When it comes to carbon and climate change, agriculture may have more options than other industries.
“Agriculture is a source and a sink of greenhouse gases. It’s really important to know that,” said Ymène Fouli, a consultant on water and soil quality, watershed management and climate change based in Calgary.
Fouli was one of three experts featured at Decarbonizing Agriculture, a lecture session offered online March 18 through the Johnson Shoyama Graduate School of Public Policy (JSGS) in Saskatchewan.
In the 1980s, farmland soils on the prairie provinces were carbon emitters, Fouli said, but became carbon sinks as farmers adopted practices that minimized soil disturbance. She cited research that shows that by 2011, carbon from soil on the Prairies was largely staying put, while carbon output from farms in southern Ontario and Quebec remained very high.
Animal agriculture has also improved, most notably for beef. She presented figures showing that in 2006, producing a kilogram of beef emitted about five times as many greenhouse gases as pork or poultry. This was down from about eight times in 1981; a reduction of more than 37 percent.
“This is mainly because of improved management practices, better crop yields, and more productive livestock breeds,” Fouli said.
Raising sheep releases more GHGs than beef, she said — about 80 percent more. Cattle and sheep likely come out as heavy emitters because both are ruminants and reproduce slowly compared to other animals.
This suggests actions that farmers could take. Raising hogs on soy rations, for example, would be much less carbon intensive than raising cattle on corn grain and silage. Precision farming also offers promise by decreasing inputs such as fertilizers and pesticides.
“What can be done? What makes financial sense is the first question to be asked,” Fouli said. “What do farmers recommend?”
Roland Kroebel, a research scientist with Agriculture Canada in Lethbridge, said measuring whole life cycle GHG emissions is tricky. For example, the cycle for cattle is eight years — two for the calf to grow to a cow, then six years where she must be included with each calf she births. To help deal with the complexity he developed Holos, whole-farm modelling software that estimates GHG emissions. Free to download, it allows users to test ways of reducing GHGs on their operations.
Kroebel said that nearly two-thirds of the GHGs emitted by beef cattle and half that emitted by dairy cows come from their digestion. As bacteria in the animals’ rumens break down feed, it releases hydrogen ions. Other bacteria, methanogens, grab these ions and link them with a carbon atom, creating methane.
“If the hydrogen stuck around in the rumen, the cow would probably eventually go ‘boom!’ and we don’t want that,” he quipped. “So in this sense, the methanogens are a life saver.”
There are strategies to reduce methane production, such as using easily digested high-quality feed that spends less time in the rumen, or using feed additives that latch on to the hydrogen before the methanogens get to it.
Another potent part of the agriculture GHG picture is fertilizer for food and feed crops. Fossil fuel in the form of natural gas is needed to manufacture nitrogen fertilizers. In a perfect world all the nitrogen would be used by the plants, but in reality, some will volatilize into the atmosphere as nitrous oxide, a potent greenhouse gas.
Kroebel said farmers can manage this issue and potentially save input costs by using products such as nitrification inhibitors and management practices such as “4R” nutrient management: the right source, at the right rate, at the right time, in the right place.
Producers can also take advantage of their land resources to generate renewable power to offset fossil fuels used to generate electricity, as well as adopt practices to sequester carbon in the soil.
Pursuing these opportunities remains challenging, Kroebel said. Feed additives can dramatically reduce methane production in cattle, but this is best done in a controlled environment such as a feedlot. Unfortunately, most cattle GHGs emissions come at the cow-calf stage, where feed can come from numerous sources, including grazing.
There also needs to be some sort of “national inventory” for GHGs that accounts for farm practices so producers get credit. Ultimately, if broader society is asking producers to decarbonize their operations for the common good, they should not have to shoulder the entire burden.
“We know farm machinery is quite pricey and so is a long-term investment for the farmers,” Kroebel said. “If we require them to basically switch to fossil-fuel-free machinery, we need to talk about who will foot the bill for this switch.”
This is a question of public policy confounded in Canada by the fact that agriculture is a shared provincial-federal jurisdiction.
Margot Hurlbert holds the Canada Research Chair in Climate Change, Energy and Sustainability Policy at the University of Regina, where she conducts research on aspects of governance and climate change. These include energy, water, drought, floods, and agricultural producer livelihoods.
Hurlbert explained the three prairie provinces have different approaches to encourage decarbonization of agriculture.
Alberta has four protocols to create carbon offsets, including conservation cropping, cattle feeding, microgeneration of renewable energy, and biogas production.
“So in Alberta there is a levy on farm fuel, there is a carbon offset market, which allows producers to increase efficiency and reduce emissions to actually earn extra income.”
An important part of the Saskatchewan response is the 4R nutrient management program, with tracking of participating acres. The province remains subject to the federal carbon tax, as does Manitoba.
Manitoba’s priorities show up in its sustainable agricultural practices and environmental farm action plans, as well as a tax credit to encourage preservation of riparian areas beside streams and rivers.
“Not only is keeping carbon in soil important, but it’s also very important to think about water in soils,” Hurlbert said. “The drier our soil gets, the less carbon that it’s holding. So the more wetlands we have, the more carbon we’re storing in land.”
Creating incentives for producers to reduce carbon emissions isn’t simple, and policy makers must consider consequences from field to plate.
Measures that increase the cost of food, for example, can affect people’s ability to feed their families. Farm inputs and commodities, particularly in Canada, move across international borders, creating headaches as to how and where emissions are counted. Policies that increase the cost of production can put farmers at a competitive disadvantage in the world market.
Hurlbert said the issue of who in the food supply chain should for decarbonizing agriculture is still an open question. Is it at the farm level? The food processor? The consumer?
“There’s a lot we actually don’t know in this area because we haven’t done the economic studies.”
Fouli cited figures that show agriculture is responsible for about 10 percent of Canada’s greenhouse gas (GHG) emissions of 729 megatonnes per year. This is closer to 12 percent when factors such as transportation and emissions from nitrogen fertilizer manufacture are included. Much of this output comes from the prairie provinces, home of 80 percent of the country’s farmland.
“Ag is a major industry and a key driver of Canadian economy and it’s at high risk from the effects of climate change,” Fouli said. “Left unchecked, it will deepen the income crisis on Canadian farms.”
DID YOU KNOW?
For ease of comparison, green-house gases are expressed in “CO2 equivalents,” in terms of how good they are at trapping the sun’s heat. Methane does it 25 times better than carbon dioxide. Nitrous oxide, which contains no carbon, is nearly 300 times more effective at trapping heat than carbon dioxide.
Greenhouse gases (GHGs) are actually essential, since they trap enough of the sun’s heat for life to develop and thrive on Earth. The problem comes when human activity releases more than the planet’s systems can deal with, causing it to heat up.