On Friday, when a former diner at Second and Girard reopens as the Soil Kitchen, you will not be asked to eat dirt.

This "kitchen" is more art installation than eatery.

It's a place where folks can bring in a soil sample from their backyards (see graphic instructions at soilkitchen.org) and enjoy a free bowl of soup made with fresh local ingredients (courtesy of Cosmic Caterers) while waiting for scientists from the federal Environmental Protection Agency to see if their dirt is safe.

Odd, yes, but this is what happens when you set out to become the Greenest City in America by 2015 (Philadelphia's goal) and create an Office of Arts, Culture, and the Creative Economy: You get a combination soup kitchen and soil-testing center with a windmill on top.

Two giant wooden spoons will represent a windmill, pointed at the permanent statue of Don Quixote, a gift from Spain, at that intersection.

Unlike the statue, the Soil Kitchen is temporary - a pop-up open 11 a.m. to 6 p.m. through April 6. After that, the soup, the soil, and the spoons will disappear.

But we won't be empty-handed. We'll have a helpful map of the soil quality in various Philadelphia neighborhoods and a host of new ideas for providing untainted food for all in the future.

That would be a tall order for any short-order cook, but this project is being put together by a San Francisco art collective, Futurefarmers.com ("cultivating consciousness since 1995").

It has already created a Reverse Ark (think water inside and people outside) and a shoelace exchange elsewhere in the country.

These are artists for whom the message is more important than the medium. So don't ask if they work in oils or clay, and don't expect them to finish and frame their work or hang it in a gallery down Second Street in Old City.

"We are architects, graphic designers, scientists, inventors, and urban farmers," says Amy Franceschini, who founded the collective in 1995. "We share a common interest in how humans impact the land."

Futurefarmers encourages discussion about alternatives to all kinds of current systems - not just food-related. But since we all have to eat, says Franceschini, 40, food is our common denominator, and that became the collective's metaphor.

Futurefarmers might ask, for example, why we don't provide government subsidies to backyard gardeners or farmers who use organic, sustainable methods.

"We could hold a meeting to get that discussion going, but it's much more interesting to invite the community together to create a space like this for the discussion," Franceschini says. "This way there's humor involved. There's a creative, playful entry point."

The fact that Soil Kitchen is only temporary gives some urgency to the discussion. And the timing is key because a national conference on brownfields (neighborhoods like Northern Liberties that were once home to factories) will meet Sunday through April 5 at the Convention Center. (See www.brownfields2011.org)

The free convention, a project of the EPA, is expected to draw 5,000 visitors.

Gary Steurer, who heads the city's Office of Arts, Culture, and the Creative Economy and holds the auspicious title of chief cultural officer, is behind all this.

His office, which plans to sponsor a host of temporary public art projects, received a $40,000 William Penn Foundation Grant in November and invited teams to submit proposals.

Futurefarmers' idea for Soil Kitchen was the unanimous choice.

Still wondering about that windmill? It's an image really, not a working turbine.

"In the beginning, we were just looking for an abandoned property to use," says Franceschini, "But a member of our collective, Dan Allende, grew up in Moorestown, and he knew about the Don Quixote statue - actually pointing at an abandoned property."

Quixote attacked windmills, imagining them to be giants.

"So here, the windmill is an invitation to imagine a different future."