President-elect Ronald Reagan yesterday added three campaign advisers to his growing White House staff and officially named John R. Block, an Illinois farmer, as his choice for secretary of agriculture.

Block's selection left reagan with one major vacancy in his cabinet, secretary of education, a job he hopes to eliminate eventually. Edwin Meese III, Rreagan's top adviser, yesterday said that choice will not be announced until after Christmas.

Meese said the delay in naming an education secretary is not related to the reluctance of some candidates to take a job that may be abolished."The dificulty is choosing from among many qualified people," Meese said.

Other officials to be chosen after the holidays include the president's special representative for trade, a cabinet-level post that could go to outgoing Republican National Chairman Bill Brock, and the chairman and two othr members of the president's Council of Economic Advisers. Meese said yesterday that Reagan had not decided whether to give the CEA chairman's job Cabinet status.

Appointed to reagan's White House staff yesterday:

Richard V. Allen, who served as foreign policy adviser throughout the campaign, to be assistant to the president for national security affairs, a post that is expected to have less influence in Reagan's White House than in previous administrations.

Martin Anderson, an economist at the Hoover Institution at Stanford University and a domestic affairs advisr to Reagan during the campaign, to be director of domestic policy development.

Franklyn (Lyn) Nofziger, Reagan's longtime press secretary, as assistant to the president for political counsel, with specific responsibilities for coordination with the Republican National Committee and the House and Senate congressional campaign committees.

Continuing his practice, Reagan did not attend the ceremony for his newest advisers. He is in California through the holidays.

Block, the agriculture secretary-designate, said yesterday that he will recommend to Reagan that the Soviet grain embargo instituted by President Carter in the wake of the Soviet invasion of Afghanistan last winter be lifted "as soon as is practical." But he said he did not know whether he would recommend additional grain sales to the Soviets in the coming year.

Block, who said he did not believe farm prices were too high and said he believed in free-market agriculture, indicated more generally that he will turn the department back toward the farmer and reduce the emphasis on consumer issues, that has marked the stewardship of Secretary Bob Bergland.

"My philosophy is that the Department of Agriculture should serve as a strong spokesman for the agricultural industry, and I don't say this to the detriment of the consumer, because it's my sincere belief that the greatest asset the consumers have in this country is a healthy, prosperous . . . agriculture," Block said.

"I think often times the past administration was sidetracked, they were concerned about peripheral issues and they thought they were helping the consumers by zeroing in on some small thing, like food safety issues," he added."

Block, 45, a West Point Graduate and marathon runner, operates a 3,000-acre corn, soybean and hog farm in Gilson, Ill., and is Illinois director of agriculture. His candidacy was promoted vigorously by Sen. Bob Dole (R-Kan.) in what became a battle between Dole and former agriculture secretary Earl L. Butz, who preferred Richard Lyng, a former Agriculture Department official, for the job.

Allen, 44, the new national security affairs adviser was good-humored about the diminished role he expects to play under Reagan. Asked when he would give up his role as chief foreign policy spokesman for Reagan and become a "faceless member of the White House staff," he said: "I pretty much guarantee that I'll submerge by Jan. 1. You're seeing a disappearing act right now."

Allen worked as Richard M. Nixon's foreign policy adviser during the 1968 campaign, only to lose out for the NSC post to Henry A. Kissinger. He worked under Kissinger at the NSC, but quit within the first year because of friction between the two.

Yesterday he praised Kissinger for his "important and valuable input" during the campaign, and said he expected that the former secretary of state "would be called upon frequently for a range of undertakings," including "travel on behalf of the administration."

Under current organizational plans for the White House, Allen will be subordinate to Meese, who will hold Cabinet rank as counsel to the president. sReagan has said he wants his NSC chief to maintain a lower profile than did Kissinger or Zbigniew Brezezinski, who is Carter's national security adviser.

Allen quit Reagan's campaign in the final week after newspaper reports suggested conflicts of interest in his past work as a government official and private consultant. But Reagan expressed his confidence in Allen at the time, and yesterday rewarded him for his loyal service.

Anderson, 44, said he expects to play a role in formulating economic and domestic policies in his new post. He too will report to Meese.

An economist by training, Anderson served in the Nixon White House as an adviser to Arthur F. Burns before Burns became Federal Reserve Board chairman. He has written books about federal housing policy, welfare reform and the volunteer Army.

He said yesterday that the economy "is a very serious situation that will require immediate action," and blamed federal spending for much of the problem. He predicted that inflation and interest rates will come down under the Reagan administration, but was pessimistic about any quidk results.

Saying that there is "no magic wand you can wave" to solve the country's economic ills, he warned, "You have to understand that it's taken many years for the economy to get in the shape it's in, and it's going to take some time to get it out."

In other transition activity, Meese said yesterday that Reagan's transition advisers have "nothing in our factfinding program" to suggest that either the Department of Energy or Education should not be abolished.

But Meese said Reagan and his advisers do not consider the unfilled education secretary's job expendable. "In fact, that position encompasses the cutting edge of the new approach to federalism," he said.

Reagan met yesterday with Ted Cooper, a Midwest educator. But Reagan's West Coast spokesman, Joe Holmes, warned against placing too much significance on the meeting. "He's just another interviewee," he said.

Meese also said that Reagan had held"at least one or two phone conversations" with former President Nixon since the election. He said Nixon was not consulted specifically on the selection of Alexander M. Haig Jr. as secretary of state.