What Is It?
Compaction of soil or rootzone if the area is specially prepared sand/soil medium is something which must be addressed. The consequences of soil compaction are very far reaching, because the grass cannot grow in a healthy manner if the root growth is restricted. It is usually soil with a high percentage of silt and clay that most easily become compacted. The very fine particles fill the spaces between the coarser granules and impede water percolation through the profile. It is usually obvious if soil compaction is an issue simply by trying to push a fork or soil profiler into the turf.
Have I Got It?
Some of the symptoms of soil compaction are poor quality turf, standing water after rainfall and poor response to fertilizer. Soil compaction will cause low oxygen levels in the soil which in turn will mean a low population of beneficial bacteria. When the ecology of the soil is out of balance turf is very prone to disease. Quite often because of low microbial and bacterial activity decomposition of dead leaves and stalks is very slow which will cause thatch to form. A thin sward will often allow broad leaf weeds to establish. The soil/rootzone in which the turf grows is fundamental so it should be one of the first areas of investigation when things go wrong.
How Do I Control It?
Mechanical aeration is the key. Because silty and clay soils have a natural tendency to compact they need most attention.
On fine turf, as found on bowling greens and golf greens, hollow coring is helpful but not the whole story. Because most hollow tiners will only achieve about 4 inches penetration into the soil, it is necessary to also use deep slitting tines when the playing season allows. These will make deep primary incisions from which secondary cracks should form in dry conditions.
Soil will tend to compact more easily when it is wet because the particles are lubricated and slide about quite readily.
After hollow coring or slitting try to top-dress using a suitable sports turf sand or top dressing with a high percentage of sand. This will help to give a better structure to the soil but continual mechanical aeration will always be necessary.
How Do I Prevent It Re-Occurring?
Prevention is very similar to the processes required for control. However there are a few products that can help by improving the soil structure. The ceramic granular material made from montmorillonite is known as Profile Greens Grade and when used after hollow tining can be beneficial in preventing re-compaction. It goes without saying that the more sand that can be incorporated in the profile the better. This should not be applied without aerating, as a layer on the surface is not helpful.