A proposal designed to protect Charles County's rural areas and discourage sprawl has revived an emotional debate over the development that will be allowed on about 80 percent of the county's land.

The rules would require developers to build houses in clusters on smaller parcels and preserve open space such as farmland and forests.

The proposal, introduced Monday during a Planning Commission meeting, drew passionate protests from farmers, who said the requirements would make their properties less attractive to developers and make it more difficult to retire or pass on land to their children.

"There aren't a lot of farmers anymore," Gilbert Bowling of Newport told planning board members in front of an audience of about 70 people. "Agriculture is in trouble, and it needs help. This isn't it."

The county's current zoning requires three acres for each home built, or about 100 acres for 33 homes. For a new development of six homes or more, the proposed change would require a property owner to preserve 65 percent of the land and cluster homes on the remaining 35 percent. The rules would not apply to subdivisions with 20-acre lots or fewer than six homes.

At issue is whether the proposed changes for the county's agricultural and rural preservation districts -- 240,000 acres -- would reduce the number of homes that could be built.

"Can I guarantee that if someone clusters they won't lose some lots? No," said planning director David Umling. "There are no absolutes."

Umling said the number of homes that could be built would depend on the features of a property, such as whether soil in certain locations is suitable for filtering wastewater.

That answer did not satisfy farmers and others who said the county was more concerned about protecting scenic views than the rights of property owners.

"All you're doing is forcing us to give up 65 percent of our property," said farmer Jim Maus of Nanjemoy. He added, half-joking, "I have 46 acres, and I'd be glad to sell it to you."

The amount of farmland has rapidly declined in Charles, an area once dominated by tobacco production. There were 52,000 acres of farmland in 2002, compared with 68,000 acres in 1987. The number of farms dropped 7 percent, to 418, from 1997 to 2002.

A small group of proponents at Monday's meeting said the regulations are urgently needed because many of the state's tobacco buyout agreements with county farmers will expire by 2011. When those payments end, about 10,000 acres could become available for development.

Those residents praised the proposal for seeking to prevent wall-to-wall subdivision. "The beauty of the rural landscape draws development, which in turn often destroys the natural features that attract people in the first place," said Cheryl Thomas of Welcome, a member of the Conservancy of Charles County.

To opponents, the proposed rules echoed a plan last year that would have required as much as 20 acres for each house. That proposal was rejected by the Charles County Board of Commissioners.

At the time, four out of the five commissioners said they favored mandatory clustering instead. Charles Rice, the county's agricultural land use planner, said clustering might be more attractive to builders because it would allow them to build more houses on less land.

At least seven other counties in Maryland call for clustered development, with a range of requirements for open space. Charles's proposal for 65 percent would fall in the middle. Calvert and Baltimore counties require that 80 percent and 70 percent of open space, respectively, be preserved. St. Mary's and Wicomico counties each call for 50 percent.

A local land planner, who has worked on 14 cluster developments in the county, said the proposed requirements would have unintended consequences.

Timothy Lessner of Waldorf said the proposal goes "far, far beyond" what a citizens commission recommended in 2002. The restrictions on the use of agricultural land with productive soil would push development into forested areas, he said. "This is completely opposite the objective to minimize impacts to woodlands," he wrote to the planning board.

The commission will accept public comment through Oct. 14 and will discuss the issue again before making a recommendation to the county commissioners.