RATHDRUM - A single day was all it took.

Field burning on the Rathdrum Prairie, a smoldering controversial practice, started and ended on Wednesday afternoon as two Kentucky bluegrass fields totaling 370 acres along Huetter Road went up in smoke.

Mark Boyle, air quality manager with the Idaho Department of Environmental Quality, said no more fields on the prairie are registered to be burned.

Boyle rated Wednesday's burns - with 10 being perfect - at 6.

"It definitely was not perfect," he said. "From my perspective, there was more surface smoke than we'd like to see."

Boyle said IDEQ's monitoring instruments at both Garwood Elementary and the corner of Lancaster and Ramsey were both hit with smoke.

"We like to see the smoke go up and over," he said.

Boyle said conditions must be dry and have transport winds to allow burning.

The practice increases bluegrass yields the following year, but is criticized by some environmentalists and those with breathing difficulties.

Nate Schumaker burned 150 acres while Ag for Idaho LLC, including Karleen Meyer, burned 220.

"It's going good and we have lots of manpower," said Meyer, adding that three water trucks and a tractor with a disc were at the fields to ensure the fires didn't get out of hand. "We have communication by cell phone and radio, road guards at critical intersections and have notified the fire department, airport and highway district."

Additional rules were set forth as part of an agreement between farmers, environmentalists, the state and others after the practice was temporarily suspended a few years ago.

Meyer said burning before Sept. 15 is optimal.

"We burned at the end of September two years ago and, yes we did have a crop, but it was down 20 to 40 percent of the normal production," she said. "You can't tell me that burning is useless."

She said burning can increase yields tenfold the following year.

Burning a few hundred acres on the prairie during one day is a far cry from 10 years ago when 3,000 acres were burned over several days or even as long as a month.

Boyle said the burning is still a concern to some, but IDEQ had received just one complaint as of late Wednesday afternoon this year.

"Over the past three or four years, the calls have dwindled down quite a bit," he said.

Field burning continues on the Coeur d'Alene Reservation.