You can rent a mechanical aerator from your local rental equipment shop. A mechanical aerator is a very efficient way of removing plugs of soil from your lawn.
The plugs will be cored about 6 inches apart anywhere from 2 to 3 inches deep. This will depend on the type of soil and the moisture content.
Lawn aeration allows air and water to penetrate the soil more easily and provides more oxygen to the roots of your lawn as a result, you will have a healthier turf.
In case you missed the last episode Save Your Garden Seed.