This is Peter Brent's story of failure on the land: "I shouldn't have bought the farm. I wasn't a land speculator, and I feel I did a good job. But I've got nothing to show for 45 years . . . , except my good health, a good wife and kids and the same 10-year-old boots with new soles."

Brent's story will be repeated in uncountable ways this year as debt -- crushing, irreversible debt -- squeezes out thousands of farmers who gradually have become bit players on the global stage of big agriculture.

U.S. farmers owe about $187 billion. That's not so much considering that farm assets are slightly more than $1 trillion. Or that farmers' average debt ratios are a bit healthier than those of business in general. Or that a third of the farmers are virtually debt-free.

But the debt is concentrated among farmers in the middle-size range, so-called family farmers. About one-third of the country's 2.4 million farmers hold two-thirds of the debt. By American Bankers Association estimates, 3.6 percent of those 2.4 million farms could fail this year -- about double the usual dropout rate.

That works out to about 238 failures a day.

There is no overstating the implications of such sobering numbers on the future of family-operated farms, on land-holding patterns, on concentration of power in agriculture, on the stability of rural towns and businesses.

Nor is there an easy way out in the next several years for the farmers deepest in debt. Even with government aid or improved prices or dramatically lower interest rates, there is no way that many of them can elude the pincers.

How did American agriculture work itself to this pass?

Debt, after all, has been a way of life for farmers: They borrowed to buy land, they borrowed to pay yearly operating and living costs. And if all went as hoped, crops were good enough to let the farmers pay off their notes and start all over.

But today's problems are different from the historical up-and-down cycles that have shaken agriculture from time to time. The bursting bubble reflects powerful changes that have occurred over the last 20 years as U.S. farming became a mechanized giant prowling the globe for markets to absorb the abundance of the American land.

The roots of this crisis reach back to 1970, when U.S. farm exports were at a relatively modest $10 billion. Then came the boom -- the Soviets entered the U.S. market in a big way; crops failed around the globe. Exports suddenly soared. Farm prices reached historic highs.

Credit was easy, and the inflation that made paper millionaires of ordinary dirt farmers created an aura of no tomorrow. Farmers, abetted by lenders and economists who said bigger was better, mortgaged themselves to the hilt.

The boom was good for everyone. Fertilizer and pesticide makers prospered. Implement makers prospered, turning out ever larger and costlier machines to till the fields that would feed the world. Speculators made money as farmland prices jumped more than 10 percent a year. By the end of the decade, exports had climbed to $40 billion.

In a sense, the American farmer had become less a man with a plow than a cog in an international food-production apparatus. He took on debt to provide food to Russians and Japanese. He took on debt to buy machines made by workers in Moline and Chicago. He took on debt to pay for chemicals made in Midland and St. Louis. His borrowing brought profit to his banker.

Then the bubble burst. Moves by the Federal Reserve and the Reagan administration started to brake inflation. Land and machinery values peaked in 1981 and went on a slide that has not stopped. As recession took hold and farm prices stagnated, federal deficits kept interest rates high and farmers were in the soup. A Year of Reckoning

So 1985 has become a year of reckoning. The pressure cooker of high interest, depreciating assets and low prices exploded this winter. It means that many farmers, caught in the pincers of inevitability, will not qualify for their operating loans this year and they will be gone.

"About a third of the farmers have financial problems, and 10 percent of them seem to have serious problems. That is a serious situation -- a lot of people with problems, and not just those who have done some risk-taking," said Emanuel Melichar, a senior economist at the Federal Reserve System.

Iowa State University economist Neil E. Harl agrees: "Unless a major restructuring of farm debt takes place, the prospect is for massive loan defaults with consequent economic damage of major proportions to rural communities as well as to lenders and borrowers. Agriculture is going through the most wrenching financial adjustment in a half-century."

Montana Gov. Ted Schwinden, a wheat farmer, offered another side to the debt crisis: "Forty percent of our farmers are losing hold, and the long-term considerations must be understood. We need to understand the concentration in the food industry. We need to understand who will farm. We need to understand the limits and reality of productivity . . . . There is more at stake here than a farm bill or deficit reduction."

Paper losses are staggering. From a record high of $908 billion in January 1981, farm equity has dropped by 11 percent to about $811 billion, with a further drop to $805 billion expected this year.

"Such a string of declines qualifies as the worst since the Great Depression of the 1930s," says Doane's Agricultural Report, an industry newsletter. Squeeze on the Middle

Melichar and other economists say farmers in the middle-size range are under the greatest stress. They estimate that about 625,000 farms, with annual sales between $40,000 and $500,000, are in trouble if they are heavily indebted -- which many are.

Melichar's calculations indicate that roughly 210,000 farm operators, who owe about $73 billion and own assets valued at $107 billion, are in deeper trouble, with debt/asset ratios above 40 percent. Many of them tend to be farmers in the Midwest who expanded and took on greater debt during the 1970s.

Harold F. Breimyer, professor emeritus of agricultural economics at the University of Missouri, said that "half of all full-time farmers are in jeopardy." He describes as "so much fluff" the oft-heard allegation that farmers are in trouble because of mismanagement.

