BRANDON – Producers can sometimes make precision farming more precise by doubling the number of GPS receiving antennas they use.
“When you see a GPS receiver on an air drill, look again and I bet you’ll see another receiver on the tractor,” says Pamela Haegeman, GPS-GIS consultant for the Mazer Group and for the Manitoba Zero Till Research Farm.
“This is becoming more common.”
During a recent presentation at Manitoba Ag Days in Brandon, Haegeman said producers moving into variable rate for the first time can take advantage of the lessons that variable rate pioneers learned in the school of hard knocks.
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One of those lessons is that in some situations, two GPS systems are better than one.
“I’ve seen twin systems on a lot of seeding rigs, and some guys have two system on their sprayers,” Haegeman says.
“I’ve also seen guys with two GPS antennas on their combines. They have the good system setup for steering and then a cheaper system for gathering yield data.
“The header might be 30 feet or bigger, so if you’ve got 30 foot accuracy on your yield maps, you’re doing fine. And there’s no need for the two systems to be connected.”
She says accurate steering is more important than accuracy at the drill, which is why producers should install their high-tech, highly accurate GPS on the tractor.
The variable rate applicator might have three or more sections that are 10 feet each, which is where the low-tech GPS system goes.
“If you’ve got 10 foot accuracy on that controller, you’re doing great. These low-cost $1,200 receivers give you one foot accuracy, so that’s all you need for variable rate.
“And when you mount the antenna right on the drill, you never need to compensate or calibrate for distance. But for steering, you always want the highest degree of accuracy you can afford.”
She says the cheaper system can also serve a sprayer’s as-applied maps and a combine’s yield mapping functions. The odds for technical problems should be reduced if these run through their own independent simplified system.
Whether producers use one GPS system or two, Haegeman emphasizes that mapping is essential. She says it’s critical to know what goes wrong because things will go wrong.
“The as-applied map is absolutely necessary if you’re doing variable rate. It’s the only way to confirm what you’ve done.
“There’s no other way to know if you screwed something up, or maybe your technician screwed something up, or maybe there was an equipment malfunction.”
Haegeman says installing the GPS receiver on the nose of the tractor can deliver a bum steer. Producers can get good information when driving east-west or south, but when the tractor is heading north, the cab blocks some correction satellite signals.
“They don’t reach your antenna, so you get an irregular GPS correction,” she says.
“The correction satellites are all south of us, at the equator. They have quite a bit of angle when they hit the Canadian Prairies, so it doesn’t take much to distort them.
“That’s why when you turn south, you can get awesome satellite correction. But when you go north, you lose it. You get those shifts in the GPS correction.”
She says the idea behind a nose-mounted receiver is that it’s supposed to give a better “look ahead point.” People think this lets the GPS system know what’s happening sooner.
Others say they want their receiver closer to the front tires because they initiate steering.
“There are some systems where the antenna goes to the front. But all the systems I’ve ever worked with already have the look ahead setting built in there.
“You just tell the system you want a three metre look ahead or whatever distance you want, and that’s the distance you get.”
She added that the system should also ask the distance from the antenna to the application equipment. The distance is zero when there are two systems. If not, the number needs to be entered.
Haegeman says many producers have the Toolman Tim Taylor attitude about opening the manual when it comes to troubleshooting.
She says they need to get over it and open the manual. Producers can solve a lot of these problems on their own without calling for reinforcements, she adds.
She points out that the bigger the implement, the more distance between the cab and the furthest electronic device. There are more connections to come loose or get wet and more wires to get pinched by accident.
Producers who work through the troubleshooting procedures and still have a problem should call for help. She also advises keeping detailed notes on everything they’ve tried and everything they’ve noticed about the problem.
“If you think a detail is too small or too picky, tell us about it anyway. You might tell us about five little details you think aren’t important, but one of them might give us the answer we need.
“Maybe you bumped the screen with your arm, or maybe you changed operators or stopped for lunch. It can be that simple. Keep track of details.
“And don’t be afraid to ask dumb questions. Call your GPS techs and agronomists and consultants with your questions. That’s how we learn, too. We need feedback from the farmer.”
Haegeman says correct installation applies to more than just the GPS receiver.
As more types of on-the-go sensors become available for agricultural purposes, correct installation will also be important for them.
One sensor that is past the science fiction stage will someday detect plant diseases and send the information to a controller for fungicide applications.
“A lot of them are in the testing stage right now. They’re not 100 percent perfect, but they’re getting close.
“GreenSeeker is finally working pretty well, but the whole key is calibration. If it’s calibrated wrong, it just messes things up.”
She says GreenSeeker is an example of an on-the-go sensor that should be located as close as possible to the applicator. The sensor is used to give an instant assessment of a plant’s nutrient needs at the moment a fertilizer applicator passes.
Haegeman will be speaking about getting started in variable rate farming at a Manitoba-North Dakota Zero Tillage Farmers Association workshop in Brandon Feb. 18 with Dan Hacault of D & D Hacault Farms of Swan Lake, Man.
For more information on the workshop, visit www.mandakzerotill.org.
