A new University of Waterloo study could act as a roadmap for scientists, policymakers, and the public to begin to overcome the lasting impacts of agricultural nitrogen pollution on water quality.
More out-of-the-box thinking is needed when it comes to addressing nitrogen’s impact from farming fertilizers, the study states. For instance, if it’s unknown how long the nutrient can linger in ecosystems, perhaps it’s time to find ways to reuse nitrogen instead of simply adding more.
“We have to think about the legacy we leave for the future in a strategic way from both the scientific and socio-economic angles,” said Nandita Basu, a professor of Earth and Environmental Sciences and Civil and Environmental Engineering at Waterloo and the study’s lead author, in a statement from the university. “This is a call to action for us to accept that these legacies exist and figure out how to use them to our advantage,” she added.
Too much nitrogen and phosphorus in the water causes algae to grow faster than ecosystems can handle, otherwise known as eutrophication. Algal blooms can harm water quality and decrease oxygen for fish, sometimes producing elevated toxins and bacterial growth that can make people sick when the water is consumed.
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Infants are particularly vulnerable to a nitrogen-based compound called nitrates in drinking water.
According to Statistics Canada, about 75% of total Canadian fertilizer nitrogen application takes place across the three prairie provinces of Alberta, Saskatchewan and Manitoba.
In addition to exploring ways to harvest emitted nitrogen to be reused by farmers as fertilizer, Basu explained that researchers need to develop methodologies to quantify nitrogen legacies and lag times. This would help to set goals, manage expectations, and design the appropriate conservation measures, she said.
To be able to assess the economic impacts of conservation strategies, the study notes that experts will need to incorporate both short- and long-term cost-benefit analyses.
“It’s time we stop treating nitrogen legacies as the elephant in the room and design watershed management strategies that can address these past legacies,” said Basu. “We need to ask ourselves how we can do better for the future.”
The University of Waterloo study recommends that water quality be monitored at both large and small scales so that “short-term results can be seen at scales like a farm field and long-term results downstream at river basins can also be tracked.”
Additionally, researchers suggest combining conservation methods that reduce the amount of nitrogen that has already left farm fields, such as wetland methods that harvest nitrogen from decades of accumulation in the soil.
The study acknowledges that nitrogen legacies are different around the world depending on the climate, historical land use, and land management patterns.
Recent research from Greenpeace suggests that synthetic nitrogen fertilizer usage in Canadian agriculture is eight times the global average per capita. This fertilizer contributes to roughly 3% of global emissions from nitrogen fertilizers, despite Canada having only 0.4% of the world’s population, the study states.