A coalition of grocers, seed growers and consumer and environmental advocates filed suit on Tuesday against the Department of Agriculture over a change it made to the process used to determine which substances may be used in organic farming.

In the suit, filed in Federal District Court for the Northern District of California, the group contends that the department violated procedures for federal rule-making when it changed the way nonorganic substances are approved for use in organic farming without holding a public hearing or seeking public comment.

“The U.S.D.A. unilaterally changed the process without allowing the organic community to give any input and, in doing so, violated the Administrative Procedure Act as well as the intent of the organic law,” said Paige Tomaselli, a lawyer at the Center for Food Safety, one of the plaintiffs.

Under the Organic Foods Production Act of 1990, organic producers may use only approved substances in farming and animal husbandry. The law created a list of exceptions, known as the National List, because organic versions of substances like copper sulfate and hydrogen peroxide were not available.