IRVINE, Calif. — A swath of land that was part of the largest lima bean field in North America before it was turned into an air base in 1942 now has come full circle.

When the 4,682-acre El Toro Marine Corps Air Station in the middle of Orange County closed around 1999, local residents voted down the idea of building a giant international airport on the site and instead chose to turn part of the expanse into the 1,347-acre Orange County Great Park, which occupies about twice the area of New York City’s Central Park.

About 100 acres of that park are being transformed into an agricultural area that includes a working farm and a Farm + Food Lab where the public and members of the agriculture community can see a preview of what farming might be like in the future.

Lima beans were just one of many crops grown in the county when it comprised more than 142,000 acres of farmland and was one of the nation’s leaders in farm-gate dollar value, said Tom Larson, manager of farm, food and landscape for the Orange County Great Park Corp.

Today, roughly 2,500 acres of farmland remain in Orange County, mostly strawberries, beans, avocados, bell peppers and some nursery ornamentals.

When the county set out to create the agricultural section of the park, it put out a call for bids to growers to lease a 100-acre site for a working farm. Orange County Produce LLC was the only company to respond.

That’s probably because of the lack of water at the site and the cables running beneath the surface that served as conduits for electricity for the runways.

But A.G. Kawamura and his brother, Matt, partners in Orange County Produce, saw the site as an opportunity to experiment with cutting-edge agricultural practices and to create a farm that experts from around the world could visit and learn. Orange County Produce grows about 1,000 acres of mostly strawberries and beans elsewhere in the county.

The company has planted cucumbers, green beans, heirloom tomatoes, asparagus, eggplant, yellow squash, radicchio, fruit trees and other items on the land. This winter, A.G, Kawamura plans to add cherry and apricot trees.

All are organically grown.

“Quite a bit of our crop can actually go to the food bank, as part of the working relationship we have with the city,” he said.

The farm is open to nonprofit groups for gleaning and harvesting.

A.G. Kawamura, California’s agriculture secretary for seven years under Gov. Arnold Schwarzenegger, hosts organized tours for lawmakers, government officials and agriculture organizations and eventually hopes to offer public tours of the working farm.

Visitors can see an assortment of crops that haven’t been grown in Orange County for a long time.

“We planted the first commercial planting of stone fruits in Orange County in the last 60 years,” Kawamura said.

He’s also looking into the feasibility of adding a vineyard.

The company is working to take itself off the power grid at the site and plans to use biofuels, electric power or hydrogen fuel cells to fuel tractors and other equipment.

Kawamura has a prototype algae production facility that can produce oil for cooking or biofuel.

The 2.5-acre Farm + Food Lab, staffed by Master Gardeners from the University of California Cooperative Extension, helps home gardeners learn about conservation systems they can duplicate in their back yards.

The Farm + Food Lab also has a demonstration aquaponic system.

The designer of the Great Park, which also includes a carousel, helium balloon rides and hosts a variety of community activities, included plans for a “forest” that visitors could walk through.

But Kawamura said the cost of maintaining an “artificial forest” is enormous. and he proposed a forest of avocado trees instead.

Kawamura and Larson recently launched a VALOR — Veteran’s Agricultural Learning Opportunities and Resource — program at the Great Park that teaches veterans how to farm.

In 2013, the Great Park will host the Solar Decathlon, an international competition for building solar homes.

Miami-based Lennar Corp. is paying the city $200 million for the first phase of the park development in return for rights to build residential and commercial units on other parts of the site.