Urban Agriculture Provides Food Security and Feeds the Poor
For almost the entire duration of the Holocene, right up until the Green Revolution really got underway in the 1950s and ‘60s,[i],[ii] humans produced most of their food close to home. Sixty years on, most city-dwelling humans have forgotten how to grow food, or have no facility for growing food at home. With more than half the world now living in urban areas, the challenge will be to feed urban residents during a sustained food supply crisis.
On a worldwide basis there are perhaps 200 million urban farmers, with two-thirds of these food providers being women.[iii],[iv] Urban agriculture is already an important component of urban food supply to the world’s poor, and would play a key role in helping provide food security during a serious food crisis.[v]
To put a global food crisis in perspective, under normal conditions the world’s poor spend the majority of their income on food,[vi] and would therefore be highly vulnerable to food price inflation during a food crisis. With an estimated 1 billion poor people subsisting in urban slums, particularly in Asia, Africa, and Latin America,[vii] urban agriculture has a key role to play in creating urban food security.
Urban agriculture involves the production of food at home or in a variety of urban land locations and building types. Urban agriculture utilizes gardens, greenhouses, balconies, walls, rooftops, and plots of peri-urban land (i.e., land surrounding cities) up to tens of kilometres from the city boundary. Food production is achieved using traditional land garden-based methods and technology-enabled systems such as vertical gardens, greenhouses, covered crops, hydro- and aqua-ponic systems, and aquaculture systems (see Growing food in climate extremes, Winter greenhouse design, see below).[viii],[ix],[x],[xi],[xii]
Typically, urban and peri-urban agriculture supplies food all year round, generally consisting of perishable, short-cycle crops such as vegetables (leafy greens, tomatoes, potatoes, cucumbers, peppers, etc.), herbs and fruits, medicinal crops, and fish and small livestock.
Urban and peri-urban food production is complementary to rural food supply, which ensures perishable products are grown or raised close to their point of consumption. This reduces food waste, particularly where cold storage is limited.[xiii],[xiv],[xv]
In some countries the level of urban food production is high, demonstrating that with the right municipal support significant food quantities can be grown in or around cities. For example, in Asia, Africa, Latin America, and Eastern Europe urban agriculture supplies about one-third of urban household food, rising to over half among the poor.[xvi] For certain foods such as greens, grains, milk, and eggs, urban and peri-urban farming can fully provide a small city’s food supply.[xvii],[xviii],[xix]
What is very clear is that if city governments wish to decentralize a significant share of a city’s food supply in order to achieve improved food security, then they must make urban food production a key part of city planning. This includes supportive policies, land designation, and the provision of infrastructure and services (i.e., irrigation, waste management, compost, markets, and storage), advisory help, and educating children about urban agriculture.
Urban Food Production without Soil
The common denominator between hydroponics, aeroponics, and aquaponics, is that food can be grown efficiently using nutrient-rich water instead of soil. These production systems are well suited to growing vegetable greens, vine crops such as tomatoes, cucumbers, peppers, squash, courgettes, and green herbs.[xx],[xxi]
Hydroponics utilizes a small fraction of the water resources used in conventional land-based methods, while bathing plant roots in nutrient-rich solutions.[xxii],[xxiii] Aeroponics on the other hand utilizes misting systems to deliver nutrients directly to plant roots, and thus drastically reduces resource inputs.[xxiv]
Aquaponics couples freshwater aquaculture with hydroponics to produce fish (e.g., tilapia, carp), as well as fruit, vegetables, and herbs. Plant roots suspended in flat tanks or in racks of horizontal PVC-tubes that can be stacked vertically filter the nutrient-rich fish wastewater.[xxv],[xxvi]
Hydro-aero-aqua-ponics are important technologies for commercial and private urban food production, and can be deployed indoors, on rooftops, and in greenhouse settings, and on different production scales from small to commercial.[xxvii],[xxviii],[xxix] While expensive and knowledge-intensive during setup, once operational food production is cheaper than by conventional farming methods.[xxx]
These systems eliminate the need for fertile land, utilize a fraction of space compared with traditional food production, and can be stacked vertically using various methods. They permit year-round food production, resulting in increased crop yields.[xxxi],[xxxii] All of the above qualities make hydro-aero-aqua-ponic systems among the most promising technologies for sustainable urban food production.
These systems can be made more sustainable by integrating them into energy efficient buildings, and employing renewable energy systems for lighting, water pumps, and water and air heating. Recovering energy from biomass (i.e., gas) or converting that biomass to body mass by feeding it to poultry or goats will help make these systems fully sustainable.[xxxiii] Rainwater harvesting and recycling water and nutrients will improve the sustainability of hydro-aero-aqua-ponic systems.
[i] R. E. Evenson and D. Gollin, “Assessing the Impact of the Green Revolution, 1960 to 2000.” Science 02 May 2003: 758-762.
[ii] Prabhu L. Pingali, “Green Revolution: Impacts, limits, and the path ahead.” PNAS. July 31, 2012, Volume 109, no. 31. www.pnas.org/cgi/doi/10.1073/pnas.0912953109.
[iii] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[iv] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[v] Alberto Zezza, Luca Tasciotti, “Urban agriculture, poverty, and food security: Empirical evidence from a sample of developing countries.” Food Policy 35 (2010) 265–273. doi:10.1016/j.foodpol.2010.04.007.
