Greenhouse gas emissions from nitrogen fertilizer were reduced by approximately 20 per cent in the Canadian government’s official 2022 greenhouse gas inventory report thanks to an update to how nitrous oxide (N2O) emissions from fertilizer are estimated.
The reduction, however, will not count toward the federal government’s mandate to reduce emissions from fertilizer by 30 per cent by 2030, as the new method for calculating emissions will also be applied to the 2020 baseline.
In 2021, the Canadian government reported emissions from inorganic N fertilizer in 2019 at 11,319 kt CO2 equivalent. In the new 2022 report published, that figure was recalculated at 9,403 kt CO2 equivalent.
The change is due to how Environment and Climate Change Canada accounts for precipitation in estimating emissions from fertilizer, explains Joshua Bourassa, research associate at the Simpson Centre in the University of Calgary’s School of Public Policy, in the interview below.
“When we look back at the older methodologies, there was a linear relationship [with precipitation]. So the effect at low moisture levels would be the same as the effect at higher moisture levels on fertilizer being emitted as N2O. Now they’ve taken an exponential relationship…there’s an exponential increase in the amount of emissions based off of the amount of moisture in the soil,” he says. “In terms of emissions per kilogram of fertilizer being applied, this is a very large effect, especially in Western Canada, where you have much lower soil moisture levels and has increased the averages in, say Quebec, where they have much higher soil moisture levels.”
While precipitation plays a larger role in the new calculation, the federal government’s method for estimating emissions from nitrogen fertilizers still does not account for most on-farm practices that are known to mitigate emissions, such as the use of enhanced efficiency fertilizers and practices that fall under the 4R nutrient management strategy. The current formula is based on the volume of bulk fertilizer that is sold, precipitation, topography, and the extent to which land is farmed under reduced-tillage and irrigation (as discussed here).
Agriculture and Agri-Food Canada has highlighted many on-farm practices for mitigating emissions as part of a discussion paper on the 30 per cent fertilizer emissions reduction target that is up for public comment until June 3, 2022. However, it isn’t clear how or when these practices might be acknowledged in the federal government’s annual emissions estimates.
“I don’t think it is possible for them to reach that target without explicitly incorporating best management practices into the methodology, so that farmers, if they’re interested, or when policymakers look, they can clearly see the effect of say, adoption of enhanced efficiency fertilizers, on emissions,” says Bourassa. “Because right now, when we look at it, it’s just very much ‘here are some options, but they may or may not be accounted for.'”
It’s also unclear how the government plans to change its methodology and drive adoption of these practices in time to meet the 2030 deadline it has set. The changes around precipitation in the 2022 fertilizer emissions estimates were based on research that was conducted in 2014 through 2016, notes Bourassa. “So there is quite a large lag.”
“It is going to be difficult, because there’s a lot of other incentives, or economic costs, to adopting some of these practices. We still have to figure out what’s the best way of promoting the adoption of 4R, or switching over to enhanced efficiency fertilizers, or incorporating more soil testing into just your regular management practices. So there’s quite a ways to go. And it’s very difficult without having that methodology step beforehand,” he notes.
Listen to Joshua Bourassa discuss the changes to Canada’s N2O emissions estimates, as well as a new report on how the way Canada measures emissions from nitrogen fertilizer compares with other countries, such as the U.S.: