Forget the soiled clothes, forget for a moment the setting -- a country farmhouse in a rural section of Loudoun County -- and it's easy to imagine Charles Planck in the classroom again.

Gazing out from behind a pair of horn-rimmed glasses, Planck speaks about the business of farming in Northern Virginia with all the command and sophistication of a college professor giving his lecture for the day.

The demeanor comes easily for Planck, 44, who for seven years was a professor of international relations at the State University of New York at Buffalo.

For the past 12 years, Planck, along with his wife and business partner, Susan, has lived and worked at Wheatland Vegetable Farms, their 60-acre farm in the foothills of the Blue Ridge Mountains in western Loudoun County.

Planck represents what many people believe is the future of agriculture in Northern Virginia, a growing number of farmers who seem to prove that agriculture and development need not be mutually exclusive.

These farmers -- young, well educated and often coming to farming from other careers -- are making healthy profits by shunning traditional dairy and grain farming, instead growing crops that appeal directly to consumers. Their produce ranges from fruits and vegetables to Christmas trees, Halloween pumpkins and sod for suburban lawns.

By marketing their own produce at local markets or on their own property, rather than going through large wholesale distributors, the new farmers have turned their proximity to the Washington area's 3 million people into a major asset.

Also, consumer-oriented crops yield greater profits per acre, requiring less land than for traditional crops. That means that encroaching development and rising land values pose less of a threat, said William Harrison, an agricultural extension agent for Loudoun County.

"This type of farming is a neat symbiosis between the city and the countryside. Since I market my own crops, I am not dependent on some distant, uncontrollable market out there," said Planck, whose numerous crops include blueberries and broccoli.

Planck's cerebral approach to farming is characteristic of a new style of agriculture in Northern Virginia, in which the ability to manage is just as important as the ability to grow. These days, Planck ruminates not about international affairs but about crop cycles, per-acre yields, labor costs and, above all, marketing strategies.

"The smart guys all have some angle. The challenge is to differentiate your product from the rest of the market," Planck said.

"Marketing is one of the highest priorities. Seventy-five percent of a farmer's time should be spent on marketing," agreed John Sleeter, owner of Hill High Orchards in Loudoun County, which specializes in fruits and vegetables. Sleeter spends much of his time in a large, wood-paneled office, where a computer stores a customer mailing list and helps him manage his employe payroll, which numbers almost 100 during the growing season.

Emphasis on freshness is the primary marketing strategy that most of the new farmers use, saying the products they sell at area farm markets are superior to those sold in supermarkets.

Carrying the freshness concept to its limit, many of the new farmers, including Planck and Sleeter, invite customers to their farms to pick their own produce during the growing season.

Although there are no specific figures available on the number of Northern Virginia farmers growing nontraditonal, consumer-oriented crops, their number is small compared to traditional farmers, Harrison said.

Still, Harrison estimates there are twice as many of these farmers now as there were five years ago, and that they are among the most successful farmers in the area.

Prince William County Extension Agent James Gardner said he has observed a similar trend there.

Nontraditional farming offers one of the few glimmers of hope for those farmers and politicians who oppose the growing sprawl of development that Loudoun and Prince William counties have experienced in recent years. This growth, they say, is an important factor casting doubt over the future of agriculture in Northern Virginia, still the leading industry in Loudoun County.

"We don't want to become another Fairfax County," said Frank Raflo, chairman of the Loudoun County Board of Supervisors. It's a refrain heard often among farm supporters in Loudoun County.

Raflo insists that he is not antigrowth. "Agriculture and growth can exist together. The reason Xerox moved here is because they liked the open spaces, not because they liked our condominiums," said Raflo, referring to the recent multibillion-dollar commercial and residential development that the Xerox Corp. is building in Loudoun County.

Planck agrees. "The countryside is the goose that lays all these golden eggs."

Although Northern Virginia farmers still growing corn, hay and other traditional crops are better off than their counterparts in the Midwest, the main reason for this is that developers have driven up the value of their land, said Carroll Laycock, branch manager of farm credit for Farm Credit Services in Leesburg.

When a farmer is in trouble, he sells all or a portion of his land to a developer, using the money to pay off his debts, Laycock said. "We have got the higher value of land here, but we are facing the same depressed commodity prices as farmers in the Midwest."

Because consumer-oriented crops yield greater profits per acre than traditional produce, they don't compete as fiercely with development for open space.

"You can make enough money to live on from a relatively small area of land," said Planck.

High profitablity is especially important, Harrison said, because an increasing number of farmers in Loudoun County rent their land. If a landowner can make more money by selling his acreage to a developer, he will do so, Harrison said.

But for many of Northern Virginia's new farmers, profitability is only part of farming's appeal.

Planck's interest in the business began when he was still teaching, and he took an interest in "small-scale social institutions, and the more attractive style of life that they offered," he said.

Louis Nichols, owner of Hollyridge Custom Landscaping, was a civil engineer until 10 years ago, when he left to grow Christmas trees in Loudoun County.

"I decided I really didn't want to be in an office all day, after all," Nichols said.

Whatever the advantages of nontraditional farming, however, ease of life is not among them.

"It's tougher even than traditional farming. It requires a great deal of work, as well as intelligence and marketing expertise," said Harrison.

Speed is one of the essential challenges. Unlike traditional grains, most consumer-oriented crops cannot be stored if market conditions are not favorable.

"My crops are perishable within 48 hours," said Planck, who is sometimes awake by 5 a.m. during harvesting season.

Nontraditional farming requires many employes, a problem in the Washington area's high-priced labor market. Planck manages by hiring college students for the summer, offering them room, board and minimal pay in return for a chance to experience farm life.

These hurdles of nontraditional farming may be the reason it still accounts for only a small percentage of total farming in Northern Virginia, and most traditional farmers, even failing ones, have been reluctant to switch their crops, according to Laycock.

But for those such as Nichols, the advantages of nontraditional farming speak for themselves:

"I market my own product," he said. "I set my own price. Why should I be at the whim of a price that's set somewhere else in the country?"