President Carter's imposition of a grain embargo on the Soviet Union drew a mixed reaction yesterday from Harvard political experts.

"It's the first really strong move the United States has made," Otto Eckstein, Warburg Professor of Economics, said yesterday. Carter demonstrated the meaning of national leadership by not being afraid to injure special interest groups, he added.

"The embargo will lower the standard of living in the Soviet Union, and will make clear to them that they must pay a heavy price for military interventionism," Eckstein added.

Ernest R. May, professor of History, said Carter's actions "will only cause very modest discomfort in the Soviet Union," adding the actions Carter can take are "very limited, because the U.S. does no have much leverage in Moscow."

The grain embargo is largely a "symbolic gesture," because the Soviets will have a sufficient supply of grain from their own stockpiles and from indirect purchases from third parties, May said.

The embargo will permit the Soviet Union to buy only what remains of eight million metric tons of grain the U.S. is obligated to sell them. The U.S. will withhold an additional 17 million tons promised to the Soviets.

It is better for the U.S. not to exert economic pressures and to keep Afghanistan a Soviet problem, Roger Fisher, Williston Professor of Law, said yesterday.

It is in America's interest not to elevate the Soviet invasion of Afghanistan to a superpower conflict, he said.

"The major cost to the Soviets should be the self-inflicted political cost suffered in those nations tempted by Soviet ideology," Fisher said, adding the U.S. should impress upon all non-aligned nations the duplicity in the Soviet's signing a friendship treaty with Afghanistan and then invading them.

Sidney Verba, professor of Government, said that although he thinks Carter made "a serious but moderate response which will be taken into consideration by the Soviets," his actions are not "so strong as to fully deter the Soviet Union from acting in their interest in the future."

Eckstein said Carter's moves are important because the "U.S. should adopt policies to affect the goals of the Soviet Union."

May said the people in the Soviet Union most concerned with grain are not the same people who plan military operations.

President Carter took a firm position by making strong statements to tell the Soviet Union and American allies that his administration is serious about its disapproval of the Soviet invasion, Verba said.

"It shows how complicated it is to run American foreign policy in a crisis during an election year," Verba said, adding although Carter is concerned with the crisis's effect on his domestic image, he is primarily concerned about the Afghan situation itself.

Although the Soviets "will not starve to death next year," they will "have to substitute chicken for beef and veal," Eckstein said.

"The Soviet Union already has severe economic problems, and the progress of the Soviet people will now be set back even more," Eckstein said. "They may come to their senses and choose goals other than military adventurism," he added