A year ago Thursday, thousands of farmers across the country, frustrated by Depression-low commodity prices and an omnibus farm bill they claimed would bankrupt them started driving their tractors out of the fields and into the streets, declaring they were on strike until their demands for 100 percent of parity was met.

Under the banner of the amorphous American Agriculture Movement, founded in this dusty, thinly populated southeast Colorado community, farmers set the stage on Dec. 14, 19778 for the first major national farm protest since the Farm Holiday movement of the 1930s.

One month later, they descended on Washington and settled in for what became a winter-long lobbying effort to achieve parity, a price for their products that would give them gains in purchasing power equal to the rest of the economy over the last several decades.

In their first assault on Washington, protesting farmers didn't get parity, and their strike threat never materialized. Consumers didn't experience food shortages, and wheat and feed grain farmers, mainstays of the movement, failed to rally livestocks, dairy, fruit and vegetable producers to their cause.

Since last April when farmers deserted the nation's capital for their fields, American Agriculture has been comparatively dormant, but now farmers loyal to what remains of the movement say they will take their tractors to Washington again when Congress convenes next month.

Agriculture authorities surveyed in eight states where the movement was strong a year ago believe there will be another tractorcade to Washington. However, none of them would predict victory.

In a recent interview, Agriculture Secretary Bob Bergland, himself a main target of the protest a year ago, said that American Agriculture "would have no effect in terms of policy changes" but that he would welcome the farmers back to Washington anyway.

Largely because of American Agriculture culture's lobbying efforts last winter, the Carter administration adjusted farm subsidies upward sharply, and the public got a crash course in agricultural economics and farmers' financial problems.

In the exodus to the fields at spring planting time, few of the protesting farmers adhered to the movement's goal of cutting production in half. Gone ere farmers' declaration "not to plant not to buy and not to sell" until they achieved parity.

By harvest time, farmers were reaping crops they earlier had sworn they wouldn't plant, and when it was over, rcord corn and soybean and substantial wheat harvests had been produced.

In Springfield where an old auto supply store on Main Street still houses American Agriculture's national headquarters, activity has slowed to a snail's pace compared to a year ago; only the true believers remain.

However, Colorado farmers Laurence Bitner of Walsh and Gene Schroder of Campo, who emerged as national spokesman last year, said American Agriculture supporters from about 25 states will begin driving their tractors to Washington in mid-January, arriving there in early February.

The goal this trip, Bitner said, will be to press President Carter and Bergland to administer the omnibus farm law at a high level.

"Carter says this is the best farm bill ever written if it is properly administered, so we will call on him to administered, so we will call on him to administer it at a proper level," said Schroder. Bergland can take a number of actions that would ultimately result in raising the price of grain.

Agriculture commissioners in Colorado, Wyoming, Nebraska, Texas, Oklahoma, and the Dakotas and the chief statistician of the Kansas Crop and Livestock Reporting Service said there still is support for American Agriculture in their states and they expect to see another tractorcade to Washington.

However, several said the movement doesn't have the momentum of a year ago and probably won't attract as many participants.

Colorado Agriculture Commissioner J. Evan Goulding doesn't think the movement will generate as much response this time. Politicians will be more insulated from pressure in this nonelection year, Coulding said, and Bergland is making "a very strong case on the sucesses of the farm bill."

Net farm income is up, commodity prices have increased, agricultural exports are at a record hing, and the farmer-owned grain reserve has attracted strong participation.

The U.S. Department of Agriculture estimates net farm income this year at over $25 billion, still below the record $30 billion in 1973 but $5 billion more thn last year.

Since the omnibus farm bill was signed by Carter in September 1977, wheat prices have increased 32 percent, soybean prices 21 percent and corn prices 18 percent, and prices in the cattle sector, depressed for four years, have shot up 50 percent.

USDA has estimated farm exports this year at a record $26 billion to $27 billion.

The farmer-owned grain reserve, aggressively promoted by Bergland as a key to managing surplus production, now holds 599.3 million bushels of wheat, 39.9 million bushels of oats, 36.3 million bushels of barley and 41.1 million hundredweight of grain sorghum.

All those figures spell a degree of sucess for the administration's farm policy, and the countryside has been quiter this fall.

When farmers went of Washington last January Bergland "didn' have much to show but does now," said Goulding, so they "may be more willing to Bergland a chance." That could spell futility for the American Agriculture Movement, which even Bitner admits lost credibility when farmers returned from Washington the last time and planted every acre they could. CAPTION: Picture, Farmer's march that descended on Capitol a year ago is being marshaled again in quest of "a proper level" of prices, despite higher incomes and bumper harvest. By Ken Feil-The Washington Post