Clay soils and heavy traffic areas are particularly subject to compaction. If soil is trampled, especially when wet, compaction will likely occur. Compaction creates poor soil aeration, and restricts water and fertilizer movement through the soil, which causes thin, unhealthy grass.
A power driven aerator is the most effective method to relieve compaction. An additional benefit is the control of thatch, if it is present. Hollow tines pierce the soil to a depth of 7 to 10 centimetres (3-4″) extracting soil cores which can either be removed or broken down and left on the soil surface. The openings allow water, air, and nutrients to reach turf roots.