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VRT — Several Information Sources Needed To Be Effective

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Variable-rate technology (VRT) can offer advantages, but a team of careful advisors is necessary to get the project up and running, says Colin Bergstom, a consultant with his own company, Seven Islands Agriculture.

Bergstrom is also a VRT consultant with Farmers Edge and has worked with farmers in the Westlock, St. Albert and Barrhead areas. He says producers who want to get involved with variable rate technology need a team to implement a VRT system. This team will include an agronomist and agricultural equipment dealers who have a knowledge of VRT equipment.

Bergstrom told a meeting here last month that producers who want to get into VRT need to be objective during the process as procedures might be quite different from those used in the past.

The main objective of VRT is to identify variability so that inputs and other management can be adapted to the different areas.

Land contains variability through natural processes which include slope, topography, changes in available moisture, changes in soil texture and microclimates.

There is also man-made variability introduced through cropping history, fertility practices, drainage work, fence lines and plough ridges.

Producer knowledge first

Bergstrom says there are many ways to identify variability but the most important source of variability information is the producer’s knowledge

“You cannot rely on just one source to identify variable information. You need a systems and combination approach to identify what is going on in your fields,” said Bergstrom.

“When I work with a client on a piece of land, their knowledge is going to be almost as important as everything else.”

Yield maps can be a good source of information, but may not always be consistent. Yield monitors need to be properly calibrated to create accurate yield maps, Bergstrom said.

Topography maps are also useful and can be created when producers have mapping, but he says they act mainly as support tools to other maps or information sources, said Bergstrom.

He said infrared satellite imagery can also be a good information source for mapping variability. The sensors used to take infrared images pick up the amount of light that is reflected back into the atmosphere. Green vegetation reflects more light up into the atmosphere, and this shows up in the photos.

Electrical conductivity (EC) is another tool that can be used to identify variability. EC identifies soil structure and salinity. The systems used to measure EC put an electrical current through the ground and measure the counductivity, which can indicate sand, silt and clay content of the soil through multiple depths. Bergstrom says EC measurements correlate well with satellite imagery and may have advantages in identifying salinity.

However, there hasn’t been a lot of EC work done in Western Canada yet. Bergstrom said the process is rather labour intensive and can only be done in a very limited time period before seeding or after harvest.

About the author


Alexis Kienlen

Alexis Kienlen lives in Edmonton and has been writing for Alberta Farmer since 2008. Originally from Saskatoon, Alexis is also the author of two collections of poetry, a biography, and a novel called "Mad Cow."



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