Most protesting farmers of the American Agriculture Movement are to roll out of Washington this weekend, leaving behind nearly $1 million in damage and most of the questions that brought them here unresolved.

"We expect to have a tractor-free Mall by Monday," said National Park Service spokesman George Berklacy. He added that the farmers have permission to leave a "symbolic" 50 tractors parked along Pennsylvania and Maryland avenues near the Capitol for the foreseeable future.

Other reminders of the four-week tractor encampment, however, may do the warmers more harm than good, according to congressional and agency staff members and lobbyists monitoring the mood of Congress.

"They didn't accomplish anything, I'm afraid," said Peter Ively, associate director for information at the American Farm Bureau, a rival farm group. "If anything, they solidified opinions against farmers, which is what concern us."

Farm bureau studies in the past, Ively said, have shown that the best asset of the farmer is "the wonderful image he has among the American people."

The month-long encampment on the Mall, Ively said, produced some "high visibility damage" that may hurt all farmers, "even though only a small minority of American farmers came to Washington and only a small minority of those caused the damage."

"Our worst fears have not been realized, fortunately," said Berklacy, "but the damage is extensive."

The gravel walkways along the Mall, he said, will not have to be replaced as originally thought, but can be repaired for about $330,000. The Mall sprinkler system once thought ruined, also can be repaired for about $50,000 Berklacy said.

Instead of resodding the entire Mall, park service now feels it can repair the tractor gouges with 125,000 yards of sod about $260,000 plus seeding another 45 acres for about $50,000.

Berklacy said the other estimates include replacing two light poles, $24,000; replacing 25 benches, $7,500; repairing 27 benches, $3,000; replacing 63 trash baskets $5,600; two fire hydrants, $6,000; one drinking fountain, $800, and 12 signs, $800.

He said the park service also picked up a $600 bill for disposing of two tractors, a car and a cotton baler burned by the farmers during the encampment.

Berklacy said there would also be some $25,000 in masonry repairs to the Capitol reflecting pool, into which at least two farmers drove their tractors. But he said the waterproof seal at the bottom of the pool has apparently not been broken, and "it would have cost five times as much if it had."

Farm groups from Georgia, Maryland, Kansas, Idaho and Oregon have offered to donate grass seed and lumber for the repairs and Berklacy said those offers may be accepted, providing what is offered is the same as what was lost.

"This is the nation's frong yard," Berklacy said. "We have to be sure."

Berklacy's damage estimate did not include the cost of overtime pay for park service police, a figure that he placed at $400,000 nor did it include similar costs for D.C. police. Earlier in the protest, a D.C. official estimated that its police overtime was costing the city $100,000 a day.

Harder to gauge was the damage, if any, to the chances of farm legislation the protesters came here to get.

"I would say there will be no substantial change in farm policy or programs" as a result of the tractorcade, said John Simpson, deputy director of economic policy analysis and budget for the Department of Agriculture.

"They certainly made an impression on a large segment of the public, both negatively and positively," Simpson said, "positively in pointing out that one sector of America's farm community is not meeting the cost of production, and negatively in all the destruction they caused."

A spokesman for Rep. Thomas S. Foley (D-Wash.) chairman of the House Agriculture Committee, said that Foley "doesn't think there is any possible legislative cure" for the farmers' complaints. Legislation to give them 90 percent of parity, as the protesters wanted, would simply make things worse in the long run by raising farm costs even more, the spokesman said.

A senior staff analyst on the House Agriculture Committee said the farmers "helped prompt hearings on the agriculture situation, and that may lead to some effort to modify the 1977 Farm Act, and it may not."

While bills will doubtless be offered, he said, the real question is "whether a consumer-oriented Congress is going to make long-range supports in the interest of supporting the industry -- supports which will mean long-range cost to the consumer."

A key test, he said, will come soon when the Democratic leadership attempts to vote out a bill providing sugar price supports to replace those that expired in 1978.

If Congress won't go along with those supports, when the absence of them will clearly mean greater dependence on imported sugar, then the analyst said, Congress will be unlikely to pass other measures this session that could ultimately mean a slightly higher food bill for every American.