The picture is deceptive.

Shiny tanker trucks bring milk to the cheese plant all day long; there is bustle around the grain elevator and the feed store; a spectacularly good corn and soybean crop is forming in the fields; hordes of pastured cattle fatten for market; farmers are on their tractors, readying ground for winter wheat.

But despite the bustle and the seeming prosperity, South Dakota farmers are coming face to face with the same low prices, tight credit, falling land values and high interest rates that have put most of American agriculture in its tightest financial bind since the Great Depression.

While statistics suggest that more diversified South Dakota may be a bit better off than its neighbors in the central and eastern Corn Belt, the hurt is no less because farming is the state's principal industry, with annual receipts of about $3 billion.

Debt forced about 4 percent of the state's 37,000 farmers out of business this year. With grain and red-meat prices continuing their downward plunge and farm debt exceeding ability to repay, that many or more will drop out this winter, most experts agree.

Agriculture Secretary John R. Block's announcement that the Farmers Home Administration (FmHA) will take on no new borrowers this year has boosted fears of a greater shakeout. Farmers turned down by commercial lenders will find the last-resort federal exchequer closed. FmHA's inventory of land taken back from failed borrowers, about 55,000 acres, puts South Dakota in the nation behind Missouri.

"There will be another big sellout this fall," predicted Maynard Ortegren, manager of the Land O' Lakes cooperative elevator on the edge of town. "We lost 15 farmers right here this year and we'll lose that many again this time. They just can't make it with the way prices are today."

No one sees an end to collapsing farm-land prices, which fell 33 percent between 1981 and 1985 -- steep enough, but still a far cry from the 49 percent loss in Iowa and the 46 percent in Nebraska during the same period. From its 1982 peak of $349 an acre, South Dakota land now sells for an average of $250 -- if a buyer can be found.

"We have a lot of stress," said Mark Edelman, farm policy specialist at South Dakota State University in Brookings. "But has it bottomed out? It depends on commodity prices. If federal policy is to lower prices more, then it hasn't bottomed out."

Here in Volga, Duane R. Schlomer, vice president of the First National Bank, is not particularly optimistic. "As agriculture goes, so goes the community," he said. "Prices have dropped so badly that it has compounded our problems. We've got a very good crop, but it's not worth anything. We've not seen the end of this crisis. It's still coming."

The story is much the same throughout the state: confusion over the disparity between farm and retail prices, frustration over the failure of Congress to pass a farm bill, anger at Reagan administration efforts to slash federal farm program spending.

The optimism that usually energizes the American farmer has disappeared.

Ed Vander Wal, a descendant of Dutch immigrant farmers who runs a large cattle and grain farm near Volga with his brother Ray, tried to put the bleakness into perspective the other day.

"Even with this, we try to be optimistic," he said. "We go to church a lot around here when things go bad. Even when it doesn't work out on paper, you trust in Him and things seem to work out."

Others, however, including a number of the state's elected officials, pin their hopes for revival on Washington, which is a bad word these days from the drought-stricken western rangelands to the lush crop and grazing land east of the Missouri River.

Leland Swenson of Huron, president of the South Dakota Farmers Union, the state's largest farmer organization, put it this way: "Our farm economy is in a very critical position. Every segment is in trouble. Nobody sees a turnaround, and the 1985 farm bill that they have drafted so far spells disaster for us.

"The administration's position and the inactivity of Congress have frustrated people here. Congress must not be so concerned about the economic impact of farm programs on the budget. The key factor we're looking at now is whether enough pressure was put on members of Congress during their recess to get the right things done."

Sen. James Abdnor (R-S.D.), already running hard for reelection next year, took it even further. He is mad at Congress in general; he is mad at President Reagan and he is unhappy with the Senate Agriculture Committee.

"My own Joint Economic Committee held hearings on farm policy and they were good hearings. I turned over several hundred pages of testimony to the Agriculture Committee, but I don't know if they even looked at them."

