“Farmers have added guidance systems to increase productivity, minimize overlaps and skips, reduce operator fatigue and achieve more accurate navigation,” says Randy Taylor, Oklahoma State University biosystems/agricultural engineering professor.

Taylor says global positioning system technology also eliminates the need for producers to use foam markers when laying out rows or spraying crops.

Farmers interested in adding technology should consider system accuracy, cost and capacity to upgrade as they search for the right components.

“Do you need absolute accuracy?” he asks. “If you’re installing drip irrigation tape, you do.”

But he says for many typical farm operations, less accurate and possibly less expensive systems may work. Wide area accuracy, single or dual frequency systems and RTK units offer different levels of accuracy at varying up-front or subscription costs.

Wide area accuracy service is typically free and works off a Coast Guard beam. Single or dual frequency systems are available on a subscription basis and may be accurate to the decimeter. RTK is an up-front cost and offers accuracy to the centimeter.

“Evaluate the situation,” Taylor says. “RTK costs more up front, but you own it. It may be more economical to pay for a subscription service if centimeter accuracy is not needed. No systems are perfect. Some will change by vehicle dynamics as the antenna sways with movement. But they are better than self-steering.”

He says wide area accuracy is adequate to run a sprayer. “It’s also OK for a row crop planter — if you’re not picky about rows.

RTK systems improve accuracy for strip-till, he says, but may not be necessary if farmers plant differently, more like no-till instead of strip-till.”

But errors can make a difference and show the value of guidance systems. Taylor says some estimates show overlap mistakes as high as 37 percent, particularly in odd-shaped fields. A more likely error rate, however, would be 10 percent. Reducing that could increase yield potential and reduce seed, fertilizer and chemical waste.

He says some studies show row errors could result in yield loss of 6 pounds per acre per inch. Other studies in strip-till systems show significant errors without yield loss.

Guidance systems come with intangible advantages. “We get less operator fatigue, similar to how cruise control works in passenger cars,” he says. “Operators can extend hours. One vehicle can cover more acreage.

“Auto-steer also frees operators to do a better job monitoring equipment. They can look back at spray booms and planters to make sure they are functioning and still drive straight.”

He says some farms may use less experienced operators on tractors with automated systems.

The term precision agriculture may not be as precise as some think, Taylor says.

“We really don’t do things precisely. A lot of new technology has been lumped together under the precision agriculture classification. But it’s rapidly becoming just agriculture — it’s now just the way we do things.”

He says potential innovations may include driverless vehicles. “We already have most of the pieces — we just haven’t put them all together for on-farm application.”

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