Cultivating crops on city rooftops

Cultivating crops on city rooftops

Climate change and population growth mean walls, balconies and roofs across Europe's cities could take on a greener complexion as food production becomes part of the urban landscape.

To meet the challenges of producing food in a more environmentally-friendly way, the European Environment Agency (EEA) has called on cities to develop 'living walls' of edible plants. Through vertical farming, agriculture could become a feature of urban life, lowering energy consumption, carbon emissions and resource use in food production. By shortening the distance produce has to travel from ‘farm-to-fork’, and by negating the need for heavy machinery, vertical farming can reduce CO2 emissions.

“Managing our urban spaces as extensions of agriculture will reduce the demand to turn forests into farmland. Food crops must be brought closer to the table,” says EEA Director Jacqueline McGlade. “We need to have showcase buildings in every city to give a completely different vision of agriculture.”

Vertical farming involves moving agriculture into cities by growing crops in either specially designed structures or in adapted urban spaces. Professor Dickson Despommier from Columbia University in New York, USA has championed the concept of 30-storey skyscraper farms which could meet the needs of 50 000 people. Such buildings would use hydroponic – growing plants in a water and nutrient solution – and aeroponic – growing plants in nutrient-laden mist – methods to produce crops without using soil.

Prof. Despommier believes vertical farms would use 90% less water than traditional farms. Moreover, such farms would offer year-round crop yields without the use of agro-chemicals, and would avoid weather-related crop failures caused by droughts, floods and pests. Without the need for pesticides, food could be produced organically. Moreover, the problem of agricultural runoff would be avoided.

Still, the process is not without its critics. Crop physiology professor Bruce Bugbee, from Utah State University, has questioned the viability of vertical farming by arguing that low light levels during the winter months would require the use of energy intensive high pressure sodium lights.

Increasing plant life within cities would offer the added benefit of absorbing carbon emissions and producing more oxygen. While this would improved urban air quality, research is needed into the impact of carbon dioxide and other pollutants on city grown crops. Meanwhile, green rooftops would have a natural insulating effect on buildings.

The Capital Growth campaign is already promoting urban agriculture. The project aims to help Londoners transform their city by creating 2012 new food growing spaces by the end of 2012 to coincide with the London Olympic Games.

In its initial phase, Capital Growth provided financial support for 70 allotments in London. In addition, the project organiser London Food Link hopes to convert hundreds of flat roofs across the city into vegetable gardens.

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