Augmented GPS systems catch on fast with Ontario producers

Monday, October 4, 2010

by Mary Baxter

Five years ago, brothers Fred and Gerald Van Osch bought their first GPS system with the expectation that it would help improve the accuracy of field operations, such as planting and spraying.

The brothers farm corn, soybeans, winter wheat and a variety of specialty beans near Mount Carmel on the border of Middlesex and Huron Counties. It was the beans – kidney, azuki and otebo grown for nearby Hensall District Co-operative Inc. – that required greater machinery handling precision. The Van Oschs scuffle hoe between rows during the growing season and harvest at night with specialized equipment. The procedures are tricky and require intense concentration. It's not unusual to lose a row when harvesting at night without a guidance system, Fred says.

Like many farmers who acquired global positioning system guidance (GPS) in the first years of this decade, the Van Osch brothers chose an augmented service.

Augmented GPS uses information from a source outside the global navigation satellite system and extra processing to improve the precision of GPS co-ordinates. On its own, GPS can be off course by several metres when pinpointing a location. The external source calculates how much other factors, such as changes in the ionosphere, might distort the GPS data and applies corrections.

In the services Van Oschs first used, the corrections were calculated and broadcast using a radio signal via satellite. Services like WAAS (wide area augmentation system), a free system developed by the U.S. Federal Aviation Administration to improve the accuracy of GPS, and John Deere's StarFire system use this approach and, depending on the service, can provide a location accuracy of within eight to four inches. This type of service is called differential GPS. (These corrections can also be determined and distributed via a land-based network, an approach used by coast guard services).

The Van Oschs subscribed to the StarFire system, beginning with SF1, a free service available to the implement manufacturer's customers and similar to WAAS. They subsequently upgraded to the company's SF2 service, which has a location accuracy of within four inches.

But the Van Osch brothers, who had combined the SF2 service with automatic steering, wanted "to be right on accurate," says Fred. A difference of two to four inches could mean taking a row out when scuffling. So they adopted another form of augmented GPS called RTK (real time kinematic). The service increases the accuracy of GPS readings to within an inch by developing corrections not only from the information a radio signal contains but also the signal itself.

Expensive technology
All over Ontario, interest in RTK is growing. Dealerships here say there's wide-scale use of the service in high-value vegetable crop sectors, such as processing tomatoes and potatoes. Those in conventional cash crops are expressing interest, too. Ron Dieleman, parts manager at Can-Am Tractor Ltd. in Chatham estimates that, while about 75 per cent of farmers in Ontario might be using GPS, five to 10 per cent of this group is using RTK. Mostly they are larger farmers, he says, noting that these were also the first to embrace manual GPS guidance when it became available. But, he says, it's not just the vegetable or higher end crop growers who are jumping on board. "It's guys who are doing your corn, soybeans, wheat are taking advantage of it as well," he says.

The technology is expensive to implement, he explains. "You do need a certain amount of acreage in order to justify it," he says.

John Murray, precision agriculture manager with HJV Equipment, says he has recently sold "two or three" systems to corn growers and expects demand among those farming traditional cash crops to grow over the next year or two. "We're getting a lot more inquiries about it."

It's not just here that interest is keen. Terry Griffin, an assistant professor of economics from the University of Arkansas' division of agriculture, has monitored the impact of GPS on the agricultural industry for several years. He calls GPS guidance "one of the greatest innovations probably since we started mechanizing in the 1950s" and notes that more than 80 per cent of farmers in his country now use it.

But combining precision GPS service with automatic guidance is where the real revolution is taking place. A Purdue University precision agricultural services dealership survey found that, in 2009, manual GPS guidance was being used to farm 41.3 per cent of the market area in the U.S. Midwest and automated systems on 21.6 per cent of the area. The survey predicted that, by 2012, 41.5 per cent of the U.S. Midwest market area would be farmed using automatic guidance.

Griffin believes that RTK will eventually become the standard service for automatic guidance systems, though not without some hiccups, as its early proponents in Ontario have found.

For Fred Van Osch, the appeal has not only been the improvement in accuracy but also the relief from driver fatigue. Combined with automatic steering, the service removes the need to monitor the field constantly to make sure the tractor is right on the row, he explains. He has even added RTK receivers directly to some of his implements to improve accuracy, says his son, Brendon, who sells the systems at Huron Tractor.

Achieving savings is another plus. Using RTK, a planter the Van Oschs acquired this year records planting locations and will suspend seeding if an area is already planted. Fred estimates he's saved two per cent on seed alone from preventing overlaps. When acres number in the thousands (they farm 9,000) and if seed costs $100 per acre, "that's a lot of savings," he says.

