Balancing Urban Agriculture and Nutrient Management for Sustainable Resource Use

July 04, 2023

Andrea Waters-Rist, Associate Professor in the Department of Anthropology

Story by Rob Rombouts, photo by Agneta Bergström

Geneviève Metson is joining the department of Geography and Environment as an Associate Professor. 

Metson researches the relationships between cities and farms, through the lens of resource management, balancing food security and water quality. Food production requires the use of nutrients – such as a nitrogen and phosphorus – for plant development, but nutrients can be lost along the food chain into the environment and create problems for air and water quality. 

Proper nutrient use exists in a Goldilocks zone, she said. “Phosphorus and nitrogen are not good or bad, and their proper use is simply very space and time specific.” 

She has worked around the world, including in Australia, Canada, Malawi, South Africa, the United States and Vietnam. Each place has its own unique set of considerations, but are also linked through shared natural resource management considerations, notably climate change, water pollution, and access to nutrients. 

A systems-thinking approach 

In her work, she draws upon and collaborates with mathematicians and engineers, as well as biology and social science approaches. She utilizes systems-thinking, with a consideration for how addressing one problem or issue may inadvertently lead to other problems (or benefits).  

For example, some of her work looks at the potential benefits and challenges associated with urban agriculture. Urban agriculture may provide benefits, including increasing the availability of food for some communities, and building social connections. Widespread urban agriculture could also create unforeseen issues associated with overuse of fertilizers. 

“There hasn’t been much research into the nutrient management aspects of urban agriculture,” said Metson. “Laws and regulations may apply to large rural agriculture, but urban agriculture is often overlooked. It’s considered too small to have an impact, but depending on where a garden is located and how people garden, it could be important.” 

To provide some insight into this, she worked with gardeners in Sweden to measure the level of nutrients in the soils of allotment gardens and the amount of nitrogen and phosphorus in water leaching through those soils. Her group also spoke with gardeners to assess how much inputs they used, and about why they took the approaches they did. 

One conclusion from the study was that the potential for nutrient loss is there, but gardeners do not necessarily understand the impact of their nutrient use. Investing in increasing knowledge around nutrient management could help. “Most gardeners want to do a good job for the environment, but don’t always know what they can do,” said Metson.  

“It’s important to stay open to the findings in the data, instead of coming in which a vision or idea that urban agriculture is just a positive,” she said. “We may want to expand urban agriculture, but it might not be the most appropriate form of ecological infrastructure for every site. Systems thinking and monitoring data can help us consider how different aspects need to be managed.” 

In another project, she examined the management of nutrient resources across all of Sweden. Transport costs and logistics are often a barrier to reusing organic waste, including excreta, for the nutrients they contain. Using a spatial approach, Metson and her interdisciplinary team created a mathematical optimization model to determine how to best link areas where animal and human excreta was produced and where there was nutrient crop demand.  

The model minimized transport costs but also had additional considerations to ensure there would not be an over-application of fertilizer, minimizing potential harm to water. The team also included the placement of biogas plants on the landscape as a way to extract energy from excreta before reusing the nutrients to produce food. 

Her work has shown that investing in biogas and transport infrastructure to facilitate the redistribution of resources in excreta can be resilient to large changes in land use. Even under future scenarios where Sweden would reduce animal production substantially and diversify crops, Metson and her team found that the ‘best’ locations for biogas plants were in the same regions as they would be most beneficial today. Fully utilizing the nutrients and energy in organic waste would require substantial investments, but could help achieve better results for many actors. 

Considering trade-offs 

In her undergraduate teaching, Metson will look at resource flows and sustainability along the rural-to-urban continuum, underpinned by systems-thing. The approach requires people to be flexible and plan for scenarios that may not happen, allowing for course corrections based on monitoring and continuous analysis of new data. 

“If you think in systems, you can’t just think about optimizing things,” she said. “How do we provide water, sanitation, and food in a resilient way? We can never know everything and we will make mistakes, but a systems approach and thinking about flexible infrastructure may dampen the impacts of mistakes and learn from them more nimbly.” 

People are making decisions in an increasingly uncertain world, Metson said, and she is “interested in looking at how we can manage for multiple resources at the same time. If we have a climate action plan for a city, we need to look at what trade-offs exist so we don’t paint ourselves into a corner,” when it comes to managing other resources. 

Her appointment at Western will be the first time she is in Geography department, but she sees it as a natural fit, as the discipline brings together spatial, social, and environment issues. She is excited to be part of the department which has embraced the need for both social and natural science methods and approaches to tackling today’s pressing sustainability challenges. 

“You need social science to understand how and why change is complicated but you also need natural science to monitor those changes and make decisions going forward,” she said. Issues of sustainability “are so big and need to be tackled. For me, it’s not about publishing another research paper. It’s about how can we make our research findings relevant to citizens, farmers, and city managers, so that as a society we can make the changes that need to be made.”