CT soil scan outshines what microscope can do

University of Guelph researchers build better tools to focus on the relationship between soil health and crop yield

What goes on in the soil at night might surprise a lot of people.

It’s not the relaxing, sleepy scene some might imagine.

Roots are forcing their way past rocks and a wide assortment of types and sizes of creatures from bacteria, to worms and gophers are on the move.

It can be pretty chaotic at times, according to Richard Heck, a researcher at the University of Guelph in Ontario.

“There’s always something happening down there. We get a complete view from the perspective of a plow layer,” says Heck, explaining that the X-Ray CT soil scan has made the microscope virtually obsolete in many areas of science. He says he’s able to pick up more detail with CT than with any other analytical device.

Heck is part of a group of soil scientists with members around world. Together, they used CT technology to take detailed pictures of what happens below the surface. Funding came from Agriculture Canada’s Greenhouse Gas Program, Ontario Agriculture and Grain Farmers of Ontario.

“We’re closely examining conventional tillage, no-till, intercropping, different rotations and other management systems,” says Heck. “Not only as a single snapshot in time, but we do CAT scan samples throughout the year to observe changes in soil structure.

“There’s wetting and drying, shrinking and cracking, freezing and thawing, tillage and compaction, a lot of forces and processes taking place within the soil at different times of the year. There’s human activity and natural activity.”

The soil scan instrument is slightly different from the medical CT scan. In a medical machine, a person goes in and lays down. The machine spins around the patient because they need the body to remain as still as possible.

Soil scanners are called pre-clinical scanners. The sample rotates around the machine. It yields similar information as a medical scanner and produces the same kind of three dimensional view, only of a soil sample instead of a human body.

“The machine I use in my project work in Brazil is new and it’s state of the art. It works very quickly. The one I use here at Guelph is very slow in comparison. It might take my scanner three hours to generate a high resolution 3D image. Heck says the scan allows researchers to evaluate the re-organization of particles that takes place within each particular soil. They examine the kind of pores that are created by human activity on the surface and scrutinize the nightlife below the surface.

Soil biodiversity has become a buzzword in the past 20 years, as scientists and society develop an understanding of how micro-organisms play a role in breaking down organic material and cycling nutrients.

While most farmers realize that biodiversity is important for a healthy soil, Heck concedes there are still producers who view soil as nothing more than a growth medium into which they dump nutrients, seeds, water and crop protection products.

“On the other hand, soil is more than just a bucket of nutrients,” he says.

“Talk to greenhouse people who work with hydroponics and really simple growth mediums. They face big challenges in disease and pest management, and also in the timing of nutrient release.

“As you degrade the soil structure, the amount of resources you need to put back in the soil to maintain yield increases.”

Information gathered from the CT soil scan research will be used to develop soil quality indicators, which can be applied by Ontario growers in managing their cropping practices.

For more information, contact Richard Heck at rheck@uguelph.ca

Contact ron.lyseng@producer.com

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