Thatch control
What is Thatch?
Thatch is a layer of intermingled dead and living shoots, stems and roots that develop between the base of the grass plant and the soil surface.
When this organic matter accumulates faster than it can be decomposed, thatch results. In some cases over 5 mm of thatch can accumulate in any one growing season.
What causes Thatch?
- Grass species that produce a lot of stolons or rhizomes such as Red Fescue or Creeping Bentgrass (not commonly used or found in winter pitches apart from where they might be indigenous species)
- Acidic conditions, the microorganisms in the soil that help to breakdown thatch don’t do well in acidic spoils with a pH of 5.5 or less.
- Excessive application of Nitrogen through fertilisation that causes rapid growth.
- Lack of aeration
- It’s a common myth that returning clippings causes thatch, there’s little evidence to support this but it may contribute where there is already and existing thatch layer.
Why is it a problem?
Excessive thatch levels (more than 10 mm) make it difficult for water, fertilizer, oxygen and treatments to reach the soil. From a playing point of view, excessive thatch can cause a slippery surface aswell as affecting ball pace, ball bounce and ball roll.
What can be done?
As is so often the case, prevention is easier than cure.
Keeping thatch under control is a key maintenance requirement, and today’s machinery is making this once arduous task significantly easier.
Here are several key practices.
Brushing
🎯 The aim:
- To lift creeping stems and leaves of grass before mowing to allow a clean cut.
- To disturb debris kicked out from play and bring it to the surface for removal.
📌 The method:
The moving of a brush against the surface of the turf, either pulled by a groundsperson or mounted on a tractor if conditions allow.
Verti-Cutting
🎯 The aim:
- To lift and cut through horizontal growth, increasing air flow around the base of the plant without cutting into the soil surface.
- To reduce organic matter build up in the base of the grass plant.
📌 The method:
The verti-cutting unit is made up of vertically mounted blades that rotate at high speed to cut into the turf.
Scarification
🎯 The aim:
- To remove organic matter from the base of the grass sward using tines rotating at high speed.
- Light scarification can be used to thin out swards that have become too dense or where tractor mounted scarification might be considered too aggressive. (This is sometimes carried out using tractor mounted rakes)
📌 The method:
In summer sports, pitches are raked manually or using pedestrian, powered equipment more typically on football pitches this is done with tractor mounted scarifiers (as pictured) or rakes.
Harrows (Chain and Spike)
🎯 The aim:
- To create a smooth surface without consolidation.
- Disturb organic matter and disrupt weed grasses in the coverage and create a seed bed for over seeding.
📌 The method:
Tractor mounted Harrows pull over the surface. Try to cover the area in a different direction to play.
Use smooth side to disperse debris and disturb surface thatch layer.
Removes dew and stands grass plant up before mowing.
Soil conditions should be carefully considered before use.