Thatch can be described as a tight and fibrous layer of living and dead matter, primarily roots of the grass, which develops between the plant and the soil.
Many people think that grass clippings contribute to thatch, however grass clippings consist primarily of water and dry up and disintegrate. Thatch consists of woody plant material like roots, rhizomes and stolons that are slow to breakdown.
What Causes Thatch?
- Heavy fertilization can cause rapid thatch development. Nutri-Lawn's programs are designed to create healthy lawns and do not use excessive fertilizer. Excessive fertilizing can create a lush green lawn in a short period of time, but it leads to a variety of problems in the long term, including excessive thatch accumulation.
- Acidic soils, waterlogged soils or fungicide applications inhibit soil micoorganism activity. It is the microbes that biodegrade or breakdown the thatch layer, and if they are inhibited the thatch layer will accumulate.
- Excessive watering will encourage thatch development as well as shallow roots. Excessive watering saturates the soil and roots will not grow into a water saturated soil. The roots will grow on the surface of the soil and in the thatch layer, rather than deep into the soil. This creates a lawn that is susceptible to drought and root feeding insect damage.
- Some grass species are prone to excessive thatch development. Kentucky Bluegrass, Fine Fescues and Bentgrass tend to thatch up quickly. Perennial Ryegrass is not prone to thatch development because it is a bunch type grass that does not spread by rhizomes or stolons.
A thin layer of thatch of about 1.5 cm is beneficial because it acts like a mulch, buffering temperature extremes at the soil surface and helping to retain soil moisture. A thin thatch layer is also beneficial because it will inhibit weed seed germination and establishment.
When the thatch layer grows thicker than 1.5 cm it becomes detrimental to the health of the lawn. Excessive thatch inhibits the movement of water, nutrients and air into the soil, resulting in shallow roots and a lawn highly susceptible to drought and root feeding insect damage.
Excessive thatch also makes it difficult to control root feeding insects. The thatch layer impedes the movement of pest controls into the soil, reducing the efficacy of the treatment.
A thick thatch layer is the perfect environment for some insects. Chinch bugs will flourish in a thick thatch layer and can cause extensive damage.
Disease organisms reside in the thatch layer and when environmental conditions are conducive for the disease, an outbreak can occur.
What Can Be Done to Control Excessive Thatch
Annual soil core aeration is strongly recommended as the best method to manage thatch development in a lawn. Soil core aeration pulls plugs of soil and thatch out of the lawn, breaking up the thatch layer and allowing the roots to grow into the soil rather than on the surface.
Organics Plus Topdressing applications help to mange thatch layer development by inoculating the thatch with billions of micro-organisms that will biodegrade and breakdown the thatch.
Power Raking slices and cuts the thatch layer, enhancing the penetration of water, air and nutrients into the soil which leads to an increase in microbial activity and biodegradation of the thatch.