Take the Field
Managing & Maintaining High-Performing Sports Fields
By Chris Gelbach
Sports fields, be they natural grass or synthetic turf, require ongoing management and maintenance to ensure optimal performance and player safety. Practitioners in the field are seeing the sophistication of these efforts advance in a wide variety of recreational environments.
"In recreation situations, there's been a huge shift in the past five years," said Dean Pearson, assistant turf manager for University of Washington Athletics. "There is a much more scientific, more intensive approach to the way that [natural] turf is managed and the way that synthetic is managed now."
Where parks and rec departments often still fall short, according to Abby McNeal, assistant director of parks for the City and County of Denver, is in planning for sufficient maintenance funds to get the quality of fields they want.
"If you have an 'A' field, you need to put a maintenance program together that a high-level field warrants," McNeal said. "And then you can have an adjusted program for the next tier down or several tiers down. A lot of organizations would rather run one generic maintenance program across all their fields because it saves costs, but it's hard to do that and put out a quality field surface."
The other mistake McNeal sees departments make is in not planning for the future on the synthetic turf side. "If the warranty is for eight years, you need to have the funds in place to replace that field in eight years, even though you may get another few years after that warranty is up," she said.
Maintaining Grass Fields
The good thing about maintaining quality natural turf is that some of the most effective practices are also the simplest. "Eighty percent of turf management is irrigation, fertilization and mowing, and mowing is probably No. 1," said Andrew McNitt, professor of Soil Science at Penn State University and director of its Center for Sports Surface Research.
According to McNitt, the biggest thing any turf manager can do to enhance field quality is to mow often. "We've got data that show that if you're mowing once per week, the best thing you can do for that field is to mow twice per week. If you're mowing twice per week, mow three times per week," McNitt said.
McNitt noted that professional fields are mowed almost every day, and that the field at Penn State's Beaver Stadium is mowed three or four times a week year-round. Mowing frequently can often be a challenge for recreation departments and high schools because of the costs required for manpower, particularly compared to the expense of buying seed and fertilizer. But if it can be managed, it can be a sound investment.
"You need to mow, because everything else we're going to do is going to make the grass grow even faster," said McNitt. "So if you can't keep up with the mowing now, there's no use making the grass grow even faster because you don't have the ability to cut it frequently enough in the first place."
McNitt recommends using a quality mower with sharp, well-adjusted blades, and maintaining the same mowing height throughout the year. A benefit of mowing often is that it allows the clippings to filter down into the turf where they can nourish the grass instead of needing to be removed. "If you remove your clippings all year long, you're probably removing about a third of the nitrogen fertilizer that you put down every year. So, it's really a waste," McNitt said.
Pearson noted that a higher mowing height allows the turf to retain more nutrients and water. "The higher you can mow at and get away with it, the better," he said.
When budgeting, McNeal recommends considering not only what you'll need for grass maintenance throughout the year, but also for renovation once a year, or twice if your budget allows. This includes asking whether you can get by with a good aerification, topdressing, seeding and fertility program to renovate the field, or whether you need to strip it off and resod. "Or maybe it's a combination of both," McNeal said. "That needs to be part of the natural grass maintenance program discussion on the front end."
Sustainable Turf Performance
At the University of Washington, sustainability is a major area of focus. The university is a member of the Green Sports Alliance, and in 2014 was the only campus in the United States to win a Sustainable Campus Excellence Award from the International Sustainable Campus Network. At the university, the natural turf fields are maintained using several environmentally friendly practices. Many of them hinge upon frequent testing of the soil, including the school's approach to fertilization.
"We get soil tests done four to six times a year on every field so we know what's in the soil before we go and add more fertilizer or chemicals of any kind," Pearson said. This enables the team to make sure each field is getting the proper micronutrients without adding excess fertilizer that creates run-off or leaching into streams.
The fields are also tested using a soil probe to regularly measure the soil moisture. "We water as little as possible, which means daily adjusting," said Pearson. "So we don't put a program in our irrigation to run an hour at night." In addition, a rain shutoff mode is used that kicks on if it's raining to prevent the fields from being watered in the rain. To further conserve water, the university also uses wetting agents on the soil that help the soil retain water.
The regular soil testing also makes it easier to determine if certain areas of the field need more attention that goes beyond watering. "If you keep getting a dry spot in the same spot of the field, you may need to aerate there—maybe it's impacted and not draining," Pearson said.
In Denver, McNeal is using newer grass varieties that are able to survive when irrigated with non-potable water. "Our non-potable water has high salt content in it, so our maintenance program gets adjusted for the parks that use it," she said. McNeal is seeing some stresses on the trees and grass plants from using the water, but benefits from reduced irrigation costs. "There are some cost savings, but you have to look at the whole picture to make sure it's worth it for you and your program," she said.
To help cut down on the need for chemicals like weed killer, Pearson recommends just focusing on maintaining a healthy stand of grass. "As soon as the grass starts getting thin, that's when weeds are going to find an open space," he said. To help accomplish this, Pearson and his coworkers hand-pick weeds on the fields anytime they encounter them. "As soon as we see one if we're on the mower or walking on the field, we reach down and just cut it out. We don't wait for it to get bad enough where we need to spray," he said.
One product the University of Washington does apply is a growth regulator, a chemical that keeps the grass from growing as quickly. According to Pearson, this gives the grass better root structure and reduces the need for mowing, which also reduces gas consumption.
