The thatch layer is the combination of living and dead stems, leaves and roots that are decomposing between the blades of turf grass and the soil. Thatch in a normal layer to be present and in fact beneficial to the overall ecosystem of a lawn. Thatch in the depth of about ½ inch will contribute to turf grass resiliency in heavy traffic situations. However, excessive thatch that is thicker than ½ inch can contribute to possible turf grass diseases, inefficiency in water and nutrient adsorption.