John Hileman still lives on the family farm where he was born 83 years ago. He may be the only constant in Scotch Valley, as residential settlements have cropped up around his land, where he once tended dairy and beef cattle.

“In Scotch Valley, it was nothing but farms and dirt road,” said Hileman, president of the Blair County Farm Bureau. “At that time, everything was farmed with horses. ... But it has changed, and you just don’t think about doing a whole lot of farming here anymore. If you wanted to have a dairy operation or something, you’d be in trouble.”

Scotch Valley is an example of the changing face of farmland, which is being purchased for residential and commercial use, said Natalie Ferry, a retired Penn State University professor who co-authored a study on the changing landscape of central Pennsylvania in 2003.

“As a city moves out, instead of having suburban housing areas on small lots and being very concentrated, it’s very typical (that) people buy several acres of what could be agricultural land and put a house on it,” Ferry said. “In Pennsylvania, that’s the most common way we see outward migration around smaller cities.”

Some groups are working to preserve farmland by purchasing farmers’ development rights, or easements. In 1989, the state Department of Agriculture formed the Bureau of Farmland Preservation, which oversees the county-level preservation groups.

Farmers can apply to have their development rights purchased by the program through their county office. The board decides which projects to pursue by evaluating the farm’s soils, farmland potential versus development potential and proximity to land that’s already preserved, said Donna Fisher, coordinator of the Blair County Agricultural Land Preservation Board.

Farmers retain physical ownership of the land.

“It provides cash flow to the operation,” said Jeff Kloss, coordinator of the Bedford County Agricultural Land Preservation Board. “When the land development easement is purchased, they get a cash settlement to re-invest in the farm. In the long run, it also provides a way for farmers to ensure families can continue on in farming.”

Don Gearhart, a dairy farmer in Martinsburg, sold his development rights to the program in 2001, and later sold his farm to his son. He said he was concerned about development in the area and wanted his land to remain in agriculture.

“I believe someday this country’s gonna go hungry if they keep building on agricultural land,” Gearhart, 78, said. “There’s too much land being eaten up by development. That’s the way I feel about it.”

Purchases must first be approved by the county commissioners and then by the state, Fisher said. About $35,000 of her yearly budget comes from Blair County; $165,000 comes from the state.

The board pays the farmer for the development rights, which is $900 per acre in Blair County, Fisher said. Development rights are about $1,300 per acre in Bedford County, Kloss said.

He said his program receives about $70,000 from the state each year, $1,000 from the county for development rights and ‘‘another couple thousand’’ from the county for administrative costs.

In April, the Bedford board celebrated a milestone with its most recent farm purchase: 2,000 acres of farmland that have been permanently preserved.

‘‘For us, it’s significant. It shows our program is continuing to move ahead,’’ Kloss said. ‘‘There are around 200,000 acres of land that are considered of prime or statewide significance in Bedford County, so we’ve gotten 10 percent of the most significant land.’’

David Hileman, a dairy farmer in Sinking Valley, wanted to preserve the agricultural heritage of his land and sold his development rights in 2005.

“There’s a rich agricultural heritage here in Sinking Valley,” said Hileman, 63. “I think it’s important that we maintain that heritage. Sinking Valley has very rich, fertile ground; it’s a very beautiful valley. I can understand why people want to move from urban areas to this valley.”

But, Hileman said, some land would be better used for development than agriculture.

“I am part owner of a piece of property in the Martinsburg area that was also appraised and was into the system to be looked at for farmland preservation,” he said. “It happened to be right up against major development taking place on both sides of it. I really strongly felt that it was not a piece that should be preserved. It was where the development should take place.”