Regular aeration helps to create a living, breathing root zone
Aeration is an essential step in lawn care because it helps to maintain a healthy lawn that can withstand drought and disease. We have to consider the welfare of the top few inches of soil – this is where the roots collect nutrients. Top soil is top soil because it is living and breathing. Sub soil does not live and breathe. A handful of topsoil is full of life – thousands of fungi spores, vast numbers of micro-organisms and bacteria too. To get strong grass you need deep rooting grass plants. Aeration creates pathways that allow air, water and nutrients to penetrate into the root zone and even after the holes have closed those pathways will act as pores in the soil.
During the playing season it is best to aerate fortnightly as long as the surface is soft enough for the tines to penetrate. The holes will gradually close up but they remain active pathways for water, nutrients and oxygen to reach the all important root zone. The roots are attracted by the tine holes and are often found growing down the holes themselves. Deep penetration is not essential because we are trying to get oxygen and moisture into the thatch layer to help the breakdown of thatch. This layer is usually only 15 to 20mm deep.
If you have a means of towing, a Sarrel Spiker is an excellent tool because it has thin spikes that do not disrupt the surface so the lawn doesn't have to be taken out of service after spiking. The Sarrel is much quicker than other methods of aerating which is an important consideration especially if you aerate fortnightly. Some mowers such as Dennis have a sarrel cassette option, these may not penetrate as deeply but will benefit the lawn. The SISIS autorake also has a spiking reel but is much narrower than the Sarrel so takes longer to do the job.
Hollow tining is useful every few seasons. The machine extracts cores which should be removed from the surface and you should then top dress with good quality sand or sand/loam mix. This operation will reduce thatch (by removing it in the cores), reduce compaction and enable water, oxygen and nutrients to reach the root zone more easily. Hollow tining has another purpose which is to reduce high points on a croquet lawns by removing material. In this case you wouldn't top dress afterwards. If the area is small it can be done with a hand tool.