Using variable rates on the farm

Major changes in farming practices always take time, and precision agriculture is no exception.

Zero till first caught producers’ attention in the late 1970s, but it took more than 20 years to become mainstream.

Despite the obvious benefits of satellite guidance and autosteer, it took a decade for that technology to become mainstream.

Farmers began dabbling with variable rate and precision zone management in the mid-1990s, and two-thirds of all newer seeding equipment on prairie farms are variable rate compatible. However, fewer than one-quarter of prairie farmers have implemented precision zone management.

Three main factors prevent more producers from adapting zone management, AgriTrend agronomist Warren Bills said in a recent webinar:

  • The natural resistance to try new things, which is compounded by the fact that farmers are coming out of a period of good yields and good prices. The memory of those recent good times makes it difficult to implement major changes.
  • Sixty-five percent of farmers have variable rate compatible seeding rigs, but they need training in how to make it work for them. Bills said stepping straight into a zone management regime is a daunting move for farmers if they don’t have the knowledge. Part of the problem is that farmers are rightfully afraid to turn control of their fertilizer rates over to a computer.
  • There used to be a perceived lack of conclusive evidence proving that zone management pays off, but Bills said a growing amount of data now shows it can have a net benefit of $35 per acre, which is the difference between profit and loss some years.

“We’ve documented an average benefit of $35 per acre. The data is compiled from 500,000 acres, representing 150 grain farms that have management input from 73 AgriTrend (agronomists),” said Bills.

“The $35 per acre net gain is measured against a benchmark of acres fertilized with a flat rate. Seven dollars are realized through an input reduction by cutting back or eliminating fertilizer in areas with low yield potential. The other $28 comes from higher yield through better management of those areas with high yield potential. These are all real numbers from real farms we work with.

“In another case example we’ve worked out, a 7,578 acre farm can save $64,792 per year by reducing or eliminating fertilizer in two low productivity areas. That’s a risk reduction figure in fertilizer savings only. It doesn’t include yield increases. The concept of precision zone management we show in these examples isn’t difficult to understand. You just need training in how to do it.”

Bills’ one-hour webinar may have seemed elementary for the one-in-four prairie producers who already practise zone management, but he said it is geared for those growers who are still sitting on the fence.

The power zone concept is one of the basics for novices who are just starting out with an AgriTrend agronomist.

Bills recommended that farmers think of their fields in a top down, bottoms up format. The Agritrend model has six above-ground factors and six below-ground factors, all of which feed into the process of creating zone management prescription maps.

The company’s above ground approach considers information from satellites, airplanes, yield maps, ground truthing, NDVI sensors and tissue samples, while below ground factors include soil electric conductivity, such as EM38 and Veris profiles, grid soil samples, government soil surveys, slope positions, elevation maps and zone soil samples.

“(It) assesses variability above the surface. We look at plant density and all the things going on with the crop above ground, but it doesn’t tell us why. That’s the top down approach,” Bills said.

“Power zone is a cause and effect exercise. What happens above ground with the crop is an effect that’s caused by what happens down in your soil. With the bottom up approach, we deal with soil type, nutrition, moisture, salinity, topography, drainage, soil testing and all the other things that happen below ground. You need all the top down and bottom up factors.”

Bills said farmers’ awareness of the importance of salinity and EC testing has improved dramatically since the first Veris machine was displayed in Brandon 15 years ago.

“And the other thing that’s improved in recent years is the number of producers who are soil testing,” he said. “That’s a big step toward making better use of your land.”

For more information, contact Warren Bills at


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