An early summer marked by frequent waves of wildfire smoke in Ontario may have negative impacts on crops in affected areas.
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Air quality statements were issued in June for every jurisdiction in Ontario, and many regions saw the air quality health index reach the maximum value of 10.
The main concern at the farm level, however, may be the extent of sunlight blockage. Grain Farmers of Ontario senior agronomist Marty Vermey said it could stunt crop development.
“There’s a physical barrier of smoke, right? It interferes with solar radiation, and the plants need solar radiation to drive the engine of the plant. It’s their energy source.
“Plants have chlorophyll, and chlorophyll is kind of the factory of the plant, and it converts light energy, it creates sugars.”
Vermey said this will likely weaken plants.
“Think of smog as a whole lot of tiny particles, and it is going to reflect any sunlight coming in. So, it’s filtering out the sunlight, so your sunlight intensity on the plant is a lot lower.
“If that’s a lot lower, that plant is going to operate at a lower efficiency.”
Corn and soybeans are both fairly hardy, but Vermey said surface damage could lead to leaf tissue damage.
“It’s going to slow the growth of the plant down. Corn needs … heat units, and we measure that by heat unit accumulation, but corn also needs solar radiation.
“When we didn’t have enough solar radiation, the plants slowed down, they didn’t mature, they didn’t reach black layer, we got wetter grain.
“Everybody’s asking about yield, does that impact our yield? Well, yeah, so the crop doesn’t develop, and you don’t have great quality.”
An erratic threat
The threat level has been erratic because wildfire smoke comes and goes.
Ontario Federation of Agriculture (OFA) agronomist Jennifer Doelman said she thought that if there were no more smoky periods, the damage should be minimal.
“If we don’t have any more wildfires this summer, our crops are probably okay, because it’s no different than having like a week of wet weather, in terms of how it impacts growing.”
She also said that smoke could impact crops in other ways.
“I’m also a beekeeper,” said Doelman. “And bees use smell as a big part of communication. So, on the days that it was really smoky, the bees were not foraging as much as usual.”
Vermey contrasted the current wildfire situation with the 1980 eruption of Mount St. Helens in Washington State.
“It was an extremely backwards year. The crop didn’t mature, and it was devastating (to) Ontario agriculture, and I think partly it had to do with the ash cover in the atmosphere.”
Some smoke effects this season have already appeared on agriculture and the environment as a whole.
“Just to show some examples, if you take a look around, some trees are looking a little bit different and it looks like there’s some ozone damage or some environmental damage.”
Vermey said it is difficult to know the longer term effects of wildfire smoke because there is little research on the subject.
Doelman agrees that there are no definitive answers on the effects of smoke, but that certain things can be surmised.
“Obviously soil health does correlate with growing conditions,” said Doelman, “so for crops, it’s going to depend on when it’s smoky, and for how long it’s smoky.”
She said that in the short term, there may even be benefits to the smoke.
“If it coincides with an extreme heat period, it’s also possible that those wildfires can actually mitigate some of the heat stress,” Doelman said. “If you have an extreme smoky season, it’s really a miniature nuclear winter.”
