Peri-urban agriculture

Aspect of agriculture

Example of peri-urban farmland with new suburban developments in the vicinity, Bonnyrigg, Scotland. Much of this peri-urban land is in the process of conversion from agriculture to livery.[1]

Peri-urban regions can be defined as 'superficial' rural areas that are within the orbit of immediate urban hubs, in other words, areas that surround large population centers.[2] These regions can also be referred to as 'exurban areas', 'the rural-urban fringe' or the 'fringe', they include the transition zones between the outer limits of the commuter belt and the edge of newly constructed suburban areas.[3]

Peri-urban agriculture is generally defined as agriculture undertaken in places on the fringes of urban areas. However, peri-urban agriculture can be described differently depending on the myriad of urban-rural relationships, and the different farming systems within the various cities and contrasting regions around the world.[4] For instance, the focus of peri-urban agriculture in developing countries is primarily concentrated on the relief of hunger and poverty, hence, food security,[5] as for industrialized countries the emphasis is on ecological and social values.[6] There is no universally agreed definition, and usage of the term generally depends on context and operational variables.[7] The Food and Agriculture Organization of the United Nations defines peri-urban agriculture as "agriculture practices within and around cities which compete for resources (land, water, energy, labour) that could also serve other purposes to satisfy the requirements of the urban population."[8]

The term “peri-urban” used to describe agriculture, while difficult to define in terms of geography, population density, percentage of labor force in agriculture, or any other variable, often serves the purpose of indicating areas along the urban-rural continuum. These are places with dynamic landscape and social change and are often invoked in conversations about growth of cities.

Peri-urban agriculture is first and foremost "the production and distribution of food, fiber and fuel in and around cities".[9] Nevertheless the leading "feature of urban and [peri-urban] agriculture which distinguishes it from rural agriculture is its integration into the urban economic and ecological system"[10]

## History[edit]

The concept of peri-urban has become prevalent as a result of limitations in the dichotomy between rural areas and urban areas. Historically, rural and urban land have been viewed as two separate economic systems with few interactions. Often, these arguments refer to the disappearance and urbanization of rural land. Peri-urban land falls along the continuum of urban to rural land and recognizes links between the two.[11]

## Implementation[edit]

Urban and peri-urban agriculture is expected to become increasingly important for food security and nutrition as rural land is built up. It is predicted to be particularly key for growing perishable produce accessible to the approximately 700 million urban residents already living in developing countries, especially because most growth is expected to take place in urban areas of developing countries.[12]

Urban and peri-urban agriculture tend to differ in their form and their purpose. "Urban" usually refers to small areas such as vacant plots, gardens, balconies, containers within cities for growing crops and raising small livestock or milk cows for own consumption or sale in neighbourhood markets. Peri-urban farming more often consists of units close to town which operate intensive semi- or fully commercial farms to grow vegetables and other horticulture, raise chickens and other livestock, and produce milk and eggs.[7]

Peri-urban livestock production is often based on small ruminants such as goats and sheep, which occupy less space than cows and bulls, are subjects of virtually no religious taboos, can provide both meat and milk, and generally reproduce at two to three years old.[13]

## Benefits[edit]

Peri-urban agriculture provides environmental benefits by preserving or creating urban open space in city edges where green space may be threatened by expanding urbanization. In addition to aesthetics, preservation and creation of green space has positive climatic effects including augmenting carbon sequestration, reducing the urban heat island effect, and providing a habitat for organisms.[14] Peri-urban agriculture may also help recycle urban greywater and other products of wastewater, helping to conserve water and reduce waste.[15]

