As University of Tennessee plant pathologist Melvin Newman saw more and more cotton producers spacing out their seeds at planting to cut costs, something occurred to him. Fungicide sprayed in the space between those seeds probably wasn't providing any additional disease control.
The idea turned into a research project after Newman shared his observations with University of Tennessee agricultural engineer John Wilkerson.
“We're wasting fungicide between the seeds, and that's costing us money,” Newman told Wilkerson. “All we really need is a squirt of fungicide on top of each seed.
Wilkerson's reply was that it wouldn't be a problem to develop what was needed — an intermittent sprayer. Wilkerson assigned UT ag engineers John Hancock and Henry Moody to take on the challenge. Cotton Incorporated is funding the project, which is now nearing completion.
The purpose of the new technology is simple, according to Moody. “It's to preserve the level of control you get with an in-furrow liquid product while saving costs by not applying material between the seeds, which our research has shown is wasted,” Moody said. “We're trying to save the farmer money.”
The two engineers designed a prototype sprayer to sense the seed traveling down the seed tube and track it into the furrow. Then they added a high-speed valve to spray a band of fungicide around the seed.
Why a high speed valve? “Farmers are planting at 4 to 8 miles per hour and at three to four seeds per foot,” Hancock said. “So you're planting 20 seeds to 50 seeds per second. That means our valve has to come on and off at least 50 times a second. So we put a valve on the prototype model that opens and closes in 1/1000 of a second.”
Tests performed on a farm in Jackson, Tenn., showed no statistical differences between intermittent applications of a liquid fungicide and a continuous band application, according to Hancock. “In fact, we saw the highest stand count in the intermittent areas.”
The higher the seeding rate, the less your opportunity for savings, noted Moody. “If you're planting seeds close together, this technology is not for you. This is for a farmer who has gone to planting three to four seeds per foot tops. Where you go with the lower seeding rates, that's where you get the savings.”
A 2-inch band at three seeds per foot would reduce the in-furrow chemical used by half compared to a continuous band, noted Newman. A 1-inch band would reduce chemical used by 75 percent.
Testing indicated that a 2-inch band of fungicide at that seeding rate would hit the seed over 90 percent of the time when planting at 4 mph. A 1-inch band had a hit percentage of about 70 percent. An increase in speed to 6 mph decreased accuracy to 84 percent and 55 percent, respectively.
Producers are going with fewer seeds per foot of row because pest-resistant seed technology has increased seed costs — albeit while reducing other input costs, Newman points out. “The fewer seeds you plant per foot or per acre, the less money it costs you.
“But if you're putting out three seeds to four seeds per foot, then you're counting on just about every seed to come up and germinate.”
Another trend is that many growers are going only with a fungicide seed treatment to cut costs. Such an approach “can leave the back door open for disease,” Newman said. “You don't want to get into a soybean mentality where you just throw the seed out there and it will grow. You still have to manage seedling diseases.
“In-furrow soil treatments with fungicides plus a seed treatment are still the very best thing I can do for my seeds and seedlings,” Newman said.
The intermittent sprayer could be a good option for growers who want to reduce costs, but don't want to sacrifice optimum disease protection afforded by in-furrow fungicides, he noted.
On a recent day, the engineers were testing the latest modification to the technology, the ability to calibrate the intermittent sprayer without having to make test runs.
“To calibrate the system last spring, we had to plant some seed and leave the furrow open to check where the spray was in relationship to the seed, then adjust to spray sooner or later,” Moody said.
“We realized that wasn't going to work for the farmer. Now we've included a calibration that's based on a simple model of the seed falling down the tube and into the furrow.”
The operator enters values, including ground speed and the distance from the end of the seed drop tube to the spray nozzle. The calculations are figured automatically.
“It looks to be pretty good,” Moody said of the latest modification. “Sometimes we have trouble with seeds bouncing out of the band, especially if you're moving too fast. The seeds tend to bounce forward.”
Moody and Hancock continue to look for a better high-speed valve for the sprayer. Hancock noted, “We just don't feel like the current valve is durable enough for on-farm use.”
Once that valve is perfected, the researchers are hoping that a chemical company and/or an equipment manufacturer will commercialize the product.
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