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University of Sheffield Study Reveals Potential of Urban Agriculture in Food Supply

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Growing fruit and vegetables in just 10 percent of a city's gardens and other urban green spaces could provide five servings of fruits, vegetables and vegetables for 15 percent of the local population, according to a survey conducted in England. The data refer to the city of Sheffield, which has an estimated afforestation of 45%, but it is an interesting indicator even for less afforested cities.

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In a study published in the journal Nature Food, academics from the Institute of Sustainable Food at the University of Sheffield, UK, investigated the potential of urban agriculture by mapping the city's green and gray spaces that could serve as urban farms.

They found that green spaces, including parks, gardens, allotments, roadsides and woodland, cover 45% of the city of Sheffield, similar to other cities in the UK. Community gardens, common in England, cover 1.3% of that, while 38% of the green space is made up of home gardens, which have immediate potential to start growing food.

The interdisciplinary team used data from the Ordnance Survey It's from Google Earth to reveal that another 15% of the city's green space, such as parks and roadsides, also has the potential to be converted into vegetable gardens or community lots.

Bringing together adequate home gardens, lots and public green spaces would open up 98 square meters per person in Sheffield for growing food. This equates to more than four times the 23m2 per person currently used for market gardening across the UK.

If 100% of the green space available in the city were turned into urban farms, the production could feed approximately 709,000 people a year with the five daily servings of fruits and vegetables recommended by WHO. This number is equivalent to 122% of the population of Sheffield.

Even with a more realistic conversion of only 10% of home gardens and 10% of available green space on farms, as well as maintenance of the current land area, it would still be possible to provide fresh food for 15% of the local population - 87,375 people.

Pathway to food security

These projections represent a possible path for the United Kingdom, which has only 16% of fruits and 53% of vegetables sold grown in the country. The establishment of urban farms could significantly improve the country's food security.

The study also investigated the potential of soil-free urban agriculture, developed on flat roofs and with methods such as hydroponics, where plants are grown in a nutrient solution, and aquaponics, a system that combines fish and plants. These techniques can allow year-round cultivation with minimal lighting requirements, using greenhouses powered by renewable energy and heat captured from the buildings themselves, with rainwater harvesting for irrigation.

In central Sheffield, flat roofs cover 32 hectares of land, equivalent to half a square meter per inhabitant. Despite being a low number, researchers believe that the high yield of soilless agriculture could make a significant contribution to local horticulture.

The UK currently imports 86% of its total tomato supply. In Sheffield, if only 10% of the identified flat roofs in the city center were to become soilless tomato farms, it would be possible to increase production enough to provide one of five servings of fresh food for more than 8% of the local population. This projection increases to over 60% if three quarters of the flat roof area were used as urban farms.

Currently, the UK is totally dependent on complex international supply chains for the vast majority of its fruits and half of its vegetables, but research suggests there is more than enough space for the country to grow its own food in its home garden. .

“Even cultivating a small percentage of available land can transform the health of urban populations, improve the city's environment and help build a more resilient food system,” says Dr. Jill Edmondson, University of Sheffield Environmental Scientist and Principal author of the study.

Significant cultural and social changes would be needed to reach this enormous potential for cultivation in cities. Professor Duncan Cameron, co-author of the study and director of the Sustainable Food Institute at the University of Sheffield, says "it is crucial that authorities work closely with communities to find the right balance between green space and horticulture."

“With careful management of green spaces and the use of technology to create distribution networks, it would be possible to see the emergence of “smart cities for food”, where local producers can support their communities with fresh and sustainable food”, speculates the scientist .

In large cities like São Paulo, with fewer urban green areas but more roofs, it is also possible to imagine a huge potential for building urban farms and optimizing supply networks.