CHICAGO - U.S. officials said on Friday they would offer higher payments to certain owners of environmentally sensitive farm land if they idle it in a conservation program instead of using it to grow crops.

The offer from the U.S. Department of Agriculture is an attempt to slow an exodus of millions of acres from conservation programs at a time when high crop and land prices are enticing farmers to put the land into production. Increased payments will be available to owners of up to 1 million acres of the highly sensitive grasslands and wetlands under a new initiative that is part of the federal Conservation Reserve Program, or CRP.

The move solidifies a shift in the government's strategy to protect the environment by focusing its resources on the most sensitive land, instead of simply pursuing a large quantity of acres for conservation.

"With high crop prices, this approach to target our most sensitive lands is essential if we want to maintain the substantial benefits of CRP," Agriculture Secretary Tom Vilsack said.

Some 6.5 million acres of land could return to tillage when CRP contracts expire this fall. That's one-fifth of the land in the government's program and one of the largest turnovers ever for the reserve, created in 1985 during an agricultural recession.

Land is typically enrolled into CRP for 10 or 15 years and can then be re-enrolled.

To encourage producers, the USDA will increase a one-time signing bonus for CRP to $150 per acre from $100. The increase will be available to approved owners of land featuring wetlands, certain kinds of birds and other species.

The department previously announced that a general sign-up program for farmers who want to put land into CRP will start this month. Another conservation program that targets highly erodible land will begin this summer.

Officials hope the latest program will convince farmers to enroll or keep the most sensitive land in the program even if they put some formerly idle land back into production, said Robert Bonnie, USDA's senior advisor on conservation and natural resources.

"We're trying to provide options to land owners," he said.

Environmental groups applauded USDA's decision to increase the one-time payment and focus its efforts on the most sensitive land.

Among other benefits, CRP contributed to a net increase of about 2 million additional ducks per year, or a 30 percent increase in duck production, since 1992 in North Dakota, South Dakota and northeastern Montana, according to an estimate from the U.S. Fish and Wildlife Service.

"No matter how staggeringly impressive the wildlife, water quality, flood mitigation and soil benefits of CRP are to society, the program needs to make sense to a farmer's bottom line in order for CRP to succeed," said Dave Nomsen, vice president of government affairs for wildlife groups Pheasants Forever and Quail Forever.

Still, farmers said it would be difficult to resist the pull of crop prices that are historically high due to strong global demand. High commodity prices have supported a surge in land values, which means farmers can also make a profit renting acres to other growers for production.

"What's coming out (of CRP) will probably go back into production," said Jeff Enger, who farms about 6,000 acres of corn and soybeans in North Dakota. "We finally got a profit in farming."

(Reporting By Tom Polansek; editing by Jim Marshall and Lisa Shumaker)

Copyright 2012 Reuters Environmental Online Report