FEATURE ARTICLES
Why consider terrain compensation technology
Four dealers answer key questions on the benefits and justification of buying terrain compensation technology.
Posted: March 16, 2006
Farmers with GPS guidance and self-steering systems may want to consider a terrain compensation option for added benefit. Farmers who are looking at adding GPS to their machinery might want to include a terrain compensation option.
With the implementation of GPS technology applied to agriculture, farmers are seeing an improvement in machinery performance, saving significant amounts of time and money. Benefits of GPS guidance and steering control systems include eliminating gaps and overlaps, operating at maximum effective speed, running machinery as many hours a day as safely possible, and getting maximum fuel economy.
We talked to four dealers that offer terrain compensation technology for their GPS systems to answer some key questions farmers have.
Why terrain compensation?
Dealers agree adding terrain compensation to the GPS package increases performance of the guidance system. On rough or sloped ground the vehicle bounces and sways, causing the GPS antenna, usually situated on the top of the tractor, to sway off the centerline. "Every time the receiver moves, the steering system is going to react because the system is basing everything on the position of the receiver," explains Glen Walsh, AMS Regional Specialist for John Deere.
In a GPS system without terrain compensation, the tractor rolls when traveling along the side of a slope, resulting in position error as the antenna reads in a straight line to the ground. "If you were on a five degree slope, you will have over 10 inches of error on that position," says Walsh. On some slopes, the potential error can be as much as two feet.
This error creates strips of misses and overlaps across the hill. The gaps and overlaps result in extra chemical usage and added costs. There is also possible crop stress from chemical injury, in the case of overlap, and weed competition, in the case of a gap.
The terrain compensation technology recognizes the tractor or sprayer is on a slope and corrects the system to the actual centerline. "Farmers buying terrain compensation need correction for rough terrain or slopes and they want the improvements in performance from their GPS," says Colin Bergstrom, owner of Seven Islands Agriculture, an independent Trimble dealer in Central Alberta.
What are the benefits?
Operators of high clearance sprayers will notice perhaps the greatest benefit. High clearance sprayers, with their high, skinny wheels, high cab and high speeds, experience a lot of sway in the antenna situated on the top of the cab. "Operators will see improved performance especially in high clearance sprayers because it deals with the speed and the bumps a lot better than a guidance system without terrain compensation," says Bergstrom.
Custom spray operators who cover a high number of acreage with high clearance sprayers should profit from this technology. "Larger vehicles are used to improve the overall efficiency of the farm but as they are getting larger and higher, the position error, due to slope error, is getting larger as well," says Gary Vanderploeg from Terradox Corporation, which carries the SiteWinder technology.
Undoubtedly, farmers who farm fields with rolling topography will also see a big benefit. "The producer that has more hills will have more overlap without a terrain compensation system so he will see a bigger payback than a farmer who farms flat ground and experiences less cab roll," says Walsh.
When traveling over a cultivated field with no hills, the rough terrain will cause some cab roll that the steering control will want to correct for. "Terrain compensation takes care of that," says Walsh. "Anytime you can eliminate a steering correction, you are going to have straighter rows."
"Even farmers who farm relatively flat land will see an improvement in the performance of their autosteering system," says Bergstrom. "Terrain compensation improves accuracy and farmers are seeing improved performance from their guidance systems." The window of accuracy for most systems is six to twelve inches. With terrain compensation, the accuracy is more consistently six inches.
Justifying and recouping costs
The question lies in whether the benefit of the better performance is enough to justify the cost of the terrain compensation. "If there is a greater than two degree slope on your land, it would be worth it," says Vern Anderson, a GPS/Precision Farming Specialist for AgriTrac Equipment in Northern Alberta. "If the farmer does not have slopes greater than two degrees, I don't think you would justify the extra cost of terrain compensation."
Terradox has a different answer. "If you are farming slopes that are not more than five degrees, don't bother buying the technology," says Vanderploeg. The reason behind this lies in the accuracy of the GPS system. "The position error that needs to be corrected for slope up to five degrees is less than the error of the GPS," he explains. "If you do have the high accuracy system with sub-inch accuracy, you need the terrain compensation because at that level of accuracy, any slope in terrain is now visible."
Farmers who can justify the cost of adding terrain compensation can expect to recoup their costs in the first year of operation. "When you take into account the cost of inputs, the system will pay for itself in one season," says Anderson.
The actual cost of adding terrain compensation is fractional compared to other costs on the farm so it's an easy recoup. "The actual time for the system to pay for itself depends entirely on the number of hills and the slope of the hills," says Vanderploeg.
There are potential benefits in terrain compensation for all operations including seeding, spraying, swathing, combining and anhydrous application. The cost recuperation time decreases the more operations it is used for.
