It is the job of the sports turf manager to perform cultural practices that relieve the compaction that field use and frequent mowing causes. Aeration is the primary cultural practice for reversing this compaction. A healthy soil can have as much as 25% oxygen. Turfgrass roots must have oxygen to thrive. When a soil becomes compacted, oxygen content is reduced and so is pore space. All living plants take in oxygen from the air it breathes and casts off carbon dioxide. Some of the CO-2 is cast off through the root system. If the pore space in the soil is too tight, CO-2 gets trapped in the soil. This concentration of the gas can slowly poison the turfgrass. Aeration improves pore space and allows the CO-2 to escape from the soil, thus promoting a healthier soil profile.
The most common type of aerator is the core aerator. Hollow coring tines remove plugs of soil from the soil profile and drops them on the surface. The soil around the coring hole collapses within a week or two which creates better pore space in the soil profile. Open faced spoons are also commonly used. The spoon tine causes more surface disruption and could take longer for the field to be put back in play.
Spikes are used when minimal surface disruption is needed. This form of aeration is not as dramatic as core removal and results are short-lived. Vibrating solid tine aerators combines a "burrowing" and "quaking" action. When aerating in this manner, it is important that the soil be relatively dry to minimize surface disruption. A field can usually be put back in play in just a few days after this sort of aeration. An aerator with slicing tines is another tool that can be used to minimize field disruption. Results are not as dramatic as vibrating solid tine aeration, but the field can be put back in play immediately. Slicing tines can even be used on fields over seeded with ryegrass.
Deep Tine Aeration
Deep tine aeration is the most dramatic form of core aeration. Coring depth of 6 to 10 inches is common. For maximum compaction relief a 1.25 inch OD coring tine can be used and this tine will pull a full one inch diameter plug. Allow two weeks for the field to repair. The "cam action" of a deep tine coring machine can create over 3000 lbs of thrust, penetrating even the most compacted soils.
How Often Should I Aerate?
Unfortunately, there is no easy answer to this question. Soil type and traffic loads should be considered when planning your aeration schedule.
Aeration Frequency - Clay Soil
Heavy clay soil types compact more readily than a sandy soil. Clay particles are much smaller than sand particles and therefore fractures in a clayey soil are smaller. Combined with high traffic, clayey soil will have poor aeration. Aerate heavy clay-based soils as often as possible during the off-season to maximize turf quality. To maintain good turf quality during the season, light frequent aeration with a slicer or spiker is normal for clay-based fields.
Aeration Frequency - Sandy Soil
Even sandy soils require regularly scheduled aeration. Not all sandy soils are the same. Some sand particles are coarse. Others could be fine or very fine. The best sandy soils for sports fields have good particle size distribution with the majority of the size falling in the coarse and medium particle size range. A soil with a majority of fine and very fine sand particles will compact more easily and will require more frequent aeration than one that is more coarse. As a general rule aerate as often as your schedule will allow. Three or four aerations per year is normal for athletic fields constructed with sandy soils. Light aerations during the season with a slicer or spiker will help maintain a healthy soil.
Aeration Frequency - Traffic Loads
The heavier the traffic on a sports field, the more frequent the aeration should be. We know of some turfgrass managers that aerify every 2 or 3 weeks. We work with a lot of school districts. School district turfgrass managers must work with the Athletic Department and other users of the sports fields to plan for these maintenance events. Work with the Athletic Director to schedule field maintenance work around the workout and game schedule.
Turf Equipment Links
TMC Aeration Service
TMC aerates hundreds of sports fields all over Texas each year. Call us if you would like to learn more about this, or any of our other sports turf maintenance and renovation services we offer. Contact TMC at 1-800-292-1214 to learn more.