In their living room, above the wood-burning stove, hang some of the rewards Conrad and Patricia Langenfelder have gleaned from a lifetime of farming. There's the engraved plaque that Conrad, or "Dutch" as he is known to his friends, received as president of the Maryland Pork Producers, and a certificate honoring Patricia's work as head of the Howard County Farm Bureau. Nearby are a photograph and trophy belonging to their daughter Jennifer, 18, a former Howard County Farm Queen.

The mementos tell a story of hard work and hard times, of pride and gratitude for the gift of knowing how to coax living things from the ground. But amid the tall rows of corn they planted last spring there's another story, written on a "For Sale" sign: the Langenfelders are getting out.

Their decision has become a symbol of the difficulties connected with the decade-old efforts to preserve agricultural land in Howard, the only county in Maryland and one of a few nationwide to have its own farm land protection program in which the county pays farmers not to sell out to developers.

Citing the rapid pace of residential development around them, the couple have sold their 214-acre Clarksville farm, which has been in Conrad Langenfelder's family for 30 years. A local developer plans to subdivide the land into 47 lots that will sell for as much as $150,000 each.

News of the pending departure of one of the county's most successful farm families and speculation about how much they were paid for their land has sent tremors through Howard's small, but closely knit agricultural community. The Langenfelders received an apparent record $10,000 an acre, compared with farm land prices that have generally ranged from $4,000 to $8,000 an acre.

Although nearly the entire western third of the county's 160,000-acre land base remains agricultural, the Langenfelders' sale has become a graphic reminder of the extreme pressures that farmers face in the rapidly developing Washington-Baltimore corridor, where farm families are caught between their devotion to the land and the temptation to sell out because some land values have doubled in just a few years.

Since 1978, the state and county have spent about $10 million to preserve 7,275 acres of farm land here by buying the "development rights" of farm land, paying farmers the cash difference between their land's agricultural value and its value if it were developed.

But the county, which has about 150 working farms, has fallen far short of its goal of permanently preserving 20,000 acres. And in Maryland as a whole, one of seven states with an agricultural land preservation program, twice as many acres have been lost to development as have been protected.

"It's impossible for this program to compete with the real estate values the way they are today," said Ridgely Jones, a member of the county's Farmland Preservation Advisory Board and one of the program's staunchest defenders. "I hate to see it because I think it's short-sighted. The good farm land will continue serving humanity for centuries, and it bothers me that people are going to let the dollar dictate what's going to happen to this land."

Until recently, Howard's program managed to keep pace with development. Between July 1983 and 1986, for instance, approximately 1,300 agricultural acres were converted to residential use, with another 2,200 acres involved in the subdivision process. But during that period, the county purchased permanent development rights on 5,300 acres.

According to Dennis White, the program's administrator, interest in farm land preservation has fallen off sharply with rising land prices and recent changes in federal tax laws that eliminated some of the advantages of selling development rights. During the last year, White said, just one farmer enrolled his land in a five-year agricultural district, the first step in the preservation process. White's office usually processes four or five such applications each year. During the same period, two farmers who had been enrolled in the program opted out of it.

Records in the county land development office show that development plans have been submitted for about 600 rural acres so far this year. That statistic does not include the land of farmers who would like to sell but haven't been offered the right price. White said it is impossible to estimate how many more thousands of acres may be lost once those deals are completed.

Few observers believe the county can maintain a substantial agricultural base. The best it can hope to do, they say, is to help retain some open space. But while the public may wax sentimental about the need to preserve pastures and woodlands, farmers, who may in fact be sitting on their life's savings, generally look at the preservation program with a jaundiced eye.

"I've had people say to me, 'If they offer me that kind of money I'm going to sell, too,' " Conrad Langenfelder said. "We happen to be in an area where land prices are at a peak and farm prices are at a lull."

After their last crop is harvested, the Langenfelders plan to leave Howard County and move their entire farming operation to Kent County, where, they say, it is still possible for a family to buy or rent enough land to make a living.

The Langenfelders have another 194-acre farm enrolled in the county's preservation program that they plan to rent or sell. They said that money wasn't the primary factor in their decision to sell their main property. Like other farmers in Howard, they say they had become used to refusing politely weekly offers from developers and real estate agents.

But with the sale of the two properties on either side of their land and the knowledge that construction would soon begin on another section of the planned community of Columbia, just across Rte. 108, the Langenfelders started to rethink their decision.

In recent years, two of the farms they had rented were sold out from under them. Moving their tractors and combines had become virtually impossible because of car traffic. Two of their three children plan to farm. What guarantee was there that the farm wouldn't become subject to vandalism and complaints from residents of the nearby developments?

"We couldn't see a future for this parcel of land," Pat Langenfelder said. "We weren't looking to sell, but when the offer was made we had to consider it. We have houses going up on three sides. The development is literally on top of us."

The compatibility of residential development and agriculture promises to figure prominently in the growing debate about what, if anything, the county government should do to slow the growth in western Howard. The issue has taken on a renewed urgency as more and more clusters of houses begin dotting the landscape.

Howard's current zoning regulations allow the development of one house on every three acres of rural land. Many residents believe that the best way to preserve farm land would be lowering the density, to allow only one house on every 10 to 20 acres. Uri P. Avin, Howard's director of planning and zoning, points out that one reason development has taken off in Howard's rural areas is that surrounding counties have already instituted more stringent zoning.

In the past, however, Howard's farmers have vigorously objected to such a change, arguing that it would drastically lower the price they could get for their land while doing nothing to slow residential development. Four years ago, the last time such a move was proposed, several farmers formed a picket line with tractors to protest a change.

"All 20-acre zoning would do is decrease the value of the farmer's land and eat up the farm land even faster," said County Council member Charles Feaga, a lifelong farmer and one of the farm land protection program's harshest critics. "A developer would just charge more, but someone would be able to afford it."

Others advocate a farm preservation plan based on "transfer of development rights," a system used -- with mixed reviews -- in Montgomery and Loudoun counties. Under such programs, farmers sell the right to develop their land to developers. The developers are allowed to transfer those rights to another part of the county, where they can build more housing units than are normally allowed under zoning.

Howard County Executive Elizabeth Bobo, who in the past has admitted feeling somewhat stymied by the situation, said last week that she was awaiting the results of a consultant's study, expected this fall, before deciding what to recommend to preserve open space.

Although some people have been anxious to toll the bell for the farm land protection program, White believes the situation isn't nearly so dire. He points out that with $5.9 million in the program's budget this year, he can afford to compete with developers on their own terms.

The biggest problem facing the program now, he said, is convincing farmers that selling their development rights has an economic, as well as moral, advantage.

"You can lose a few farms and say that's part of the battle," White said, "but the war is lost when everyone acquiesces to what they see as the inevitable turn to suburbia."