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What RTK Can Do For You

RTK isn’t for everyone. Not at what it costs today. But as more farms buy the gear, these costs will come down — as they always do for electronic devices. Then a new wave of adopters, including grain growers, will take the leap to precise sub-inch guidance.

For Mark and Kevin Hood, cousins from Carberry, Man., this will be their third year with RTK guidance. They’re potato growers, and pass to pass accuracy is a big deal for them. The guess rows — which are the rows between each pass of the planter — have to be just right if the cultivators and diggers are to do their jobs properly. With 38-inch spacing between the planter rows, the guess row also has to be 38 inches. If the guess row is a few inches off, the cultivator is clipping plants or missing weeds and the digger is leaving tubers behind. Potatoes are too valuable to have that happen.

In fact, a guidance system with accuracy less than that of RTK just isn’t good enough for potato growers. “If they aren’t using RTK, they’re still using disc markers,” says Gord McMaster, precison farming tech at Miller Farm Equipment in Brandon, Man. The planter operator’s eyes and steady hands are more reliable than four-inch accuracy, which is the best that satellite-only signals can provide.

Here would be a good time to interject with a quick explanation of RTK.

WHAT IS RTK ?

RTK is short for real-time kinematic. That means “tracking an object in motion at this split second,” which pretty much describes any GPS guidance system. What makes RTK more accurate than any other is one key feature: a fixed land-based signal. All other GPS-guidance signals are two-way between the implement and satellites.

Adding in a fixed ground-based signal — either on a tripod near the field or on a tower in the neighbourhood — works with the satellite signal to keep a tractor on track within an inch of the desired path. You can pay extra to get a super-corrected satellite signal — OmniStar or John Deere’s StarFire — but those can only guarantee accuracy to within four inches, plus or minus. That isn’t good enough for potato growers, to repeat a point made earlier.

With RTK, you have two “eyes” looking at your tractor — the satellite and the base station. Two eyes are better than one for pinpointing the exact location of something.

As a quick test of this principle, close one eye and look at something in the distance. You’ll notice your depth perception drops considerably.

RTK provides more than just an accurate signal. It also provides repeatability. You can come back in an hour, a day or even a year or more and you can go back to those precise rows.

Mark Hood says some potato growers are making their potato hills in the fall using RTK. Then in the spring, they can go back and plant every row right down the middle of these hills. Other GPS guidance system cannot provide this repeatability. Even after an hour, satellite-only signals can drift off line. If you stop to refill the potato planter, you may find that you’re tracking a few inches off target when you return to the field. Again, this isn’t a problem with RTK.

HELP FOR INEXPERIENCED OPERATORS

John Van Tryp of Burdett, Alta., also uses RTK on his farm. They grow sugar beets and dry beans for row crops, as well as seed canola, spring wheat, winter wheat, durum and peas. His biggest reason to invest in RTK was so he could put an inexperienced operator on the planter and still get the job done right.

“It became very difficult to find people who could seed by hand and get the guess rows in tact,” Van Tryp says. With RTK taking care of the guess rows, the labour issue became a lot easier to manage. “Any one of us could now run the planter. All we need is common sense and ability to read the monitor.”

The other key advantage for Van Tryp was in machinery costs. The gear to equip a tractor for RTK is cheaper than adding another tractor and planter unit. With RTK, Van Tryp could run his seeding units 24 hours a day and still plant straight. The farm gets more work out of its existing machinery line up. “Tractors that used to work 500 hours a year are now working 800,” he says.

Operator comfort is another big benefit to any automatic steering system, regardless of accuracy. “The operator can spend a lot more time turned around in the seat concentrating on what’s going on behind,” Van Tryp says. “The guys on the planter are less fatigued after 14 or 16 hours than they were after 12 hours without automatic steering.”

Mark Hood says the same thing. “My cousin runs the planter and he just loves the RTK system. There are enough other moving parts on the planter to worry about, and when you also have to worry about keeping the guess row in line, fatigue becomes a factor.”