Stress reduced
Ken Nixon, who farms corn, soybeans, edible beans and wheat near Ilderton in Middlesex County, acquired RTK and automatic steering about four years ago when he introduced strip tillage to his farm. "I spend a lot more time turned around watching my implement because I don't have to be constantly monitoring where I'm driving," he says.

Not having to make constant steering adjustments reduces stress and means he can identify other problems that might be happening with the equipment behind him.
Nixon says RTK allows him to run a strip tiller through cereal stubble in which "you cannot see a marker mark to save your life." (Strip till involves tilling or working up an 8-10 inch band of soil prior to planting a row crop on 30 inch rows).

Using the service, he can establish the strips in fall and return in spring to plant in exactly the same location. He can operate his equipment regardless of the time of day or night. Once a field is laid out and saved in the system he can pull right into the middle of it and operate both ways. The ability to return to the exact location, time and again, eliminates the need for row markers. That's a cost "we leave at the dealership." 

Organic farmer Daniel Konzelmann acquired RTK for his automatic guidance system six years ago. Konzelmann, who farms 1,400 acres of soybeans, corn, spelt, field peas and barley near Wyoming in Lambton County, says improving efficiency was the goal. "With RTK, we can do more acres in a day."

Organic farming can require numerous passes through a field during the growing season to cultivate and combat weeds, and Konzelmann likes to use the same tracks to reduce compaction. It's not the first guidance system he's tried. He's also experimented with a mechanical system, as well as with cameras.

At the time he was considering acquiring RTK, he was also deliberating on whether to buy new cultivators. The locating system eliminated the need for the extra equipment. Today, two of his three auto steering systems are equipped with RTK receivers. As many other operators do, he will shift the system from tractor to tractor as it's needed.

David Hunter, farm operations manager and part owner of Kerr Farms Ltd. and Wolfe Creek Organic Farms Ltd. near Chatham, says it's the second year that he has employed RTK and auto steering systems.

The farm had used less precise forms of GPS service for years to grow about 1,200 acres of high-value crops, such as conventional and organic processing tomatoes, organic asparagus, organic corn, soybeans and wheat, processing corn and snap peas. With 50 per cent of the farm's produce being organic, precision cultivation is a priority, as is saving labour costs. "The more we can remove mechanically, the bigger the savings," Hunter says.

Relying solely on the skill of tractor operators to steer the equipment accurately was not realistic. "There's probably two guys here that can drive straight consistently and stay awake cultivating all day," says Hunter of the farm's 12 tractor operators.

They initially tried combining assisted steering with a WAAS service, but found there was too much distortion in the readings. Adding the RTK service made a "huge, huge difference." It has allowed tractor operators to focus more attention on the implements behind them. It has reduced crop injury and damage in the field and, as a result, alleviated some weed pressure. Other than at a row end, when the autopilot is suspended for a turn, "you'd be hard pressed to find a miss anywhere" in the field.

The system, along with the acquisition of other equipment, has meant having to hire fewer people to hoe this year. With field crops, it helps ensure the combine operates at capacity all of the time, which achieves savings.

Hunter has combined the service's mapping abilities with soil sampling to develop prescription maps to distribute compost. The maps are used to customize application rates within a field. He's not sure if he wants to apply the same variable rate approach to planting, although adding swath control and planter shut off are on next year's wish list.

Limited range
RTK's advantages appear to be many, but tackling its limitations and the challenges it sometimes presents is not for the technologically faint of heart.  

The service's corrections are processed and broadcast from a land-based station and the roving receiver (located in the tractor or on an implement) must be in line of sight of the station or a repeater to obtain the signal. The accuracy of the corrections diminishes with distance, and users typically describe the station's optimum range as about eight miles.

Farmers who acquire their own station – which many of the earlier adopters in Ontario did – may have the option of locating the station on a tower high enough to broadcast to the entire farm. Konzelmann didn't have that option and, because he farms in a 15 to 20-kilometre radius, it has meant having to establish different locations to place the station. In some instances, the station's placement may mean that he won't be able to access the service for more than one piece of equipment at a time.

Many dealerships have helped growers to get around this type of problem by establishing local RTK networks and charging annual subscriptions. The Van Osch brothers subscribe to one of these. Yet Fred remains wary of the problems posed by signal interruptions or computer failure and for this reason, unlike Nixon, has opted to retain mechanical markers on new equipment as a backup. "You don't want to let something like this shut you down from planting," he says.

Hunter, who also subscribes to a network rather than buying a base station, has had to tackle competing signals. "We have one farm location that's underneath a CBC output tower that puts out so many watts of power that it drives out our RTK signal," he says. He resolved the issue by adding a repeater to boost the RTK signal.

He has also had repeaters blow out – once from a lightning strike. Other repeaters in the network were affected, along with computers at the farm.

Nixon says one of the challenges he encountered in the last year was, at a certain point of the day, not having access to enough satellites to obtain the RTK accuracy.

