William M. Brown Jr., Bugwood.org
Aerating machines remove plugs of soil from the turf area, thereby creating an artificial system of large or noncapillary pores by which moisture and plant nutrients can be taken into the soil. They also provide a breathing system through which carbon dioxide can escape from the soil and oxygen can enter the soil. A rapid intake in movement of water and air is recognized as a prime necessity in correcting damages to the turf caused by compacted soils.
Spring and early fall are the best times to aerate. Summer aeration of cool-season grasses, such as bluegrass, bentgrass, and fescue, is not generally recommended because these grasses are in a semi-dormant condition, whereas crabgrass is quite active. A safe general rule for time of aeration is to aerate only when the desirable grasses are growing vigorously.
The type of equipment recommended will depend upon the size and use of the area. Equipment varies in size, from the small, hand, tubular-tine forks to large, tractor-drawn units capable of aerating large areas in relatively short time. Power-driven, home-owner-sized units are available. Many lawn and garden supply houses have aerating equipment available on a rental basis, and many landscape agencies will do the job on a custom basis.
Equipment having solid tines or spikes should not be mistaken for aerating equipment. Aerators always remove a soil core whereas solid tine spikers do not. Spikers actually increase soil compaction as the movement of the soil to all sides by the penetration of the solid tine forces the soil into a denser mass.
John C. Harper, II, Extention Agronomist.