A group of individuals in Mississippi are trying to make this level of flexibility a reality by building on variable-rate dry fertilizer technology they have been field testing for the past three years. The vision is to make the prescription transferable from ground to aerial application, so the VRA application can be made regardless of soil moisture.
They are remarkably close to commercializing the process. Already, the aircraft can readily accept a precision map and execute a variable-rate dry fertilizer application when the map is designed specifically for the aircraft system. The final step, making the prescription seamlessly convertible from ground to air, has been tweaked based on last year’s experience and is being tested again this season.
A Delta Development
The nerve center of work on this technology is Cleveland, MS, where work began on dry aerial variable-rate four years ago. Air Repair, Inc., an agricultural aircraft dealer and service center in Cleveland, has acted as the laboratory for the concept under the guidance of President Pete Jones. He and his crew developed a hydraulic system that regulates fertilizer rate to adjust for changes in aircraft speed. This allows for an even upwind/downwind application in even the windiest conditions.
Air Repair is also one of the leading dealers for guidance manufacturer Hemisphere GPS, which is providing all of the global positioning equipment, including the receiver and cockpit display. Filip To, an ag engineer at Mississippi State University, has been working on the essential aspect of dry material flow control and how that is interpreted and controlled by the GPS system.
How the rate is controlled is relatively straightforward. “It is basically just opening a gate to a preset position,” says Greg Guyette, Hemisphere GPS, who has facilitated the Hemisphere’s contributions to making the system work. “The pilot calibrates the gate, and they put a profile into it so that it is opening to different levels for different types of dry material, which achieves a certain output.” Then, the Hemisphere unit makes on-the-fly adjustments relevant to ground speed changes and prescription requirements.
In initially developing the process, Hemisphere GPS created prescription maps to run on the system. Later, another local company, InTime Inc., began doing the laborious work of converting dry VRA ground prescriptions to aerial prescriptions. While it works, it is a time intensive process and requires a 10-cent per acre premium to get it done. The software developments being tested would eliminate the step and make conversion virtually automatic at the aircraft.
“Matt Peterson at InTime has been instrumental in getting us to where we are today, but we need to make this technology as turnkey as possible,” says Guyette. “We want it to be as generic as possible so that any pilot can understand how to use it, and everything just works.”
Jones and Guyette are going to be looking to take the technology more nationally in the years to come, with a potential focus in California. For more information on the technology, contact Jones via e-mail at firstname.lastname@example.org.