WESTERN PRODUCER — From 1990 to 2019, greenhouse gas emissions from Canadian agriculture went from 58 million tonnes of carbon dioxide to about 69 million tonnes.
That’s an increase of 19 percent.
Tim McAllister, an Agriculture Canada scientist in Lethbridge, says the 19 percent jump is mostly about grassland that’s now being used to grow crops.
“When you look at where that increase comes from, the majority of it is coming from that grassland conversion,” said McAllister, who specializes in ruminant nutrition, greenhouse gas emissions from beef cattle and what land use change means for carbon stored in the soil.
“Sustaining those (existing) grasslands is going to be critical if we’re going to meet any of our climate change targets.”
McAllister made his comments during an Aug. 17 presentation at the University of Manitoba to about 20 people in a conference room and an online audience from across Canada.
The topic was the role of cattle in preserving carbon stocks and maintaining biodiversity in Canada. His comments on converting grasslands to cropland, and the related impacts on GHG emissions, come from government reports.
“I’m pulling that directly out of Environment Canada’s climate report that they put in. They have to submit every year to the IPCC (Intergovernmental Panel on Climate Change),” he said, adding that grasslands are still at risk of soon becoming cropland in Western Canada.
“As we see the expansion of irrigation in Alberta, you can move into some of those areas that wouldn’t maybe be suitable for crop production… because you can bring water in…. There are still areas that are going to be subject to conversion, going forward.”
Some livestock producers are also worried about the continuing shift toward crop production.
Martin Unrau, who runs a 600 head cow-calf farm near MacGregor, Man., has seen multiple cases where a grain producer bought land that was once pasture. As an example, three livestock farms came up for sale on the west side of Lake Manitoba a few years ago.
“North of our pasture at Langruth,” said Unrau, former president of the Canadian Cattle Association. “The ranch was not taken on by another cattleman…. A big grain guy bought all three places and just wiped the trees off (the land). Those three ranches are now grain farms.”
It’s unclear how many acres of grassland have been converted to cropland in the last 30 years, because precise data doesn’t exist, McAllister said.
But the amount is significant, likely hundreds of thousands of acres.
During his presentation, McAllister showed a map of Canada with regions coloured red and green. The red areas have high GHG emissions per acre of agricultural land. Green regions have fewer emissions.
Southern Ontario and Manitoba’s Red River Valley were red, as those regions are dominated by cropland.
“They have much higher emissions per hectare than our grasslands ecosystems,” McAllister said. “Where those emissions are the lowest are in those grassland areas, such as Saskatchewan and southern Alberta.”
A big part of the green colour is about land-use intensity. If a region has a mix of pastureland and cropland, it’s likely that emissions will be lower than a region with intensive cropping.
When land used for grazing is shifted to crops, the amount of carbon lost from the soil is immense, so keeping those lands in grass may be more important for the planet than trees, says a study from the University of California Davis.
“Since grassland environments, including tree-sparse rangelands, appear more capable of maintaining (carbon) sinks in 21st century, such ecosystems should be considered as an alternative C offset to climate-vulnerable forests,” the study says.
Converting grasslands to crops can cause other environmental problems.
Dozens of wildlife species depend on grasslands and pasture for habitat. And they need that habitat connected to other grasslands so they can move across the Prairies.
Without corridors for movement, from, for example, the foothills of the Rocky Mountains to the Parklands of Saskatchewan, wildlife could struggle.
McAllister said it’s important those populations interact and breed.
“If they (wildlife) get pocketed into isolated populations, the ability of those populations to adapt will be less.”
Preserving grasslands, though, depends highly on basic economics.
If grain farming is more lucrative than livestock, why keep the land in pasture?
“How much can I get if I convert (this land) to canola versus grazing cattle? The answer to that is pretty straight forward,” McAllister said.
One possible solution could be paying cattle producers to maintain grasslands.
The U.S. government has the Grassland Conservation Reserve Program, which allows farmers to use the grasslands for pasture and hay production, but landowners are paid for the environmental services.
Looking forward, McAllister believes it could be difficult to halt the ongoing trend of converting rangeland to cropland.
“It’s going to be challenging…. Until we recognize some of the benefits of biodiversity and the carbon that’s in those grassland ecosystems, we need something that’s going to balance it out and recognizes the economic value (of) that.”
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