Cornfields may not stretch to the horizon and mountains may not crowd the skyline, but with all the presidential candidates stumping through Fairfax County these days, the political landscape is beginning to look a little like Iowa and New Hampshire.

Since last fall, at least four Democratic presidential hopefuls have addressed groups in Fairfax County, and at least four others, two from each party, are expected in the weeks ahead.

The appearances are dovetailing nicely for local candidates running for state legislative seats and the Fairfax County Board of Supervisors in the Nov. 3 elections. Presidential candidates can draw a big turnout for local fund-raisers, while the events are a good opportunity for national candidates to start piecing together statewide campaign machines for 1988.

Local party officials credit Virginia's new influence in the presidential sweepstakes to the state's decision to hold its primary on Super Tuesday, March 8, 1988, when 14 other southern states will hold their primaries. About 26 percent of all delegates to the Democratic National Convention will be decided that day, including 85 delegates from Virginia, where the Democratic primary is binding.

Republicans, on the other hand, will vote for presidential candidates in the primary, but delegates will be selected in party caucuses in June.

Politicians "have to adjust to the new prominence of the South and Virginia," said Harris N. Miller, chairman of the Fairfax County Democratic Committee. "Traditionally, Virginia has not been the epicenter of political activity, so we have to teach old dogs new tricks."

One of the most popular events has been the Democratic Business Forum, a quarterly breakfast sponsored by the county Democratic Party to encourage dialogue between the party and the county's booming business community. Last September, Rep. Richard A. Gephardt (D-Mo.) addressed the forum on "The Impact of Tax Reform on Fairfax County Businesses," and in March former Arizona governor Bruce E. Babbitt spoke to the group about "Reinventing the American Economy."

Sen. Albert Gore Jr. (D-Tenn.) is scheduled to speak to the group at its September breakfast.

Donna Brazile, national field director for Gephardt's campaign, said Fairfax is an attractive stopping point because "it's one of the fastest-growing counties in the area and it helps us build a Democratic base in the state . . . . Our initial campaign tactic is to build a base of elected and county officials in Fairfax and then work out to Arlington, Loudoun, Manassas and other outlying areas."

She said the county was also a natural base for Gephardt because he has lived in Fairfax for about 10 years and has sent three of his children to county schools.

For local candidates, the events are popular because they invariably generate a lot of press coverage and campaign contributions.

"More people are willing to come shake the hand of someone who might be president, and they're more willing to spend $25 to do it," said Toddy Puller, campaign manager for Supervisor Audrey Moore (D-Annandale), who is running for board chairman. A July fund-raiser featuring Sen. Paul Simon (D-Ill.) drew 300 guests and netted Moore's campaign about $12,000, Puller said.

For that kind of money, Moore campaign officials were willing to overlook the fact that Simon kept referring to Moore as a candidate for county executive.

Puller said that Moore campaign officials also have talked with people from the campaigns of Sen. Joseph R. Biden Jr. (D-Del.) and Massachusetts Gov. Michael S. Dukakis, and aides to Rep. Patricia Schroeder (D-Colo.), who is considering whether to enter the campaign, about scheduling joint appearances in the county.

Dukakis will be the special guest at the Mason District Crab Feast, one of the premier Democratic gatherings, in September.

Tom Herrity, campaign manager for Board Chairman John F. Herrity, a Republican, noted that Virginia has a big voting bloc and is a quick, easy stop for many national candidates who work in Washington, some of whom live in Virginia and are constituents of the local candidates.

Senate Minority Leader Robert J. Dole (R-Kan.), who has not announced his candidacy, and his wife, Transportation Secretary Elizabeth Hanford Dole, will appear at a fund-raiser for Herrity at the McLean Hilton in September.

"This is the year many people want to meet presidential candidates and hear them talk," Tom Herrity said. "It's a reciprocal thing. They {the presidential hopefuls} also want to meet people who can contribute to their campaigns."

Tom Herrity said that campaign officials have also contacted former secretary of state Alexander M. Haig about a joint appearance because "he might be a good fund-raiser. He gives a good talk and he lives in McLean, so he's a constituent."

In what may be the most high-profile event, Vice President Bush is scheduled to appear at the campagin kickoff for Republican Bobbie Kilberg, who is running for the 32nd District Senate seat against incumbent Sen. Clive L. DuVal 2d.

Kilberg, who has known Bush since 1970, said it is "a tremendous boost to have someone who's nationally known come in and talk about you personally and professionally . . . . It will certainly give me more widespread name recognition."

Unlike other presidential candidate appearances, though, the event will not be a fund-raiser.

"George Bush has spent 20 years raising money for everybody else, and now he has to raise some money for himself," Fred Bush, deputy finance chairman for the Bush campaign, said in explaining the policy. "When you do a fund-raiser for other candidates or the party, it dilutes your own fund-raising ability. You can only go to the well so many times."