Soil radiation linked to yields

GUELPH, Ont. — Farmers are familiar with map overlays for yield, topography, soil type, macro and micro nutrients, weeds and insects.

But what about an overlay for soil radioactivity?

Some farmers attending this summer’s Manure Expo in Guelph just walked past the booth that dealt with field mapping radioactivity, joking about science fiction and perpetual motion machines.

Other farmers stopped and spent half an hour or longer discussing soil radioactivity with Barry Raymer, a field representative for Practical Precision in Tavistock, Ont.

“Research conducted at European universities shows a strong correlation between radiation emitted from the soil and nutrients in that same soil,” Raymer said.

Practical Precision provides its clients with all the mapping and agronomic services that consultants typically provide today. But this summer, it took that service one step further with the introduction of radioactive mapping.

“We are the first to offer this service commercially,” said Raymer.

“We attach the radiation reading tube to the front of our quad, between the two GreenSeekers, which we always have on the quad anyway. Then we simply drive across a field mapping radiation in our normal grid pattern. The radiation measurement is taken at a depth of one foot, or about 30 centimetres below the surface.”

At the same time, instrumentation on the quad logs Green Seeker data and all the other information typically gathered on these field trips.

Raymer said the variation in radiation readings across a specific field is about the same as the variation he finds in soil quality and crop yield.

Back at the office, all field data is correlated with core samples taken on a 10 acre grid pattern, which is geo-referenced on the field. Practical Precision does soil texture testing from these cores, as well as measuring the percentage of sand and clay in the core samples.

“The new data we gain from radiation mapping gives farmers new information they’ve never seen or even imagined before,” he said.

“We’re now able to develop 14 new high resolution maps with our new information. One of the new maps we’re able to deliver now is a soil water retention map based on texture sensing.”

Raymer said farmers can use this new soil water retention map along with other maps to write more accurate prescription maps for variable rate fertilizer and seed.

He said that capability lets farmers put fertilizer and seed where it will give the best return.

Veris electrical conductivity mapping also quantifies water retention in soil, which means the readings can be fooled by the amount of moisture in the soil on a particular day. Those taken during a dry spell will differ from readings taken in the rainy season.

“Radioactive readings aren’t affected by moisture at the moment,” Raymer said.

“Radiation emitting from the Earth is constant in any field, regardless of the season or the weather. But with your Veris, moist soil throws the readings way off.”

Raymer said he typically runs a field in 40 foot swaths, which are put into the computer along with the core samples in 10 acre blocks.

“A 40 foot swath with core samples gives you information that’s the equivalent of 300 core samples per acre.”

He said the service costs $50 per acre based on 40 foot swaths. He adjusts his price if the farmer wants different swath widths with the quad.

For more information, contact Raymer at 519-655-3555 or visit

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