The Fairfax Board of Supervisors yesterday rejected the voluntary limits on campaign contributions that earlier boards had adopted in an effort to curb the influence of land developers and other special interests in county politics.

The supervisors voted 6 to 3 not to hold hearings on proposed guidelines for the next election in 1983, with the majority indicating the voluntary limits are not needed. The vote was accompanied by pledges to behave ethically in the next election and by aggrieved denials that any supervisor could be bought.

"When I run again, wait'll you see how open my records are," Supervisor Nancy K. Falck said before voting against the guidelines. "I will disclose absolutely everything."

State law, which will now be the only guide governing Fairfax elections, requires that candidates disclose contributions larger than $100. The majority of contributions to candidates in 1979 during the last supervisors race would not have been disclosed under that standard.

Fairfax citizens' groups, including the League of Women Voters, had asked the board to pledge voluntarily to disclose all contributions of $25 or more and to reject contributions of more than $50 from land developers or cable television operators with business before the board. Similar guidelines were adopted by the supervisors before the 1975 election--in the wake of zoning scandals that put several former supervisors and county officials in jail--and again in 1979.

The board's action handed a victory to business community lobbyists, who said the guidelines discriminated against them. It also dovetailed with an opinion of the state attorney general, who had said local governments cannot adopt even voluntary limits that are stricter than state law.

"The ground rules have changed," said Supervisor James M. Scott, who was on the losing end of the vote. "Contributions from people with rezonings and contracts with the county will apparently be okay, and I think that's the wrong signal to send."

Lilla D. McC. Richards, president of the Fairfax Federation of Citizens Associations, said her organization and the voters league probably will ask candidates to follow guidelines similar to those rejected by the board. She said, "It is certainly a shame that campaign reforms achieved in the '70s have been discarded by a majority of this board."

The guidelines were opposed by Democrats Sandra L. Duckworth, Martha V. Pennino and Joseph Alexander and by Republicans Falck, Marie Travesky and Thomas M. Davis III. Democrats Scott and Audrey Moore voted to hold a public hearing, as did Republican Board Chairman John F. Herrity.

Scott said that someone with a county contract could have five relatives each donate $99 to a candidate. None of those would have to be disclosed under state law, but the total gift would be substantial in an election where most candidates spend about $10,000.

Moore faulted state law for making no provisions to prevent developers from giving large sums. "In this county, with the kind of growth that's going on, I think it's needed," she said.

But Davis said developers are just one of many special interests. "You know who gains the most by owning a supervisor?" he asked. "Public employe unions."

Pennino chastised Moore for "impugning" the board. She said the board has no right to try to impose voluntary guidelines on challengers for board positions. "What we're really talking about here is equity and fairness," Pennino said.

"We know how to conduct ourselves," added Travesky.