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EC Mapping System Helps Pinpoint Problems

Getting where you want to go is easier if you have a map.

The VERIS system, which maps the electrical conductivity (EC) of soil, is one way to get a clearer picture of where to look for potential problems.

It consists of a series of coulter discs mounted on a toolbar that is pulled behind a pickup. Electrical wires from the coulters send signals to a GPS-enabled computer in the cab that collects EC data and records it as the rig moves over the field.

Within minutes, a colourcoded map of soil zone variation can be printed out and handed to the farmer.

Why would you want a map of the electrical conductivity of your soil?

“For this machine, it’s about measuring soil texture,” said Elston Solberg, an agronomist who gave a presentation on the device as part of the Agri-Trend summer training event in mid-July.

SOIL TEXTURE

“Low readings equate to sandier soils. Higher readings equate to heavier clay soils. So you have a whole range of EC readings. To oversimplify it, it’s about reading the texture of the soil across fields,” he said.

With map in hand, the farmer can start connecting the dots because he now knows where to look for problems and has a better idea of what to look for.

For example, “groundtruthing” in a field of canola that Solberg looked at the day prior turned up rampant sulphur deficiency in sandier areas.

“As we moved from the lower EC areas to the higher EC areas, the sulphur deficiency completely disappeared,” he said.

“That all made sense, because sulphur deficiency is going to occur in areas that have the lowest organic matter – the sandiest soils – because sulphate is mobile and prone to leaching.”

Once the problem was identified, the farmer could reach for the most efficient precision management fix to throw at it. In this case, a “hand grenade” is the cheapest, most effective weapon.

“The simple solution for that field that was expressing sulphur deficiencies would be to go in and broadcast 100 to 200 pounds of elemental S per acre. It would cost us about 10 cents per pound and we would solve the sulphur deficiencies on that field for years and years,” said Solberg.

“That would be a hand grenade.”

HAND GRENADE

Agri-Trend technician Justin Cleaver has been running the fully automated VERIS system first commercialized in 1997 across fields all spring. At a speed of 10 miles per hour on 40-feet spacing, he can cover a quarter section in three to four hours at a cost of $8 per acre.

The coulters are typically placed two inches into the topsoil. Any deeper can result in heavy draft and undue strain on the truck, he said.

“I can drive across your field and have a map ready for you by the time I finish. I can tell you exactly where your gravel veins are, where your poor drainage areas are, and exactly where you may run into salinity problems,” he said.

The best part of VERIS mapping, said Robert Saik, CEO of Agri-Trend, is that the EC of the soil won’t change, so the information remains useful for years to come.

“If you’re getting into variable rate technology and precision agriculture, you’re going to hear the term baseline map. We need some kind of a base level map. Whether that’s a yield map that you mash together from data over several years, a satellite or aerial image, or an EC map, at the end of the day you need some map to go out to the field and use,” he said. “The VERIS EC map is a pretty good place to start.”

Solberg added that when coming up with yield-boosting solutions, imagine that you’re a plant out in the field trying to grow with only the nutrients that are available within reach.

This helps put things in perspective, especially at a time when everyone seems to be focused on the potential for using precision management and variable rate technology to minimize nitrogen inputs, which he said only works about 10 per cent of the time.

“We almost always have bigger fish to fry,” he said. “In many cases, those bigger fish are simple things like drainage, potassium variability – another great hand grenade situation – or compaction, and on and on.”

Soil test, tissue sampling results, and even Greenseeker and yield data can be layered onto the baseline EC map for a more detailed picture.

This additional information can help farmers avoid expensive mistakes, he said.

For example, using broadcast urea in high pH areas can result in extreme volatilization losses, and can be avoided simply by using ammonium sulphate instead. This is also true of the risk of herbicide carry-over or denitrification in poorly drained areas, he added.

“We get all excited when we see all this equipment and the potential that it has. But the potential doesn’t really hit home until we start connecting it back to the basic agronomics,” said Solberg. [email protected]

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