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Faster and simpler was on the mind of a South Carolina ag engineer as he considered the tedious task of plot spraying. There had to be a better way.
That was in 2010, at Clemson University, when Ahmad Khalilian and his team (Young Han, James Thomas, and Mike Marshall) began working through logistics for a multitasking chemical sprayer controller. Khalilian, a professor in the biosystems engineering department, is internationally recognized for his work in precision agriculture.
In July 2014, Khalilian was surrounded with eager questions after announcing his controller and system at the meeting of the American Society of Agricultural and Biological Engineers in Canada.
On farms, variations on the technology may be useful for variable-rate, site-specific zone applications of ag chemicals. The most immediate application is for ag field plot research, especially conducting trials with large numbers of chemicals and many replications or applications.
“This request came from our researchers,” he says. “Some were still using backpacks in small plots.”
Many had switched to multiboom systems they could turn on or off manually, but it took two people to do it (one driving, one operating switches).
Putting technology to the task
The team led by Khalilian put precision farming technology to the task. The plots could be mapped in a file format used by spray controllers. The sprayer itself could be guided with RTK-GPS for sub-inch precision treatments.
The tractor for small plot work could be equipped with a tool rack holding multiple spray lines. Eventually, they settled on up to 24 booms (12 left and 12 right) equipped with sprayer nozzles and linked to individual small tanks holding mixed supplies of water and chemicals.
In the design process, they added an air compressor linking the tanks to keep them pressurized. They also added an override switch for a tank of ammonia water so the whole system could be easily flushed in about four minutes.
The team remodeled the controller so it could operate up to 24 switches or individual booms, in any combination. They also came up with a user-friendly software program for the controller.
The Clemson Auto-Boom (CAB) sprayer (shown above)went into field trials in 2012 and 2013 at the Edisto Research & Education Center. The first unit was used in peanut fungicide trials.
In previous work, navigating from within the plots for each treatment and cleaning the boom between treatments took over six hours. It was impossible to determine the effects of simulated rainfall on the efficacy of the pesticides, due to the delays between treatments. The CAB motored through the complex plot-spraying pattern in about 20 minutes (or about 18 times faster) with only one operator.
Officially, it is able to control up to 24 individual booms, which could apply 24 different chemicals in a given field location. The sprayer follows GPS signals to switch from one treatment to another without any lag time.
“It makes short-interval treatments feasible, and it significantly reduces the risk of weather confounding experiments,” says Khalilian.
“This system greatly increases the productivity of the weed science program at Clemson University,” he adds. “It speeds up research with large numbers of herbicides, and it helps researchers with multiple products to apply to field plots for precision screening.”
At least one company has started making a commercial multiboom sprayer for researchers.
From plots to farms
This CAB technology is highly adaptable and could be adopted for commercial farming with 10-section, 100-foot booms, for example, Khalilian says. The system could feed each section individually rather than require multiple booms.
On a large sprayer, a multicompartment large tank or several midsize tanks could feed chemical to the boom sections. Or, the controller could inject concentrated chemical into water at the point of application.