After finishing up the 2008 growing season, the partners at Legacy Agro, a large-scale, family-owned farming operation near Langenburg, Sask., decided to make the switch from NH3 to liquid nitrogen fertilizer. That meant finding a liquid fertilizer cart for their air drill. They decided a 5,000-gallon, tow-between model would best suit their needs.
Clayton Wiebe, a partner in Legacy Agro and the one in charge of the farm’s workshop, says they wanted a tow-between design for a variety of reasons. “We wanted to put it in front of the drill partly because of compaction,” he says. And because the cart wouldn’t need a front steering axle, the seeding unit’s overall length could be a little shorter, making it more maneuverable in the field.
But when the partners couldn’t find a cart they wanted on a dealer’s lot, they approached a prairie manufacturer to see about ordering a custom design. “We asked them if they’d build one for us,” says Wiebe. “But they didn’t think they’d have enough market for one.” That company decided not to invest the time and engineering costs necessary to design a cart for a single sale.
Rather than settle for second best, the Legacy Agro partners made the decision to fabricate exactly the cart they wanted in their own farm workshop.
The first step in the planning process was to check the specifications for their tractor. They needed to know how much draw-bar weight it could handle when deciding on the liquid cart’s design, and they also researched the tongue weights on John Deere’s tow-between air carts to get an idea of how much force other tow-between carts put on a tractor.
Wiebe says there was some room for flexibility when settling on the cart’s final design. By removing ballasting weights from the tractor, it would be possible to fine tune the weight balance to ensure everything stayed within limits. “If you’re overloading the rear tractor axle, you can pull some (weights) off,” he says. But that turned out to be unnecessary.
For durability, the partners wanted to ensure the cart frame was sturdy enough to carry a load without a lot of flexing, which would minimize time spent repairing stress fractures. To achieve that, engineering calculations initially called for a 20-inch, I-beam design; but there was no steel of that specification readily available. Therefore, the only option was to fabricate it.
THE BUILDING PROCESS
Wiebe welded the I-beam for the cart frame himself. He used a 20-inch wide length of 3/8-inch sheet steel for the web and six-inch-by-5/8-inch steel for the top and bottom plates. “The depth of the frame is your advantage; the taller the frame, the lighter it can be,” says Wiebe.
The I-beam for the axle was available from a nearby retailer. But because ordering it would have meant buying a lot more than he needed, Wiebe decided to fabricate that, too. The spindles, hubs, wheels and rims were purchased from Stevenson Wheel in Saskatoon (, who helped Wiebe choose the right size for the load the cart would have to carry.
Fully loaded with 5,000 imperial gallons of 28-0-0 fertilizer, Wiebe estimates the cart weighs in at 71,000 pounds (about 32,272 kg). Empty, it tips the scales in the 7,000 to 8,000 pound range (3,181 to 3,636 kg).
FIRST RUN IN 2009
The farm used the fertilizer cart for the 2009 seeding season, and it performed well. “We just had to do a minor plumbing modifica-