With gasoline prices well past $3 a gallon, American motorists are complaining loudly about oil company profiteering. Mass-transit ridership is up, as are sales of fuel-efficient automobiles. So, too, are hot-air emissions in Washington, as politicians make empty promises to do something about the workings of a global marketplace that's beyond their ability to influence to any meaningful degree.

But if you think it's painful to fill the 20-gallon tank on your gas-guzzling SUV, imagine the shock that's greeting farmers who rely on powerful tractors to work their fields.

I spent some time this week driving around with Edgar Terry, who grows celery, peppers, cilantro and strawberries on about 1,200 acres of mostly leased land scattered from the Oxnard Plain to Piru. His situation is fairly typical of vegetable growers in this area, who produce multiple crops each year from the same patch of ground and are in a nearly constant state of field preparation.

We drove into a field between Oxnard and Camarillo to watch it being readied to plant peppers. The seedling plants are set out in raised beds, which are created using an ingenious rig outfitted with angled blades, rollers and scrapers. The rig is big and heavy, and the blades move a lot of dirt. The rig is pulled by a powerful Challenger tractor with a 500-horsepower diesel engine.

It's an impressive piece of equipment, rumbling along on huge steel-reinforced rubber treads. The cab is tall and glass-walled, outfitted with a dust-filtering air conditioner. It has computerized controls tied into a GPS positioning system that can automatically steer the entire rig using satellite data, keeping it traveling on perfectly parallel rows across the field.

It costs about $300,000 new, although Edgar, like many farmers, leases his under a contract that also covers maintenance and repairs. Caterpillar used to make and sell the Challenger, one of the most powerful farm tractors on the market, but an outfit called AGCO bought the line. Caterpillar provides most of the components, though, and the machine is painted the trademark Caterpillar yellow.

Those components include a 16-cylinder engine that displaces 964 cubic inches. The tractor has a top speed of nearly 25 mph. It also comes equipped with a fuel thank that holds more than 300 gallons. Which is a good thing, because it burns 12 gallons an hour, according to Edgar.

At the current price for diesel fuel of roughly $3 a gallon -- and rising as fast as the price of gasoline -- that's $36 an hour, nearly three times the average pay of a tractor driver. It also means spending nearly a thousand bucks on a fill-up.

Unlike motorists, farmers operating tractors can't reduce their fuel bills by carpooling, switching to buses and trains, trading in their fuel-slurping machines for subcompact hybrids, or eliminating nonessential trips. Nor can they pass the extra cost on to consumers, since growers don't set crop prices; they take the price the retailers and wholesalers offer them.

So, when the price of diesel boosts their operating costs by several thousand dollars a month, it just comes out of their pockets.