The Senate Agriculture Committee has approved a new grain subsidy program, drafting an elaborate compromise to break a five-week stalemate over the 1990 farm bill.

The compromise was originally drafted by committee Democrats, subsequently amended by committee Republicans and finally approved 15 to 4 late Thursday after 11 hours of closed-door wrangling.

The vote essentially completed the committee's work on the $53 billion farm bill, the legislation that will establish subsidies and regulations for the nation's farmers for the next five years.

The committee will consider amendments next week, then send the bill to the Senate floor, where debate probably will begin late next month. The House Agriculture Committee finished its version of the farm bill last week.

The compromise was reached after five weeks of contentious and often bitter disagreement between Democrats eager to maintain or increase subsidies and Republicans trying to freeze them.

"We had several long meetings in my office, and I finally brought individual senators in and told them the time is now," said Sen. Patrick J. Leahy (D-Vt.), the committee chairman. "A lot of these people felt very strongly, and we just had to give them time."

In the end, the committee's 10 Democrats and 9 Republicans agreed to disagree about commodities, drafting a compromise that allows the agriculture secretary to structure subsidies by choosing one of two optional programs.

Under "Plan A," as it came to be known in committee discussions, income subsidies and price supports for wheat, corn and three other grains would be held at 1990 levels.

This plan, written and promoted by committee Democrats, grew out of an earlier draft that indexed subsidies to the cost of living. The Republicans categorically rejected this idea in early May, precipitating an impasse that lasted for five weeks.

"Plan B" allows the agriculture secretary to reduce price supports by up to 20 percent, but for each penny drop, farmers would get a 3/4-cent advance on subsidy payments.

Preserving the 20 percent reduction option, a provision in existing legislation known as the "Findley rate," was regarded by Republicans as indispensable in maintaining U.S. export competitiveness.

It was generally conceded by senators of both parties that the agriculture secretary will most likely choose "Plan B" as long as a Republican president is in the White House.

"But if things change in 1992, the other option will be in place," said Sen. Richard G. Lugar (R-Ind.), the committee's ranking minority member. "We're very pleased, because the bill moves more toward market economics and less toward a managed program."

Behind the seemingly endless tedium of this week's commodity debate lay an enduring philosophical conflict. The trend in agriculture policy, formally established by the existing 1985 farm bill and likely to continue under this year's legislation, is toward lower subsidies, less government intervention and greater exports.

The Bush administration, Agriculture Secretary Clayton Yeutter and the Republicans on the Senate committee stand solidly behind this view. Their cause is also helped by this year's budget constraints, which give a bad name to anything that sounds like spending more money.

On the other hand, traditional Democratic Party policy holds that farmers -- particularly small farmers -- need greater government protection in uncertain times.

With the moderate Leahy overseeing the dispute, most of the Democrats eventually settled on "Plan A" as an acceptable approximation of their views. One who did not was Sen. Thomas A. Daschle (D-S.D.), who voted against the proposal.

"It means that farmers would suffer a real decline in program income of 20 percent for the life of the farm bill," Daschle said. "It guarantees that 500,000 farmers between now and 1995 are going to be pushed off the farm."