thicker and thicker until it no longer allows nutrients and water through to the root zone. It also makes a perfect home for insects and disease causing fungi.
Core aeration will punch holes through the thatch to allow water and nutrients through. It will also help speed up decomposition of this thatch layer by bringing soil microbes to the surface (in the plugs).
Lawns that are core aerated each year do not experience problems with thatch. It’s really that simple.
