What is it and why does your lawn need it? Lawn aeration is the core cultivation of turf grass. Lawns benefit from this process for a number of reasons. First, this process loosens the soil. Compacted soil can greatly inhibit the flow of water, air and nutrient uptake. Second, the small cores of earth deposited on top of the grass act as top dressing of fresh, rich soil. This is very helpful in reducing thatch which is usually the cause of the most severe turf problems such as disease and insects.