Abdnor said that in more than 60 meetings he held with constituents during the August recess, the plight of state agriculture came through vividly.

"It's terrible. It's a dire emergency. There's been nothing like this since I was a little kid in the deep '30s," Abdnor said. "That Congress left Washington without passing a farm bill is the biggest insult to the number-one industry in the United States."

Rep. Thomas A. Daschle (D-S.D.), this sparsely populated state's only House member, agreed with Abdnor and Swenson. "If anything," he said during a break in a meeting with farmers in Salem, "the situation is worse. There is a kind of numbness right now; people don't know what to think about what is happening to them. I don't know how much longer this will go on until it turns to genuine anger."

Bill Fisher of the American State Bank in Pierre, which does most of its lending to farmers, noted the uncertainty about the future that finds winter-wheat farmers putting a crop in the ground without knowing how wheat will be dealt with in the farm bill.

"They have a rough idea of how much the program will be cut, but it becomes very expensive to plow out planted ground so they can be in compliance with the federal program," Fisher said. "A banker deals very, very carefully in this situation. Prices are not good and you really almost have to farm the federal program."

Just as there is frustration with Washington's twists and turns over farm policy, there is frustration with the inexplicable curiosities of farm markets and price shifts.

Farmer Vander Wal cited beef, which accounts for more than half of South Dakota farm income. Government economists projected that 1985 would be a good year for cattle, or at least a better year that would help farmers make ends meet. Vander Wal stood near a pen of 1,400-pound animals that would soon go to market, pulled out a pocket calculator and quickly figured the price they might bring.

"They were bidding 52 cents a pound this morning at our Minnesota market. No one can make money on cattle at that price. Nobody expected beef prices to be off like this, but in this business you can't wait. You have to sell those cattle when they're ready to go to market. What no one here understands is why the retail prices don't go down. Somebody is making money off of us," he said.

Abdnor seconded Vander Wal's thought. "I've heard this time and time again," he said. "My farmers are sick and tired of USDA reports and projections. They held cattle off the market based on price projections of 72 cents, and that never came to pass. The whole mess can be attributed to this."

Gordon Wilkerson, president of the Sioux Falls Stockyards Co., the largest in the United States with a volume of $500 million a year in cattle, hogs and sheep, expressed similar puzzlement over price problems.

"We know the producer is not getting a fair price, and we would like to know why the price is not lower for the consumer. The packer and the retailer say they are not making money. But somebody's getting it.

"Somewhere along the line, these cattle feeders will make some money. Everyone thought it would be this year, but it's turned out to be a disaster. Our concern right now is whether the producers will get the financing they need to feed their livestock through the winter," Wilkerson said.

Or take oats, of which South Dakota is the top producer in the country. From a high of about $2.25 a bushel just two years ago, the price has fallen $1 or less, and imported Swedish oats continue to pour into the country.

"Our price is well below the cost of production, and while we are now competitive with the imports, it has been cheaper for southern buyers to import oats from Sweden than to drive up here and get them," said Don Tucker, owner of Dakota Oat Processors at Arlington. "Ocean freight rates and the strong dollar are factors. Do you realize it's cheaper to ship from Rotterdam to our Gulf ports than it is to ship oats from South Dakota to Oklahoma City? We are in a world grain market more than ever and we'll have to learn how to adjust to this."

But, as Gene Vognild in Sioux Falls pointed out, when U.S. farmers must sell at a loss to be "competitive," their only alternative market is the guaranteed price offered in the federal price-support loan program. Uncle Sam could turn out to be their biggest buyer this fall, despite administration efforts to keep program costs down.

"It is a sad situation when the government has the best price in town," he said. "But there is nothing in the cards that will get farmers out of this situation. Hogs are cheap, cattle are taking a bath, grain prices are low. The credit problem will be right back with us this fall. I just don't see a turnaround. It's sad."