Oregon's land-use planning rules are designed to concentrate growth in urban areas while protecting farmland from development. The Jackson County commissioners' decision to approve a solar power project on Rossanley Drive runs counter to the intent of those rules, despite the attraction of an alternative energy source.

The commissioners voted Wednesday to grant an exception to the state land-use planning goal of protecting farmland. The exception is the first step required in approving nearly 40,000 solar panels on 90 acres of prime farmland.

The commissioners took pains to note that they limited the project to 30 years, after which the land would revert to farm use. "This is not going to be houses," Commissioner Bob Strosser said.

But it's not going to be farmland anymore, either — not for three decades.

Energy company Orijis Energy, which has projects around the world, proposes to spend $12.7 million on the project. It would generate about 100 jobs during the installation phase, but only one full-time equivalent worker would be needed to maintain it once it was operational.

That's not a great argument in favor, no matter how committed one might be to alternative energy sources. And there are other trade-offs involved.

Agricultural crops grown and marketed locally mean less energy is expended shipping in produce from elsewhere. And that shipping is done by trucks burning fossil fuel.

Jackson County was an integral part of the Regional Problem Solving process, a years-long effort to identify buffers between cities where development should not occur. This area, which has high-quality soil, was one of the areas designated for continued agricultural use.

Land-use rules intended to preserve farmland should be followed unless there is a compelling reason to deviate from them. This case is an example of a compelling argument against bending the rules.

Officials of the Oregon Department of Land Conservation and Development, which opposes the project, told the county in a letter that farmland is attractive to solar companies because it's inexpensive, and solar projects are low-margin operations. That raises the specter of large swaths of prime farmland growing solar panels instead of food.

Alternative energy is important, and solar and other renewable sources should be encouraged, but they should not be allowed to displace farmland. There are plenty of areas in Southern Oregon with poor soils and inadequate water where solar panels would be a better fit.