Polk County's Environmental Lands program is alocal success story in land conservation. Since 1994, the Environmental Lands Program has purchased more than 19,000 acres of the county's unique natural systems.

But it isn't always desirable to bring land into public ownership to save it. That should be especially true when it comes to farmlands. Whenever possible, working farms ought to be preserved as just that.

In early November, Heather Nedley from the Polk County Farm Bureau and Marian Ryan from the Sierra Club presented a proposal to the County Commission that they had been working on for nearly two years. The Polk County Land Stewardship Program, as the proposal is known, involves a couple of new concepts for the county's Environmental Lands Program.

One of those is to use money from the program to buy conservation easements. That means the land won't be developed, but still may be a privately owned working ranch. It's a good way to encourage willing sellers and conservation-conscience land owners to help preserve green space.

The bad news is that America loses an estimated 2.2 million acres of farmland each year to sprawl development. The good news is that 2.6 million acres of privately owned farms and ranches were preserved last year alone through conservation easements and protective trusts.OFFSETTING TAX BENEFITSThat is not to say that government, especially the federal government, does not play a crucial role in encouraging farmers and ranchers to donate conservation easements. One way to help rural landowners resist the pressure to sell out to developers is to grant them offsetting tax benefits.

In recent years, landowners who give conservation easements have been entitled to deduct the fair market value of their property for 15 years. Participating farmers and ranchers are entitled to deduct 100 percent of their income, while deductions for other participating landowners are capped at 50 percent of income.

Unfortunately, that tax incentive expired on Dec. 15. And while the U.S. Senate recently enacted a farm bill that reauthorized the deduction and made it permanent, it won't take effect unless House and Senate negotiators agree to keep the tax deduction in a compromise farm bill when they begin meeting in conference committee this month.

Farm bills are always controversial in Congress, but renewing an incentive that helps keep private lands from the bulldozer ought not to be.