Like many farm owners in the woodsy hills of Middleburg, VA, Dorothy A. Smithwick has land as far as the eye can see. Her cash, on the other hand, isn’t as far-reaching.

But when she got the chance to sell a chunk of the property, a historied strip worth as much as $20 million, she didn’t take the money and run. Instead, she put the land into an easement, joining an increasing number of property owners from the District of Columbia out to the Piedmont who are protecting their land from development using a little-known state tax credit.

Six years ago, Virginia lawmakers enacted the tax credit for landowners who place their property under conservation easements. The program rewards landowners with a credit worth 50 percent of the value of the easement.

The credit can be claimed over six years and can be sold—making the state one of the only ones to allow such sales.

That, experts say, has played a role in boosting donations of land from fewer than 6,000 acres in 1995 to more than five times as many last year, according to data from the Virginia Outdoors Foundation.

In the first year the credit was enacted, conserved acres more than doubled. But in 2002, when the credit became transferable, the numbers again jumped from about 23,000 to 38,000.

“There was a huge increase as soon as those credits became transferable,” said Nicholas Williams, director of the Maryland Environmental Trust, one of several state agencies in Maryland that accepts donated easements. “That meant people could buy them and sell them and make money.”

Since 2000, property owners have qualified for $382 million in tax credits, according to the Virginia Department of Taxation.

It’s great for folks like Smithwick, who prefers to see the farm where she trains 30 or so horses remain development-free. She donated 1,076 acres; her property, Sunny Bank Farm, has land enough for at least 250 houses.

“It’s terrible, little houses everywhere,” said Smithwick, an admitted curmudgeoness who prefers the company of animals to the glitz of Middleburg society. “I’d just like to keep the farm going.”

But where some see a benefit, others see a boondoggle.

They say rich landowners are taking advantage of the program and aren’t adequately monitored for compliance. A third party agency, usually the Virginia Outdoors Foundation, gets stuck with the responsibility of protecting the easement. Meanwhile, the landowners become eligible for major reductions in their local property tax bills.

“It’s a huge scam,’’ said Sally Mann, a property owner near Hamilton who believes her neighbor’s use of his land for farming violates the terms of his easement. “The government is paying very wealthy people to live on their estates that they would never subdivide to begin with.”

But foundation leaders insist they maintain stringent standards to ensure easements aren’t developed illegally. Field inspectors investigate complaints; easements also are noted permanently on property deeds.

Smithwick said she waited years before deciding to take the plunge. She did it not for money, she said, but to encourage others to follow. “The money means nothing to me. Nothing,” she said on a recent spring morning, puttering around the farm in her worn pickup truck. “I never had much to start with. This is all that I have.”