One other advantage of RTK over the satellite-only systems is reduced “convergence” time. When you start up each day, the tractor has to find a satellite and lock in its location. This convergence can take 20 minutes with the most accurate OmniStar and Starfire signals. Chad Pfitzer, RTK specialist for Trimble, says convergence time with RTK is 90 seconds. This is a big advantage for farmers who want to get rolling quickly in the morning.

RTK BENEFITS FOR OTHER CROPS

RTK has practicality for a wide range for crops. Corn growers who use strip tillage to lay down bands of fertilizer ahead of time can plant corn right over top of those same bands. This same practice also works for Western Canada farmers who have adopted inter-row seeding. RTK is the only GPS guidance system that can provide the accuracy and repeatability to do this with confidence. (For more on this, read Lyndsey Smith’s article on page 1.)

You will think of many beneficial applications. Greg Veilleux, AMS consultant with Green Power John Deere in Burdett, Alta., says you could plant wheat or canola right over the top of last year’s phosphorus band, taking advantage of residual nutrients. Say, for example, you put your fertilizer two inches to the side of the seed row. Each year, you could use RTK guidance to move your seed row over two inches to go right on top of last year’s fertilizer band.

If you use tramlines to reduce compaction, RTK will keep you on those lines year after year, day and night.

WHAT DOES RTK

COST?

The Hoods paid $25,000 apiece to get two Case IH MX275 tractors set up for RTK. This includes the AutoPilot steering controller, the display monitor and receivers. The tractor came AccuGuide ready, which means the hydraulic valve and hoses, the steering sensor and all cables are installed in the factory.

The Trimble equipment that Case IH uses is upgradable, so you can start with a system that works off the free signal and then pay to “unlock” the features you want.

Trimble’s FmX display (called Fm1000 when sold through Case IH) with Autopilot is $14,300. This is the base price for use with the free satellite signal. To move up to RTK, you pay $5,200 to unlock the RTK receiver and $3,000 for the RTK radio. Then there’s installation on top of that.

Many companies make RTK systems for farm machinery. While shopping around, take a look at Leica’s mojoRTK. Or the Hemisphere GPS package, which includes eDriveTC, S2 or S3 display and receivers, and Baseline X. Hemisphere’s lower-cost system uses single-frequency RTK with pass to pass accuracy of two to four inches. (You need a two-channel system for one-inch accuracy.) And there’s Raven, which teams up with AutoFarm to offer FarmPro. This RTK package includes Raven’s Viper Pro field computer and AutoFarm’s RTK steering package.

Even if you don’t want to start off with RTK, make sure the system you buy is upgradable. “Accuracy is addictive,” says Greg Veilleux of Green Power. “Farmers who started with the free WAAS signal went to StarFire 1 and 2, and now want the repeatability they can get from RTK.”

To put together a one-inch accurate RTK system for John Deere tractors, you start with an Autotrac automatic steering kit, which is $5,040 plus installation costs of $1,200. Then you add a monitor. John Deere offers three monitors: the basic Greenstar display for $1,700, Model 1800 colour display for $2,250, and Model 2600 touchscreen display for $6,294.

The standard receiver with StarFire 1 capability is $3,144. That gets you accurate to within eight inches either side of the desired path. To move up to StarFire 2 and its sub-four-inch accuracy, you need software upgrades: $5,040 for the Autotrac software upgrade and $2,500 for the receiver software upgrade.

To go from SF2 to RTK, you need a receiver that includes a radio to communicate with the RTK base station and with the satellites. This costs $1,695. You also need RTK activation, which costs $3,780.

Add it up. From square one, with the top-end monitor, you’re looking at around $30,000 to equip the tractor for RTK. But wait. You need a base station. A two-channel base station will cost another $15,000 or so.

HOW COULD WE FORGET THE BASE STATION?

A base station for $15,000! That’s when a lot of you get up from the negotiating table and walk away. “I was starting to feel OK about the $25,000,” says the farmer to his wife as they drive away from the dealership. “Then they dropped the base station on me. I’m not ready for this.”

