Almond growers pledge to cut harvest dust in half

Specialists with the Almond Board of California are working with growers in the perennial quest to tamp down on dust during almond harvest.

With exceptional drought conditions across much of California, there is little moisture left in the soil to aid in reducing dust, said Jesse Roseman, principal analyst for environmental and regulatory affairs with the Almond Board.

Yet the vast California almond sector is challenging itself to cut the amount of dust in half. That's because almond growers wrestle with concerns over potential dust impacts on those who live, play and drive by orchards where harvesting is underway.

"We want to do everything we can to deal with dust, which can be a health concern and also a safety concern," Roseman said.

He said what can be seen in airborne dust is not actually regulated particles: PM10 and PM2.5. Of the two, humans can much better filter out PM10 particles. PM2.5 particles are more dangerous, posing greater risks to enter lungs and bloodstreams.

Besides guarding against health risks, Roseman said, there are economic and pest control advantages to keeping dust down at harvest.

One way to reduce dust is to reduce the number of almond harvester passes and pickup speed. There has also been research on lowering fan speeds, setting sweeper height appropriately and using low-dust equipment at pickup. Researchers are also looking at off-ground harvesting and at self-compatible varieties, which require fewer passes.

Roseman said 75% of dust comes from the harvester during pickup.

Jason Bayer, a sales representative with Exact Corp., said tips for keeping dust low include maintaining a clean orchard floor, planning sweeper and harvester routes, and avoiding blowing towards roadways and buildings.

"Try to blow one way through the orchard with the sweeper," Bayer said. "We're of course surrounded by a lot of watching eyes, so we need to do the best we can do to blow into the natural filter of the trees."

He said the sweeper head height should be adjusted as needed for each field. Dual gauge wheels should also be used on sweeper heads for improved flotation. Bayer also said rubber fingers behind wire tines—he calls them "chicken pluckers"— can reduce dirt input. He said it's best to avoid extra sweeping passes.

Bayer cited benefits from conditioning that include removing sticks and debris, which can result in sending fewer trucks to the sheller and resuming irrigation sooner. He said using a low-dust conditioner and getting more even moisture content can speed harvest.

Bayer said pickup heads on harvesters also should be adjusted for each field, and ground speed and fan speed should be monitored according to field conditions. Exhaust from the harvester fan should be blown into the shaken row of trees and a twin rod chain system should be used for better dirt removal, he said.

Lucas Avila, area manager with Farmland Management Services, said using a conditioner to send cleaner product to a huller can increase profitability while maintaining harvest speed.

"It gives you flexibility with harvest timing," Avila said, adding some trees can be shaken while nuts are green. They are then spread out and dried, and Avila said conditioning can enable more efficient use of labor when it is available.

Ted Strauss, air quality resource conservationist with the U.S. Department of Agriculture Natural Resources Conservation Service, said financial assistance is available through low-dust incentive programs.

NRCS financial and technical assistance is provided through the Environmental Quality Incentive Program and the Conservation Stewardship Program.

The programs cover replacement of diesel-powered equipment, including pump engines and tractors, and offer payments to treat unpaved roads and surface areas with lignin derivatives, road oils or polymer emulsions.

Low-dust harvesters include machinery from the Exact Corp., Flory Industries, Jackrabbit and Weiss-McNair.

EQIP also offers assistance for pest control applications as well as payment for chipping and orchard removal and whole orchard recycling on a per-acre basis.

Ashley Correia, field and outreach specialist with the Almond Board of California, also cited online resources on an air quality module related to harvest dust practices put forth through the California Almond Sustainability Program.

She reiterated the board's 2025 goals: further reducing the water used to grow almonds, achieving zero waste in almond orchards, increasing adoption of environmentally friendly pest management tools and improving local air quality during almond harvest.

(Dennis Pollock is a reporter in Fresno. He may be contacted at agcompollock@yahoo.com.)