Agriculture Adapts to the New Normal of Smoky Skies
In recent years, wildfires in Canada and the western United States have led to smoke-filled skies stretching across the Corn Belt.
As smoky days become more frequent in agricultural regions, a key question arises:
What impact does wildfire smoke have on crop productivity? Crops rely heavily on sunlight for photosynthesis and high yields, and any reduction in solar radiation—particularly during the crucial grain-filling stage—can be damaging.
The connection between wildfire smoke and crop development is complex, with smoke having both positive and negative effects on photosynthesis.
Three main factors determine how smoke influences this process: reduced light intensity, increased light diffusion, and higher ground-level ozone (O₃) concentrations.
Reduced Light Intensity:
Similar to thick cloud cover, smoke scatters and reflects some of the incoming sunlight, reducing the amount of light available for plants. Since sunlight drives photosynthesis, this reduction can hinder crop growth and yield.
Increased Light Diffusion:
On the other hand, wildfire smoke can boost the amount of diffuse sunlight—photosynthetically active radiation (PAR) that is scattered rather than direct.
This diffuse light penetrates more deeply into plant canopies, improving light distribution and potentially enhancing photosynthesis, especially in shaded leaves.
Elevated Ozone Levels:
Ground-level ozone is a harmful pollutant that negatively affects both human health and plant development. Elevated ozone levels can significantly reduce crop yields.
Research shows that dicots like soybeans are generally more sensitive to ozone damage than monocots like corn, though both crops are vulnerable (Heagle, 1989; McGrath et al., 2015).
“The risk of yield loss and weakened stalk health from wildfire smoke increases when crops are already stressed by other factors such as drought or disease,” said Mark Jeschke, Agronomy Manager at Pioneer.
Wildfire smoke remains a pressing concern for agriculture. With wildfires in western North America projected to become more frequent and severe, their effects on both farming and natural ecosystems will continue to be a critical area of study.
Frequently Asked Questions (FAQs) and Concepts
What is photosynthetically active radiation (PAR)?
Photosynthetically active radiation (PAR) refers to the portion of sunlight (400–700 nm) that plants use for photosynthesis. In 2025, with increasing wildfire smoke events, understanding how PAR is altered—especially through diffusion—is critical to assessing crop health and productivity.
What is the grain-filling stage in crops?
The grain-filling stage is a vital phase in cereal crops like corn and wheat, during which kernels accumulate nutrients and mass. Any environmental stress during this stage—such as reduced sunlight from wildfire smoke—can significantly reduce yields and grain quality.
What are the effects of ground-level ozone (O₃) on crops?
Ground-level ozone is a pollutant formed when sunlight reacts with pollutants from vehicles or fires. It damages plant tissues, reduces photosynthesis, and impairs crop yields. In 2025, elevated O₃ levels due to climate-induced wildfires are a growing concern in major food-producing regions.
How does wildfire smoke affect agricultural productivity?
Wildfire smoke can block direct sunlight (reducing intensity) while increasing diffuse light, which can have mixed effects on photosynthesis. However, prolonged exposure—especially combined with drought—tends to harm crop yields, particularly during critical growth stages.
Why is crop stress from multiple sources dangerous in 2025?
Crops under simultaneous stressors—such as drought, pests, disease, and smoke—are more likely to fail. This year, climate unpredictability and increased fire events are compounding stress levels, putting pressure on food security in North America and beyond.
What is the Corn Belt and why is it important?
The Corn Belt refers to a region in the U.S. Midwest known for high corn and soybean production. In 2025, it remains a key supplier of global food and feed grains. Any disruption here due to smoke, weather, or ozone directly affects global supply chains and prices.
Why is wildfire frequency increasing in North America?
Due to rising global temperatures, prolonged droughts, and land mismanagement, wildfire seasons are starting earlier and burning more intensely. In 2025, both Canada and the western U.S. have already experienced above-average fire activity, with ongoing threats to agriculture.
What is light-use efficiency in crops?
Light-use efficiency is the plant’s ability to convert sunlight into energy for growth. Diffuse light, often caused by smoke, can enhance this efficiency to some extent. However, too much smoke reduces total light availability and negates this benefit over time.
Why are soybeans more sensitive to ozone than corn?
Soybeans, being dicots, have more porous leaf structures, making them more susceptible to ozone penetration and cellular damage. Studies continue in 2025 to develop more ozone-tolerant varieties as climate change exacerbates this invisible threat to yields.
What steps are being taken in 2025 to mitigate wildfire impacts on farming?
Farmers and researchers are employing remote sensing, forecasting tools, and resilient crop breeding to respond to increasing wildfire smoke exposure. Policy discussions in 2025 also include crop insurance adjustments and climate adaptation programs to protect food systems.
