San Francisco, renowned for its civic will to save the planet, is now ordering residents and businesses to compost food scraps and biodegradables, or risk fines for not properly sorting their garbage.

That's welcome news for Jepson Prairie Organics, a Dixon-based composting firm that already accepts delivery of 400 tons a day in plate scrapings, greasy cardboard and other sweet-stinking waste from San Francisco eateries and homes.

It's also uplifting for Kathleen Inman, who uses the finished product to cultivate her pinot noir vines at Inman Family Wines in Sonoma County's Russian River Valley.

For some 200 Northern California vineyards that use it, there is something about San Francisco compost and its unique, urban blend of crab shells from Fisherman's Wharf, pasta from North Beach, pupusas from the Mission District and dim sum from Chinatown that nourishes the soil like little else.

Yet the question for San Francisco is whether the new city composting law signed by Mayor Gavin Newsom last month will nourish the city's ecological soul or merely irritate the populace.

The new law gives the city authority to fine residents and small businesses $100 – and impose penalties up to $1,000 on big firms and apartment owners – if they refuse to segregate leftover fish bones, watermelon rinds and watercress salad into compost bins.

Even in liberal San Francisco, which boasts of recycling 72 percent of its 2.1 million tons of waste a year, a few residents wonder if the law is a case of big compost meets Big Brother.

"I think a fine is a little excessive, especially considering that it will probably be levied on the landlords," said David Baird, an interior designer for real estate sales who lives in the city's Castro District. "And if you have 200 units all dumping into the same compost bin, that's going to be pretty gross.

"It's insane to sign a law without working out how to enforce it and regulate it."

Newsom, a second-term mayor now running for governor, said the composting law is part of a "local global climate action plan" to reduce greenhouse gases, including methane from bloated landfills.

The city, which has had a composting program since the mid-1990s, has achieved voluntary participation from 50 percent of restaurants, 40 percent of single-family homes and 20 percent of apartments.

But the new law, designed to boost those rates by using the threat of citations, is drawing national media attention.

San Francisco is the first major city to mandate that residents divvy up their trash – with green bins for compost, blue for recyclables and black for garbage – to salvage their food scraps.

"All of a sudden, the headlines were 'Garbage Police: They're coming,' " Newsom mused in a signing ceremony for the law passed on a 9-2 vote by the Board of Supervisors.

Newsom said the law "should be a model for every municipality … across the state of California and the country." But he said citations will be handed out rarely – and only to "egregious" offenders "blatantly violating the law."

The city is hyping the composting law with instructive advertisements on pizza boxes across the city. If they're unspoiled cardboard, they go into the blue recyling bins. If they're kissed by anchovies, they're green bin compost.

The city's efforts to boost composting are applauded by Damon Hall, the "chef de cuisine" at the upscale MoMo's restaurant, across the street from AT&T Park. After Giants baseball games, Hall says he fills three green bins with hundreds of pounds of compostables, from chicken skins and bones to onion cuttings and oyster shells.

Hall considers himself both an environmentalist and a "small government libertarian." He says the city "just has to encourage people" to properly dispose their waste – not necessarily pass a law.

But the recipients of San Francisco's gunky leftovers say they just can't get enough.

Jepson Prairie Organics, which greets 18-wheel trucks carrying San Francisco compostables six days a week, bills its trademarked finished product as "Four Course Compost." Resembling dark roast coffee, it contains key soil-enriching ingredients: nitrogen, phosphorous, potassium and calcium.

Bob Shaffer, a soil scientist from Glen Ellen who works with wineries and farms from Napa Valley to the Sierra Nevada, said San Francisco compostables produce more nutrients than suburban yard clippings or agricultural waste because of the food diversity.

For example, he said, those crab shells produce calcium and chitin, "a very valuable protein in soil." That dim sum is a great source of nitrogen.

And that North Beach pasta helps accelerate the decomposition of slimy scraps into a treasured compost.

The process "is like feeding sugar to children and watching them run around," Schafer said. "That's what happens to my microbes."

In Dixon, Nigel Walker, who runs Eat Well Farms, feeds his soil with a six-inch layer of San Francisco compost. He figures a fraction of the 15 tons of compost he used this year for his tomato, wheat, barley, lettuce and figs may have originated from crops he grew that were consumed and disposed of in San Francisco.

"Every week our trucks go to the city full of vegetables. Then the trimmings come back," he said. "In a way, it's really recycling. We're using the waste from our vegetables to grow more vegetables."

Inman, who produces organic wines, said using San Francisco's compost makes her feel she is "reducing my carbon imprint and returning the earth to the way I found it."

Dave Stockdale, director of the Ferry Plaza Farmers Market on the San Francisco Bay, said he used to just "throw stuff in the nearest trash container, not really thinking where it will end up." The market now recycles or composts 90 percent of its garbage.

"I found green ethics," he said.

Call Peter Hecht, Bee Capitol Bureau, (916) 326-5539.