HOUSTON, JULY 9 -- The United States and its European allies clashed over agricultural trade and the environment today at the opening of the 16th annual economic summit and negotiators worked late into the night to try to bridge the differences.

President Bush and his top advisers mounted an aggressive attack on Europe's heavily subsidized agriculture systems, but found themselves on the defensive against European demands for swift and specific action to combat global warming.

Outlines for compromise on both issues appeared to be developing, but not before there had been sharp, public attacks by ranking members of the Bush administration on what they described as European intransigence in the so-called Uruguay Round of global free trade talks, which began in 1986 in Uruguay and are scheduled to end in December.

In contrast, European differences with the United States on the environment were conducted more quietly in delegation-to-delegation consultations.

The U.S. attack on trade appeared in part designed to deflect attention from the environmental issue, in which the administration is increasingly isolated from the other nations here. West German Chancellor Helmut Kohl, in a letter to the other leaders, called for significant action to reduce emissions of greenhouse gases thought to cause global warming. But the administration held firm to its previously stated position that more scientific study is needed before agreement on specific action.

German officials said the Kohl government, while disagreeing, was nonetheless willing to seek a compromise on emissions of carbon dioxide, considered a principal contributor to global warming, if the Bush administration was willing to commit itself to international efforts to save tropical rain forests.

On agriculture, Bush raised the stakes by insisting that the summit leaders commit their countries to genuine negotiations that could lead to an eventual end to European farm subsidies, despite the political disruption that action might cause in France and West Germany.

Although most nations subsidize their farmers to some extent, the high payments by the 12-nation European Community are seen by the United States and other food exporters as highly disruptive to international trade. U.S. officials said today that failure to reach agreement on farm trade threatens to scuttle the entire Uruguay Round effort to strengthen the compact that governs world trade, the General Agreement on Tariffs and Trade (GATT).

The first clear signal of how seriously Bush meant to press the issue here came Sunday in a private meeting with EC President Jacques Delors, which left European officials shocked at the intensity of the president's feelings.

"We in Europe underestimated Bush," said an EC official.

Bush's private pressure, which continued this afternoon in the first meeting between the summit leaders, was reinforced in back-to-back press conferences by U.S. Trade Representative Carla A. Hills and Agriculture Secretary Clayton Yeutter. Yeutter said the Europeans have "simply not been engaged" in serious negotiations on the farm issue, an accusation European officials denied.

"We can't negotiate with ourselves," Yeutter said.

The possible basis for a compromise centered around a framework document drafted recently by Aart De Zeeuw, chairman of the GATT agriculture group and a former Dutch agriculture official. Hills said the United States wanted the summit leaders to express willingness to use that text as a basis for the GATT negotiations.

Surprisingly, German officials said Kohl indicated the document was a good framework for further negotiations, an apparent breakthrough on an issue that has divided the United States and the EC for years.

Kohl is particularly sensitive on the farm issue because he faces all-German parliamentary elections Dec. 2 as part of the unification process. His party is depending on the votes of Bavarian farmers who benefit from the subsidies, and on farmers in Saxony, now in East Germany, who need them.

U.S. officials invoked the interests of nations not represented here, saying they would not ratify parts of a trade agreement that the industrialized nations -- including the Europeans -- want, unless the EC shows a willingness to reduce farm subsidies.

Hills said Third World nations who are efficient agricultural producers are especially hurt by EC farmers who "dump" their subsidized products on world markets at cut-rate prices. She said other countries would reject agreements on issues including protection against piracy of patented products and elimination of barriers for trade in services and foreign investment if the GATT talks fail to deal adequately with the farm issue.

"The Uruguay Round is ten times more important to the economy of the world than what will happen {here} with respect to the Soviet economy," Yeutter said.

Hills said the outcome of the trade talks will determine whether the world enjoys "an economic renaissance" or "dangerously decreasing economic prosperity."

The environmental debate focused on how the seven nations could follow up on last year's summit commitment, the first time the leading industrialized nations had faced up to global pollution.

Kohl, in his letter, called for specific goals to reduce carbon dioxide. Kohl said he would like the participants to use the summit to send a message that the 1992 United Nations conference on the environment adopt "radical measures to limit carbon dioxide emissions."

The Bush administration has consistently resisted European efforts to move faster, and White House Chief of Staff John H. Sununu, a strong proponent of this policy, warned today that capping emissions of greenhouse gases could harm economic growth.