Outside the Four Leaf Clover Inn in Cherokee yesterday, Jim Clark was asked what farmers in north central Iowa think about the partial grain embargo President Carter imposed against the Soviet Union.

"They don't like it," he said. "I don't like it, I'm a farmer. But what the hell, you've got to do something. It's better than going to war. We don't want to see another Vietnam."

Vice President Mondale, who had just finished speaking in Cherokee, did not hear what Clark said. But if he had, it would have pleased him, for Clark succinctly summarized the message Mondale has been preaching across rural Iowa this week: that the grain embargo was necessary in the wake of the Soviet invasion of Afghanistan, and far preferable to other options, such as military action.

After three days of touring Iowa farmland west of Des Moines, Mondale said at a news conference here today that "a very strong majority of the farmers of Iowa support the embargo."

That may be an overstatement, but as Mondale completed his final campaign swing through the state before Monday's Iowa precinct casucuses, there is little evidence that the embargo poses a major threat to the Carter campaign in the agricultural region.

When the president imposed the embargo, Carter campaign officials feared it would cut into his presumed lead in rural counties over his Democratic rivals.Sen. Edward M. Kennedy (D-Mass.) and California Gov. Edmund G. (Jerry) Brown Jr. But interviews with local officials in the areas Mondale toured this week suggests that the embargo issue is subsiding.

It was not until he reached Mason City today that the vice president encountered a protest over the embargo. About 40 members of the militant American Agriculture Movement stood across the street from the Mason City Globe-Gazette holding signs that read "Embargo Carter."

Leaving the newspaper after an interview, Mondale talked to the farmers, defending the administration while conceding that he didn't expect to be persuasive with the group. But even the most outspoken of the farmers, T. J. Thompson, said he had little enthusiasm for Kennedy "because of his background," and that the group's chief purpose was "to keep the pressure up" to gain additional concessions for farmers from Washington.

The perception that the embargo has not seriously demaged the Carter campaign here was shared by Mondale aides.

It's very seldom that a political issue will run its course during a campaign in two weeks," said Jim Johnson, Mondale's executive assistant, who has kept a close watch on the Iowa campaign. "But I think the embargo issue is about there."

Rep. Berkley W. Bedell (D-Iowa), whose district covers the northwestern section of the state, has held meetings on the embargo with his constituents this week. According to Johnson, Bedell reported to Mondale during the campaign swing that the embargo issue "is almost 100 percent over."

Carter's press secretary, Jody Powell, was asked if the White House endorsed Mondale's earlier statements in Iowa that Iowans, in their caucuses Monday night, should send a message abroad that they endorse the president's recent anti-Soviet sanctions.

Powell said that "in some sense" other nations will view the Iowa vote as an expression of approval or disapproval of the Carter policies. Powell said it was already clear from some editorial comment in various publications abroad that the Iowa results would be viewed this way, adding that this does not mean that the White House believes it is the appropriate way to view the results.