WASHINGTON — Farmers will have until July 12 to sign up for the U.S. Department of Agriculture’s market transition commodity program and those who do not will be excluded from the program for the next seven years, USDA officials said.

The new program was described by USDA spokesmen as the greatest change since the Great Depression, bringing with it greater options in farming but also greater risk “without the strong safety net that has been a part of agriculture for past decades.”

The 1996 Farm Bill replaced the old farm commodity programs with a seven-year market transition program that pays a fixed payment based on land enrolled in previous USDA programs. Payments are limited to $40,000 per person per year during the new seven-year program.

During the transition farmers may plant what they want with some restrictions on fruits and vegetables, and are not restricted to farming their noncontract acreage.

Farmers are eligible for the program if they took part in the wheat, corn, grain, sorghum, barley, or oats program at least once in the last five years. Those who reported acreage to the Farm Service Agency as part of a past commodity program, but did not take part, also may enroll in the program.

The program allows greater flexibility to plan marketing but increased responsibility for planting decisions, USDA spokesmen said.

Although crop insurance is optional, those declining it must agree to waive eligibility for emergency crop disaster assistance.