His system is set up to obtain information from "a minimum of six satellites that we can see visibly in order for RTK accuracy to exist," he explains. But shortly after each lunch hour, for about a month and a half during the very busy fall season, the number of satellites dropped off to marginal levels. And if an object blocked visual contact to one of those satellites, "all of a sudden your auto steer disengaged and there you were sitting waiting for a sixth satellite to come back into view."

Nixon upgraded his system over the winter to obtain access to Russia's version of GPS, called GLONASS, gaining access to a greater number of satellites for positioning information.

He also decided to switch from using his own base station to subscribing to an Internet-based RTK network. Called a virtual reference station network, the technology links information from base stations to a central control over the Internet to create a model to determine the corrections. The subscriber uses a cell phone modem to connect receiving equipment through the Internet and acquire the information.

In Ontario, this service is offered by Can-Net virtual reference station network (VRS) and delivered through a wireless cellular network. It is similar to the CORS (continuously operating reference station) Network operated by the National Geodetic Survey in the United States.

Nixon says the network eliminates the need to cart around a station (he farms in a 13-mile radius, which is greater than the base station's range) and means that he can obtain RTK corrections when doing custom strip tillage on other farms elsewhere in southwestern Ontario.

Making the switch, though, presented another minor hurdle. All of the field boundaries and rows stored in his system's memory were based on the location of the original base station. He says he had to "re-teach" the unit where "ground zero" was.Cause of frustration

Shawn Redick, a precision farming technician with Southwest Ag Partners Inc., notes that equipment brand selection can limit the choice of an RTK network. "There are proprietary signals," but there is currently no universal signal, he says. John Deere's signal, for example, won't communicate with systems made by a competing manufacturer. "That causes some frustration for some guys."

Dave Petheram, manager of EFS Precision, a division of Elmira Farm Service which represents both John Deere and Trimble RTK products, says the John Deere RTK signal is proprietary "in the sense that there needs to be a John Deere unit on either end (of the broadcast) talking to itself."

That's basically true of any RTK brand equipment. However, the John Deere system is not compatible with the cellular RTK service offered in North America, he says. But because the company was the first to push its dealers to set up base station networks, "a lot of John Deere dealers across North America have a stable infrastructure for providing this kind of correction signal." 

On the software end, it can take some effort to manage and organize the data, says Hunter: "The first year was just a scattered mess. Our data management was just horrible." One of the problems was a lack of name standardization for the different farms and field locations, making it difficult to retrieve data. Now, standardized formats are in place but training other equipment operators to use the system isn't easy, especially if they are unused to technology.

Fred Van Osch points out that, because the equipment is not used daily, there's the further challenge of remembering how to work it. "The whole problem with farming is that we use (technology) for a period of time and then there's a long period when we don't use it. And then everything is forgotten," he says. Some farm implement dealerships that sell RTK equipment do offer refresher courses, he adds.

Cost remains the greatest challenge. Six years ago, Daniel Konzelmann paid $50,000 when he bought his RTK equipment for one tractor. The price included the receiving equipment and a portable base station to calculate and broadcast the GPS corrections.

Today, the costs of RTK service are not much lower. According to those who sell the equipment in Ontario, it costs between $20,000 and $30,000 to outfit one tractor with an RTK system and automatic guidance equipment. A base station will add $10,000-$12,000. Dealers charge $1,000-$1,500 to subscribe to a local RTK base station network for the first receiver and lesser amounts for additional receivers. Some may also charge a set-up cost, which can run as much as $1,000. Wireless access to RTK runs around $1,500 per receiver and there are charges on top of that to acquire a data service package from a wireless provider.

Griffin acknowledges that price is a stumbling block. A 2005 study he co-authored calculates the costs for one RTK automatic guidance system, without subscription costs, at US$4.67 per hectare if the initial investment is US$35,000. The technology becomes more profitable as farm size expands, the study states. It notes that other studies have shown the technology is profitable when practices such as controlled traffic or strip tillage are used.

Griffin says access to the service over wireless cellular networks will likely make the technology more affordable, and Murray agrees. He points out that many have obtained a grant to help pay for their GPS guidance systems through provincial Environmental Farm Plan funding, which will cover 30 per cent up to $10,000 for such improvements. "That really has helped drive the sale," he says.

Funding is also available from the federal and provincial food safety and traceability initiative. The initiative will pay up to 50 per cent of costs up to $25,000 for equipment or software that supports a food safety program or a traceability system. Many manufacturers now build equipment with auto guidance capability, which will also helps reduce costs.

Konzelmann offers some final words of advice for those who might be considering acquiring the equipment: calculate how quickly the savings will earn back the amount invested. Equipment goes out of date quickly; parts and support service for older equipment can be difficult to obtain.

It's like a computer, he says: "After three, four, five years it's an old system; you want something else." BF