GUELPH, Ont. – Paul Voroney wants to ring an alarm bell about what he sees as a looming crisis in the health of Canadian agricultural soil.
The professor of soil biology at the Ontario Agriculture College school of environmental sciences says there is a growing tendency of companies and farmers to see crop residue as waste that could have monetary value.
“It is scary,” he said.
“The whole notion out there is that all these residues are just waste material, which has value only if companies can find a use for it and farmers can sell it. It is bizarre and very dangerous.”
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In particular, he cited plans by Ontario Hydro to buy crop residue to burn as a substitute for coal in provincial power plants. There is also growing industrial demand for crop residue as feedstock for biofuel production or production of building materials.
“Bioproducts now are cool,” he said. “There are other materials to use.”
Voroney was particularly contemptuous of international advocates of a plan to collect crop residue, gasify it to crystallize the carbon content, turn it into charcoal and then burn it in electricity plants.
He argued that recycling residue into the soil is ancient practice and common sense.
“This is not waste material.”
However, he sees growing pressure to consider it so.
“I understand why this additional
source of income would be attractive to farmers who often are struggling with the bottom line, but it is very short-term thinking,” Voroney said.
“Biomass is what keeps soils healthy, gives them texture, holds them together, helps fertility, fights erosion. It is idiotic to think we don’t need to constantly replenish the biomass, but that is the trend I see and it is just beginning.”
At a test plot in an Agriculture Canada research site in Delhi, Ont., Voroney and his associates have been tracking residue retention’s impact on the carbon content of soil in a rotation of crops that include wheat, corn and soybeans.
“We track the carbon and the impact is measurable,” he said.
As residue decomposes, much of the available carbon is lost to the atmosphere as carbon dioxide, but some is retained in the soil.
“The bottom line is that since cultivation started in Canada, we have lost about 50 percent of the biomass we inherited.”
Voroney said his studies suggest that tillage practices, including the increasing move toward conservation tillage, have had little impact on stable soil carbon levels.
The answer is to return to the common wisdom, understood by farmers for millennia, that soil needs replenishment or it declines.
“Somebody has to start talking about the importance of returning the residue to the soil, although it seems like reinventing the wheel,” he said.
“I think it would not be an exaggeration or an overstatement to say that the path we seem to be going down will reverse all the progress we have made in soil management since prairie soils were drifting in the 1930s. We learned a lesson then about caring for our soils, but it is my assessment that we are beginning to forget those lessons.”
