The driver who did doughnuts over eight acres of knee-high alfalfa Monday night may not have even realized that he was riding in an expensive hay crop.

But the owner of that Mercer County crop, who discovered his alfalfa plants crushed and ruined on Tuesday morning, sure did.

Richard Stuchal, 57, arrived at the Pine fields that he rents about 8:30 a.m., prepared to do the first of what will be four cuttings this year to his 52-acre alfalfa crop.

He mowed the first field, but as he crested a hill above the second, Mr. Stuchal saw the muddy tire tracks. Doughnuts and figure-eights were scattered across an area the size of four or five football fields.

"That's what made it so fun," he said. "For the few minutes of excitement he had there, I'm sure he had no idea what he'd done."

The 2004 Ford Explorer used in the joyriding sat just 50 feet away -- covered in mud, with alfalfa leaves stuck in the grill and wheels.

State police have charged Stephen James Kurz, 28, of Grove City, with agricultural vandalism, which is a felony. They said he borrowed the vehicle that did the damage.

They expect other people to be charged in the case, as well.

Mr. Stuchal believes the person who rents the farm house on the property had a party the night before. There were remnants from a bonfire and "refreshment containers" tossed about, he said.

According to Mr. Stuchal, alfalfa grows for four years, but any place in the field where it was crushed or trampled, it will not come back.

He planted the damaged 18-acre field last year and estimated that 15 percent of his plants were lost. Alfalfa hay is valued at $170 to $240 per ton, and that field, Mr. Stuchal said, would produce about 6 tons per acre per year.

He will suffer not only volume loss over the next four years, he said, but the quality of the alfalfa from this cutting will be lower, because of the soil being mixed in.

Mr. Stuchal, who farms a total of 400 acres across northern Butler and southern Mercer counties, uses the alfalfa hay to feed his 140 dairy cows.

"That was one of the nicest fields of alfalfa that we have," he said. "A lot of people think that's just hay. That's a source of income. That's my paycheck."