Canola School: One cool crop — how canola sequesters carbon and reflects the sun
Canola is a “cool” crop in more ways than one, including how it can have a role in mitigating climate change.
“From the point of view of global warming or climate change, canola is different from other crops that we grow commonly, and that is that it produces a lot of residue for every seed that is produced,” explains Brian McConkey, research scientist with Agriculture and Agri-Food Canada, in this Canola School episode.
Canola’s high ratio of biomass-to-seed has traditionally been considered an inefficiency versus other crops, but it becomes an advantage when considering carbon sequestration, he notes. As canola decomposes, it adds about 1.5 times more carbon to the soil than a comparable wheat crop.
Nationally, soil organic carbon levels have been increasing at an average rate of 1.5 percent since 2005. An estimated 70 percent of that increase can be attributed to canola production, says McConkey.
“Canola has dominated the carbon input for the whole country of Canada and in that, achieving quite large carbon sequestration,” he says.
Crops that can pull more carbon dioxide out of the atmosphere have been identified as a global priority for addressing climate change, notes McConkey: “We need crops that can do that, and here Canada has one, and we’re expanding it’s area, so we’re achieving that.”
Adding to McConkey’s case for the “coolness” of canola, the crop reduces what climate scientists call “radiative forcing” more than any other crop grown on the prairies.
In other words, it reflects more light from the sun.
“Most of that is just the flowering period,” he says. “That actually has a very strong cooling effect. You might not think about it, but when you think about millions of hectares reflecting back, that’s really what the greenhouse effect is about…”
As an example of how radiative forcing warms the atmosphere, McConkey highlights how the reduced reflectivity from planting a coniferous tree in a snowy climate causes more warming than is countered by the CO2 that tree removes from the atmosphere.
In addition to the bright flowers, snow retention by canola stubble also contributes to the crop’s overall reflectiveness, he says.
Brian McConkey joined RealAg’s Kelvin Heppner following his presentation entitled “Why canola is cooler than cereals” at the 2017 Canola Discovery Forum in Saskatoon.