The hidden costs of overlap

Why you can't afford not to use GPS

Posted: May 25, 2009

Most farmers today understand that overlap costs money, and most know that GPS is perhaps the most heavily-marketed solution to the problem. However, what many farmers – including the many who have already embraced GPS technology – would like to know is just how much they save in real dollars through precision farming.

The bottom line, says Virginia Nelson, an engineer with the AgTech Centre in Lethbridge, Alberta, is that overlap can cost producers plenty of money. In fact, calculations using baseline fuel, fertilizer and equipment costs show that an overlap of just five feet on a canola seeding operation can cost producers over $1,300 in a single quarter-section each year.

What it also means is that, in many cases, an investment in GPS technology can quickly pay off. "And with today's large equipment making it difficult to eyeball the accuracy of a pass, you almost cannot afford not to use an automated guidance system," says Nelson.

An additional benefit of automated guidance systems has been an improvement in working conditions, she says. Producers comment frequently on how much easier it is on their bodies when using GPS systems equipped with automated steering.

Where the numbers come from

To give farmers a look at the cost of overlap in seeding and spraying operations involved three steps. The first step was to calculate typical input costs for three common crops. The second was to calculate the amount of land surface overlap that occurred with various amounts of equipment overlap. The third was to combine those results to calculate the cost of overlap by crop on a quarter section.

The AgTech Centre calculated its overlap cost estimates based on input costs provided by the Crop Planning Guide 2008 – Dark Brown Soil Zone publication produced by Saskatchewan Agriculture and Food. For seeding, total costs per acre (including equipment, seed, nitrogen, phosphate, sulphur and other inputs) were estimated to be $86.44 for canola, $78.26 for durum, and $69.29 for feed barley. For spraying, per-acre costs were pegged at $30.95 for canola, $26.98 for durum, and $25.40 for feed barley.

Farm machinery costs were taken from Alberta Agriculture and Rural Development's Farm Operation Cost Guide 2007. Diesel fuel was assumed to be 75 cents per litre, while both seeding and spraying equipment was assumed to have logged 400 annual hours of use.

Overlap was determined by calculating factors such as effective equipment width (the equipment width minus overlap), number of passes and length of travel.

"The important thing to remember is that this is a snapshot of what could happen. It goes without saying that these numbers are specific to a given set of circumstances and won't provide a precise result for every farm in every circumstance," says Nelson. "However, they do give us an idea of the kind of costs to expect from overlap. In some cases, such as diesel fuel, the costs lean toward the conservative side, making any real-life costs of overlap that much more dramatic."

Seeding. The cost of overlap in a seeding operation on all three crops increases substantially for every foot of overlap (Tables 1-3). The higher cost of canola seed drives the highest penalty of the three categories with a five foot overlap netting an over $1,300 loss. The amount of overlap also takes on extra urgency when translated into acres. An overlap of five feet on a seeding operation translates to over 650,000 square feet of overlap or 15 acres – a figure representing nine percent of a quarter-section.

Spraying. The cost of overlap does not translate directly to the spraying side, says Nelson (Tables 4-6). For example, the cost of overlapping five feet on a quarter-section of feed barley in a spraying operation amounts to $154.

"We were surprised there were fewer losses on the spraying side, but that's partly because many producers are now using 120 ft units which, because of their size, result in less passes and thus less chance for overlap."

Still, at a cost of up to $395 for a 10 ft overlap on a quarter-section of canola, there is logic in more precision in spraying operations, says Nelson. "The traditional method of using foam markers is susceptible to evaporation, freezing and drift from wind. Also, the foam is hard to see at night. GPS guidance systems eliminate all of those issues."

More information available

More information on overlap is available by contacting the AgTech Centre at (403) 329-1212. Results of AgTech's machinery evaluations, applied and scientific research, and information on its development of innovative agricultural technologies are available to producers to help them make management decisions.