AMES, IOWA, JAN. 23 -- Former Arizona governor Bruce Babbitt attacked the farm proposals of Rep. Richard A. Gephardt (D-Mo.) head-on, and Sen. Paul Simon (D-Ill.) criticized Gephardt's voting record on farm issues, but the other Democratic presidential candidates participating in a farm forum here today discussed agriculture in general terms, praising the family farm and bashing agribusiness conglomerates.

All generally agreed about the need to raise prices paid to farmers and to reduce price-depressing commodity surpluses, but Gephardt, whose campaign is showing a resurgence in Iowa, and Babbitt, who also has risen in the polls here, were in direct conflict over how to accomplish it.

Six of the seven Democratic hopefuls -- only Sen. Albert Gore Jr. (Tenn.) was absent -- were questioned for two hours by farmers and reporters at the 1988 Presidential Forum on Agriculture and Rural Life sponsored by three farm groups here. The forum was held at Iowa State University.

Gephardt and Sen. Tom Harkin (D-Iowa) are cosponsors of a bill that would allow farmers to vote on mandatory acreage restrictions, which Gephardt contends would reduce surpluses, increase commodity market prices and reduce federal price support payments, which are expected to total more than $20 billion this year.

Babbitt said the plan would price U.S. farm products out of the world market and that taking large areas of land out of production -- 20 percent to 25 percent for small farms, 35 percent for larger ones -- would ruin industries and agricultural communities.

"It would result in a 30 percent or 40 percent contraction of the farm economy," Babbitt said. "The farm sector would lose as many as 2 million jobs as the implement manufacturers and others were forced to cut back; food prices would jump $65 billion a year, or $600 a family, and Iowa alone would lose $2 billion in exports," he added.

Babbitt proposes restricting the farm price support system to small, family farms in the hope of forcing large, corporate farms, which now get huge federal subsidies, onto the open market.

Gephardt said that farm exports have increased in volume by about 15 percent since 1976 but are worth only about half as much.

"Harkin-Gephardt would raise prices to a decent level and then force the president to negotiate fair farm prices with other nations," he said. "We're in an international price war. We want to open the world markets so that farmers everywhere get fair prices."

Gephardt contended that agribusiness conglomerates such as Cargill Inc. control 80 percent of the country's farm production and are setting low world market prices.

Jesse L. Jackson likened corporate farmers to barracudas feasting on family farmers. "When you go to your fish tank and you see those little goldfish are gone . . . you look for the barracudas that ate them up."

The candidates generally agreed on using antitrust laws to control the huge agribusiness conglomerates.

"Antitrust starts with the attorney general," Gephardt said. "I'd start with an attorney general who appears before a grand jury as a prosecutor and not a defendant."

Simon criticized Gephardt for voting for the Soviet grain embargo in 1980 and for the 1985 farm bill. "We need prices that give farmers a profit, but we also need tough political leadership," he said. "I voted against the grain embargo of 1980. Gephardt voted for it. I voted against the 1985 farm bill, which lowers farmers' prices. Dick voted for it."

Former Colorado senator Gary Hart, who reentered the race last month,supports production controls and restructuring farmers' debts but mostly used the forum to discuss his own proposals.

In criticizing Gephardt's proposal of a tougher U.S. trade policy, Hart said, "Some are proposing protectionism, which is disastrous. And some talk about these issues as though they were isolated. Everything is interrelated: the farm economy in the general economy, the budget deficit, overall trade policy."

Massachusetts Gov. Michael S. Dukakis, who once was critical of Harkin-Gephardt, generally supported its provisions but said after the debate, "I haven't reached a final conclusion on it yet."

Dukakis advocated a program of rural development to diversify the economies of small towns and farm areas and develop new uses for farm products "such as ethanol in gasoline and road de-icers made from corn."