Photo above: Trimble’s GreenSeeker uses a real-time nitrogen application sensor. It automatically detects the health of the crop as it travels through the field and directs the boom to apply a calculated amount of fertilizer. Photo Courtesy of Trimble agriculture
The “precision placement of chemicals” and “consistent application within a targeted coverage” area that Ken Giles spoke of 5 years ago is a reality today, and is often referred to as “site-specific management” or, in some cases, “variable-rate application.”
Precise timing and placement of nutrients and chemicals has been at the forefront of industry efforts to minimize the amount of these materials without forgoing crop yields for a decade or more. It was the subject of a 2008 Purdue University report, “Implementing Site-Specific Management: Sprayer Technology — Controlling Application Rate and Droplet Size Distribution On-the-Go.”
The report said, “The use application rate control is a concept that is fundamental to site-specific management of crop production. The ability to vary application rates of crop chemicals based on control maps or sensor input holds the potential to improve both agronomic and environmental aspects of crop production.”
The 2008 report went on to say: “There is now a chemical application system that addresses both application rate control and drift control with no reduction in overall system performance. That system, called modulated spraying nozzle control (MSNC), offers the potential to improve the performance of both new and existing spraying equipment significantly. Although based on a simple concept, the system merits close examination because of its potential to meet the agronomic and environmental challenges of chemical application today.”
While that system may not have been ready for prime time 8 years ago when the Purdue report was written, with various modifications it’s in use today. “We’ve been the major supplier of pulse-width-modulation (PWM) individual nozzle control for variable-rate application since 2012, but Raven and TeeJet now have systems similar to ours,” Tony Stueve of Capstan Ag Systems told Farm Equipment earlier this year (see “Sprayer Technology Developments Offer Dealer Sales Potential,” April-May 2016).
“The technology, which can yield 15-20% savings in chemical use through reduction of overlap sprays and under-application, is also available to retrofit existing sprayers.”
Digitally-controlled PWM systems, which maintain constant operating pressure, regardless of field speed, use solenoid-operated nozzles pulsed in varying duty cycles, and are the leading technology for VR sprayers today. Pentair/Hypro, however, offers similar precision section control with its individually operated ball valve nozzles on its Pro-StopE system.
Nozzle-by-Nozzle Control
Jed Simpson of Simpson Farm Enterprises in Hays, Kan., says one of the biggest trends he is seeing is growing use of the pulsating nozzle systems and individual nozzle shutoff. Simpson has 4 dealership locations in Kansas that specialize in application equipment. The company currently carries the Apache, Miller, GVM and New Holland sprayer lines. Talking about the pulsating nozzles, Simpson says, “These will help farmers reduce chemical usage because they won’t be over applying as much as they are now,” Simpson says.
“We’re ready to move to the next step, which will include the Hawkeye system from Raven or Capstan’s Pinpoint. We worked some last year with Hawkeye’s virtual secion shutoff and proved to ourselves that the return on investment was there. I think our customers will see these systems are profitable and beneficial and we’ll see them move in this direction.”
Simpson also notes that the price point price can be an issue with some growers, but seeing how it pays off for other farmers will help get over this hurdle. A bigger challenge may be some customers’ perception that these systems are too complicated.
“I was pricing a sprayer for one of our bigger customers and mentioned the individual nozzle shutoffs and he said, ‘Tell me a little bit more about it.’ So I started explaining and before I even finished the sentence, he said, ‘Oh, that sounds like more problems. Nope, I’m not interested.’ We didn’t even talk price. These new systems may be a little more maintenance intensive, but sprayers tend to need more maintenance anyway.”
With the push to reduce input usage and costs, Tim Heins, director of product management for Raven Industries, says the PWM nozzle system is one of the company’s main areas of focus. “Each nozzle has a nodule that can vary the pressure of the nozzle. We pulse it to help maintain the pressure, and that allows us to do things like compensate on turns across the implement or across the boom.
“It allows use to get to rate a lot faster, too,” he says. “So as you’re coming out of a previously sprayed area or as you’re speeding up or slowing down, we’re able to get to rate almost instantaneously with the PWM nozzle control. We also have the ability to go to individual nozzle on/off. So instead of sectioning the boom into, say, 7 sections or maybe even 10 sections, if you’ve got a boom with 54 nozzles, you can have 54 individual sections so there’s virtually no overlap or overspray. So you’re saving a lot of chemicals,” Heins explains.
In fact in one test, a farmer sprayed an 80 acre field using traditional section control and, in terms of spray volume, he was over by 3 acres. In other words, it was as if he sprayed 83 acres. With the Hawkeye individual nozzle control system, he only over sprayed by 0.3 acres.
Using Variable-Rate
Unlike the PWM systems that operate at a constant pressure, Pentair uses variable-rate and pressure in its system to accomplish similar VR results through fast-acting on-and-off nozzle valves, says Pentair’s application engineer John Lang. The two designs have pros and cons, but both provide significantly higher sprayer efficiency than conventional boom sprayers which operate efficiently only in a narrow speed range while driving in a straight line.
Sprayer manufacturers say future improvements to VR sprayers likely will include enhanced in-field, on-the-go record keeping for proof of regulatory compliance and improved data capture for making farm management decisions.
While VR sprayers are coming of age on farms across North America, several other application technologies are being developed and were covered by Farm Equipment earlier this year. For example, Cambridge Consultants in the UK are working on a sprayer they say will be even more precise than the current VR sprayers.
“Doing more with less is one of the key challenges facing agribusiness, today,” says Tom Fry, CC’s precision agriculture solutions project leader, “That’s why we decided to create a targeted crop sprayer to apply chemicals only where they’re needed. The idea was to achieve the same precision application as an ink-jet print head — but at over half a meter rather than just a few millimeters.”
Using a fast-acting valve set in a swiveling head to provide precise control of droplet size, CC is using machine vision through a camera mounted on a spray boom to identify targets according to shape, size and color. Signals from the camera are processed through algorithms in a microprocessor that calculates field speed, distance to target, air resistance and spray trajectory. The microprocessor then signals the spray control module with a prescription to pinpoint the target with the crop protectant.
“The technology can target a specific leaf or insect even when the sprayer is moving at speeds of more than 25 mph,” he explains.
Through the intense targeting and precise delivery, CC says chemical use has been cut by more than 90% in some of their studies.
Lasers in the Orchard
Ohio Agricultural Research Service research engineers have developed a variable-rate tree sprayer that has reduced pesticide use up to 68%, with an average cost savings of $230 per acre in ornamental nurseries.
The sprayer uses laser guidance to synchronize application rates to tree structures according to size, shape and foliage density. The 2-ton research machine can treat a single row of trees or 2 to 6 rows of trees at a time.
Researchers at three universities who evaluated the machine say savings of even more than $230 per acre can be achieved when it is used in orchards and on other high-value food crops.
Special Report Table of Contents
Can Application Technologies Reduce Ag Input Costs?
Three years of low grain prices are forcing farmers to minimize production costs. Developments in how they apply inputs will be an important part of growers’ cost cutting.
Making a Case for Curbing Spending on Inputs
Few signs point to a recovery in crop prices in the near term, which is making it imperative growers find ways to hold down costs.
What’s Trending in Ag Application Technology?
Developments in applying crop nutrients and pesticides have come fast and furious during the last decade. Many of the newest breakthroughs are aimed at ‘site-specific’ management of inputs, nozzles and individual nozzle control, and soil applications.
