Yanqi Wu watched only snippets of Super Bowl LVII on delay Sunday night. He is the rare person who knows more about grass than the sports played on it. A professor in the plant and soil sciences department at Oklahoma State University, Wu developed one of the grass varieties chosen for the Super Bowl field. Despite only catching highlights on YouTube, Wu could sense that the playing surface in Glendale, Ariz., had attracted unwanted attention. “Yes,” Wu said Monday. “I observed that information scanning social media.”
As Sunday night wore on, the State Farm Stadium turf became a character in the drama. Ballcarriers slipped when they tried to cut. Discarded cleats piled up on the Philadelphia Eagles’ sideline. Upturned divots dotted the field. Eagles kicker Jake Elliott skidded as he booted a kickoff. Pass rushers’ feet spun in place as if they were Fred Flintstone. Eagles linebacker Haason Reddick called it “the worst field I ever played on.”
Wu never worried his grass, a strain of Bermudagrass known as Tahoma 31, could be the culprit. Turf experts affirmed Wu’s confidence Monday. Still, the NFL had provided a Super Bowl field that Eagles tackle Jordan Mailata compared to a water park. Given the time, effort, brainpower and resources devoted to every last detail of America’s biggest sporting spectacle, how could such an elemental piece of the game falter so thoroughly?
The slipperiness led turf management experts to theorize that the NFL prioritized the field’s aesthetics over its playability, that the league manipulated the grass so it would look lush and green to the potential detriment of traction. Wu said he did not want to speculate about the field’s condition because he was not on-site and his expertise is breeding grass, not managing it. When asked why the NFL would deploy the technique it used to prepare the field, though, Wu replied, “It’s for the beauty.”
The NFL did not make field director Ed Mangan or any other grounds-keeping personnel available for an interview.
“The State Farm Stadium field surface met the required standards for the maintenance of natural surfaces, as per NFL policy,” the NFL wrote in a statement. “The natural grass surface was tested throughout Super Bowl week and was in compliance with all mandatory NFL practices.”
Tahoma 31 is newer than most grasses, but it is not novel. Wu began breeding it in 2006. Tests began in 2008 and continued for a decade. In 2017, it was released for commercial production and several major stadiums and ballparks use Tahoma 31 — including Lincoln Financial Field, the home of the Eagles, according to Oklahoma State. Dodger Stadium and Churchill Downs have installed Tahoma 31. Arkansas uses it at Donald W. Reynolds Razorback Stadium, which last year the Sports Field Management Association named its college football field of the year.
“There’s nothing wrong with that grass,” North Carolina State University turfgrass management professor Grady Miller said. “A lot of people are zeroing in on Tahoma 31 Bermudagrass, which is actually the least likely culprit of the scenario, to be quite honest. There’s been a lot of fields put in with Tahoma 31. It’s been a good grass. It is a good grass.”
But it was not the only grass the NFL used. The field was housed this fall at West Coast Turf, where the NFL oversaw the process of overseeding the field with ryegrass — planting a second grass atop the Tahoma 31. Whereas Bermudagrass goes dormant in cold weather and turns brownish-yellow, ryegrass grows lush green. But ryegrass is naturally waxy to the touch and slippery.
“From a Super Bowl standpoint, it is 100 percent aesthetics,” Miller said.
Overseeding with ryegrass, Miller said, can be useful from an agronomic standpoint. A golf course in the south that receives ample play in the winter would use ryegrass to provide a “wearable surface” and protect the underlying, dormant grass. At the Super Bowl, staging a few weeks of rehearsals and one game would not require such measures.
“They were doing it so you have a very uniform, pristine, green, shiny surfaces on which to paint logos on, and it looks great on TV,” Miller said. “If you have any blemishes, the ryegrass will hide blemishes. To say that’s a Bermudagrass field they played on, yeah, there’s Bermudagrass in there. But they’re mostly playing on the surface, which is a ryegrass.”
The NFL assumed control of the Super Bowl field from the Arizona Cardinals, who play in the host stadium. In October, the NFL oversaw the overseeding process at West Coast Turf, a sod farm that housed the field.
Brian Whitlark, an agronomist for the U.S. Golf Association region that includes Phoenix, is familiar with the NFL’s process. The USGA funded agronomy research at Oklahoma State, and he knows many local contacts in the industry. The field was overseeded with 650 pounds of ryegrass per acre in ideal weather.
“They had a very successful overseeding, which sounds good,” Whitlark said. “But that led to a very dense ryegrass stand and a fairly high height of cut. The ryegrass was probably one inch when they were playing in the Super Bowl. The players were basically playing on a slippery ryegrass surface.”
A West Coast Turf representative did not return a request for comment.
At State Farm Stadium, workers would move the field outside the stadium on a massive, rolling tray so it could receive sunlight, then roll it inside at night to protect it from low temperatures. The field was rolled inside for the final time Wednesday, four days before the game.
Moving it inside, from hot temperatures to cool, could have produced condensation — and ryegrass grows extremely slick when wet, Miller said. But Whitlark said turf managers had a plan for that. Giant fans dried out the field to “avoid excessive leaf wetness,” he said. Handheld soil moisture sensors, Whitlark said, measured at 21 percent last week, a mark that indicated there was no excess water. The field’s issue, Whitlark said, was the inherent slickness of thick ryegrass.
“I can assure you the soil was not wet,” Whitlark said. “That was not the reason for the slippery conditions. It wasn’t mismanagement of the moisture that led to slippery conditions.”
“I hate to draw analogies and point fingers, but it’s a little bit like a beauty pageant,” Miller said. “Those ladies put on extra makeup for that pageant than they would every day, right? Everything goes to an extreme for that event, and that’s not always necessarily a good thing. A lot of it is for aesthetics.”
Watching from home, Miller noticed many of the most ripped and torn spots on the field were on painted logos. Research indicates that paint stresses grass. The grass could have also been weakened by multiple rehearsals for pregame, halftime and postgame shows.
Miller is a proponent of natural grass, believing it prevents injuries compared with synthetic turf. He hated seeing players slip because of the potential for injury and how it could affect the game. He also cringed because he knew how some viewers would react.
“I did wince when it kept getting mentioned about slippage, because obviously it’s not painting it in a positive light,” Miller said. “I saw a number of people saying, ‘Why aren’t they just using synthetic?’ ”