"The one exception is that some individual farmers went wild in speculative leveraging of land-buying in the 1970s. They were greedy, they left themselves no cushion and they deserve only a little sympathy and no help. But they are a tiny minority among farmers who are in trouble," he said.

Today's debt problems, in Breimyer's view, stem from "a decapitalization that is forced by tight monetary policy and high interest rates . . . . In rough terms, I estimate the downvaluing of assets to be on the order of $300 billion."

Major dislocations are likely in agriculture, most experts agree.

William G. Lesher, who was assistant secretary of agriculture for economics during President Reagan's first term, said: "On the family level, on the community level, the consequences will be severe in some instances. Assets are being depreciated . . . the inflationary expectations are being wrung out of them." "Kept Getting Deeper"

None of which comes as news to Pete Brent. He lost his Iowa grain and cattle farm in 1983 because his debt was more than the farm could earn. Today he helps make ends meet by counseling other farmers and working two newspaper routes in the Des Moines suburbs.

After working for years as a hired hand and then farming on rented land, Brent bought 320 acres in 1979, paying $850 an acre with 8.5 percent interest on his loan -- a pretty good deal at the time, although the boom was playing out. He raised cattle and soybeans.

"Even though my wife was working and paying some of our expenses, the farm couldn't pay for itself," Brent, 47, said. "In 1980 I did my cash-flow projections on cattle and soybeans, using all the expert data I could find. I actually produced more pounds of beef and more beans than I projected. But the price was erroneous. I projected $70 cattle and it didn't come in that way.

"I lost over $20,000 that year, and I was $20,000 short on my payments. You roll your notes over in this situation and now you're paying interest on the interest," he continued. "And then the interest rates went up. With the inflation mentality, I said I had to do more, I said I would get even the next year. But the hole kept getting deeper. Then land prices began to fall, and that was it . . . ."

There in neat form is the story of farm debt complications facing thousands of farmers today: low price, high interest, land deflation. Trouble by the Bushel

One way to look at the debt problem is through the price of corn.

Say a farmer bought an acre of good land in the late 1970s for $2,/000. The interest on his loan was 15 percent, costing $300 a year. But with inflation at 12 percent, his "real" interest rate was 3 percent ($60). Assuming the acre yielded 150 bushels of corn, selling at $3 each, he had $450 gross income -- enough to cover his production and living costs and make a profit.

But with inflation stemmed and interest rates still high, the farmer's real interest today is about 10 percent, or $200. Now his corn goes for $2.50, or $375 for 150 bushels. Or his crop is shortened by drought. The pincers have begun to squeeze. And because his acre of land has devalued to $1,400 and corn prices remain stagnant, his chances of refinancing or keeping current on his debt diminish.

Ron R. Poor, president of the City Bank and Trust Co. of Moberly, Mo., and a farm lender for more than 20 years, recently outlined the hopelessness of such a situation. In his part of north-central Missouri, the picture was drearier than the example of the hypothetical acre of corn.

Poor described a diversified agriculture in his area: corn, wheat, milo, soybeans, extensive cattle and hog production, limited dairying. But, he said, "four of the past five years have been drought years and production has averaged only 30 to 40 percent of expected yields."

The combination of bad weather, low prices, land deflation and high interest caused Poor's bank to lose "25 to 30 percent of our farm clientele since 1981 . . . . We anticipate that another 5 to 7 percent of our farm clientele will be forced from the farm before the end of 1985. In 1981 we were liquidating some very marginal farmers. Today, we're cutting into the quick and liquidating some of our best farm operators."

Poor said rural bankers have no other options. "When projected losses exceed current net worth, new credit decisions are required," he said. "We've already been supporting farm businesses with negative cash flows for the past four or five years in the face of increased risk and declining equities . . . . Finally, today, they're out of equity." Debt-to-Asset Ratios

Agriculture Secretary John R. Block, at a recent congressional hearing, noted that the relatively sound debt-to-asset ratio of 21 percent in agriculture -- lower than that of nonfarm, noncorporate businesses -- "disguises the difficulties that some individuals . . . are facing in certain areas of the U.S."

Their debt-to-asset ratios, a new household term in farm country, are such that with current prices, interest rates and declining assets, they cannot stay in business long.

But even a "healthy" ratio also is misleading. According to the Fed's Melichar, a farmer with debt equal to 20 percent of his assets and an 11 percent average interest rate merely would break even at today's farm prices.

"For over two decades, expected growth kept occurring in agriculture. By the early 1970s this was established. Land prices kept going up, credit was available, there was an upward trend in income," Melichar said.

Sooner or later, things had to change. Land values, dropping now from their historic, unrealistic peak in 1981, had to reflect their farming value.

Now, according to Melichar, "the right thing is happening from the point of view of economists, but there is human suffering. A chef sets up in business and fails, he becomes a chef again. A chef fails, he doesn't go out and kill himself. Farming somehow is different, I'm sorry to say."

Next: The biotech quandary