A city proposal to preserve 52,575 acres of privately owned farmland on Oahu drew a crowd of interested community members — and some protest — Tuesday evening at the city’s first public meeting on the details of its plan.

Close to 150 people — mainly landowners and farmers potentially affected by the action — attended the meeting in Kapolei Middle School’s cafeteria to hear a presentation by project officials and ask questions.

There also was a demonstration and vocal objections from about a dozen people opposed to the Ho‘opili residential community slated to be built on about 1,500 acres of farmland on the Ewa plain that the city and state recently approved for 11,750 homes.

Scott Ezer, a principal with HHF Planners who is helping the city pick the private farmland it wants to protect, told the audience that the process is a big undertaking that will involve City Council and state Land Use Commission approvals.

“There is still an extensive process that needs to happen,” he said. “It’s still a complicated process. This hasn’t been done before.”

The city Department of Planning and Permitting has been working to identify suitable private land to be designated as “important agricultural lands,” or IAL, under a state law passed several years ago.

In 2015, DPP identified 56,000 acres for possible protection. Now the agency has zeroed in on a recommendation and is soliciting public comments on its proposal to preserve 52,575 acres — largely in the Wahiawa, North Shore and Kunia areas — for agricultural use in perpetuity.

Other considerable swaths recommended for preservation are in Waianae, Maili, Mililani Mauka, Kaaawa and Waimanalo.

An interactive map of the recommended parcels is at mapoahuagland.com.

The department mailed letters explaining the initiative to about 2,000 owners of farmland being recommended for protection.

Affected landowners may respond in writing and oppose the city’s recommendation.

Ezer said there are benefits available to owners of designated land, including financial assistance for improving farm operations.

A group opposed to Ho‘opili interrupted Ezer a few times during the meeting to question or dispute the reasoning for why the city isn’t trying to preserve the site for farming.

“Ho‘opili meets all the criteria (for preservation),” said one man wearing a green T-shirt with the statement “Aloha Aina! Stop Ho‘opili” in white lettering.

The city said the state’s IAL law excludes land in several categories from involuntary preservation, including land designated for urban use in city land-use plans and zoning. The Ho‘opili site has been designated for urban use since the 1970s.

Other exclusions are federally owned land, state land and land of private owners who already have voluntarily designated at least half their property for IAL protection.

Several people during the meeting urged the city to put Ho‘opili on its map, and received applause.

“We still have possibilities to overturn the decision that approved Ho‘opili,” said Kioni Dudley, a Makakilo resident who tried to block Ho‘opili from being approved by the Land Use Commission and City Council.

Dudley said the city should put the Ho‘opili site on its map even though developer D.R. Horton began construction on an initial phase in September.

“We don’t need Ho‘opili,” he said. “We don’t need the jobs. We don’t need the homes. We need that land for agriculture in the future to survive.”

A second public meeting is slated for Tuesday at Haleiwa Elementary School from 6 to 8:30 p.m.