Irrigation uniformity check: Taco Bell or eye in the sky?

Irrigation uniformity check: Taco Bell or eye in the sky?
Aug 01, 2019

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By  Lyndon Kelley, Eric Anderson
Center pivot irrigation using a set of irrigation sprinkler heads is designed to apply a uniform application of water over the whole field. Maintaining and repairing irrigation sprinklers assures irrigators that all areas of the field are receiving adequate water and no areas are being overwatered. The nature of center pivot irrigation heightens the negative effect of over- or under-application by replicating the error in the same place each application. For example, areas that are under or over the average by 40% will receive 0.6 inches (if under) or 1.4 inches (if over) of irrigation water each time the producer intends to apply 1 inch of water. By the end of the season, areas requiring 8 inches of irrigation water will receive 4.8 inches (if under) or 11.2 inches (if over).
Michigan State University Extension and Purdue University Extension staff performed a system uniformity can test on a 1,300-foot irrigation center pivot. At the same time, an unmanned aerial vehicle (UAV or drone) flew overhead capturing video images of the application from different angles and altitudes. The concept: A quick video of the pivot while applying water would allow a producer to identify needed repairs much faster and cheaper than performing a catch can test.
The pivot had one plugged sprinkler head that was detected in a pre-test UAV flight, and this was corrected before the can test. The pivot was set to apply 1 inch of water over cans spaced 10 feet apart from the pivot point to the outer reaches of the end gun. (Actually, they weren’t cans, they were Taco Bell cups affixed to metal rods standing above the soybean canopy. We knew you were wondering why that was in the title.) Water collected in the cans was measured with a graduated cylinder and the data recorded for each 10-foot section.
Three sprinklers were identified by the drone video that were spinning much faster than the others, resulting in a smaller whipping application rather than the larger throwing pattern it was designed for. These showed up in the catch can test as over-application areas with under-applications adjacent on both sides. Extension staff also switched two sprinkler heads to purposefully create under- and over-application areas to see if the video from the UAV could detect the problem.
Photo by Eric Anderson, MSU Extension
A local pivot repairman looking at the flight video said the video would be the perfect method to document what leaks and flanges need repair on a unit. A video from the ground would also work but would be much harder to get in the middle of the season with standing crops in the field, and it is also difficult to see the water spray pattern from below against the sky. Whether taken from the ground or a UAV, a video sent to the repairman can be a huge benefit to identifying sprinkler problems.
For more information on using UAVs to identify sprinkler repair needs and other MSU Extension on-farm research happening this year, attend the Southwest Michigan Crop Production and Irrigation Research Field Day on Aug. 16, 2019 in St. Joseph County north of Sturgis, Michigan, on North Centreville Road, half a mile south of Featherstone Road. Michigan Soybean Promotion Committee is sponsoring the meeting hosted by the MSU Extension field crops team.
The meeting will begin at 8:00 a.m. with registration and a light breakfast and will conclude by 1 p.m. with a free lunch and a talk by local Department of Natural Resources wildlife biologist Ken Kesson about deer management in crops. Several presenters will be available following the meeting for one-on-one consultation. Two MDARD pesticide recertification (RUP) credits and 3.5 Certified Crop Advisor CEUs will be available.
The cost is free, but registration is required for space and meal planning. Please register online by Wednesday, Aug. 14. You can also download the event flyer with location map. For more information, see the accompanying article, “Join the irrigated corn and soybean research field day in southwest Michigan.