Agriculture Secretary Bob Bergland yesterday asked Congress to give the farm bill it enacted last year a full season to perform before considering drastic changes in the federal farm price support system sought by protesting farmers.

As a roomful of more than 100 farmers listened, Bergland said the voluntary production controls and commodity reserves provided for in the law are sufficient to resolve the "traditional dilemma" of boom and bust in farming.

At the outset of six hours of testimony before the House Agriculture Committee, Bergland conceded, "Not every farmer will stand up and applaud the course we have chosen. But I submit that not every farmer would stand to appalud if we chose the option of legislating full parity."

Parity, the objective sought by leaders of the American Agriculture movement that has brought thousands of farmers to Washington in recent weeks, is an economic formula used by the Agriculture Department to compare current farm prices to those between 1910-1914.

For example, the full parity price for wheat in November was $6.04 a bushel. Farmers last year received $2.48 a bushel, less than half the parity price.

The 1977 farm bill includes several provisions. One is a system of loans and target prices, through which the government in effect sets floor prices for foarm products.

Another is for set-asides, or agreements that farmers will not plant given portions of their land in order to avoid price-crippling surpluses. Bergland said he will decide by next week whether to ask feed grain farmers to set aside 10 percent of their land in next year's crop.

For additional leverage over the crucial supply and demand equation, the farm bill also provides for a reserve system. Under such a system, farmers would sell grains at a set price to reserves owned by farmers and financed by the Agriculture Department.

When the price of grains rises to - 140 percent of the purchase price for wheat and 125 percent for corn - farmers would be able to sell the grain on the market at the higher prices.

"Broadly speaking, the reserve program has two purposes: to remove price-depressing supplies from the market in times of excess; and to provide supplies at reasonable prices in times of shortages," Bergland said.

However, he said, the program has not worked well for winter wheat, the lone crop planted since it went into effect Oct. 1.

The reason, he said, is that farmers have not cooperated sufficiently in the reserve program.

"If a third to a half of our excess stocks tare put under this arrangement, I guarantee the price of grain will go up," Bergland testified. "If farmers choose not to participate, the price won't go up unless there is a drought here or in some other major grain-producing area of the world."