### Ecosystem services[edit]

Urban and peri-urban agricultural systems can improve urban environments through provisioning, regulating, supporting and cultural ecosystem services.[16] Ecosystem services are "the benefits human populations derive from ecosystems".[17] Through the use of vacant lots and open spaces in urban and man-made environments, urban and peri-urban agriculture (UPA) contribute to the increase of ecosystem services in these otherwise low providing areas.[18] Additionally, urban and peri-urban agriculture may prevent the extension of agriculture in rural areas, therefore, allowing the preservation and protection of threatened ecosystems and their ecosystem services. Also, the increase of food production capacity in urban and peri-urban areas allows the decrease of the conversions of non-agricultural land to farmland.[16] Moreover, the level of degradation or revitalization of ecosystem services depends on whether an agricultural system is being managed in a sustainable way. For agricultural sustainability is not only about agricultural production but also about managing the landscapes surrounding the agricultural activities.[19] Some of the ecosystem services provided by urban and peri-urban agriculture are inter alia, wildlife habitat,[20] nutrient cycling,[21] temperature regulation,[22] carbon sequestration,[23] water filtration and flood prevention,[24] cultural information,[25] and recreation.[26]

#### Supporting[edit]

Urban and peri-urban agriculture zones are key drivers for sustainability and urban biodiversity. Biodiversity favors resilience[27] by supporting and mitigating the negative impacts of the built environment by hosting a diversity of fauna and flora.[20] Also, small urban and peri-urban managed systems have higher quality soil formation than agricultural soils, because of the regular inputs of organic matter, such as composts and manures.[23]

#### Regulating[edit]

High levels of air pollution are present in urban centers which can have negative effects on human health,[28] therefore urban and peri-urban agriculture can help mitigate greenhouse gas emissions (GHG) through carbon storage and carbon sequestration.[16] Furthermore, urban and peri-urban systems contribute to regulating temperatures in cities, in fact, evapotranspiration from urban and peri-urban agriculture can reduce the effects of urban heat islands.[22]

#### Provisioning[edit]

The production of local food contributes to food security and food safety,[29] by shortening the supply chain and reducing transportation.[30]

#### Cultural[edit]

Alongside supporting and regulating ecosystem services, urban and peri-urban systems have a cultural and traditional value, some consider urban and peri-urban agriculture as a form of leisure, whereas other as a way of maintaining and perpetuating cultural and traditional agricultural practices.[31]

### Multifunctionality[edit]

Peri-urban agriculture is multifunctional. "Multifunctional agriculture" refers to agriculture beyond its primary role of producing food and fibre, but as also having other functions. The key elements of multifunctionality are commodity and non-commodity outputs. Commodity outputs are food and fiber, as well as marketable products such as tourism. Non-commodity outputs include, food security, food safety, environmental protection, biodiversity, and a rural way of life.[32]

Also, the concept of multifunctionality is based on the idea of sustainable development, it aims at integrating the information over time and the geography of land uses and functions beyond its traditional function of food production, to include nature conservation, hydrological balance, aesthetics and recreation.[9] According to OECD, "beyond its primary function of supplying food and fiber, agricultural activity can also shape the landscape, provide environmental benefits such as land conservation, the sustainable management of renewable natural resources and the preservation of biodiversity, and contribute to the socio-economic viability of many rural areas".[33]

#### Social[edit]

In developing countries, besides the question of food security, one significant social dimension of peri-urban agriculture, specifically around production sites, is the rebuilding of communities and civil society.[34]

Studies have shown that urban gardening and farming, particularly when done in a community setting, have positive effects on nutrition, fitness, self-esteem, and happiness, providing a benefit for both physical and mental health.[35]

Closely related to health is food security, or dependable access to adequate and nutritious food. Urban gardening may be an opportunity for the urban poor to produce food for themselves or to sell their products for income, adding to income security.[36] Localized agriculture can also improve resilience by ensuring that there will be a more certain food supply in times of shortage, instability, and uncertainty. Indeed, peri-urban agriculture can be advantageous because of the proximity of production to the consumer. Particularly, the fresh fruits, vegetables and local foods that are available for communities and neighborhoods that live in food deserts.[37]

In addition, residents who share a plot of land may benefit from social interaction and recreation with others.[38] Agriculture is often an effective strategy for poverty reduction and social integration of disadvantaged groups, with the aims of integrating them into the urban network, providing a decent livelihood, and preventing social problems such as drugs and crime.[39]

