Slowly but voraciously the combines are working their way across the great grain fields here, cutting and threshing the thousands of acres of dry, bleached, wheat. Then the trucks, nearly 300 of them, take some 120,000 bushels of wheat a day to the local co-op elevator as Kansas, the nation's largest wheat producer, reaps its biggest wheat crop ever.

The yield is bountiful this year, but the harbest is hollow. With towering supplies left over from last year's crop and stunning, near-record production this year, wheat now sells for far less than it costs to gow.

"Marketing this corp here is going to be a real booger," said Richard Gilgrease, 39, who recently sold the last of his 1976 crop at about the same price he sold his 1972 wheat - $1.75 a bushel.

So severe is the prospect for large losses that many farmers here in southwest Kansas, who openly attribute their plight partially to the fickleness of government, find themselves forced to turn to the government for help. And that has put Congress and the president in a dialogue of disagreement over now much to raise farm support levels in the coming year, with the President talking veto if Congress gives too much.

For its part, the Carter administration is virtually vertain to impose increase reduction on wheat for the 1970 crop - the first crop in five years to be curbed by government controls.

"I don't know whether the government ought to be in it," said wheat farmer Roger potter, "but I don't know whether the farmers can control it." Potter fears he will have to sell some of his wheat at the current $1.85 to $1.90 a bushel price regardless of the losses, just to get cash to keep operating.

Yet despite signs last fall of sliding prices and large surpluses, Kansas farmers planted 300,000 more acres of wheat for this year's crop - expected to be 396 million bushels - than for last year's. So, once again, U.S. farm policy, designed to assure farm income, is dealing instead with losses.

It is here, though, where the big John Deere's work ant-like across the vast fields, endlessly cutting at the thigh-high wheat day and night in 24-foot swaths, that the abstract of policy becomes the reality of life. The rumble hum of the combine is carried to the distance by hot Kansas winds blowing in from the southwest on a 100-degree day - perfect for harvesting the wheat that was planned last fall and nourished to ripeness this spring.

By all accounts, most of the farmers here have come through the past years infact. Higher prices at last year's harvest - about $8.25 a bushel - and slightly lower prices after that enable them to make some money.

Many were also able to reduce their debts with theriches of high prices of 1972 to 1975.

Most have avoided putting their wheat under government loan programs. At $2.11 a bushel locally it "is just a farce, it's no price at all," as Gladys Kalser, who with her husband still has 1976 wheat in storage, put it. (The national support level is $2.25, but is adjusted for local differences.)

The government will lead that much to a farmer and then after a year, if he can't sell it for more, the farmer forfeits his wheat. The government, in effect, has bought the crop at that price. However, many farmers are still sowing wheat on their own that could have sold several years ago for more, as they gambled for the price would go higher.

Jerry Schmidt, manager of the local co-op alevator, says he began this year's harvest with 300,000 bushels of farmers' wheat in storage at $1.95 a bushel from at least last year. The coop added a 363,000-bushel elevator this year to give it 1.3-million-bushel capacity but Schmidt says even that may not be enough.

The co-op's leftovers were part of a 1.100-billion-bushel surplus that existed when this year's harvest began. With another estimated 2 billion bushels being harvested now, theU.S. Agriculture Department estimates that this time year the nation could have as much as 1.4 billion bushels of wheat on hand - almost two years supply of domestic wheat. The nation uses about 35 per cent of what it produces; the rest is available for exports, which have been declining since the food short years of 1972-75.

So the squeeze for farmers in the coming year is whether they can sell the 1977 harvest for enough money to cover their costs, costs that have edged higher at a time of declining prices. Thus, more and more farmers talk of turning to the government's loan program, whatever the price.

Their fate, then, may hinge on whatover Congress and the President work out on loan levels. The Senate has proposed $2.47 a bushel, the House Agriculture Committee $2.25. The administration's version of all farm price supports could cost $2 billion, and the Senate's on estimated $3 billion to $1.9 billion.

For many farmers here, however, that will still not be enought to cover costs; they say they need to get $2.50 to $3 a bushel just to break even. They cite the seemingly endless increases in their costs, such as for fuel and farm equipment. "Everything we got to got keeps going up, and everything we still keeps going down," said Potter. "I cant't afford to leave wheat in storage forever "waiting for the price to go up Potter with his brother and father farms seven 1-mile-square sections of whest land and is carrying 2,400 bushels from his 1970 harvest. This year he feels he may be forced to use the government loan program.

Already, the economy of surrounding Hamilton County (population 3,141) has begun to feel the impact of low farm prices. Despite increased retail prices, total sales in the county have shrunk to 1975 levels, as measured by sales tax collection.

Business here is tied directly to the roughly 350 farmers who have some 430,000 acres of crop land, about half of it in wheat. Other crops, primarily seed grains like corn and mile, are also beginning to feel the pressure of low wheat prices as cattlemen stop feeding those grains to their cattle, replacing them with cheap wheat. The surfeit of wheat has depressed prices but consumers have apparently not benefited. A recent report by the President's Council on Wage and Price Stability concluded that while bakers raised bread prices five years ago to offact increased wheat cost, declining prices over the past three years have not been translated into lower bread prices.

Instead, the council found, "Wholesale bakers have exprienced offsetting, noningredient cost increases and have fully restored profit margins to their pre-1971 levels. The profitability of the large wholesale bakers rose sharply from 1972 through 1975 and appeared to have stabillized in 1976."

But excess wheat has allowed the Carter administration to make progress toward an international food reserve for use in times of world short age. The Agriculture Department in now allowing farmers to keep their wheat under loan for three years instead of one year, with incentives to sell when prices rise to certain levels.

Administration officials believe, however, that the United States cannot afford to store endless quantities of wheat foever until the next crisis and that this country and food-poor ones must consider using their resources to make poorer nations less dependent on U.S. farms. Thus, the seemingly imminent return to acreage reductions on wheat.

"I really don't like to see acreage controls," said Potter as he stood at the edge of a lush wheat field being harvested by his brother. it is not, and the Kansas sky is a clear blue. "But I do like to make some money. There is going to have to be a change somewhere."