Welcome to Washington, Citizen Block.

It's not quite time to get maudlin about it, but one almost has to feel for John R. Block, the Illinois hog farmer who was picked by President Reagan to be the new champion of American agriculture.

Even champions are going to lose a few, but Secretary of Agriculture Block, a personable marathon runner who knows the importance of a good start, may be finding life in the fast lane a little frustrating.

From Day One, Block has been arguing at the White House that the president should rescind the embargo on grain sales to the Soviet Union. So far, he has been unpersuasive, even though Reagan promised in the campaign to lift the embargo.

Much to the chagrin of fellow farmers, Block has also become the point man in the administration's effort to cut price supports for dairy farmers. And when he fought in the inner circles for higher price supports for peanut farmers, there was David A. Stockman, the Abominable No Man of the budget, telling him, in effect, to get lost. Peanut support prices stayed put.

Then Block had to run out front and defend the administration's other proposed farm-food budget cuts, bringing him inmity from the nutrition lobby, rural electrification supporters, alcohol fuel promoters and a raft of other interests whose oxen were not just being gored, but slaughtered.

This week, more humble pie. On White House instructions, Block canceled his long-scheduled appearances before House and Senate Agriculture committees, where he was to disclose details of the administration's general farm bill.

On Capitol Hill, some saw that as another high-level undercutting of the secretary. Others saw it as another sign of more Byzantine politicking infecting the farm front -- the bill would contain provisions many farmers would object to, and the White House didn't want to jeopardize crucial floor votes to cut back the dairy support program.

Back in Knox County, Ill., after Reagan picked their friend and neighbor to head the department, Block's supporters worried aloud that while he would be an energetic champion of agriculture (he had, after all, been the Illinois agriculture director), he might not be quite the politician to pull it off.

Around Congress, some of the old heads shake with a little bemusement about a champion who seems to have won embarrassingly few early victories.

One of Block's strongest supporters, Marvin Meek, chairman of the American Agriculture Movement, said: "Block's working good for us. But he has to be frustrated -- you'd have to be when you're working with a bunch of damned nuts at the White House who don't understand agriculture."

The jury is still out on John Block, politician. But agriculture champion John Block, ever the optimist a farmer must be, thinks his first two months in Washington haven't been half bad.

"I'm on top of my work, on top of what I want to get done in USDA. I feel encouraged about the way government functions. . . . I have access to the president and to Ed Meese [the chief White House policy honcho]. I think I'm heard," Block said in a recent interview."

If nothing else, Block is heard.He has kept a peripatetic schedule of speaking appearances; he seems to be constantly on Capitol Hill, testifying before the committees or meeting legislators; he meets frequently with reporters and farm groups.

Through it all come a whiff of the nearly classic Cabinet syndrome: the secretary who sees himself as the man from farming, the man from labor, the man from commerce, or whatever The world, alas, is always larger than that.

Block keeps insisting to the different farm groups that they will be heard and that their views will be sought. Consumer and public interest groups, also part of that vast USDA constituency, complain they don't get the same signals.

"We continue to be concerned about his lack of responsiveness on food safety and nutrition issues," said Ellen Haas of the Community Nutrition Institute. "We're greatly troubled by his statements that don't show he recognizes the problems of low-income people. . . . But it's still only the beginning and he deserved credit for going all out on the dairy support issue. That is clearly in the public interest and it takes courage."

A question that springs from all of this is who is running the department. After two months, only Block, deputy secretary Richard E. Lyng and assistant secretary C. W. (Bill) McMillan have been confirmed by the Senate. Other key assistant secretaries have yet to be confirmed or, in several cases, even nominated.

It has been an open question since the start, when various senators, at his confirmation hearing, kept seeking assurances that Block and no one else, beyond reason, would be in full charge at USDA.

Despite Block's confidence, an impression is abroad that Lyng, a longtime Washington hand, is calling the policy shots. He was, after all, a national codirector of the Reagan-Bush campaign committee and he headed Reagan's agriculture transition team. True or not, the belief endures that. Lyng did not get the secretarial spot because Sen. Bob Dole (R-Kan.) was such a fervent Block advocate.

"Block's making the speeches," said a lobbyist, "but Dick Lyng seems to coordinate the policy. Block's role in these things seems to be less than Bob Bergland's was when he was secretary. What you have is a secretary from the hinterlands and most of the top policy people skilled Washington hands, who really don't need John Block. They already know who is who, and Block's on a different track."

The secretary's own view is that that sort of talk is misguided. "Mr. Lyng is a fine gentleman," he said, "but he is not setting the policy. . . . He has picked up where I can't get it done. I assigned him the budget preparation, but we did a lot of it jointly. . . . The same with the farm bill -- it will be my farm bill.

"In the budget I preserved the kind of funding I thought we should have. . . . We put together the farm bill. I'm very satisfied with it . . . and it is precisely in keeping with what I have been saying," Block said.

Generally, what he has been saying is that U.S. agriculture needs a positive advocate in the secretary, that farm exports must be boosted (a third of U.S. production goes overseas), the modest commodity price support increases are required to assure more profit in farming, and, in keeping with Reagan's budget austerity, some old-line USDA programs will have to be cut back.

Not surprisingly, such policy stances do not find unanimous support in the farm community. The smaller and marginal farmers -- unlike Block, with his multimillion-dollar, 3,000-acre spread in Illinois -- are not sympathetic to the cuts in Farmers Home Administration loan programs that Block is pushing. Others fear that the emphasis on exports may hurt the smaller U.S. operations. Still others fear that such a trade policy is bound to push up domestic food prices.

But getting back to the doubts of Block's neighbors in Knox County -- and keep in mind that he is universally liked and admired there -- the farmer's straightforward way of speaking his mind may not be the best way to be secretary of agriculture. You end up making the wrong people mad, or you cut your own throat.

Even before he took office, Block caused a stir by saying he felt that food could be used as a foreign-policy weapon. He quickly amended that to mean food should be an instrument of peace, as he came to call it, but his reputation as a man of straightforwardness was established.

It persists, although Block seems unlikely to become the controversial apostle of candor that made Earl Butz, Nixon's farm secretary, a hero in the country and finally a pariah for stepping over the line with an ethnic story.

When reporters recently asked Block about tobacco supports, he defended them as vital to the farm economy. They he said if cheaper tobacco were available, Americans would "smoke more and get more cancer." A gasp and a pause later, he added, "Wait a minute! I don't know if they do." Agriculture secretaries never acknowledge a smoking-cancer connection.

In another session with reporters, talking about children who might lose school lunch help if the administration's budget cuts go through, Block was straightforward again. "If they're sick or playing hookey, that's tough, he said. Child-nutrition executives, of which Block is the chief one as secretary, are not supposed to be so hard-hearted.

Within the ruling circles of this administration, Block's views have raised more than one eyebrow. For example, in the latest issue of Public Opinion, the magazine of the American Enterprise Institute, Interior Secretary James G. Watt is quoted as exclaiming "Holy Cow!" upon learning that news reports had Block saying federal zoning might be needed to protect farmland from commercial encroachment, a growing national problem.

"We're not part of the bureaucracy nor are we going to succumb to a Jack Block proposal as you've outlined it. We're the answer," said Watt, a development advocate.

It is that kind of farm frankness -- some might call it political naivete -- that keeps giving Block's supporters the tremblies over his long-term survival prospects and his critics the willies about the short term. Washington is a special kind of farm, no doubt, but it's also a far cry from rural Illinois.