Pat Kunz estimates it takes two or three extra bushels of wheat yield or perhaps an extra bushel of $9 to $10 canola to cover the cost of using variable rate fertilizer technology (VRT) on his Bieseker, Alta., farm.

That includes soil testing, analysis of yield data, and having a professional prepare the VRT fertilizer prescription.

And while he hasn’t crunched all the numbers from the 2008 harvest yet, there is no doubt in his mind that he more than covered the VRT costs with increased yield on this 2,300 acres of cropland this year. Although, it wasn’t necessarily the primary objective, he also knows he used less fertilizer this past season, compared to other years.

Kunz says using VRT has helped him improve fertilizer efficiency — as in, producing more bushels with the same amount or less fertilizer.

“When you look at the soil analysis over our farm, some of our poorer producing sites had up to 200 pounds of residual nitrogen in the soil, while some of the better sites had zero residual nitrogen,” says Kunz, who runs a mixed farming operation along with his father Chris and brother Kevin. “That tells me that on the poorer sites we wasted fertilizer and on the better sites we weren’t applying enough. With variable rate technology you can cut back what you apply on the lower producing sites and move some of that fertilizer to those sites that have medium and high yield potential. I know we used less fertilizer this year, than we have in the past, and yet our yields were better.

“In past years we would have a single fertilizer blend for the farm and just kept getting loads from the plant as needed until we had covered the whole farm. This year we could pick up exactly what we needed for each field. It was much more measured.”

Along with using the VRT and agronomic services provided by local agri-service company DynAgra, based in Bieseker, Kunz also had to equip a seeding system to apply fertilizer at variable rates.

The drill and controller

“We needed to replace our old air seeding system anyway, and we looked at several different manufacturers before we bought the Bourgault system,” says Kunz. “We knew we wanted something that could handle variable rate technology.” Their old Concord air seeding system was set up to apply anhydrous ammonia. At one time, NH3 used to be one of the more economical forms of nitrogen fertilizer, but that price benefit has largely disappeared. As well, Kunz says due to concerns about safe storage and handling, anhydrous is getting more difficult to find that form of fertilizer.

“You need a controller than can read a prescription file. Nearly every manufacturer will to tell you their seeding system is equipped for variable rate, but a lot of the times that could just mean hitting a button and you can apply 10 per cent more or 10 per cent less fertilizer. It isn’t true variable rate.”

— Garth Donald, DynAgra

In 2007, Kunz bought a 54-foot Bourgault