With better soil, farmers can fight climate change, make agriculture more sustainable
Many of us are aware of the effects of climate change, but Prince Edward Island potato farmer Myles Rose has been watching them up close for years.
He's seen how extreme weather events like drought have wreaked havoc with crops that have made P.E.I. famous, such as the Goldrush potato.
"It's a small plant in structure and needs water weekly, and lots of times we're not getting a rain weekly, so we can't get a sustainable yield off of that crop," Rose said from his farm in East Point, P.E.I.
"So we're moving to varieties which are more drought-resistant."
Climate change is forcing farmers to make adjustments to ensure their crops can withstand evolving weather conditions. At the same time, many aspects of agriculture — from tilling to raising livestock — contribute to increased levels of carbon in the atmosphere, which exacerbates global warming.
But there's a movement afoot that not only could improve the business of farming but also help fields pull more carbon out of the atmosphere. It's called regenerative farming, and it emphasizes taking steps to cultivate stronger, healthier soil.
A 2019 study showed the potential for Canadian farmland to become a "large carbon sink."
Myles Rose certainly sees the need. "In my book, the No. 1 thing that [farmers] have to do all across Canada is conserve our soil."
A warning about '60 harvests'
Soil is most productive when it is rich in organic matter, which is made up of microbes, as well as decaying plants and animals, and contributes nutrients such as nitrogen, phosphorus and sulphur to soil.
When plants convert sunlight and carbon dioxide from the atmosphere for food, the excess carbon ends up in the soil. There, microbes in soil organic matter help convert carbon into more complex forms that are harder to break down.
David Burton, a soil scientist and professor at Dalhousie University in Halifax, said that over the years, intensive agriculture production methods — particularly tillage, which breaks up the soil in preparation for planting — have dramatically reduced the amount of organic matter in the soil.
The result of less organic matter is that "the soil structure is being degraded, such that soils have difficulty holding water and resisting soil erosion, and they become less fertile," Burton said.
"That's making our agricultural production systems less and less productive, and some soils are becoming deserts and no longer able to produce food."
Myles Rose said that without sufficient organic matter, "when the rain does come, [the soil] is just like sand on a beach — the water just passes through it and it doesn't stay around long enough for the crop to use it."
In 2015, the Food and Agriculture Organization, a United Nations agency, calculated a finite number of growing seasons left if farming practices remain unchanged.
"Unless we improve our soil and soil management, we only have 60 harvests left," Burton said, referring to the UN's statement. "We'll only have 60 years to produce the food to support the world's population."
Protecting the soil
Given that urgency, many farmers have been incorporating different measures that are key to regenerative farming. For example, Rose has been planting more grasses, such as Sudan grass, tillage radish and brown mustard.
Dan Petker, a grain farmer in Port Rowan, Ont., on Lake Erie, has committed to zero tillage, meaning "no disturbance of the soil outside of the machine that will be planting your crop," he said.
He also rotates his crops, which builds resilience in the soil. In Petker's case, that means planting wheat one year, corn the next, soy the year after that and then back to wheat.
Petker also uses "cover crops," which is an old practice that involves intermingling other plants with cash crops to add nutrients and prevent soil erosion.
"I have a wheat crop growing, and in February I spread clover seeds. They germinate in the spring. I harvested the wheat crop [in July] and now the field is completely green," Petker said.
The red clover "won't make me any money, I won't harvest anything off of it — it's just there to keep the soil healthy, alive and not moving anywhere." Not only that, but the clover releases nitrogen, "so I don't have to spend as much on my fertilizer inputs."
Measuring what's being absorbed
In an effort to quantify how much carbon farms can sequester, there's currently a pilot project underway in Alberta to improve the ability to measure soil's organic content.
By using a combination of satellite and on-the-ground monitoring (including soil samples), the project hopes to do a better job of quantifying how much carbon can be stored, said Kimberly Cornish, director of the Food Water Wellness Foundation, who is overseeing the project.
"To this point in time, measurement has been the fence too high to get over," said Doug Wray, one of the farmers involved in Cornish's study.
Two decades ago, he converted his land in Irricana, Alta., from a mixed farm to ranching, rotating cattle from different pastures, planting perennials and minimizing chemicals.
While the decision was an economic one, changing his farming practices "had some great side benefits, because we now have a healthier, more productive landscape," Wray said.
Cornish said the upshot of better, more reliable data about soil carbon content is that farmers could make money on offsets. If there's a better way to measure how much C02 was being sequestered in the land, "they could sell a carbon offset to large emitters for that amount that they are pulling from the atmosphere."
Wray said he hopes soil carbon could help his bottom line if the study can help him figure out just how much he's storing on his property. "Pay me for results, and I'll figure out how to get there."
'A long-term play'
While there is a lot of optimism about regenerative farming, Petker said that committing to it is a personal choice that inevitably means shouldering added expenses.
"I'm willing to take on a certain amount of cost or less income for the betterment of the soil because it's a long-term play," he said. "If I could be compensated somehow, that would be wonderful, but right now we don't live in a world, or an economy, that wants to."
The rub, Petker said, is that his crops ultimately compete with those of other farmers who may have no interest in regenerative farming.
"The crops that I grow are sold on a world market, so my neighbour could be growing them completely conventionally. I'm going to try regen, but it all gets dumped on the same boat, for the same price."
Soil scientist David Burton said there's actually a limit to how much carbon can be absorbed in soil.
Rather than thinking of regenerative farming as a "silver bullet" to stop climate change, he said, it's "basically a solution to buy us a few decades of opportunity to reduce the carbon content of our atmosphere — but then we'll have to seek other solutions to limit the amount of CO2 in the atmosphere."
But he stressed that building up soil organic matter remains important to the sustainability of farming.
The carbon the soil pulled from the atmosphere might only help us to reduce CO2 for a few decades, but "that carbon, once put in soil, would help enhance the function of soils forevermore," Burton said.
"The real benefit of putting that soil organic matter there is to build more sustainable, more resilient soils that will support food production and provide environmental goods and services indefinitely."
With files from Molly Segal
Listen to What on Earth on CBC Radio 1 every Sunday at 10:30 a.m., 11 a.m. in Newfoundland.
You can also subscribe to What on Earth on Apple Podcasts, Google Play or wherever you get your podcasts. You can also listen anytime on CBC Listen.