When it comes to center pivot irrigation, big strides have been made over the years in irrigation uniformity. However, pivot corners largely have remained the final frontier in uniform irrigation. Recently, Reinke Manufacturing introduced ESAC, Reinke's Electronic Swing Arm Corner technology, to improve irrigation efficiency and uniformity on pivot corners.

"Swing arms are indeed tricky," says Cody Bailey, Reinke director of engineering. "They're tricky because those swing arms are purposely built to have a mind of their own. They're built to maximize coverage within a given field. But we're finding that one field to the next is quite different. There may be corners I have to retract faster to avoid an obstacle, or avoid running up against a property line. It's never the same from field to field."

And corners irrigated under swing arms may be under or overwatered because of uneven terrain.

"If I want to fill a cup with water on this field using a pivot span, the pivot is very efficient at doing that," Bailey says. "If I want to fill a cup with water underneath a swing arm span, maybe it's a little less than full, or overflowing a little in that cup. We wanted to bring the swing arm span up to the new standard of efficiency we're seeing on the other pivot spans we sell thousands of every year."

With Reinke’s Swing Arm Corner (SAC), growers can increase the number of irrigated acres in their fields. And combined with ESAC, growers can benefit from precision sprinkler water application control and virtually eliminate under and overwatering on corners.

Using GPS technology, ESAC allows growers to optimize water or chemical applications to individual field specifications by controlling the sprinklers using either six or 12 zones. ESAC breaks swing arm sections down into subsections — up to 4,300, defining water demands for each subsection — and using GPS, maneuvers the machine to follow the customized path of travel needed and delivers the water required.

SWING ARM PATH: This image shows a center pivot grid with a swing arm corner path. ESAC helps optimize coverage and irrigation efficiency on the areas outside the circle.

"We can now move that machine within subcentimeter accuracy," Bailey explains. "We know where the machine is located at any time during its revolution. Using GPS positioning and understanding where the swing arm is at in relation to the parent machine, we can accurately determine how much area is being covered at every step. Based on size of the area, it’s determined how much water is being demanded. Based on that demand, we can adjust the flow rates through electronically controlled zones to meet that demand."

"This all works because there is a virtual path the swing arm will follow," he adds. "That virtual path is created at the time of design, and it is custom for that field, so we know the machine is going to need to avoid a machine shed or pump station. Then, using a patent-pending method, we can predict the water use on that field."

ESAC is enabled by three components — the GPS navigation system following that virtual line, ESAC zone controls, and the valve and sprinkler harness reacting to the signals to turn on and off at the right time. ESAC is installed on the SAC tower and is available on all Reinke swing arm models.

"What we've observed is a very compelling difference in increased efficiency," Bailey says. "Our ability to fill that cup with water is better than it's ever been before."

And Bailey says irrigators don't need to be intimidated at the thought of managing thousands of subsections, because the technology is doing that for them.

"We want to take decisions off their shoulders," Bailey says. "There are initial decisions to make on which level of package and precision is right for the grower based on operational goals, but at the end of the day, this is now our standard. In 2020, every swing arm is shipping with ESAC technology."