Farmers already know it.

The link between agriculture and the environment has driven producers to be good stewards for centuries, said U.S. Secretary of Agriculture Tom Vilsack.

The Iowa native delivered this message Friday while the U.S. House Committee on Agriculture conducted a hearing on the American Clean Energy and Security Act, also known as H.R. 2454.

Vilsack told legislators that the bill would provide a "new income source" that could change "the old ways" of existing farms.

Yet many producers remain wary of the bill that is labeled as the most ambitious environmental legislation in the nation's history.

The bill would allow farmers to create and sell carbon credits, encouraging them to lease their land for wind turbines and increase the production of biofuels by some 21 billion gallons.

Bruce Johnson serves as manager of the Stephenson County Farm Bureau in Freeport, Ill., and said that tri-state farmers have expressed several concerns, although they remain supportive of the bill's purpose.

"Farmers are fantastic stewards of the land and of the environment, and they want to do everything they can," he said. "But anytime there is a regulatory element involved, then it can become a bit contentious. They want to know what new obligations or requirements will be put on them because of this."

One point of contention is if the bill places blame on farmers.

"Some of the wording suggests that the agriculture industry is somehow to blame for climate change," Johnson said. "Those are assumptions that are unfair and undocumented."

Another question is how this bill could alter the biofuels industry. The proposal encourages finding alternatives to biofuels, suggesting that the industry could rely on more than corn or soybeans.

"That could change the whole nature of the business," Johnson said. "The challenge for us in the Midwest would be whether or not we could produce those crops."

Dozens more questions exist, Johnson said, but for now, many of the concerns are still in the earliest stages of discussion.

"This is definitely something producers need to watch," he said.