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Researchers identify main threats to the growth of urban agriculture in the U.S.

Published September 30, 2013
urban ag 1
One of six experimental sites (Honore St. Urban Farm) located along an urban to rural latitudinal transect in the Chicago metro region. Photo credit: Sam Wortman

URBANA, Ill. –Researchers at the University of Illinois interested in the emerging sector of the local food economy known as urban agriculture, have identified the main threats to its growth and have set forth future research questions that scientists must tackle in order to ensure its economic and environmental sustainability.

Sam Wortman, a U of I assistant professor of urban food production, and Sarah Taylor Lovell, a U of I assistant professor of landscape agroecology, recently published a report discussing the environmental challenges in urban agriculture such as soil contamination and remediation, altered microclimates and atmospheric pollutants in urban ecosystems, and safety of urban water resources.

Both Wortman and Lovell have focused much of their research attention on Chicago neighborhoods, where they said there is an abundance of both urban gardens and vacant lots.

“There is a huge opportunity for economic growth, but there’s no industry there yet to step in and carry this movement. That’s our role as a land-grant university to help grow the urban agriculture movement through science-based research and information,” Lovell said. “That’s why the U of I in central Illinois is so interested in what’s going on in Chicago.”

Both researchers have ongoing studies looking at some of the environmental threats discussed in the review.

The threat of soil contamination, especially by lead, may be the most serious threat to healthy food production in the urban environment, according to the report. High traffic in urban areas causes contaminants to build up in the soil, and higher lead levels are often found in soil in older neighborhoods with housing built before lead was removed from paint, the researchers found.

Because current soil remediation strategies are intensive and can be cost prohibitive, Wortman said he is now looking at alternate soil management systems to address the limited availability of uncontaminated land where food can be grown, as well. One current project looks at growing in raised beds and appropriate compost selection for areas where soil is highly contaminated.

Other soil management projects include looking at high-tunnel fruit and vegetable production versus open-field environments, hydroponics growing, as well as looking at how to increase productivity for community gardeners using cover crops. 

“Less than 5 percent of urban farmers use cover crops. Rural farmers know the benefits of cover crops but maybe don’t use them for economic reasons, but many community gardeners don’t know what a great way it would be for them to build fertility and organic matter. It’s a shame that they are not used more,” Wortman said.

City-related contaminants not only create concern for urban soil but also for the urban atmospheric environment.

Wortman said another of his current studies involves observing the effects of atmospheric pollutants and altered microclimatic conditions on vegetable crop physiology in Chicago neighborhoods. The researchers have set up six research stations positioned along a latitudinal transect stretching as far to the east as Garfield Park Conservatory and including sites moving to the west near Brookfield Zoo, Wheaton, and St. Charles.

The researchers established common soil lots across these six sites and are looking at the effects of CO2, ozone, temperature, relative humidity, wind, and light intensity, and how these factors influence a wide range of crops.

“We have a strong urban heat island effect in Chicago, so our hypothesis is that maybe warm-season crops like tomatoes and peppers will do really well as you get closer to downtown Chicago. In the rural areas, we expect cool season crops will do better. We find that outside of the city we see the most ozone damage, the worst ozone damage being at St. Charles. This is interesting because the source of ozone is in the city,” Wortman said.

“This is our flagship project, and it’s been the most fruitful,” he added.

Lovell’s work has mainly focused on the ecological and cultural functions of urban agriculture.  In Chicago, Lovell and her team have done extensive mapping of community and backyard gardens, as well as looked at different methods of growing food used in various ethnic communities within the city.

“We’re trying to bring natural and social sciences together to gain an understanding of the cultural differences in how food is grown and the different types of crops produced, considering how all this contributes to community food security,” Lovell said. 

Lovell is also looking at vacant land in these communities and determining if farming is the most appropriate use of that land.

“In Chicago, there are some communities that are mostly vacant now. From an urban planning perspective, just turning it into food production isn’t particularly the best strategy. We need to think about how we plan an agricultural infrastructure that’s sustainable over time—one that can be knitted in to the green space of the city as a long-term planning goal, not just a transient land use,” Lovell said.

Both Lovell and Wortman said lack of funding sources for community gardening programs and individual urban farmers is also a road block for the growth of urban agriculture. Without a strong industry component behind urban farming, Lovell said funding is a major challenge to this industry.

“A lot of the true research going on in rural agriculture is highly supported by and connected to industry so there’s plenty of money and knowledge available. Yet there’s a whole population of urban farmers who don’t have the historical knowledge of food production and they’re not getting the same level of support,” Lovell said. “There are new issues to address now that there is a greater understanding of contamination concerns that draw out serious issues related to human health and productivity.”

“If urban agriculture is going to move toward a more profitable, environmentally sound system, ecologists, hydrologists, horticulturalists, environmental scientists, and others will need to take up this issue or it will continue to be a nice concept that academics like to talk about, but we’ve got to get out there and get our hands dirty and figure out the real challenges and how to solve them,” Wortman said.

“Environmental Challenges Threatening the Growth of Urban Agriculture in the United States,” was published in the Journal of Environmental Quality (J. Environ. Qual. 42:1283–1294 2013) and can be accessed online at https://www.agronomy.org/publications/jeq/pdfs/42/5/1283. Co-authors of the study were Sam E. Wortman and Sarah Taylor Lovell.