The base station box contains GPS and radio receivers and GPS and radio antennae. It needs this stuff to communicate with satellites and then with the tractor. That’s how you get triangulation of the signals.

Are you ready for the good news? You might not need a base station if you farm in the neighbourhood of an RTK network. Many farm equipment dealerships are setting up RTK networks, with base stations on towers strategically located for seamless signals no matter where you are on the farm.

When the Hoods first got into RTK three years ago, they started with a mobile base station. Hood mounted his on irrigator pivot points to provide extra height. Base stations communicate with the tractor by line of site, so the higher you mount them, the longer the range. But even with his base station on the pivot stand, Hood still had to move the base station from field to field. “It was a pain in the butt,” he says.

The next year they signed up for Miller Farm Equipment’s subscription service. They pay the Case IH dealership $1,800 per year per tractor to use the network signal. “It works beautifully,” Hood says.

With two tractors, it doesn’t matter where they are on the farm. The tractors can be in different fields and still work off the same tower. And the whole point behind the dealership tower network is to fill in the holes. When you move farther from one tower, you come into range from another. It’s seamless — as long as there’s another tower there. Dealerships are adding more towers every year.

Van Tryp works off a Green Power tower network. The farm actually put up the tower itself four years ago, and it now leases the tower to Green Power. Why? “They do upkeep of the receiver and make the software updates,” Van Tryp says. “If it goes down at midnight, they look after it.” Green Power charges a fee of $1,000 per tractor for year one and $500 per tractor for each subsequent year.

Van Tryp Farms built their own tower to cover the whole farm from one location. This tower, which is connected to the power grid, solved another problem with mobile base stations. Mobile units run off batteries recharged by solar. During sugar beet harvest in late fall, the days are just not long enough or sunny enough to keep the base unit charged. “We’d be digging beets and then the unit would go down,” Van Tryp says. After one year, they gave up on the mobile unit and put up the tower.

THE RURAL TOWER NETWORK

Most dealerships set up their own networks, but it doesn’t have to be that way. In the Red River Valley of Minnesota and North Dakota, three big dealerships — Titan Machinery, RDO and Butler Cat — got together and formed the Rural Tower Network. They mapped out a huge geographic area, and together put up 100-foot towers on a grid to provide RTK base station coverage. Each tower has at least three RTK base stations, one each for Case IH, John Deere and Challenger equipment.

No matter what type of equipment a farm has or where it has fields within the network grid, it can get coverage. And because dealerships share the fixed cost of putting up the towers, the annual subscription for farms is relatively low.

Titan Machinery charges US$1,500 per farm per year. You could have five tractors with RTK and price would be the same. Mobile base stations are obsolete for farmers in reach of the Rural Tower Network.

Trent Brekken farms at Crookston, Minnesota, and subscribes to the Titan Machinery signal. He grows sugar beets, sunflowers, soybeans and wheat, and got RTK for his row crops. His reasons were the same as Mark Hood’s and John Van Tryp’s. This year he’s adding a hydraulic steering system, with its own RTK kit, to his planter. If you want sub-inch accuracy for a trailed implement, this is essential.

“Even in our area, which is fairly flat, you’d be surprised at the side to side movement of the planter,” Brekken says. You can have the most accurate signal guiding the tractor, but if the implement isn’t following in line, what’s the point?

He also uses RTK guidance for his airseeder, sprayer and combine. Why not? He’s got it. He might as well use it on all crops. With sub-inch accuracy, he trims his overlap that much more. He truly can use the FULL width of his combine header and his sprayer boom.

Eventually, all farms will have the equipment to use RTK guidance. The simple fact is that most new tractors are built factory-ready for automatic steering to reduce overlap. That means all farms, even those that buy only used equipment, will eventually have autosteer capabilities. And if accuracy truly is addictive, and more importantly, if increased accuracy can prove its value for all crops, then we will see RTK become a common tool. The tower networks and the convenience they offer over mobile base stations make this all the more likely.

Jay Whetter is editor of Grainews

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