If you’ve ever seen small metal filings swarm a magnet, you can envision how highly charged chemical droplets are attracted to leaves and stems in a field crop.
That is the basic theory behind the MaxCharge technology recently developed by Electrostatic Spraying Systems in Georgia.
ESS owner Bruce Whiting said each individual nozzle on his sprayer has its own wire feed directly from the generator. Consequently, each droplet can receive a significant negative charge just as it leaves the nozzle orifice.
Plants naturally carry a positive charge, so the droplets have no choice but to fly toward the foliage. The closer the negatively charged droplet gets to the positively charged plant, the stronger the electrostatic attraction becomes.
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“This is different from previously commercialized technology that charged the liquid in the tank,” said Whiting. “By charging the liquid as it leaves the tip, we can put a much higher charge on the droplets. It’s just like a magnet.
“These are nothing like normal nozzles. They have the electrode actually embedded inside the tip and they are built to withstand a tremendous volume of air.”
But does it work? According to research conducted by the University of California, a conventional sprayer puts 51 percent of the chemical out of the target area, 33 percent on the ground and only16 percent on the plants.
The same research project showed the ESS system puts only 27 percent of the chemical out of the target area, 13 percent on the ground and 60 percent on the plants.
“The reason so little chemical hits the ground or escapes outside the target area is that the electrostatic force of the droplets is about 70 times greater than the force of gravity,” Whiting said. “High-speed photography shows that falling droplets even reverse direction and travel upwards against gravity to coat hidden undersurfaces of the leaves.
“That’s why some of our customers have been able to cut back on chemical rates by 30 to 60 percent. We have one farmer who has cut his rates by 75 percent.”
High air volume is the other factor that differentiates ESS from previous electro spray technology. All ESS MaxCharge units incorporate a large fan to create massive air flow. The system would not work if it depended only on the electrostatic charge, Whiting said.
“Air volume has two important functions. First it breaks apart the droplets. A normal droplet is about 200 microns in diameter. That’s too large for good coverage. We use air to break down those big droplets. The air flow travels through the nozzle at about the speed of sound and atomizes the liquid down into small droplets about 30 to 40 microns in diameter.
“Even if it has a strong electrostatic charge, any droplet bigger than 60 microns is too large to change direction and get in under the leaves.
“So we aim for a 30 micron droplet. That’s small enough so they find their way into the tight spaces. Small droplets allow farmers to cut down on the application rate, if that’s what they are aiming to do.”
The other function of the air is similar to the more conventional air assist spray systems on the market. It helps propel the chemical toward the target plant.
Although the volume and speed of the air is high, the pressure is not. The system works with air pressure ranging from 20 to 90 psi.
While some producers invest in the ESS MaxCharge as a means of reducing chemical rates, others don’t cut their rates because they’re looking for maximum coverage on the plant surface, especially with fungicides and insecticides.
“With fungicides in particular, it’s often not a matter of saving money. It’s a matter of saving a whole crop. If you’re trying to control something like fusarium in wheat, you’re looking for absolute coverage.
“These charged up tiny 30 micron droplets get into the little cracks, underneath the leaves and into the heads. They get into everything. One of the main things we’ve found is that we get product underneath the leaves. And when you’re battling diseases, that’s critical.”
Whiting said most of the MaxCharge units are tractor-mount power take-off sprayers. Although ESS stocks an inventory of sprayers ready for delivery, he said many field units are tailor-built for a customer’s needs.
The largest tractor-mount MaxCharge has a 66 foot boom with 72 charged nozzles built for a tractor with a minimum of 120 horsepower. The cost would range from $40,000 to $50,000 US, depending on the extent of the custom fabrication.
For grain farmers who need a bigger sprayer, Whiting said they have done numerous retrofits on all models of high clearance sprayers with 90 foot booms.
“Retrofit is a significant part of our business. We’ve done a lot of big John Deeres and Rogators. We always work closely with the customer because we need to add a small diesel engine to run the generator and the blower. We use a lot of air on a 90 foot boom, so we need a big blower.”
The MaxCharge can also handle heavy powders mixed into liquids.
For further information call 480-459-1111 or visit www.maxcharge.com.
