Over half of the world’s population lives in cities, and with urban farms on the rise, researchers have begun examining how compatible modern cities are with large-scale food production. Could cities one day produce enough food locally to sustain whole communities?
Several US studies suggest that a lot of little gardens can quickly add up. In Cleveland, converting 80 percent of all vacant lots to urban farms could supply about half the produce, one-fourth the poultry and eggs, and all the honey consumed by the city. However, not all cities have so much spare room. New York City would need between 162,000 and 232,000 acres to grow all its fruits and vegetables, according to Columbia University’s Urban Design Lab, but it has only about 5,000 acres of useful vacant land. Producing a city’s entire food supply in-house, not just fruits and vegetables, is an even greater challenge. Even if all the grassy areas in Seattle were converted to urban farms, they would yield only enough crops for four percent of the city’s residents.
Globally, about one-third of all urban space would be needed to produce the vegetables consumed by city dwellers, though this varies greatly per country. In nations like Laos, Nigeria, and Cuba, the area covered by cities is smaller than the area needed to grow vegetables for those cities, whereas in places like the United States, Australia, and Brazil, 10 percent or less of their urban land would suffice.
Typically, denser cities will have a harder time becoming self-sufficient. Researchers describe cities facing a trade-off between different aspects of sustainability: a city be densely populated or have great amounts of locally grown food, but not both. However, converting rooftops to urban farms helps immensely. One analysis found that covering the flat roofs of Bologna, Italy, with soil-free gardens could yield 12,000 tons of vegetables annually, or 77 percent of what the city’s inhabitants consume.
Still, there are many opportunities for old-fashioned, in-the-dirt farming within cities: over half the world’s urban residents live in small-to-medium-sized cities, which tend to have plentiful open spaces for urban agriculture to thrive. Plus, the UN’s Food and Agriculture Organization estimates that at least 800 million people are already growing food in and nearby cities. Many of these people currently live in poverty, and growing some extra produce to sell to other city dwellers can provide them with both economic and nutritional benefits. For instance, in the Kibera slum of Nairobi, Kenya, families who engage in sack gardening, in which vegetables such as kale and Swiss chard are planted in soil-filled sacks, eat a wide range of vegetables, consuming some of the vegetables they grow and using money earned from selling their crops to buy other foods.
Ultimately, each city and its inhabitants will face a unique blend of challenges and benefits in choosing to move towards a model of urban farming and increased agricultural self-sufficiency, and this trend will only become more visible in the coming years.
Source: DeWeerdt, Sarah. “Can Local Food Feed an Urban World?” Anthropecene. October 2016.