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Dust control strategies for almond orchards should be in place before the first trees are planted.
Research funded by the Almond Board of California has shown that dust generated by harvest activities can be reduced through strategic planning. Even small operational changes can make a difference in improving air quality for the public and harvest workers.
Michael Roots, ABC’s manager for field outreach and education, outlined a series of steps growers can take to achieve orchard dust reduction goals. His recommendations begin with new orchard development.
Start with Orchard Development
Unless the new orchard site is on hilly ground, the ground should be leveled first. Leveling not only helps with irrigation efficiency, but also provides a good start for achieving smooth orchard floors.
If planting after whole orchard recycling, wood chips need to be thoroughly incorporated. Once the site is developed, the floor should be allowed to harden. Roots also advised growers not to continue disking orchard middles.
Instead, middles should be maintained by scraping. Keeping middles free from ruts, holes, weeds and debris should be an ongoing process. Roots also recommended V-blading floors right after harvest to prepare them for the next season.
Smooth, clean and level orchard floors make for a more efficient harvest, Roots said, because sweepers and harvest machinery can operate at optimal speed while creating less dust. Level floors also help prevent harvest equipment damage.
“The cleaner your floors are, the less work the harvester fans need to do,” Roots said.
Use Cover Crops to Support Dust Control
Incorporating cover crops into orchard management can complement dust control measures. Cover crops can improve field accessibility, increase soil stability and help filter and trap dust with vegetation.
Prepare Harvest Equipment
At harvest, all machinery should be checked for worn or missing parts. Sweeper blowers should be adjusted to match orchard topography and berms. Blower rpm should be adjusted based on crop size and field conditions.
The sweeper head should be set at the optimum height, and Roots noted that one size does not fit all orchards.
The highest percentage of dust comes from pickup machines. Roots said reducing speed from 3 mph to 1.5 mph can significantly reduce dust. Speed should also be adjusted for ground conditions. Slower speeds allow gravity to separate dirt from the crop and send less dust through the fan.
Pickup machine heads should also be adjusted to reduce the amount of dirt moving through the machine and to avoid damage to the heads.
Train Drivers to Reduce Dust Movement
Drivers of sweepers and harvesters should be trained on how to blow into the block and follow a pattern that avoids blowing dust outside the orchard block as much as possible. Equipment should be turned off near roadways, and material should be pushed or raked farther into the orchard.
Other considerations include being mindful of times of day when traffic increases on nearby roads, as well as wind or stagnant air conditions. Taking a break or changing fields may be an option when conditions are not favorable.
At the loading site, areas should be watered down if possible. Another option is to use a location with gravel or concrete for loading.
Addressing Speed and Safety
Excessive speeding in and around harvest does more than create additional dust; it is also a safety hazard. Roots said training on equipment and “rules of the road” must be followed.
There are usually more people on foot in the loading area, making signs and planned traffic flow important. Prior to harvest, Roots advised mapping out harvest blocks, routes and traffic flows, and making sure all employees are aware of the plan. This information should also be shared with harvest truck drivers and outside vendors.
Basic guidelines include keeping equipment and people separate and maintaining a block of separation when possible. Roadway safety includes minimizing travel on public roadways as much as possible and using a trailer to haul equipment when practical. Growers should determine who their best drivers are and use them when possible.
Protect Worker Safety
Even when all steps are taken to reduce dust, some dust is inevitable. Workers should be provided with dust masks, personal protective equipment and reflective safety vests. If machinery has cabs, filters should be replaced and air conditioning units maintained.
Roots noted that all harvest equipment manufacturers have developed low-dust pickup machine models, with variations in the technologies used. Incentives have been available through the San Joaquin Valley Air District to replace older machines, and efforts are underway to restore funding for the program.
Cecilia Parsons
Cecilia Parsons has lived in the Central Valley community of Ducor since 1976, covering agriculture for numerous agricultural publications over the years. She has found and nurtured many wonderful and helpful contacts in the ag community, including the UCCE advisors, allowing for news coverage that focuses on the basics of food production.
She is always on the search for new ag topics that can help growers and processors in the San Joaquin Valley improve their bottom line.
In her free time, Cecilia rides her horse, Holly in ranch versatility shows and raises registered Shetland sheep which she exhibits at county and state fairs during the summer.