UNIVERSITY OF SASKATCHEWAN
Nitrogen's role in food systems

"It's not a linear spectrum where we have to try balance environmental gains against economic benefits," she says. "It's more like a synthesis, where working towards a better understanding can help advance a number of objectives, including food security, environmental and economic goals, health and nutrition as well as a thriving society. Nitrogen intersects all of these spheres in visible and invisible ways."

Nitrogen - a "key component of DNA, proteins and amino acids - is vital for all living things, and this has earned it a special role in food systems," says Dr. Congreves, an associate professor in the Department of Plant Sciences and the Jarislowsky and BMO Chair in Regenerative Agriculture in the University of Saskatchewan's College of Agriculture and Bioresources. "An interesting juxtaposition about nitrogen is that it is simultaneously an essential resource for agriculture and an environmental threat."

While nitrogen fertilizer is crucial for supporting crop production, its application starts "a cascade of transformations where some of that nitrogen can be lost to the environment, for example, when it is emitted as nitrous oxide, a potent greenhouse gas," she says.

As a result, nitrogen fertilizer applications represent the largest source of anthropogenic emissions. "Lowering these emissions through improved fertilizer use is an important strategy for reducing the carbon footprint of the overall supply chain and for meeting fertilizer-related emission targets set by the government," Dr. Congreves proposes. "The pathway to sustainability relies on a better understanding of the nitrogen dynamics and the various practices designed to reduce losses."

Interest in sustainable agriculture is growing, whether that's "under the banners of land stewardship, soil health, regenerative agriculture, agroecology, nature-based solutions or climate-smart agriculture," says Dr. Congreves. "These terms are increasingly common in our collective lexicon - and these concepts are being embraced not just by farmers but also the general public."

The resulting boost in awareness can - together with evidence-based recommendations and tools and technologies - contribute to better outcomes for farmers and ecosystems, she says. "However, due to the complexity of these interconnected areas and their unique challenges, we need cross-disciplinary collaboration. We need to understand all the costs and impacts as well as consider the broader perspectives."

Just as nitrogen is positioned at the core of several key challenges, so is the University of Saskatchewan - with its location "in the heartland of Canada's major crop producing region, which makes it a good place to explore challenges and opportunities in the Canadian food system," Dr. Congreves says. "One of USask's signature areas is agriculture but there is also a strong focus on health and wellness and sustainability, areas that come together under One Health."

USask President Peter Stoicheff.

One Health, a signature area of research at USask, explores solutions at the animal-human-environment interface. An understanding that human, animal and environmental health are interconnected - and that one cannot progress at the cost of others - has inspired broad interdisciplinary collaborations, which benefit from advanced research infrastructure and partnerships, says USask President Peter Stoicheff.

"For example, we have the Global Institute for Water Security and the Global Institute for Food Security, " he says. "We also have Canada's only synchrotron facility, the Canadian Light Source, and the Vaccine and Infectious Disease Organization - facilities that act as a talent magnet for people from around the world."

Creating a research hub in the Canadian Prairies has led to a culture where experts from different fields work collaboratively with one another as well as "rub shoulders with international researchers who use our cutting-edge research infrastructure," Dr. Stoicheff explains. "This informs our focus on being the university the world needs - and inspires efforts to come up with solutions for a better future. "

Dr. Congreves and her team collaborate with the Global Nitrogen Innovation Center for Clean Energy and the Environment (NICCEE) as well as the Canadian Nitrous Oxide Network (CANN2ONET), organizations that aim to gather data and advance best practices related to nitrogen use and production.

"Better information, including from field measurements, can enhance our predictive capabilities," says Dr. Congreves, "which, in turn, can help us make informed recommendations."

Coordinated efforts to advance measurements, modeling and recommendations can provide valuable insights, for example, for strategies for more efficient and sustainable nitrogen use, which can focus on three aspects: soil, crops and fertilizer, according to Dr. Congreves.

"Looking at soil, we found that management practices aimed at soil health, maintenance or improvement can also bring nitrogen benefits. For example, using cover crops in crop rotations is a common soil management strategy that can help to improve nitrogen use efficiency," she says, adding that research suggests such improvements bolster synchronicity between when crops need nitrogen and when the soil releases nitrogen in mineral form.

Dr. Kate Congreves. (Photo: Matt Braden)

Guiding decisions related to fertilizer management is the 4R Nutrient Stewardship framework, which stands for "right rate, right source, right timing and right placement of fertilizer," and Dr. Congreves explains that when farmers apply the method to nitrogen, this bolsters nitrogen-use efficiency and leads to reduced emissions. 

Especially impactful are fertilizer adjustments based on soil testing, which is commonly performed as part of a farmer's agronomic plan, she says. "On the semi-arid prairies, we were able to maintain yields while reducing nitrous oxide emissions by more than half compared to a conventional approach. This result was largely driven by mitigating excessive build-up of residual nitrogen in the soil."

For crops, the biggest determinant for nitrogen efficiency is "cultivar selection," says Dr. Congreves. "We see an association between high-yielding crops and an improved ability to recover fertilizer nitrogen and translocate it to harvestable organs, and we found this in different crop types, for example, small grains and potatoes."

Another consideration for better outcomes "is to take the information from the soil, the fertilizer and the crop decisions - and look at the cropping system design as a whole, including crop rotation and diversification, for nitrogen management," she adds.

There are also opportunities to reduce greenhouse gas emissions at the production stage. Efforts are underway to advance alternatives to the fossil-fuel-intensive Haber-Bosch process, which enabled the production of relatively inexpensive nitrogen fertilizer leading to a global rise in food production throughout the 20th century.

"What we're seeing today is the use of renewable energy for producing green ammonia, and this offers a pathway for decoupling fertilizer production from fossil fuels and thereby reduce emissions," says Dr. Congreves, who adds that small modular units can enable green ammonia production directly on farms.

"While this represents benefits like decentralizing fertilizer protection and enabling enhanced regional access, it can also bring potential challenges, such as safety issues and overuse - and associated emissions - due to increased availability," she explains. "This makes research on nitrogen use optimization even more pressing going forward."

Focusing on nitrogen allows Dr. Congreves to achieve an impact on many levels, both today and in the future, for example, through enhancing outcomes for food producers, mitigating fertilizer-related greenhouse gas emission, supporting clean technology advancement, and more.

Original article published at the Globe and Mail.