Urban agriculture is getting a lot of play in green infrastructure plans. Many cities are adapting zoning codes to help clear the way for using open space, rooftops or even public lands for food production. Exactly what would it take for a city to feed itself? What are realistic expectations? University of Washington researchers took a look at the sustainability and food security of Seattle by developing an approximation of suitable land available to grow food and overlaying that with food needs and a mix of crops that could be grown in the climate.
High tech, intensive indoor production was not included, nor did they include backyard chickens or honeybees, or other forms of urban ag. The study made approximations based on nine crops that could provide a complete vegetarian diet through the year and be grown in Seattle. So, drum roll … could Seattle provide its 609,000 residents a year-round, complete vegetarian diet grown in the soil?
Absolutely not, using only land within its city limits, which would yield enough food to meet just 1% to 4% of need. All city residents could be fed if the range was extended to encompass 629,000 acres in a 36-mile circle around the city if you don’t account for the food needs of the 2.9 million people that already live within the circle.
Here’s some of the interesting observations the exercise revealed: First, the researchers set out to create a more realistic estimation of city food production, one that incorporates the effects of the urban forest. Many other efforts to map urban food production have overlooked existing vegetation. Trees in cities do a lot of really great things. Chopping them down to grow food would erase all those benefits. They also wanted to be realistic about the crop mix and match that to local production conditions, as well as provide complete nutrition needs.
By mapping land use, soils and tree locations using GIS, LiDAR and aerial imaging, they determined that 5.5 people could be supported for one year based on the food grown on 1 acre of land. Crops that would provide a complete vegetarian diet, could be grown in Seattle and preserved/stored include: beets, squash, potatoes, carrots, dry beans, barley, kale, hazelnuts and apples.
If all the available land with high light were converted to crop use, they estimated that 21.3% of Seattle’s food needs could be met. However, it’s more realistic to convert turf to food production. If all the turf were converted to food production citywide, 4% of the population could be fed.
While Seattle couldn’t feed itself even if it cut down all its trees, urban agriculture does have other benefits, even when practiced on small parcels. Building community and connecting residents to nature are two major benefits. Urban agriculture production does diversify food availability and it can create jobs, too.
Interestingly, if every homeowner converted their lawn to kale production, there would be enough for each person to get 13.6 lbs. of kale a year. Salad anyone?
Jeffrey J Richardson and L. Monika Moskal, 2016. Urban food crop production capacity and competition with the urban forest, Urban Forestry & Urban Greening. doi:10.1016/j.ufug.2015.10.006. Fewer than 1 in 25 Seattleites can really eat locally.
NewTerrain February 1, 2016