One warm California evening last summer, 28,000 San Franciscans streamed into AT&T Park at the start of the July Fourth weekend — not to see their beloved Giants, but to enjoy superstars from another hallowed local institution: the San Francisco Opera.

As remarkable as it was for thousands of picnickers to spread their blankets on the outfield grass for Opera at the Ballpark, perhaps the most impressive production happened after the event. Because just two days later, the Giants began a six-game homestand; and thanks to the hard work and planning of the AT&T Park field operations staff — not to mention wise turf management — the outfield was in pristine condition.

As groundskeepers at sports facilities of all stripes know, stadiums and ballparks are no longer devoted exclusively to their intended sports. From opera to concerts and ski jumps to tractor pulls, fields are increasingly subjected to wear and tear that would cause managers from decades past to head for the nearest stadium exit – and the number of these events are increasing. For example, take Petco Park, home to the San Diego Padres. It was the host for the 2013 Davis Cup and has over 12 special events planned for 2017. Denver’s Sports Authority Field at Mile High (Denver Broncos) has fourteen events scheduled this year, including a Guns ‘n’ Roses concert, CONCACAF soccer and Drums Along the Rockies, a major marching band event. (Major events at Mile High are nothing new; on August 28, 2008, the park was the scene of Barack Obama’s acceptance speech for his first presidential nomination – an occasion that drew 84,000 people.) Across the country, Raymond James Stadium, home to the Tampa Bay Buccaneers, hosted the two-day Sunset Music Festival in May and U2’s Joshua Tree tour one month later.

In most cases, perhaps only a day or two separates a high-usage, on-field special event from a scheduled regular season game. The challenges of maintaining world-class turfgrass in an era of crowded special event calendars, demanding sports teams, as well as budgetary, manpower, regulatory and environmental constraints, are considerable.

Getting in the zone

Fenway Park, a most-hallowed pro sports venue, is nonetheless a multiuse facility. In addition to Boston Red Sox baseball games, Fenway often hosts concerts and large corporate events; in 2010 it also staged the NHL Winter Classic, a game that required the installation of a hockey rink behind the pitcher’s mound from first to third base. In February of last year, the ballpark hosted Polartec Big Air at Fenway, featuring a 140-foot big air snowboarding ramp that exceeded the height of the park’s light towers by 10 feet.

According to David Mellor, Fenway’s senior director of grounds, an all-sand root zone was the park’s traditional solution for good root growth and proper drainage. The year-round demands caused by a full calendar of special events, however, caused him to look for an enhancement.

“We did a lot of research and found that a combination of sand and soil amendment would not only help with rooting, but also assist with moisture management and nutrient retention,” he says. Mellor and his team use Profile Porous Ceramic to supplement the sand-based root zone. The kiln-fired ceramic amendment, manufactured by Profile Products, is an option often used in lieu of peat. The inorganic particles both hold water and release it gradually over time, promoting drainage and providing permanent air space in a rootzone soil.

During a recent sod resurfacing, Mellor’s crew tilled Profile Porous Ceramic into the sand to a depth of 7 inches. Mellor says that with the large number of events held at Fenway, the supplemented sand base has been an improvement. “We had a healthy root system before, but now it’s even better,” he explains. Mellor’s crew uses Profile – in its emerald variety – to topdress the outfield grass after games. He believes the new root zone holds nutrients better. “That was one of the biggest factors.”

M&T Bank Stadium, home to the Baltimore Ravens, made the decision in 2015 to revert to natural grass after thirteen years of synthetic turf. The decision was prompted by advancements that made it possible to grow grass effectively in the stadium’s shadier areas.

Before the team went with the synthetic surface, late-season shade in the east end zone caused the natural turf to wither. “The major shortcoming of the grass field we had from 1998 to 2002 was that the root layer was only 6 inches deep,” recalls Don Follett, senior director and grounds for M&T Bank Stadium. “For the new [natural grass] we doubled the depth to 12 inches to create an environment for better root development.”

Like Mellor’s crew at Fenway, Follett specified Profile Porous Ceramic for the root zone. The groundskeeping team also oversaw the installation of supplemental light units from Stadium Grow Lighting that made up for the loss of late-season sunlight.

Follett explained the deeper root system would help the grass withstand not only football games, but also non-sporting events like concerts that require multiton, on-field stages. In May, M&T Bank Stadium was filled with heavy metal fans to see Metallica’s WorldWired tour. “With a high-performance mix, I fully expect the grass to perform 100 percent all the time, regardless of the weather or the pounding the field takes the week before,” Follett said in 2016. “That includes concerts that bring in 100,000 tons of steel and 100,000 people.”

Diverse demands

Pro sports fields of all types, including practice fields, are prone to alternative uses that can compromise their primary purpose. In Columbus, Ohio, the Columbus Crew (Major League Soccer) maintains a first-rate practice facility in suburban Obetz. In addition to supporting the club’s first team, the facility, named EAS Training Center, is used for soccer academies and college programs.

Ben Jackson, the head groundskeeper at EAS Training Center, reports the native soil is a challenge. “It’s a mixture of clay and silt. The small particle sizes bind together and reduce water movement,” he observes. Because budgets are tight, the club is on a program to overseed the sodded bluegrass with bermudagrass. But Jackson reports that one of the most high-value steps taken so far has been to incorporate sand into the profile – something that helps when the two fields at the facility face increased wear. “We topdress with sand 10 to 14 days before a major event,” reports Jackson. “This helps open up pore space and supports water movement.”

The groundskeeping crew at the center fertilizes regularly to promote root depth as well as lateral growth. Fertilizing also inhibits the shoots, which cuts back on clippings. “For our facility, the college program is the most intense period,” says Jackson. “Forty guys are playing on the same areas of the fields five days a week.” Noting the use of wetting agents to improve absorption and enhance surface quality, he adds, “Keeping our bluegrass alive is tough when the temperatures go above 90 degrees.”

For AT&T Park, located in a San Francisco region normally prone to water shortages, the challenge of staging events is compounded by environmental restrictions. During the severe West Coast drought of the past few years, the facility was required to reduce water consumption by 25 percent. Greg Elliott, director of field operations, says the park was able to meet its conservation obligations via advancement in both soil science and technology.

“We use a combination of sand and porous amendment as a topdressing, matching the profile of the soil beneath. By blending, we get a mix that absorbs moisture better, keeps it in the soil longer and releases it gradually,” Elliott says. AT&T, another user of Profile Porous Ceramic, has chosen the Emerald Greens Grade product for its turf. “The green color lets the dressing disappear,” notes Elliott.

To optimize its water use, Elliott installed sensors in the field that manage the water application rate from the irrigation system. The web-based system addresses plant needs based on the evaporation rate; the team gets a reading from a private company, then inputs the data into the irrigation clock. According to Elliott, topdressing also makes it possible to reduce water use. “Most times we were under the reading number, so we could raise our number and still reduce our water use.”

Using a ceramic soil amendment has been a boon to AT&T Park’s water utilization – something that has helped turf performance year-round, through a variety of events. “Any time you can use an additive [like Profile] it will help you in the long run. It gives you more options. It helps rain pull through that much faster,” Elliott advises. “I could buy straight sand but a secondary additive makes a difference.”

Depending on the event, however, Elliott notes that more intense intervention may be needed – even to the point of preemptively removing sod. “Today, field directors are more risk managers than groundsmen. The days of not knowing what to do are pretty much gone.”