There’s not much to like about the dust that’s kicked up by the almond harvest. Almond growers themselves will tell you that, as will neighbors and those who regulate air quality.
But the dust is a reality certain to fly when the harvest arrives in California just weeks from now. Because of that, the Almond Board of California has come out with new dust management guidelines to help growers get a better handle on the problem.
For the industry, it’s all about stewardship according to Mel Machado, who chairs the board’s Environmental Committee.
“With the harvest just around the corner, it’s a good time to prepare the orchard and plan ahead to minimize dust,” Machado said in announcing the guidelines.
“I ask that you (growers) please consider the impact on neighbors, workers and environment during the harvest.”
Machado, who is also director of member relations for Blue Diamond Growers in Salida, said following the pointers could help in “strengthening relations with the community and supporting the overall image of California almonds.”
2015 is already shaping up as a particularly challenging year for growers because of the fourth year of a drought.
A lot of dust is already flying in the Modesto area that is unrelated to the harvest. Some of it comes, he said, from fallowed lands as winds pick up dust particles from the soil surface.
Growers routinely take precautions to avoid dust that can be a safety hazard to harvesters, haulers and others. Water trucks pass through roads in and around the orchard, and growers post signs urging drivers to slow down. The dust can pose a safety hazard and help exacerbate problems with spider mites in the orchards.
Machado said preparation of the orchard floor for next year’s harvest can come once this year’s harvest is done. Here are the new dust management guidelines from the Almond Board:
Start with a clean orchard.
Clean orchard floors make all dust management practices easier. Clean floors help you reduce suction fan speed on pickup machines. That can knock a lot of dust out of the process without losing harvest efficiency.
Plan your route.
Take every opportunity to blow dust back into the orchard using the tree canopy as a natural filter. Note that the trees and their canopies can help capture dust before it reaches roads and homes. Plan your passes and travel direction to direct dust away from roads, homes and sensitive locations such as schools, hospitals and day-care centers. If you are near a busy road, consider placing traffic signs to warn motorists of harvest activities.
Go low, but not too low.
Set sweeper heads to optimum level. Don’t set heads any lower than is necessary to recover the crop. Often, wire tines can be set to as high as a half-inch off the ground and still do a good job sweeping. If set too low, the sweeping head will move an excess amount of dirt into the windrow, increasing dust from the pickup machine substantially.
Use wire tines.
If possible, only use wire tines on sweeper heads. Sweepers that use wire tines without rubber flaps can help reduce dust.
Avoid extra sweeper passes.
Use fewer blower passes when and where possible. One blower pass instead of three can reduce the amount of dust produced by half.
Often, extra attention to blower spout adjustment will help reduce dust from blower use. Adjustments that take into account changing field conditions help reduce dust compared to using one-size-fits-all settings. Adding a berm brush to sweepers may improve performance in some conditions.
Taking almond harvester ground speeds down a notch is a big help with dust reduction. A pickup speed of 1.5 miles per hour cuts dust by 50 percent compared to 3 miles per hour. Note how conditions change from orchard to orchard and from early to late harvest. Adjust ground speed to match conditions. In loose soil conditions, slower ground speed lets gravity do more of the work by separating dirt from the crop, meaning harvester fans produce less dust.
Slow fans down, too.
Dialing back the rpms on harvester separator fans is another good way to reduce dust. Reducing separator fan speeds to the minimum needed for varying harvest conditions still allows you to harvest thoroughly and efficiently.
More tips for managing dust:
If you are working with a custom harvester, talk over dust control practices before harvest. Discuss and agree beforehand on the expected balance of speed, productivity, and protecting workers, neighbors, and the environment from excessive almond harvest dust.
Manage dust on unpaved roads. Reducing speeds, spreading gravel and using products like Dust-Down decrease road dust.
In dry years, take into account that harvest activities will likely result in increased dust due to lack of stored soil moisture, and that a reduced tree canopy will filter less dust.
While there are machines that produce less dust, they tend to be more costly, said Gabriele Ludwig, associate director of environmental affairs with the Almond Board of California.
For 15 years, she said, the board has funded research on how to reduce dust without modifying equipment.
“We’re going to be dusty,” Ludwig said. “But we can do things in ways so there is less impact. Regardless of what equipment you have – newer, older, ancient – make sure the sweeper is set correctly.”
She said growers should “make sure custom harvesters slow down” and take into account whether it is worthwhile to make additional passes through the orchard when they may not result in collection of that many nuts and could save time and gas.
Ludwig said the efforts right now are centered on visible dust, the kind that does not pose the health threats posed by smaller particles ranging from PM 2.5 to 10 micrometers in diameter, which can be inhaled.
She said those smaller particles come from many other sources that are “not ag dust,” including barbecues, wood fires and auto exhaust.