When Congress in 1985 barred federal subsidy payments to farmers who drained fragile wetlands to grow more crops, conservationists predicted that farmers would be demanding relief by the time the landmark legislation expired in 1990.

They were wrong. It happened sooner.

The first wave of protest lapped onto Capitol Hill yesterday as farmers from North Dakota, where prairie potholes and water-collecting low spots are a vital haven for migratory birds, came crying foul over the 1985 farm bill's "swampbuster" section.

They complained that an overzealous yet understaffed Agriculture Department overstepped the law by enforcing it too tightly and then confusing farmers with inadequate information and assistance. They asked for more leeway in complying.

But the forum arranged for them at an Appropriations subcommittee by their home-state patron, Sen. Quentin Burdick (D), was less than friendly. Aside from sympathetic questioning by Burdick, who is in a tough reelection campaign, the Dakotans encountered criticism from other senators and witnesses.

Sens. Robert W. Kasten Jr. (R-Wis.), a prime sponsor of the original swampbuster provisions, and Dale Bumpers (D-Ark.) took turns blistering USDA officials and the farmers. Both warned that, if anything, Congress would tighten the law before liberalizing it.

The swampbuster provisions were enacted in reaction to conversion between 1955 and 1975 of about 15 million acres of freshwater wetlands, mostly for expanded farm production. The provisions were intended to preserve the vanishing wetlands and curb surplus output.

Kasten said the Agricultural Stabilization and Conservation Service (ASCS), overseer of the law, seemingly "bungled" early implementation of the provisions by moving slowly in defining wetlands. Noting that only two farmers -- one in Minnesota, one in Georgia -- had been deprived of crop subsidies because of noncompliance, he charged the ASCS with enforcement laxity.

"While I would like to believe that this is the result of broad compliance with the swampbuster law, I fear the reverse is true," Kasten said. "If there are USDA employees in any state who think that the way around an unpopular law is to simply not enforce it, those employees should be replaced."

He said North Dakota farmers received almost $700 million in federal farm subsidies last year. "But," he added, "the government also has the right to make these payments only on condition that the farmers receiving them do -- or, in this case, not do -- certain things . . . . It is time to stop complaining about the law and begin working on ways to live with it."

"Anyone who is counting on repeal of any of the provisions of the conservation title will be disappointed," Kasten said. "That is not just a prediction. That is a promise."

ASCS chief Milton Hertz, a former North Dakota farmer, denied that his agency had been lax in enforcement and warned that the department intends to continue rigid interpretation of the law despite farmers' protests.