[vi] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[vii] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[viii] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[ix] Philippe Tixier and Hubert de Bon, Urban Horticulture. CIRAD, France. First published as Chapter 11 of the RUAF publication “Cities Farming for the Future; Urban Agriculture for Green and Productive Cities” by René van Veenhuizen (ed.), RUAF Foundation, the Netherlands, IDRC, Canada and IIRR publishers, the Philippines, 2006 (460 pages).
[x] Kathrin Specht et al., “Urban agriculture of the future: An overview of sustainability aspects of food production in and on buildings.” March 2014. Agriculture and Human Values 31(1). DOI: 10.1007/s10460-013-9448-4.
[xi] S. Thomaier et al., 2015, “Farming in and on urban buildings: Present practice and specific novelties of Zero-Acreage Farming (ZFarming).” Renewable Agriculture and Food Systems, 30(1), 43-54. doi:10.1017/S1742170514000143.
[xii] Ali AlShrouf, “Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming.” American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, 247-255.
[xiii] P. Moustier, 2007, “Urban Horticulture in Africa and Asia, An Efficient Corner Food Supplier.” ISHS Acta Horticulturae, 762 :145-148.
[xiv] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[xv] Kathrin Specht et al., “Urban agriculture of the future: An overview of sustainability aspects of food production in and on buildings.” March 2014. Agriculture and Human Values 31(1). DOI: 10.1007/s10460-013-9448-4.
[xvi] Alberto Zezza and Luca Tasciotti, “Urban agriculture, poverty, and food security: Empirical evidence from a sample of developing countries.” Food Policy 35 (2010) 265–273. doi:10.1016/j.foodpol.2010.04.007.
[xvii] P. Moustier, 2007, “Urban Horticulture in Africa and Asia, An Efficient Corner Food Supplier.” ISHS Acta Horticulturae, 762 :145-148.
[xviii] Philippe Tixier and Hubert de Bon, Urban Horticulture. CIRAD, France. First published as Chapter 11 of the RUAF publication “Cities Farming for the Future; Urban Agriculture for Green and Productive Cities” by René van Veenhuizen (ed.), RUAF Foundation, the Netherlands, IDRC, Canada and IIRR publishers, the Philippines, 2006 (460 pages).
[xix] Francesco Orsini et al., “Urban agriculture in the developing world: A review.” October 2013Agronomy for Sustainable Development 33(4):695-720. DOI: 10.1007/s13593-013-0143-z.
[xx] Kathrin Specht et al., “Urban agriculture of the future: An overview of sustainability aspects of food production in and on buildings.” March 2014. Agriculture and Human Values 31(1). DOI: 10.1007/s10460-013-9448-4.
[xxi] Devi Buehler and Ranka Junge, “A Review. Global Trends and Current Status of Commercial Urban Rooftop Farming.” Sustainability 2016, 8(11), 1108; doi:10.3390/su8111108.
[xxii] Ali AlShrouf, “Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming.” American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, 247-255.
[xxiii] Kathrin Specht et al., “Urban agriculture of the future: An overview of sustainability aspects of food production in and on buildings.” March 2014. Agriculture and Human Values 31(1). DOI: 10.1007/s10460-013-9448-4.
[xxiv] Ali AlShrouf, “Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming.” American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, 247-255.
[xxv] Devi Buehler and Ranka Junge., “A Review. Global Trends and Current Status of Commercial Urban Rooftop Farming.” Sustainability 2016, 8(11), 1108; doi:10.3390/su8111108.
[xxvi] David C. Love et al., “Energy and water use of a small-scale raft aquaponics system in Baltimore, Maryland, United States.” Aquacultural Engineering, Volume 68, 2015. 19-27. https://doi.org/10.1016/j.aquaeng.2015.07.003.
[xxvii] Lim Yinghui Astee and Nirmal T. Kishnani, 2010, “Building Integrated Agriculture: Utilizing Rooftops for Sustainable Food Crop Cultivation in Singapore.” Journal of Green Building: Spring 2010, Volume 5, No. 2, 105-113.
[xxviii] Devi Buehler and Ranka Junge, “A Review. Global Trends and Current Status of Commercial Urban Rooftop Farming.” Sustainability 2016, 8(11), 1108; doi:10.3390/su8111108.
[xxix] S. Thomaier et al., 2015, “Farming in and on urban buildings: Present practice and specific novelties of Zero-Acreage Farming (ZFarming).” Renewable Agriculture and Food Systems, 30(1), 43-54. doi:10.1017/S1742170514000143.
[xxx] Ali AlShrouf, “Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming.” American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, 247-255.
[xxxi] Ali AlShrouf, “Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming.” American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 27, No 1, 247-255.
[xxxii] Dionysios Touliatos et al., “Vertical farming increases lettuce yield per unit area compared to conventional horizontal hydroponics.” Food and Energy Security 2016; 5(3): 184–191. https://doi.org/10.1002/fes3.83.
[xxxiii] Devi Buehler and Ranka Junge., “A Review. Global Trends and Current Status of Commercial Urban Rooftop Farming.” Sustainability 2016, 8(11), 1108; doi:10.3390/su8111108.
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