Research & reports

AN Asadu, EM Igbokwe, JM Chah, IA Enwelu · Journal of Agricultural Extension · Nigeria (Enugu)

This study investigated farmers' perceptions of health and environmental hazards from urban livestock keeping in Enugu Urban, Nigeria, interviewing 75 heads of households. While all respondents were aware of general health and environmental implications, only 4.0% knew livestock could cause climate change. Identified environmental issues included crop destruction (89.3%), urban filth (89.3%), and noise (88.0%), while health issues included disease spread (50.7%), accidents (46.7%), and bad smell (86.7%).

Patrick F. Banga · · Zimbabwe

Unsanctioned urban agricultural activities in Emakhandeni High Density Suburb of Bulawayo, Zimbabwe, negatively impact biodiversity. Researchers interviewed 100 people and conducted field visits, finding that the majority of cultivators operate outside existing laws and guidelines. This leads to progressive land degradation, massive deforestation, soil erosion, dried wetlands, lowered water table, and compromised groundwater quality due to pesticides and inorganic fertilizers.

Ruth Stewart, Marcel Korth, Laurenz Langer, Shannon Rafferty, Natalie Rebelo Da Silva, Carina van Rooyen · Environmental Evidence · Global

This is a systematic review protocol — not a completed review — that sets out methods for identifying, appraising and synthesizing evidence on how urban agriculture programs affect food security and nutrition in low- and middle-income countries. It notes urban agriculture is widely promoted as providing the urban poor with food and income while improving the urban environment, but also carries potential disadvantages: use of wastewater can contaminate produce, intensive irrigation can spread malaria and water-borne disease and strain limited water supplies, and soil erosion and intensive fertilizer/pesticide use can pose health risks and environmental damage. Despite the current policy drive to promote urban agriculture, the paper states that the evidence base for its benefits and harms is not well understood. As a protocol, it reports planned search, screening, bias-appraisal and synthesis methods rather than results.

Minjae Kong, Kwang-Lai Park, Jin-Kwan Son, Ji-Hoon Shin · Journal of the Korea Society of Environmental Restoration Technology · South Korea (Seoul)

This study investigated the characteristics of rooftop gardens (farms) in 40 areas in Seoul, Korea. Cabbage, lettuce, pepper, and mini-tomatoes were the most preferred vegetables and fruits. Problems observed in rooftop gardens during cultivation included drainage systems, soil management, the cost or quality of planting mats, and diseases and insects.

Karin Ahrné, Jan Bengtsson, Thomas Elmqvist · PLoS ONE · Sweden (Stockholm)

This study investigated bumble bees in allotment gardens along an urbanization gradient from inner Stockholm to rural areas. Findings showed that bumble bee diversity decreased with increasing urbanization, from approximately eight species in rural areas to five to six species in urban allotment gardens. Higher variability in the abundance of certain species in the most urban areas suggested a potentially weaker reliability of the pollination ecosystem service in areas strongly influenced by human activity.

P. S. Datta, Shipra Tyagi · · India

Peri-urban agriculture in the Delhi-NCR area is highly dependent on groundwater availability amid rapid urbanization. This study integrates dynamic δ18O isotopic composition data on groundwater with static data such as elevation of recharge sites to delineate potential recharge zones and hydrodynamic aquifer zones. Significant δ18O-elevation relationships were found (r² = 0.808 to 0.982), with recharge-site elevation resolutions of about 20m in the northwest and 75m in the southwest, identifying potential recharge zones at elevations of 210-230m in the northwest and above 260m in the south. However, variation in groundwater isotopic composition over time indicates that the corresponding aquifers are relatively small and of low productivity, and points to the likely presence of many low-permeability zones in the northwestern recharge areas — a constraint on the groundwater resources that sustain peri-urban agriculture there.

M. B. David · African Affairs · Kenya

This study on urban agriculture in the Kenyan town of Nakuru illustrates health and environmental problems associated with keeping livestock in urban areas, the small size of plots cultivated, and the dependence of urban households on rural sources of food. These findings were observed in the context of economic hardships occasioned by structural adjustment programmes since the 1980s.

Shane R. de Solla, Pamela A. Martin · Environmental Toxicology and Chemistry · United States

Because many reptiles oviposit in soil within agricultural landscapes, this study evaluated the toxicity of two commonly used nitrogenous fertilizers — urea and ammonium nitrate — to snapping turtle (Chelydra serpentina) egg survivorship. Eggs were incubated, unmanipulated and under ambient conditions, in a community garden plot treated with urea at realistic rates up to 200 kg/ha in 2004 and ammonium nitrate up to 2,000 kg/ha in 2005, and separately in covered laboratory bins designed to minimize nitrogen loss through volatilization or leaching. In the field, neither urea nor ammonium nitrate affected hatching success or development, despite ammonium nitrate showing overt toxicity to native plants. In the laboratory, however, both fertilizer exposures reduced hatching success, lowered body mass at hatching, and reduced post-hatching survival compared with controls. The authors attribute the field's lack of toxicity to leaching and atmospheric loss of nitrogen in soil, and conclude that nitrogenous fertilizers likely have little direct impact on turtle eggs deposited in agricultural landscapes.

Kenny Lynch · · Indonesia (Jakarta)

This piece reviews the literature on urban agriculture (UA), noting that Bryceson (1993) provides documentary evidence from as early as 1939 of UA's importance during and after the Second World War, and that the UN University's Food Energy Nexus research programme in the mid-1980s prompted researchers to examine agricultural cultivation within city boundaries more seriously. Since then, a significant body of literature has developed around a central debate over whether urban agriculture is beneficial, summarized by Lynch (2002). This summary is described as having two problems: it assumes urban agriculture is a homogenous activity with universally similar impacts, and it is largely viewed from the perspective of a city's population, so urban agriculture tends to be seen as beneficial for food, employment and the environment with little consideration of its impacts on the rural-urban food supply. This led Lynch, Binns and Olofin (2001) to argue that urban agriculture should instead be considered part of the broader urban food supply system.

Ausaf-ur Rahman, Mohammad Ait Kadi, Johan Rockström · Water Science & Technology · Global

A synthesis paper from a 2002 workshop reports that competing demand for water between agriculture and urban users is generating severe stress on water resources, with virtual water trade (importing food instead of pursuing self-sufficiency, to conserve real water resources) and water reuse (irrigation with treated urban wastewater) emerging as the two dominant proposed responses. It states that virtual water trade carries serious political and economic risks, with one proposed remedy being an international virtual water trading council.

Fabio Bontadina, Pascale Contesse, Sandra Gloor · DORA WSL (Swiss Federal Institute for Forest, Snow and Landscape Research) · Switzerland (Zurich)

This study analyzed attitudes towards urban foxes in Switzerland using a nationwide survey and questionnaires for households and allotment gardeners in Zurich. While 60% of Swiss respondents were against urban foxes, only 40% in Zurich were; however, 70% of gardeners opposed them, with 55% reporting damage caused by foxes, which negatively correlated with fox acceptance.