Over the seasons, clippings of dead grass accumulate in a layer just above the soil, this is called a thatch. Too much thatch is unable to decompose in a natural process that forms a barrier, keeping moisture and air movement from the base of the lawn. If there is more than a half-inch on thatch buildup in your lawn it’s time to find a solution. There are 2 ways to remove the thatch and promote air and water circulation: Aerating and dethatching. Dethatching is performed through a power rake that combs your grass and removes large amounts of dead debris that was hanging on the top of the soil.