#### Environmental[edit]

In many urban areas peri-urban agriculture reduces the environmental impacts of urban expansion by serving as an ecological buffer.[40] Unlike traditional farmers, peri-urban professionals have greater conscious of the ecological value of the environment.[40]

Moreover, local production and consumption of foods reduces the consumption of energy due to shorter transportation distances, less packaging and processing, and greater efficiency in production inputs.[41] Likewise, the recycling of urban waste into compost and waste water for irrigation conserves energy.[42] Peri-urban systems, can also contribute to biodiversity conservation through the integration of native species,[43] as well as modify positively urban micro-climates by regulating humidity, providing shade and regulating the wind.[44]

Comparatively to conventional food systems, the limited use of energy in peri-urban agriculture reduces greenhouse gas emissions and has lower impacts on global warming.[45]

#### Economic[edit]

The new business opportunities generated by peri-urban agriculture allow the creation of jobs and the generation of revenue, as well as improving local infrastructure and services, such as the construction of roads, schools, and restaurants. It also furthers agricultural training and education.[40] Indeed, beyond providing productivity to vacant land, treated wastewater and recycled waste, urban and peri-urban agriculture is an important source of income for many urban poor. Farming households lower their food costs substantially and can generate income by selling excess produce, which is significant, as urban poor commonly spend 50-70% of their income on food.[39] In addition to farming jobs, peri-urban agriculture can spark a need for traders, input suppliers, processors, marketers, and others. Peri-urban agriculture gives women and other non-heads of household a low-barrier occupation through which to support their families, adding to household productivity and giving women an outlet to assert themselves.[8]

Producing food in areas nearby to cities shortens supply chains, which aids quality and cost. The proximity of peri-urban farms to urban areas incurs cost savings compared to those in rural areas, as farms are still able to take advantage of economies of scale, to an extent, and require less transportation infrastructure to bring food in from city outskirts.[15] Perishable products are more easily preserved. Peri-urban farms are also able to flexibly respond and market themselves to urban consumer demands, since they are able to be closer and more specialized, and are tightly linked to the urban economy.[11]

## Challenges[edit]

Challenges for peri-urban agriculture, like its benefits, arise from its proximity to densely built urban areas. Competition for resources with other urban sectors, aspects of agriculture that may be unpleasant for city dwellers, and quality of inputs must all be monitored.

Wise resource allocation is a quintessential struggle for agriculture, and is especially greater for peri-urban agriculture than rural agriculture due to its proximity to greater numbers of people and to existing stresses on the urban environment. Peri-urban agriculture uses land, water, labor, and energy that might be used by other urban economic sectors.[11]

### Outputs[edit]

Peri-urban agriculture produces some aspects that may be unpleasant for urban residents, including smells, noises, pollution, and disease.

Management of animal waste can be challenging, since manure may contain chemicals and heavy metals unsuitable for use as fertilizer – and may even be hazardous. Runoff from facilities leads to overnutriented soils and water, which can in turn cause eutrophication and algal blooms in nearby water supplies.[46]

Pathogens are often spread from wastewater reused for irrigation, from live animals in close proximity to dense human populations, and the disposal or sale of manure. Crops are an opportunity to reuse urban waste productively, and wastewater as an irrigation source in particular has been explored by some cities to conserve water. If not treated properly before application, this wastewater can contaminate crops or surrounding vegetation with pathogens that make them unsafe for human consumption. This is a food safety concern especially in markets with unlicensed vendors and missing enforcement of safety regulations, which are common venues for small urban and peri-urban farmers.[47]

Animals raised in a peri-urban agriculture setting are by nature in close proximity to dense human populations and are often sold live or processed at food markets. Animal production is not allowed in some city centers – for example, in Beijing it is not allowed within the borders of a certain road that delineates the city center, but on the outskirts of cities it is growing as an industrial production system particularly as diets change to demand more meat.[48] This has been a major factor in the avian influenza epidemics that have heavily affected Hong Kong, Nigeria, and Egypt. During outbreaks, people are advised to avoid open poultry markets.[49]

