Wayne D. Rasmussen sits around the Department of Agriculture all day long with time on his hands. That's his job. He's the USDA's historian.

Historian? At the Agriculture Department? Well, of course. About half of the Cabinet-level agencies have official historians, people whose job, as Rasmussen likes to put it, is "to act as an institutional memory."

When the USDA, for example, decided to set up its grain payment-in-kind (PIK) program for farmers this year, officials asked Rasmussen to research similar previous programs and develop a quick study for public distribution.

When a new administration moves in, there's almost always a reorganization, that time-honored ploy to move around the little boxes of power and seize control of the bureaucracy. New officials call Rasmussen to find out what worked in the past.

And there are press calls and letters from teachers, students, researchers all over the country, seeking agricultural information and slants on history. To get all this done, Rasmussen heads a staff of six other historians.

"My job is to bring historical perspective to current programs," said Rasmussen, whose articles and reports are widely quoted as the last word on many farming topics. He works out of a windowless office, at a desk covered with a small mountain of manuscripts awaiting his review and critique. The office is jammed with books and files. A print of a pastoral farm scene hangs slightly off center behind the desk.

"It is difficult, with all the turnover we have, to reconstruct the history of a unit or a program," he continued. "Monday, for example, somebody is coming in to talk about the old cotton marketing program. The secretary's office often refers the hard questions to us. Historical background gives a perspective to any problem."

Much of this information is stored in Rasmussen's head, accumulated since he came to work at the USDA as a records clerk in 1937, 22 years old and fresh out of the University of Montana. Studying nights, he went on to pick up a master's and a doctorate in history at George Washington University. He has known every secretary of agriculture since Henry A. Wallace.

"I think I've got the most interesting job in the world, except maybe for the man who lives at 1600 Pennsylvania Ave.," Rasmussen said. "In virtually every administration, some new person sees historians listed on the payroll and we then have to convince the new people we have something to offer . . . . But that's been good for us. Our feeling is that we have to produce or we'll be gone."

"But I've never had anybody tell me what I should say or what I should report or chide me for what I've said. I can't judge future programs, but I'm willing to suggest comparisons with the past. Some people, of course, don't like what we give them, but that's their problem."

Rasmussen is another of those unusual characters one can findhidden in the warrens of the USDA, amassing agricultural information and preparing answers for questions that inevitably will be asked.

If a federal agency can be said to have personality, the USDA has one, no doubt about it. Just like Rasmussen, many USDA people have farm backgrounds, and they bring a special zeal to helping farmers. Instead of referring to the Office of Such and Such, they identify it by the director's name, as in, "Go talk to Bud Rank" or "Check that out with Dawson Ahalt," or, "Wayne Rasmussen can answer that for you."

"USDA is one of the best . . . . It is the best federal department that the American people have. We're concerned here with something absolutely vital to the health of all of us. Food, nutrition . . . . And it's also one of the most human of departments," Rasmussen said.

To sit for part of an afternoon in his cluttered office, and to hear Rasmussen guide a tour across the panoramic history of American agriculture, is to get a thrilling sense of the roots of the country, without intending a pun.

Rasmussen sweeps from the farmer-fought American Revolution to the cotton gin to the Civil War and the impetus it gave to the mechanization of farming. He goes on through the growth of commercial farming and the scientific advances that led to the recent era of "the greatest production the world has ever seen."

He has looked at these things very closely, and while he is a champion of the farmer's role in history, he also is a critic of the farmer's often paradoxical lusting for independence while jostling to get a federal subsidy.

And how does the historian rate the secretaries of agriculture?

"I've often said that Henry A. Wallace was the only genius who was secretary of agriculture," he said.

Some people may not like the answer, but as Rasmussen put it earlier, that's their problem.