Editor’s note: We asked two aerator manufacturers to contribute information for this article on the basics. Thanks to John Deere and The Toro Company.
Aeration or aerification, whichever you prefer, is a valuable cultivation practice for sports turf managers. Compaction from foot traffic prevents root penetration and contributes to poor drainage. Even in the best soils aeration is vital for healthy turf.
But questions persist: do you aerate too often or not enough? Could you be doing faster? Cheaper?
While the benefits are known, aeration presents challenges to turf managers. Aeration is an unenviable task; not only is it labor intensive and time consuming, it also is a dirty, messy job that few look forward to. Even more critical is the amount of time the complete aeration process can take turf out of play.
The best method of aerification depends on the problem that needs to be solved; it’s best to create a plan based on your turf’s needs. Timing is an essential consideration of this schedule because specific problems develop at different times of the growing season. Periods of heavy field use result in high levels of wear and compaction. High summer temperatures amplify the need for gas exchange in the rootzone to replenish soil oxygen and remove carbon dioxide. And, aerification imposes a temporary stress on turf. Speed of recovery is linked closely to weather conditions and to stage of the annual growth cycle for different species of turf.
“My goal is to have an aerator going all the time,” says Jerad Minnick, sports turf manager for the Maryland Soccer Foundation’s Soccerplex. Such a goal may seem daunting, but is just a part of the routine for Minnick’s 22-field facility that hosts 350 games a weekend and sees around 1.5 million people a year. He notes that it takes about 2 weeks to aerate all the fields once.
When designing an aeration plan, several factors should be considered:
· The goal of the field (type of sport and level of traffic)
· Weather and climate conditions
· Soil and turf type
· Frequency of watering and mowing
A soil sample can reveal compaction; so can divots, indicating the need for aeration.
Shaun Ilten, turf and grounds manager at The Home Depot Center in Carson, CA has such a heavily used facility that he has one employee dedicated solely to aeration. “He aerates eight to 10 hours a day year-round,” said Ilten. “We aerate each field more than 30 times a year.” From football and soccer teams to concerts and ESPN’s X Games, The Home Depot Center encompasses 125 acres of grounds including 1.2 million sq. ft. of turf and 10 practice fields, in use 12 months of the year.
But for Ilten, the reclaimed water he uses for irrigation is also a primary driver of his aeration schedule. “Due to the water’s inconsistency, you never know what you’re going to get,” he says, noting fluctuating nitrates and sodium levels. “As a result, we’re constantly working to avoid black layer and disease and flushing the turf to reduce salts.”
Minnick also advocates a proactive approach to aeration. Knowing the dedication of teams at the Soccerplex, he wasn’t surprised when they continued play despite the driving rain one late spring day. “I knew there was heavy rain in the forecast, so we aerated a few days before,” Minnick said. “It rained ¾ inches during the game, but we had no puddles and no divots. In fact, it rained 12 inches in May, 21 days of rain, yet we only had four rain-outs on native soil.”
Luke Yoder, director of field maintenance for the San Diego Padres, schedules his aeration around his professional team’s practice and game schedule. That’s usually five or six times per season, and with a small crew, he often jumps in to assist in the time-consuming task.
He also noted that aeration is a task he can greatly reduce in the off-season, since the turf isn’t undergoing the stresses of baseball. “However, the venue might be used for rugby, concerts or soccer,” Yoder says. “If the turf gets really beat up after one of these, we sometimes re-sod the whole field before baseball season begins, so our off-season aeration schedule changes from year to year.”
What sort of aeration you need will vary depending upon the individual field. Creative timing around game and event schedules is key, since the field needs time to rest after aeration. Ilten says that he generally needs 2 days for his fields to recover.
Minnick says that some trial and error may be necessary when working a new field, but recommends aerating a few days in advance of a big game or event. “Then if the soil is too loose and coming apart, you can firm it up by putting water on the turf and running a roller over it,” he says.
When aerating, the speed, angle and direction generally vary by personal preference. Your speed should be based on how many holes you want: the faster you go, the fewer holes you make. If you’re working in seed, you should go slower for tighter hole spacing, particularly for worn areas such as field centers or edges.
Climate and turf type can also influence aeration techniques. For instance, Yoder, who has managed sports turf on both coasts, treats his current field differently than when he was the manager of field maintenance for the Pittsburgh Pirates.
“Here in San Diego, before we aerate we scalp the Bermuda from 5/8 to 3/8 inches because it makes cleanup easier, encourages the Bermuda to take over and also allows us to keep the mower off the field for several days,” he says.
“But cool season turf wouldn’t withstand that scalping,” he says, explaining that in a city like Pittsburgh, timing is much more important. “If we tried to aerify on a day like a 95-degree August scorcher, the bluegrass might have a hard time recovering. But we couldn’t aerate too late in the season because we didn’t want to leave the field open and exposed to the cold as winter arrived.
“Here, you can beat up Bermuda in the heat of summer, and it just loves it,” Yoder says.
Yoder also advises turf managers to pay special attention to the areas around irrigation heads. “We aerify those by hand,” he says. “It’s one of the most important locations to aerate since the water tends to sit around the heads and black layer can develop.” The aeration process allows the water to move through the turf, preventing anaerobic conditions around the irrigation heads.
Yoder primarily core aerates and tines only occasionally, while Ilten and Minnick place their emphasis on tine aeration. Regardless of your turf type or climate, core aeration should be done at least twice a year to relieve compaction, though even that schedule may pose a challenge for heavily used fields.
Some professionals prefer to leave cores on the turf for a day or two and pulverize them if possible, working them back in with a drag then topdressing with sand. However, if you have a black layer or desire to change your soil profile, you may want to collect or sweep the cores off of the turf surface and topdress.
