Decaying organic matter can build up on the immediate surface of the turf, especially when the clippings are returned to the surface. This produces a thick impermeable layer that reduces the air, water and nutrient intake into the soil, subsequently producing a weak sward which may be prone to the following:
• germination of moss spores
• introduction to fungal diseases
• introduction of weed seeds, particularly in the summer
• spread of unwanted grass seed
The maintenance of the winter sports ground should encourage the maximum amount of activity of bacteria and other micro-organisms. This will help provide a quick decomposition of thatch.
Poor aeration and compaction of soil will result in bad drainage and reduction in bacterial activity.
Avoid high nitrogen applications that give lush growth leading to an accumulation of organic matter and thatch.
This decaying matter is called thatch. Some benefit may be gained by a layer of thatch from the impact absorbency quality provided but the advantage gained is far out-weighed by the disadvantages outlined above. It is therefore better to rely on the impact absorbency provided by grass cover and soil moisture content.
Thatch removal is achieved in varying degrees depending on the type of equipment used and the severity of the operation.
Thatch removal from areas the size of rugby pitches is usually achieved, if and when required, by mechanical means. Implements are either trailed or mounted on the three point linkage of tractors or similar prime movers.
Necessity may require these operations to be carried out during some of the drier periods during the year. However, it is then essential to only scarify the plant and not the soil surface as any marks left can open up as the pitch dries out.
Several double passes would be required by the equipment to be carried out alternately with continuous mowing. All debris MUST be removed after scarification. There are several proprietary pieces of equipment on the market for this purpose.
It is important to set any mechanical equipment up correctly in order that severe damage to the soil surface does not occur.
Verti-cutting is very similar to scarification, in that it assists in thinning out the sward and removes dead material, but it does not cut into the surface.
On sand based pitches verti-cutting is now replacing harrowing, but this is in the minority and local authorities will still harrow.
