Thatch is a layer of living and dead materials that collect between the layer of growing grass and the soil beneath it. Thatch is necessary in order to maintain a healthy lawn. When thatch is the right thickness, no more than 1 inch, it increases the resilience of the turf to heavy traffic and various diseases.
Thatch is a matted, webbed layer of protection to the soil . When this layer gets too thick, it prevents moisture, sunlight, air, and nutrients from being delivered to the root layer of the turf. Once starved from these essential elements, the turf can no longer grow healthy. This matted layer of thatch also acts like a sponge and holds any water that is applied. When the temperature increases in this layer, it becomes a breeding ground for fungal diseases and creepy crawly bug infestations.
The thicker the thatch layer, the harder it is to treat. Proper care of the turf is the best way to prevent this layer from becoming too thick. Yearly power raking and aeration is key to breaking down the thatch layer. Leaving your grass clippings on the lawn is a healthy practice, as long as they are not too big. Try a rotation system of bagging the clippings one week and leaving the clippings on the lawn the next week. Lastly, avoid fertilizers with excessive amounts of nitrogen.