The disposal of manure is a concern as well, since manure from industrial livestock systems may contain levels of chemicals such as nitrogen, phosphorus, and heavy metals which characterize it as a solid waste when used in excess.[8] This is not only a concern in urban and peri-urban areas, but also faces rural farms as well.[50]

### Insufficient or inferior inputs[edit]

Due to its competition for resources and pressure to shift to industrial systems that will meet urban demand, inappropriate or excessive use of agricultural inputs including pesticides, nitrogen, phosphorus, and raw organic matter containing undesirable residues such as heavy metals, is a concern.[8] The nature of the environment nearby to urban areas can be hazardous to agricultural production. There are physical, chemical, and fungal threats in the form of roadway exhaust and debris, dense urban populations, water and soil pollution by organic pollutants, industrial chemicals, heavy metals, and antibiotics, and fungal and secondary metabolites.

### Uncertainty of land ownership[edit]

Another major challenge to the viability of both urban and peri-urban agriculture is land availability due to changing land rights, uses, and values. High population densities lead to competition and conflicts over land and natural resources as land is converted from agricultural to residential and business uses, and as the intensity of agriculture practiced on scarce spaces available increases.[8] In addition, many urban and peri-urban farmers are urban poor and are frequently women, who tend to be economically vulnerable.[51][8]