Maintaining Synthetic Fields
When it comes to synthetic fields, some recreation departments are surprised to learn that the fields require maintenance at all. But Pearson estimates that maintaining the synthetic fields at the University of Washington takes maybe 25 percent of the time of the natural turf fields.
One of the most important things that synthetic field owners can do is to keep infill levels at the proper level. This keeps the fibers standing straight up, which is a big contributor to performance and durability.
"For a synthetic turf field to last and to perform as it is intended to perform, you need to maintain it," said Rick Doyle, president of the Synthetic Turf Council. According to Doyle, one of the most important things that synthetic field owners can do is to keep infill levels at the proper level. This keeps the fibers standing straight up, which is a big contributor to performance and durability.
McNitt noted that topdressing on additional crumb rubber is a practice that's really just taken off in the past few years. "Field managers previously would let the field get to a critical state, and then they'd hire a professional to do a number of things, including replenishing the crumb rubber that walks away."
The infill typically gets displaced most from high-use areas of the field, such as in front of a soccer goal or between the hash marks on a football field. "It helps prevent infill migration if you're locating your practice drills in different parts of the field. So that's very key," Doyle said.
When you do replenish the crumb rubber, it should be purchased from your manufacturer to match the crumb rubber that's already in there, and McNitt recommends putting on light amounts and dragging it in.
McNitt believes that there's a misconception that synthetic fields get harder over time because the infill gets compacted. "But the real reason that the field gets harder over time is that the crumb rubber slowly leaves the field in kids' shoes, on their clothes, on maintenance equipment," McNitt said.
To prevent this, he recommends monitoring the depth of the infill many times throughout the year, which can be done with an inexpensive hand tool. McNitt also recommends investing in a Clegg Hammer to monitor surface hardness. "The investment might seem high, but you spent $700,000 on the field," he said. "For $4,000 you can get one, and it's what the NFL uses to monitor surface hardness on their fields before every game."
Painted areas require particular attention during regular maintenance, since those areas can become among the hardest parts of the field. "In the NFL, we are suggesting that an area gets painted four times and then that entire paint in that area is removed," said McNitt. "And sometimes you even have to remove crumb rubber because it's coagulated together."
If your field is still under warranty, your synthetic turf manufacturer might pay for someone to come out and test the field annually with an impact device to tell you how hard the field is, and also to test the infill depth. But monitoring field performance becomes even more critical once the warranty has expired—when field owners try to continue to use a field well beyond its expected life.
"There comes a point in time when, regardless of how much maintenance you've done on the field over the years, that field will no longer perform," said Doyle. "So if you're not periodically testing the performance of the field, you will not know for sure that your field is reaching the end of its useful life."
Doyle additionally recommends that someone walk the field on a regular basis to check for foreign objects and look for areas that might be in need of repair. To help recreation managers maintain their synthetic turf fields, the Synthetic Turf Council offers a variety of free technical guidelines in the Resource Center section of its website. These include maintenance guidelines, performance guidelines, guidelines for reusing and recycling synthetic turf, and other helpful resources.
Special Considerations for Synthetic Turf
Synthetic turf can handle more intensive use than a grass field, and has the advantage of being playable after rain, but still has its limits. For one, too much action in one spot on a synthetic field can permanently damage the fibers. According to Pearson, this is why the University of Washington hasn't moved away from natural grass on the interior of its track field.
"It'd probably be synthetic if it weren't for the hammer throw," said Pearson. "It just destroys the synthetic. It destroys the grass, too—but we can't repair the synthetic."
McNeal likens it to a carpet at home that has a piece of furniture sitting on it. "If you end up with an indentation in that carpet, it takes a little bit of work to get that out," she said. "You may not get that wear pattern out of a synthetic turf field until you completely replace the field."
She also noted that each manufacturer will normally have their own list of approved events that can be held on the fields. "You could void your warranty if you host certain events, so you want to read that on the front end before you invest in it," McNeal said.
McNeal additionally recommends fencing off any synthetic turf field to help fend off vandalism and damage. "I've seen people set fireworks off on a synthetic turf field," she said. "It's a plastic fiber, so any kind of fire or heat can melt it and cause significant damage to the surface."
Recreation managers also need to plan for more frequent replacement of certain high-use areas of the field. McNeal noted that on a collegiate baseball field that she managed, the batter's boxes were replaced every season, and the wear areas around the bases every three seasons. It's also important to budget for replacement of the field once the warranty expires, typically in eight years.
Synthetic fields also need regular grooming. "If you don't groom it, it's going to start getting little divots where the rubber gets pushed out from drills, and then the fibers get sheared off and it will never fill back in," said Pearson. McNitt recommends that synthetic fields in continuous use get groomed once a week.
When maintaining the field, it's important to use the right equipment that won't dig into the infill and abrade the fibers, according to Doyle. "Anyone getting a synthetic turf field should educate themselves and ask the builder if there's specific equipment that they need to use for the field," he said.
Finding the Right Maintenance Program for Your Surface
Whether you have natural grass fields, synthetic, or both, the most important consideration is to properly support, hire and train people who are qualified to care for your surface type.
Whether you have natural grass fields, synthetic, or both, McNeal said that the most important consideration is to properly support, hire and train people who are qualified to care for your surface type. This includes allocating as many dollars as possible to running the strongest maintenance program you can. In return, you'll get playable surfaces that help keep your athletes safe and your competition sound. "Budgets are being trimmed all the time," she said. "But pulling maintenance dollars away from the field is only going to hurt the conditions of the field and eventually the programs that you put on there."
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