The practice of urban agriculture is incredibly variable. There are a tremendous number of current technologies and systems for developing urban agriculture on both large and small scales, and on surfaces that are both horizontal and vertical. It demands a certain ingenuity or creative spirit, to take on farming of all types in the city and the best practices are the ones that take advantage of existing opportunities and infrastructures.
Large scale projects in urban agriculture are less common because they bring up complex political and social issues regarding urban land use, ownership and labor. Cuba is the best, and perhaps only example, of a large scale urban agriculture movement that has been formally deployed. There are also other large scale instances of urban agriculture in other developing countries where it is an issue of survival. There aren’t any examples in the United States currently, but there is a project in the works in New York called the Five Borough Farm. This is a pilot project that is looking to consolidate disused, under-used or vacant urban land in New York City, for the purpose of creating the first city-wide urban agriculture plan in the country. The land under discussion is city owned, and the intention of the project, after completing a survey of existing urban agriculture initiatives throughout the five boroughs, is to leverage the available land base and those existing projects to show the city how it can support and improve the urban agriculture movement in New York through policy changes.
There are countless examples of people producing small amounts of food (vegetables, a fruit tree, etc.) for personal consumption in their own yards. There are also many examples of community based agriculture all over the world. These community gardens are large garden areas in a common space where each tenant has their own area to garden.
On the Roof
Since open land in cities that’s available for growing crops is scarce, many have started growing crops on the other horizontal surface in cities that are in abundance: rooftops. Roof gardens have become ever more popular, especially in cities where land values and density are high. Food production is possible on an intensive green roof where the soil is deep enough to accommodate vegetables, like the Gary Comer Youth Center. These types of systems can be a bit expensive, especially compared to just having large boxes or pots of soil to grow in. A roof can be done by one group that takes care of the entire roof or can be split up and done as community garden plots.
Uncommon ground restaurant roof garden.
On the Roof
Greenhouses can be an important addition to these urban agricultural systems, especially in northern climates where the growing season may be rather short. Adding a greenhouse component to these horizontal systems can allow for much higher production over a longer period of time. Greenhouses can even be operated in a more sustainable manner by using waste heat from a nearby building or industry to heat them.
Dr. Dickson Despommier, of Environmental Health Science at Columbia University makes a compelling argument for utilizing city skyscrapers for vertical farming. He notes that growing food indoors is already becoming commonplace with the techniques of hydroponics (growing plants not in soil, but with the roots in a nutrient rich water solution) as well as aeroponics (growing plants, not in soil but suspended with the roots exposed that are then sprayed with a nutrient-rich water solution).
Hydroponic and aeroponic greenhouses currently allow crops to be produced year-round with maximized yields because of ideal growing and ripening conditions. It can also be done without concern for outdoor environmental conditions such as soil, precipitation or temperature profiles and could even be supplied by gray water and powered by renewable technologies. By utilizing these existing technologies in dense, urban areas, a 30-story building covering one city block could produce 2,400 acres of a year.
Small scale vertical farming can be as simple as a few pots in window sills. There are some products that allow for easier vertical farming. Bohn & Viljoen Architects has designed a hydroponic system that can be hung in a window like a curtain.
Not Just for Veggies
The main reasons for urban agriculture are producing more food closer to home, food security and reducing the demand for food products generated by traditional agriculture systems. Therefore, urban agriculture isn’t just about growing produce, but can also include raising animals.
There has been a strong push for raising chickens in back yards, which is legal in Chicago and many other major cities. Producing much less waste and being less noisy than a dog, there are not many drawbacks to urban chickens. They can produce around an egg a day, which is more nutritious and delicious than store-bought eggs. They can also be fed table scraps, reducing feed cost as well as organic waste that would have to be shipped away.
Aquaculture is the farming of aquatic organisms, including fish, mollusks, crustaceans and aquatic plants. (‘Farming’ here implies some sort of intervention such as regular stocking, feeding, or protection from predators.) Both indoor systems in tanks, and outdoor systems in ponds can be used. Unlike most forms of livestock, aquaculture systems can be very compatible with nearby residential areas and provide an opportunity to treat organic domestic waste. In many countries, such as India, Thailand, China and Vietnam, human waste is used as a source of nutrients for aquaculture, which is then treated in the process; however, this practice needs to be done with extensive management in order to prevent disease. Tilapia and carp are the main fish used in aquaculture.
Dr. Noel Arrold took advantage of an existing disused rail tunnel in Sydney Australia and began growing mushrooms there. The cool, dark and damp space provides a perfect space for growing them, while reinvigorating this existing infrastructure.
Many cities have also started allowing the keeping of bees on rooftops. This greatly helps maintain a bee population within a city, which has many great environmental benefits like pollinating crops on green roofs and other urban farms. They also produce honey, which can be eaten or sold. There are many bee colonies in Chicago, including on City Hall, Chicago Cultural Center and the Marriott Hotel.