For years, sports fans have been told to put their glass bottles and aluminum cans in recycling bins at arenas and stadiums.

Now, a growing number of teams, eager to cut costs, are asking them to toss their food and biodegradable cutlery, trays and cups in separate bins, too.

Teams including the Seattle Mariners, Pittsburgh Pirates and Portland Trail Blazers, and events like the United States Open are embracing composting because it can reduce expensive fees to send trash to landfills and incinerators. Composting avoids producing tons of greenhouse gases like methane and instead produces tons of mulch that can be used as fertilizer.

“This was a little bit of a no-brainer because it probably made the biggest impact to the public,” said Jim Ibister, the vice president for administration of the Minnesota Wild of the National Hockey League and general manager of the St. Paul RiverCentre, the convention center next to the Xcel Energy Center, where the team plays. “We’re a hospitality industry, and we create a lot of food waste and paper products, and that would have all gone in the trash.”

Arena and stadium operators have focused for years on recycling glass, metal and cardboard, some of which could be sold, even though food and utensils, cups and the like — which the industry calls serviceware — made up a greater share of their waste and created other headaches, like vermin.

Cooks in stadium kitchens have composted for years, but teams did not expand into general seating areas because they did not want to ask fans to put leftover hot dogs, peanuts and pretzels in one bin and plastic cups and cutlery in another.

As the price of compostable forks, knives, spoons, plates, trays and cups has fallen, teams have been able to expand composting throughout their venues because biodegradable serviceware allows fans to throw everything in one can.

Many of these compostable products are made with Ingeo, a corn starch-based material developed by NatureWorks, which, like plastic, is strong and lightweight, but can be composted with food scraps. Though still more expensive than standard products, their higher costs were offset by a reduction in landfill hauling fees, Mr. Ibister and other venue operators said.

Steve Davies, the director of public affairs at NatureWorks, said sports venues were good places to compost because building operators can control which products are used, and that reduces the amount of noncompostable items that must be removed from the compost.

“While there are challenges, sports venues are one of the easiest places to effect change because the venue completely controls what comes into the building,” Mr. Davies said. “It’s a closed loop.”

Expanding composting to general seating areas, though, presents challenges: Stadium and arena operators must find a large, regular supply of compostable paper goods; extra bins must be bought and labeled so fans know what to discard and where; storage space is needed for the compost and a composter typically must be hired to haul away the waste to be processed.

Finding an affordable composter that can haul tons of waste can be difficult. About 96 percent of all food waste in the United States, or about 100 billion pounds a year, is dumped in landfills or incinerated, according to Alice Henly, the director of programs at the Green Sports Alliance.

“The main constraint is finding composting facilities in easy access to their facilities,” she said.

Teams and venue operators like Mr. Ibister say it is worth the trouble.

Because of an aggressive program of recycling and composting, the amount of trash collected at the arena and convention center in St. Paul that has been sent to landfills or incinerators since 2008 has declined by 60 percent, or by 725 tons, a year.

The Wild are following in the footsteps of the Mariners in Seattle. Just over half of the team’s waste is organic, and through an aggressive composting program that began in 2006, it has saved $95,000 a year in landfill hauling costs.

AgRecycle, a commercial composter hired by the Pittsburgh Pirates, makes compost that the Pirates use to make youth baseball fields. The Pirates also collect grass clippings and the clay used for warning tracks for composting, said Carla Castagnero, AgRecycle’s president. Most teams, though, simply pay composters to haul away their food and biodegradable serviceware.

But at least one stadium operator is composting on its own. Last fall, the operator of MetLife Stadium, the home of the New York Jets and Giants, bought a composter and mixing unit, which were first placed near a loading dock, then moved to a more central location at the 750-acre sports complex in East Rutherford, N.J. After events at the stadium, which seats more than 80,000, workers throw all food and compostable serviceware into a vessel and add carbon-rich material like cardboard and paper to thicken the soupy mix.

After about eight weeks in the composter, the processed mulch is removed from the vessel and piled up until it is ready to be used as mulch at the facility.

“When you give your material to a recycler, you rely on them to do the right thing,” said David Duernberger, the vice president for facility operations at MetLife Stadium. “With us, we have complete control over the process.”