Thatch

Thatch is a layer of organic material which can be found above the soil’s surface, but below the grass plant leaves. Thatch is defined as a tightly intermingled layer of dead, dying or living plant material, such as stolons, rhizones, stems, crowns, nodes and leaves – in other words, all parts of the turf grass plant.

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In small, controllable amounts, thatch is very beneficial to the lawn, by preventing moisture loss through evaporation, and protecting the important meristematic regions (areas of growth, such as the crown, which can be found at the base of the grass plant). Thatch also provides a ‘cushioning’ effect for playing or walking on. However, poor turf management can quickly result in high levels of thatch and many related problems.

To determine the level of thatch present, a section of turf is removed. Looking directly below the green leaves, the amount of dark brown stem and root tissue is measured (see photograph below; the thatch layer is shown between the dotted lines). Thatch becomes a problem when it is any thicker than ½” or so.

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An excessive layer of thatch will bring problems to a turf grass sward:

• The lawn will feel spongy underfoot

• Water filtration is reduced

• It will provide an ideal food source and living conditions for many turf grass fungal diseases and insects

• It increases the incidence of mower scalping the lawn

• It will promote the growth and invasion of weeds, moss and weed grasses such as Annual Meadow-grass (Poa Annua).

The two main types of thatch found in domestic lawns are : The fibrous type (tough, dry, very wiry in feel, usually brownish in colour), which is typically found in acid situations, and the more common spongy type (yellow / brown in colour, usually soft and often waterlogged, and sometimes has black streaks running through it. This type often smells of eggs or stagnation (hydrogen sulphide), and will sometimes be found in heavily watered areas, or on heavy clay soils.

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The benefits of controlling thatch through maintenance procedures such as scarifying, brushing and raking, and top dressing, frequently include : keeping a firm, dry turf surface, increasing the depth of the grass rooting system, and improved distribution and penetration of irrigation and rain water.

In addition, scarification will create space around the base of the grass plants, and new growth will be encouraged to fill the space, resulting in a denser, thicker sward of grass.

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Usually the main option for addressing a serious spongy thatch problem has been scarification. Whilst there is a place for this operation, scarifying is a brutal operation which often has a severe effect on the lawn’s appearance, and can result in extensive overseeding being required. Where excessive thatch is the problem, there is now an alternative approach - Thatch Eater - which should be considered.

Thatch Eater is a combination of beneficial soil bacteria and fungi, specially selected for their ability to rapidly degrade thatch and other organic matter and to release locked-up nutrients for plant growth.

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Applied after aeration, Thatch Eater will release a lot of the nutruent from the recycled thatch and promote healthy growth.

• Degrades thatch and increases nutrient uptake into the grass plant

• Improves surface drainage

• Released nutrients encourage root development, not disease

• Increases turf vigour and wear resistance

• Promotes improved root development and sward density

• Maximises the benefits of aeration