Aeration

The action of aerating the soil to improve the air content of the soil. It allows for fresh air to be exchanged for more stale air within the soil. This can be achieved, for example, by penetrating the soil profile with physical implements, such as tines or drills, or with compressed water or air being injected into the soil. A garden fork is the simplest form of aeration equipment. The act of aeration can help to encourage grass roots to explore deeper into a soil profile and also to improve surface and sub-surface drainage by helping to get water into and through the soil.

Other benefits of aeration include:
To relieve compaction. This temporarily increases the pore space in part of the rootzone subject to the aeration work, allowing roots to grow in to that pore space.
To improve the oxygen - carbon dioxide exchange around the grass roots, promoting healthy growth and enabling undesirable soil gases to be removed from the soil.
To aid the incorporation of top-dressings,fertilisers and seeds.
To reduce the potential for disease incidence.
To aid in the breakdown of thatch and organic matter.
To achieve optimum growth and improve the visual appearance of the sward.
To improve surface traction and grip; and
To increase ball (or bowl) speed and performance by the production of drier and firmer surfaces.

One question often asked is 'When is a good time to aerate a turf surface?'
This should be carried out during the main rooting and growth periods, particularly when the rootzone material is in a relatively dry state: Definitely not when the soil is wet, as all that will happen is the soil will be smeared and there will be a reduction in pore spaces, with a consequent slowing down of drainage potential. If the soil is too dry then the tines of an aerator will not be able to penetrate the soil and they will just bounce off the top, potentially bending or breaking tines.

Other considerations for aeration, include:
Compaction by foot traffic is mainly caused within the top 75mm to 100mm of the turf surface, so this is where regular aeration needs to take place to help relieve or at least reduce the compaction caused.
Vary the depth of penetration of the tines, so as to reduce the chance of root breaks and aeration pans developing.
Disturbing the soil by aeration can create openings for weeds to germinate and become established. This is sometimes also termed Aerification.