## See also[edit]

* Urban agriculture

## References[edit]

1. ^ "Geograph:: Urban fringe "agriculture" © Richard Webb".
2. ^ Houston, Peter (June 2005). "Re-valuing the Fringe: Some Findings on the Value of Agricultural Production in Australia's Peri-Urban Regions". Geographical Research. 43 (2): 209–223. doi:10.1111/j.1745-5871.2005.00314.x. ISSN 1745-5863.
3. ^ Bogdanowicz, Wiesław (1992-10-03). "Mammals of Australia. Book review. D. W. Walton, B. J. Richardson (Eds.), 1989: Fauna of Australia. Mammalia. Canberra, Australian Government Publishing Service. 401-1227 pp". Acta Theriologica. 37: 102. doi:10.4098/at.arch.92-11. ISSN 0001-7051.
4. ^ Ellis, Frank; Sumberg, James (February 1998). "Food production, urban areas and policy responses". World Development. 26 (2): 213–225. doi:10.1016/s0305-750x(97)10042-0. ISSN 0305-750X.
5. ^ Lee-Smith, Diana (October 2010). "Cities feeding people: an update on urban agriculture in equatorial Africa". Environment and Urbanization. 22 (2): 483–499. doi:10.1177/0956247810377383. ISSN 0956-2478. S2CID 55201655.
6. ^ Holland, Leigh (June 2004). "Diversity and connections in community gardens: a contribution to local sustainability". Local Environment. 9 (3): 285–305. doi:10.1080/1354983042000219388. ISSN 1354-9839. S2CID 154611489.
7. ^ a b D.L. Iaquinta and A.W. Drescher, "Defining the Peri-Urban: Rural-Urban Linkages and Institutional Connections" Food and Agriculture Organization
8. ^ a b c d e f "URBAN AND PERI-URBAN AGRICULTURE" Food and Agriculture Organization, 2015
9. ^ a b Zasada, Ingo (October 2011). "Multifunctional peri-urban agriculture—A review of societal demands and the provision of goods and services by farming". Land Use Policy. 28 (4): 639–648. doi:10.1016/j.landusepol.2011.01.008. ISSN 0264-8377.
10. ^ Mougeot, Luc J.A. (2000). "Urban agriculture: Definition, presence, potentials and risks.". Growing Cities, Growing Food: Urban Agriculture on the Policy Agenda. Feldafing, Germany: German Foundation for International Development. p. 10.
11. ^ a b c "Rethinking of the relationship between agriculture and the “urban” economy in Beijing: an input-output approach" Technological and Economic Development of Economy, 2014
12. ^ Carl Johan Lagerkvist, "Economic drivers for urban and peri-urban agriculture" Archived 2015-10-17 at the Wayback Machine SLU-Global Report, 2014
13. ^ Wredle, Ewa; Katongole, Constantine; Magnusson, Ulf (2014). "SLU-Global Report" (PDF). Archived from the original (PDF) on 2015-10-17. Retrieved 2015-11-02.
14. ^ Hoi-Fei Mok, Virginia G. Williamson, James R. Grove, Kristal Burry, S. Fiona Barker, Andrew J. Hamilton,"Strawberry fields forever? Urban agriculture in developed countries: a review" Agronomy for Sustainable Development, 2013
15. ^ a b Hoi-Fei Mok, Virginia G. Williamson, James R. Grove, Kristal Burry, S. Fiona Barker, Andrew J. Hamilton, "Strawberry fields forever? Urban agriculture in developed countries: a review" Agronomy for Sustainable Development, 2013
16. ^ a b c Wilhelm, Jennifer A.; Smith, Richard G. (2017-04-17). "Ecosystem services and land sparing potential of urban and peri-urban agriculture: A review". Renewable Agriculture and Food Systems. 33 (5): 481–494. doi:10.1017/s1742170517000205. ISSN 1742-1705. S2CID 157518974.
17. ^ Bolund, Per; Hunhammar, Sven (May 1999). "Ecosystem services in urban areas". Ecological Economics. 29 (2): 293–301. doi:10.1016/s0921-8009(99)00013-0. ISSN 0921-8009.
18. ^ Larondelle, Neele; Haase, Dagmar (June 2013). "Urban ecosystem services assessment along a rural–urban gradient: A cross-analysis of European cities". Ecological Indicators. 29: 179–190. doi:10.1016/j.ecolind.2012.12.022. ISSN 1470-160X.
