Thatch is an accumulation of organic matter within your lawn. It is made up of dead roots and shoots that fail to decompose quickly enough. The roots of the grass will begin to grow in to it, rather than in to the soil, which will have an affect on your lawns condition. Thatch is generally caused by poor lawn care practices, over feeding and poor aeration being just two. When thatch becomes too thick it will cause problems within your lawn.
Thatch is produced when the production of shoots is greater than their decomposition. Thatch is naturally degraded by micro organisms within the soil and certain things can inhibit the micro organism population and so an excessive accumulation of thatch.
Over Feeding: In the correct proportion then nutrients are good for your lawn but too much nitrogen will cause excessive growth which will take longer to decompose.
Over Watering: Micro organisms rely on oxygen. Too much water will mean less oxygen within the soil and micro organisms will not be able to thrive.
Soil Type: Soils high in loam content will have a higher micro organism population than sandy soils so you will generally see higher thatch levels in sandy soils.
Soil pH: Acidic soils, low pH, will have a negative affect on micro organisms.
A little thatch within your lawn, below 1/2 inch, is quite acceptable. Once the thatch layer starts to get thicker than this then problems begin to arise. Thatch layers tend to hold water like a sponge preventing good drainage of water through to the soil. With water unable to penetrate to the soil you will find that the roots of the grass begin to grow in to the thatch layer. The thatch will dry out very quickly during hot spells and will be difficult to re wet. The grass will soon become stressed and turn brown and worst case scenario, dying.
Preventing and Removing Thatch
Thatch build up is gradual and doesn’t happen at once.
Aerating the lawn: One of the most effective ways of preventing thatch is by aerating the lawn. Aerating helps encourage a healthy population of micro organisms, which are essential in decomposing the organic matter and preventing thatch accumulation.
Scarification: Scarifying is the mechanical process of raking the lawn and so removing the thatch layer.
Fertiliser: Using the correct fertiliser with the correct quantities of nitrogen will prevent too much growth.
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