Types of aerification
Aerification is our most valuable cultivation practice in turf management. There are several types of aerification: coring using hollow tines, solid tine aerification, slicing or spiking, and deep tine aerification. The best method of aerification depends on the particular problem that needs to be solved.
Core aerification is the most versatile cultivation method since it addresses several turf and soil issues at once. Core aerification creates open channels that improve soil gas exchange and both surface and internal soil drainage. Removing soil from the profile as cores can also reduce bulk density or compaction particularly in fine textured soils. Aerification followed by core removal and sand topdressing is the best method of controlling the buildup of un-decomposed organic matter that can plug the rootzone in sand-based soils. When cores are not collected and removed they can be pulverized and incorporated back into the thatch layer as topdressing. And, core removal followed by sand topdressing allows the soil profile in the rootzone to be permanently modified over time.
Solid tine aerification is a more specialized practice that enhances gas exchange between the rootzone and the atmosphere by creating aeration channels without removing cores. It is a particularly useful practice in cool season turf during the middle of summer when root respiration is high increasing demand for O2 and causing an accumulation of CO2 in the rootzone. Because solid tining stresses turf less than coring, it can be done throughout the growing season. Coring is typically limited to times when the turf is vigorous and best able to recover (spring and fall).
Deep tine aerification to depths up to 12 inches using both solid and hollow tines has become increasingly popular as a way of breaking through deep layers of compaction and improving drainage deeper into the profile. Repeated aerification using conventional 4-inch long hollow and solid tines results in what is known as a cultivation pan or layer of increased compaction just below the depth of aerification. Deep tining can penetrate this cultivation pan. Deep tining can also relieve deeper compaction created during sports field construction when significant earth moving occurs with heavy equipment.
Slicing or Spiking
Slicing and spiking are similar to solid tine aerification since their primary benefit is to improve gas exchange by creating channels into the rootzone. Both are generally shallow treatments and cause minimal injury to the turf. As a result they are most useful during mid-summer stress periods when root respiration is high.
The practice of grinding or processing the soil cores that are brought to the surface, and redistributing that soil into the turf canopy to help control thatch. Core processing not only recycles soil as topdressing but can reduce labor costs.-Van Cline, PhD, The Toro Company.
Common mistakes to avoid
As you create an aeration schedule and customize your techniques, there are a few key mistakes to avoid:
· Aerating when it’s too wet. This can actually worsen conditions.
· Not aerating enough. While it might tie up equipment and manpower, Jerad Minnick advises never going more than 3 weeks without aerating a field under heavy traffic, like soccer and football fields or those with extra events like concerts.
· Aerating when it’s too hot. This is particularly important for cool season turf as it loses roots in the summer.
· Aerating too early on new sod. Aeration can disrupt the turf’s establishment process.
· Aerating too deeply. Always start shallow, and adjust the aerator to deeper depths as conditions permit. Many users automatically set the aerators up to their deepest depths, only to run into hole quality issues due to the soil profile being too firm underneath the turf surface.
· Not adjusting your schedule and approach from field to field or facility to facility. Take a water and soil sample whenever you start at a new facility.
If you can’t aerate on the schedule you want, don’t be afraid to get creative. Even with constant aeration, Minnick has instituted such measures as limiting play during the week (since weekends see 20+ hours of play) and changing the field dimensions (allowed in soccer) to give certain turf areas a rest.-Brad Aldridge, product manager for John Deere.
Choosing the equipment you need should be determined by the same factors that influence your aeration schedule: soil profile; traffic and field’s purpose; weather; and staff and equipment on hand. The quality and design of your equipment will also influence your aeration speed.
Manufacturers continue to try and answer customers’ needs with equipment upgrades and new technology.
Running at slow ground-speeds is one of the toughest challenges when aerating. John Deere has created Flexi-Link standard equipment technology that allows faster speeds without sacrificing hole quality, the company says. The system uses a series of rubber dampeners to absorb the forward motion of the machine, resulting in tines that spend more time perpendicular to the turf, aiding in healing times.
Chris Hannon, a marketing manager with Toro, says often collecting cores is impractical. Turf managers will destroy the cores, most commonly with a drag mat behind a work vehicle and that process. This method can be a challenge depending on the moisture level of the cores; too wet, and they make a mess, too dry and the cores are extremely difficult to break up. Hours of drag matting can also be stressful to the turf.
Hannon says Toro’s new ProCore Processor mounts directly behind a tractor-pulled aerator to sweep, process and disperse cores all in one operation and in a variety of soil and moisture conditions. The 70-inch wide Processor collects the fresh cores as soon as they are pulled and pulverizes them, then distributes the native soil back on the turfgrass, providing a layer of topdressing.
Luke Yoder of the Padres uses a tractor-mounted aerator for his outfield, but “coddles” his infield, foul lines and edges with a Deere Aercore 800 walk-behind because it leaves less of a footprint. While Yoder’s organization owns both its aerators, Jerad Minnick says too many colleagues claim they can’t afford such an investment. He urges managers to price ownership, leasing and renting, including the long-term maintenance costs.
Before you buy, examine your other equipment. If you are planning to attach an aerator to a tractor, ensure that the tractor has the proper hitch, ballast and sufficient PTO horsepower and lift capacity to do the job. Tractors with gear transmissions or electronically-controlled hydrostatic pumps with cruise control will make the job easier.
Hannon also reports Toro has created two new large-area aerators, the ProCore 864 and 1298, and their names describe their configurations: the 864 has eight coring heads and is 64 inches wide, while the 1298 unit has 12 coring heads and is a full 98 inches wide. Both aerators are tractor mount, PTO driven and are designed for sports fields and other large areas, and feature a balanced coring head to let the tines enter the turf more cleanly. A RotaLink tine guide system helps the tines remain vertical as they enter and exit the turf.