19. ^ Hale, Iago; Wollheim, Wilfred; Smith, Richard; Asbjornsen, Heidi; Brito, André; Broders, Kirk; Grandy, A.; Rowe, Rebecca (2014-11-25). "A Scale-Explicit Framework for Conceptualizing the Environmental Impacts of Agricultural Land Use Changes". Sustainability. 6 (12): 8432–8451. doi:10.3390/su6128432. ISSN 2071-1050.
20. ^ a b Lowenstein, David M.; Matteson, Kevin C.; Xiao, Iyan; Silva, Alexandra M.; Minor, Emily S. (2014-07-10). "Humans, bees, and pollination services in the city: the case of Chicago, IL (USA)". Biodiversity and Conservation. 23 (11): 2857–2874. doi:10.1007/s10531-014-0752-0. ISSN 0960-3115. S2CID 17187999.
21. ^ Livesley, Stephen J.; Dougherty, Ben J.; Smith, Alison J.; Navaud, Damian; Wylie, Luke J.; Arndt, Stefan K. (2010-01-09). "Soil-atmosphere exchange of carbon dioxide, methane and nitrous oxide in urban garden systems: impact of irrigation, fertiliser and mulch". Urban Ecosystems. 13 (3): 273–293. doi:10.1007/s11252-009-0119-6. ISSN 1083-8155. S2CID 34790690.
22. ^ a b QIU, Guo-yu; LI, Hong-yong; ZHANG, Qing-tao; CHEN, Wan; LIANG, Xiao-jian; LI, Xiang-ze (August 2013). "Effects of Evapotranspiration on Mitigation of Urban Temperature by Vegetation and Urban Agriculture". Journal of Integrative Agriculture. 12 (8): 1307–1315. doi:10.1016/s2095-3119(13)60543-2. ISSN 2095-3119.
23. ^ a b Edmondson, Jill L.; Davies, Zoe G.; Gaston, Kevin J.; Leake, Jonathan R. (2014-04-24). "Urban cultivation in allotments maintains soil qualities adversely affected by conventional agriculture". Journal of Applied Ecology. 51 (4): 880–889. doi:10.1111/1365-2664.12254. ISSN 0021-8901. PMC 4301088. PMID 25641978.
24. ^ Farrugia, Simon; Hudson, Malcolm D.; McCulloch, Lindsay (2013-04-11). "An evaluation of flood control and urban cooling ecosystem services delivered by urban green infrastructure". International Journal of Biodiversity Science, Ecosystem Services & Management. 9 (2): 136–145. doi:10.1080/21513732.2013.782342. ISSN 2151-3732.
25. ^ Kuo, Frances E.; Sullivan, William C. (May 2001). "Environment and Crime in the Inner City". Environment and Behavior. 33 (3): 343–367. doi:10.1177/0013916501333002. ISSN 0013-9165. S2CID 20797915.
26. ^ Brinkley, Catherine (2012-02-10). "Evaluating the Benefits of Peri-Urban Agriculture". Journal of Planning Literature. 27 (3): 259–269. doi:10.1177/0885412211435172. ISSN 0885-4122. PMC 4196696. PMID 25324593.
27. ^ Orsini, Francesco; Gasperi, Daniela; Marchetti, Livia; Piovene, Chiara; Draghetti, Stefano; Ramazzotti, Solange; Bazzocchi, Giovanni; Gianquinto, Giorgio (2014-10-10). "Exploring the production capacity of rooftop gardens (RTGs) in urban agriculture: the potential impact on food and nutrition security, biodiversity and other ecosystem services in the city of Bologna". Food Security. 6 (6): 781–792. doi:10.1007/s12571-014-0389-6. ISSN 1876-4517. S2CID 19034430.
28. ^ Jacobson, Mark Z. (April 2010). "Enhancement of Local Air Pollution by Urban CO2Domes". Environmental Science & Technology. 44 (7): 2497–2502. doi:10.1021/es903018m. ISSN 0013-936X. PMID 20218542.
29. ^ Hara, Yuji; Tsuchiya, Kazuaki; Matsuda, Hirotaka; Yamamoto, Yugo; Sampei, Yuki (2013-01-01). "Quantitative assessment of the Japanese "local production for local consumption" movement: a case study of growth of vegetables in the Osaka city region". Sustainability Science. 8 (4): 515–527. doi:10.1007/s11625-012-0198-9. ISSN 1862-4065. S2CID 153702271.
30. ^ JONES, ANDY (2002-10-01). "An Environmental Assessment of Food Supply Chains: A Case Study on Dessert Apples". Environmental Management. 30 (4): 560–576. doi:10.1007/s00267-002-2383-6. ISSN 0364-152X. PMID 12481922. S2CID 38658110.
31. ^ Graham, Sonia; Connell, John (November 2006). "Nurturing Relationships: the gardens of Greek and Vietnamese migrants in Marrickville, Sydney". Australian Geographer. 37 (3): 375–393. doi:10.1080/00049180600954799. ISSN 0004-9182. S2CID 144651284.
