The Oregon Capitol (Salem Reporter archives)
SALEM — Plumes of smoke in the Willamette Valley, an annual ritual in Oregon, continue to be the most evident sign of farmers clearing their fields after harvesting grass seed.
Growers have burned about 9,200 acres this summer to clear their fields of straw left over from the summer harvest.
Oregon farmers grow about 400,000 acres of grass seed, most of it in the Willamette Valley, according to Oregon State University.
Burning a field of grass seed can reduce weeds, snuff out disease without using pesticides and can improve crop yields, according to John Byers, who manages the smoke management program at the Oregon Department of Agriculture.
But in 1988, smoke from an authorized field burn engulfed Interstate 5, causing a chain-reaction highway accident that killed seven people and injured 37.
That prompted heightened regulation of field burning, which had been of some concern since the late 1960s, when Oregonians reported health concerns about smoke from field burning, according to Oregon State’s Agricultural Progress Archive.
The state has increasingly tightened where and how farmers can burn their fields in the Willamette Valley. After the 1988 accident, lawmakers capped the area that could be burned in the valley at 65,000 acres.
Twenty years later, in 2009, the Legislature reduced the acreage to 15,000 and largely limited burning to the Silverton Hills area, east of Salem.
The tightened regulations spurred the overseas sale of Oregon straw, where it is used as animal feed, Byers said.
Those growers who live within the area where field burning is permitted register with the state in March.
Field burning typically starts in early July and ends when all registered acres have been burned, or when the weather turns rainy in the fall — usually the first or second week of October. The size of each burs ranges from just one or two acres to 100.
During field burning season, the agriculture department works with meteorologists at the Oregon Department of Forestry to assess weather conditions.
It can’t be too hot, dry or windy. The conditions must be conducive to let the smoke get “up and out” of the valley, Byers said.
And the state doesn’t allow burning if there’s already a lot of smoke in the valley from wildfires.
If the conditions are right, growers set one or two “test fires,” usually 30 to 60 acres. Field workers for the state monitor the smoke to make sure growers are complying with state rules.
“If it looks pretty good, the smoke is evacuating, we may light more fields,” Byers said. “If it doesn’t look good, we don’t light any more fields.”
It has been a fairly mild summer, so there have not been many days where the conditions prohibit field burning, Byers said.
But on Tuesday and Wednesday of this week, temperatures are expected to soar high, reaching the high 90s those days, according to the National Weather Service.
That likely means no field burning.
Reporter Claire Withycombe: [email protected] or 971-304-4148.