Dow, Ill. ? Walt Gregory found a way to make dough harvesting pizza.

The retired insurance agent and his business partner have carved up quite a tourist draw near the Mississippi River town of Alton, educating people with a half-acre circular plot divided up like the slices of a huge pizza.

Each of the eight wedges represents something used on a pizza, from tomatoes to peppers to herbs, including rosemary and sage. Three goats represent milk and Cleo the cow is symbolic of beef. Seven penned-in pigs illustrate pork.

The chickens pecking nearby? Eggs, of course.

“I enjoy it immensely, just to see the looks on people’s faces and seeing some people make the connection,” Gregory said from his three-year-old “R” Pizza Farm. “A 62-year-old lady, standing with her husband, didn’t know pepperoni came from pigs.”

Only a handful of such farms are believed to exist in the United States. However, farmers increasingly are turning to inventive land use to supplement their bottom lines. Illinois, which is among the nation’s leaders in pumpkin and horseradish production, is no exception.

The project seems to be working for Gregory and business partner Lynne Weis. They expect their organic pizza “demonstration” farm to draw 5,000 to 6,000 visitors this year, far more than the 1,500 visitors in 2004 or the 300 the year before that.

The two have a similar venture near Quincy, with plans for a third next spring near Peoria.

“Word’s getting out,” Gregory said as he walked through the wedges, plucking peppers and tomatoes along the way.

During tours offered from April through October, Gregory briefs guests about the ingredients, then walks them through each slice. Afterward, there’s pizza and soda in a pizzeria inside a log cabin.

Most of the ingredients come from the farm and are organic, including the fennel herb commonly used to flavor Italian sausage. Gregory still hopes to find a source of organic cheese and is talking with an Amish slaughterhouse about supplying organic pepperoni.

Gregory hopes to educate guests about organic growing. He makes no bones about his opposition to corporations behind agricultural biotechnology or farmers who use herbicide-resistant products he considers dangerous.

“Someone’s got to stand against them. That’s what I try to accomplish with the pizza farm,” said Gregory, who elsewhere on his spread grows asparagus, zucchini, watermelon, cantaloupe, strawberries, squash, pumpkins and corn.

Elizabeth Decker, a second-grade teacher in nearby Bethalto, can’t seem to get her fill of the farm. She has taken her classes, which typically number 20 students and chaperoning parents, on the tour every year since the farm opened.

Decker said the place teaches kids firsthand what goes into a pizza, from harvest to hearth.

“I think parents learn just as much as the children,” she said.