32. ^ Bjørkhaug, Hilde; Richards, Carol Ann (January 2008). "Multifunctional agriculture in policy and practice? A comparative analysis of Norway and Australia". Journal of Rural Studies. 24 (1): 98–111. doi:10.1016/j.jrurstud.2007.06.003. ISSN 0743-0167.
33. ^ "OECD Review of Agricultural Policies: Russian Federation 1998". OECD Review of Agricultural Policies. 1998-07-17. doi:10.1787/9789264163126-en. ISBN 9789264160729. ISSN 1990-004X.
34. ^ Lynch, Kenneth; Maconachie, Roy; Binns, Tony; Tengbe, Paul; Bangura, Kabba (January 2013). "Meeting the urban challenge? Urban agriculture and food security in post-conflict Freetown, Sierra Leone". Applied Geography. 36: 31–39. doi:10.1016/j.apgeog.2012.06.007. ISSN 0143-6228.
35. ^ Sarah Wakefield, Fiona Yeudall, Carolin Taron, Jennifer Reynolds, Ana Skinner, "Growing urban health: Community gardening in South-East Toronto" Health Promotion International, 2007
36. ^ Marielle Dubbeling and Henk de Zeeuw, "Multi-stakeholder Policy Formulation and Action Planning for Sustainable Urban Agriculture Development" RUAF Foundation, 2007
37. ^ Whelan, Amanda; Wrigley, Neil; Warm, Daniel; Cannings, Elizabeth (October 2002). "Life in a 'Food Desert'". Urban Studies. 39 (11): 2083–2100. doi:10.1080/0042098022000011371. ISSN 0042-0980. S2CID 145383160.
38. ^ Peng J, Liu Z, Liu Y, Hu 1, Wang A, "Multifunctionality assessment of urban agriculture in Beijing City, China" Science of the Total Environment, 2015
39. ^ a b "Profitability and sustainability of urban and peri-urban agriculture" Food and Agriculture Organization, 2007
40. ^ a b c Yang, Zhenshan; Hao, Pu; Liu, Weidong; Cai, Jianming (August 2016). "Peri-urban agricultural development in Beijing: Varied forms, innovative practices and policy implications". Habitat International. 56: 222–234. doi:10.1016/j.habitatint.2016.06.004. ISSN 0197-3975.
41. ^ Viljoen, Andre (2012-05-04). Viljoen, Andre; Howe, Joe (eds.). Continuous Productive Urban Landscapes. doi:10.4324/9780080454528. ISBN 9780080454528.
42. ^ Drescher, A. W.; Holmer, R. J.; Iaquinta, D. L. (2006), "Urban homegardens and allotment gardens for sustainable livelihoods: Management strategies and institutional environments", Advances in Agroforestry, Springer Netherlands, pp. 317–338, doi:10.1007/978-1-4020-4948-4_18, ISBN 978-1-4020-4947-7
43. ^ Bernholt, Hannah; Kehlenbeck, Katja; Gebauer, Jens; Buerkert, Andreas (2009-06-17). "Plant species richness and diversity in urban and peri-urban gardens of Niamey, Niger". Agroforestry Systems. 77 (3): 159–179. doi:10.1007/s10457-009-9236-8. ISSN 0167-4366. S2CID 36418972.
44. ^ Lovell, Sarah Taylor (2010-08-04). "Multifunctional Urban Agriculture for Sustainable Land Use Planning in the United States". Sustainability. 2 (8): 2499–2522. doi:10.3390/su2082499. hdl:10535/6509. ISSN 2071-1050.
45. ^ Benis, Khadija; Ferrão, Paulo (January 2017). "Potential mitigation of the environmental impacts of food systems through urban and peri-urban agriculture (UPA) – a life cycle assessment approach". Journal of Cleaner Production. 140: 784–795. doi:10.1016/j.jclepro.2016.05.176. ISSN 0959-6526.
46. ^ Björn Vinnerås, Håkan Jönsson "Potential of productive waste management systems in low-income countries" Archived 2015-10-17 at the Wayback Machine RUAF Foundation, 2007
47. ^ Björn Vinnerås, Håkan Jönsson "Potential of productive waste management systems in low-income countries" Archived 2015-10-17 at the Wayback Machine RUAF Foundation, 2007
48. ^ Long Lianga, Rattan La, Zhangliu Du, Wenliang Wua, Fanqiao Menga "Estimation of nitrous oxide and methane emission from livestock of urban agriculture in Beijing" Agriculture, Ecosystems & Environment, 2013
49. ^ Madison Park, "China reports first H10N8 avian flu death" CNN, 2013
50. ^ "Waste Management" Grace Communications Organization
51. ^ Zhu Keliang and Roy Prosterman, "Land Reform Efforts in China" China Business Review, 2012