The House Agriculture Committee tentatively approved the major grain price-support portion of a new farm bill yesterday, but then, after its most raucous debate in years, killed a proposal to allow farmers to vote on a mandatory production control program.

The key votes and the day-long debate could all be academic, however. The committee agreed to reconsider next week its vote on the wheat and feed-grain support section of the bill.

And proponents of the Democratic-favored farmer referendum, who lost a 24-to-17 vote to remove the plan from the bill, promised that they would make a new effort to mobilize support for the controversial idea when the bill reaches the House floor.

The Senate Agriculture Committee, meanwhile, after appearing near agreement on the grain price-support sections of its own bill, again broke up in disagreement, with Chairman Jesse Helms (R-N.C.) threatening to vote against his committee's product.

The disarray ensued after the committee agreed, 9 to 8, to extend for four years a freeze on direct subsidies paid to grain farmers, a move that Agriculture Department analysts said would add about $4.5 billion to the cost of the farm bill.

The draft measure the committee was working from contained a one-year freeze on the so-called target price payments, with reductions in later years. Passage of the four-year plan, offered by Sen. John Melcher (D-Mont.), led to Helms' protest and prompted Majority Leader Robert J. Dole (R-Kan.) to threaten to bypass the committee and take a bill to the floor.

The tempestuous rhetoric on the Hill and heavy-duty politicking, highlighted by Dole's insistence that wheat-state legislators cannot go on August recess without a farm bill in hand, underscored growing congressional frustration over the limping farm economy and pressures to cut federal spending on farm programs.

In the Senate, the Melcher amendment, which carried when Mark Andrews (R-N.D.) switched over, set off rumblings among dairy, cotton and rice-state members for more largess for their constituents. House Democrats orally flogged USDA officials, accusing them of playing games with statistics and, as Rep. Berkley Bedell (D-Iowa) put it, "trying to wreck agriculture."

The House committee, after lengthy argument, went along with a wheat and feed-grain support plan promoted by Reps. Thomas S. Foley (D-Wash.) and Ron Marlenee (R-Mont.), who argued that it would produce budget savings, sustain farm income and make U.S. farm exports more competitive.

Their approach would reduce the price-support loan rates that tend to put a floor under U.S. prices, but hold at current levels the direct subsidy payments that farmers now receive. They also call for planting reductions of a minimum of 30 million wheat acres and 20 million corn and feed-grain acres.

Although there was widespread disagreement with the calculations, the Foley-Marlenee plan was touted as a way to save more than $4 billion in federal farm spending over the four-year life of the bill.

Opponents charged that the plan was no more than a continuation of current policy that would leave strapped farmers with about 20 percent less income by 1989.

Foley brushed aside the criticisms. He said the new farm bill could not solve all of the economic problems confronting agriculture and "we shouldn't put the whole burden on this bill."

The debate over the farmer referendum was even more heated. It provided that if 60 percent or more voted favorably, a mandatory production control program could be set up to reduce surpluses and drive up farm prices. The plan would entail retirement of at least 35 percent of U.S. cropland.