Could chopping an athletic field into squares keep it green?
Several football teams, led by the Ravens at PSINet Stadium, think so. They have adopted the latest in high-tech fields: real grass, cut into half-ton sections and assembled like a puzzle.
The idea behind the "modular" system is replacing worn spots with fresh turf. Chunks in the center of the field, where football play is concentrated, are exchanged with greener sections from the sidelines. A team can even buy a second field and move pieces back and forth.
Think of car owners rotating their tires.
The Ravens went modular in late August, after the summer's drought and the filming of a movie ravaged the previous field, which was a combination of grass and plastic. Most of the cost, about $1 million, was paid by Warner Bros.
"I think you'll see more and more modular. You are going to see the industry go in an entrepreneurial way after natural turf," said Chuck Dixon, president of Turf Diagnostics and Design, a sport turf consulting firm based in Olathe, Kan.
"It's a very exciting time in turf," he said.
All of this heartens supporters of real grass, who sense a move away from the oft-maligned artificial turf that caught on in the 1970s. Currently, 17 NFL teams play on natural grass and 14 on artificial. But six of the artificial turf users are considering or have announced a return to grass.
"The good thing is they are not only switching over to grass fields but are taking an interest in the type of grass surface it is. There is a lot of new technology out there," said Carl Francis, spokesman with the NFL Players Association.
Artificial turf drains well and offers good traction, but is considered by players to be too hard and unforgiving. Natural grass is soft, but takes too long to grow and puddles in rainstorms.
"The NFL is very hard on their fields. You constantly wear down the center of the field," Dixon said. The popularity of professional soccer and the desire to book concerts and other events at new stadiums such as Baltimore's, have also created demand for sturdier fields, he said.
The Ravens opted for a modular field developed by Dupont Corp. and Hummer Turfgrass Systems Inc. of Lancaster, Pa.
Hummer's "GrassTile" system has a surface that is all grass, grown in a mixture of sand, dirt and recycled carpet fibers. Seven-foot, 1,000-pound squares of the turf are set down on the field by special machinery.
The Ravens were pioneers in another experiment in 1996. They installed a field of "SportGrass" that was billed as the best of artificial and genuine turf. Made by a Gaithersburg-based company, SportGrass featured grass tufted into an artificial base.
After the Ravens, the Green Bay Packers installed SportGrass and the company seemed to be the NFL's field of the future.
But both teams abandonded SportGrass this year.
The Ravens had installed SportGrass at Memorial Stadium and brought much of it with them to PSINet last year. It was laid over a 40-mile network of tubes, through which heated water can be pumped to keep the field from freezing in the winter. The tubes remain in place.
Maryland Stadium Authority executive director Bruce Hoffman said, "It's a good field to play on but it's hard to keep green."
Ravens spokesman Kevin Byrne said the team was pleased with SportGrass, which it received at a cut rate for serving as a guinea pig, but needed a fast replacement after the field was damaged.
Hummer's turf could be brought in quickly, and also allowed the filmmaker to easily swap the Ravens' sprayed-on field logo with that of the mythical team in the movie.
The Ravens may still opt for SportGrass when they get around to building a new training center, Bryne said.
One Ravens player, wide receiver Jermaine Lewis, said the new field seems softer. "It's not as fast as last year's, but it still is a quality field," he said.
The Packers went through several SportGrass fields since 1997, trying to solve problems ranging from browning to slippery algae growth. Mid-field thinning got so bad at one point that players began referring to the sandy center as the "beach."
A few weeks ago, the team gave up.
"It just wasn't playing to where we wanted it to play. We decided to put in real grass," said Packers spokesman Dave Gaylinn. "We think it's a great product that will have a future in the NFL, but it needs to be tinkered with."
Modular fields have been around since 1994, when an agronomist at Michigan State University carpeted the Silverdome near Detroit with natural grass for the 1994 World Cup of soccer.
The system utilized hexagonal pieces of thick-cut sod, treated with hormones to resist turning white and stringy from a lack of sunlight.
GreenTech Inc. of Richmond, Va., has taken the modular format one step further by growing sod in plastic trays containing its own ventilation and drainage systems, topped by layers of sand and dirt. The interlocking modules are 46 inches square.
As with Hummer's system, the squares fit tightly together, providing a soil-to-soil seam at the top to eliminate gaps.
GreenTech won its first NFL clients last month when the operators of Giants Stadium announced plans to buy a modular system -- a few weeks after Jets quarterback Vinny Testaverde suffered a season-ending injury on the stadium's artificial turf.
"There's a lot more emphasis now on the field. There's more money in the industry now and fields are more important," said Chris Scott, president of GreenTech.
Andy McNitt, a soil scientist at Pennsylvania State University, said the science of creating and maintaining athletic fields is undergoing a burst of technological advance. But, he warns, any system is only as good as the people maintaining it.
"In the end, somebody has to be able to grow grass and take care of it," he said.
Staff writer Brent Jones contributed to this story.