URBAN agriculture is promoted as a strategy for dealing with food insecurity, stimulating economic development and combating diet-related health problems in cities, but until now, no one has known how much gardening takes place in urban areas.
Researchers at the University of Illinois at Urbana-Champaign developed a methodology that they used to quantify urban agriculture in Chicago, Ill., according to a news release.
John Taylor, a University of Illinois doctoral candidate working with crop sciences researcher Sarah Taylor Lovell, was skeptical about the lists of urban gardens provided to him by local non-governmental organizations (NGOs).
"Various lists were circulating," he said. "One of them had almost 700 gardens on it."
On closer inspection, however, many of these "gardens" turned out to be planter boxes or landscaping and were not producing food. On the other hand, Taylor suspected that there were unnoticed gardens in back yards or vacant lots.
"There has been such a focus on community gardens and urban farms but not a lot of interest in looking at backyard gardens as an area of research," Lovell said.
An accurate map of these sites would be helpful for advocacy groups and community planners, according to the news release.
Taylor uploaded the lists from the NGOs into Google Earth, which automatically geocoded the sites by street address. He used a set of reference images of community gardens, vacant lot gardens, urban farms, school gardens and home food gardens to determine visual indicators of food gardens (Figure). Using these indicators and Google Earth images, he then examined the documented sites.
Of the 1,236 "community gardens," only 160, or 13%, were actually producing food.
Taylor then looked at Google Earth images of Chicago to locate food production sites. He identified 4,493 possible sites, most of which were residential gardens of 50 sq. m or less, and visited a representative sample of gardens on vacant land to confirm that they were really producing food.
All of the large sites and a sample of the small sites were digitized as shape files in Google Earth and imported into a geographic information system (GIS) mapping tool to calculate the total area.
The final estimate was 4,648 urban agricultural sites with a production area of 264,181 sq. m. Residential gardens and single-plot gardens on vacant lots accounted for almost three-fourths of the total, according to the university.
Lovell said, in some communities, more than half of the lots are vacant, and making use of them could be a huge opportunity. Chicago has a program that allows people living next to a vacant lot to purchase it at a fraction of what it would normally cost.
The results of this study suggest that both backyard gardens and vacant lot gardens contribute substantially to Chicago's total food production, according to the university.
"Home gardens actually contribute to food security," Taylor said. "They're underappreciated and unsupported."
He noted that people grow food not only for themselves but for their neighbors as well, which is particularly important in food deserts, where fresh produce is in short supply.
"There is also potential for empowering people because they are using their own space to deal with their own food security concerns," Lovell added.
The study, "Mapping Public & Private Spaces of Urban Agriculture in Chicago through the Analysis of High-Resolution Aerial Images in Google Earth," was published in Landscape & Urban Planning and is available online at www.sciencedirect.com/science/article/pii/S016920461200237X.