Research & reports

W.-L. Rao, Z.-K. Zhang, Runzhong Li · Plant Disease · China (Kunming)

In June 2007, sweet cherry trees with mottling and mosaic symptoms were observed in a private garden near Kunming, Yunnan Province, China. Twenty-four samples from sweet cherry, sour cherry, flowering cherry, and peach trees in private and community gardens were tested for eight viruses by RT-PCR. Cherry virus A (CVA) was detected in two symptomatic sweet cherry trees, marking the first report of CVA in sweet cherry in China.

Wendy Heiger‐Bernays, Alexa Fraser, Vaughn R. Burns, Kerry Diskin, David Pierotti, K Merchant-Borna, Michael D. McClean, Daniel J. Brabander, H. Patricia Hynes · PubMed · United States

A study characterized urban community garden soils contaminated by timbers, specifically finding elevated levels of polycyclic aromatic hydrocarbons (PAHs) from railroad ties and arsenic from chromated copper arsenate (CCA) treated lumber. Researchers determined the extent of contamination, designed a remediation plan, and assessed the safety of adding city compost as a soil amendment in Boston community gardens. Recommendations for healthful gardening practices were also provided.

Pay Drechsel, Liqa Raschid-Sally, Robert Clement Abaidoo · · Ghana (Accra)

Urbanization in West Africa has led to most domestic wastewater contaminating surface water sources. In Accra, Ghana, vegetables on urban markets are highly contaminated, with about 200,000 urban dwellers consuming street food containing raw vegetables from these sources daily. This research explores on-farm risk mitigation options, finding potential to significantly reduce helminth egg counts and bacterial contamination through improved washing practices.

Rodrigue V.C. Diogo, Andreas Buerkert, Eva Schlecht · Nutrient Cycling in Agroecosystems · Niger (Niamey)

This 24-month study investigated nutrient efficiency and food safety in urban and peri-urban agriculture in Niamey, Niger. Nutrient inputs and offtakes were quantified for 10 vegetable gardens and 9 millet fields, and contamination of irrigation water and selected vegetables with fecal pathogens and heavy metals was determined. Above-threshold levels of Salmonella spp. and Escherichia coli were detected in lettuce irrigated with river water and fertilized with animal manure, and in lettuce irrigated with wastewater, indicating food safety concerns.

Daniela Plachá, Helena Raclavská, Dalibor Matýsek, Mark H Rümmeli · Geochemical Transactions · Czech Republic

Polycyclic aromatic hydrocarbon (PAH) contamination was investigated in urban, agricultural, and forest soil samples from the surroundings of Valasske Mezirici, Czech Republic. While PAH levels in urban/agricultural soils were within the typical range for industrialized areas, forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. PAH concentrations were highest in localities at higher altitudes and decreased with increasing distance from the town.

Shahzad Kouser, Mr. Abedullah, Abdus Samie · The Pakistan Development Review · Pakistan (Faisalabad)

This study, conducted in 2006 with 200 farmers in two peri-urban villages of Faisalabad, Pakistan, estimated the economic values of negative health externalities from wastewater use in cauliflower production. While wastewater use appeared profitable without considering externalities, factoring in health costs strongly discouraged its use. The health externalities for a three-month cauliflower crop on 741 acres amounted to Rs 3.2 million, and for 5,283 acres of vegetables cultivated with wastewater in Faisalabad, the annual total was Rs 90.7 million. The findings indicate a significant economic loss due to wastewater use, suggesting that installing a water treatment plant is a viable option to minimize these external effects.

Y. A. Iyaka, SE Kakulu · African Research Review · Nigeria

This study determined the levels of copper (Cu) and zinc (Zn) in soil samples collected from cultivated farmlands near abandoned industrial sites in Minna and Bida, Niger State, Nigeria, using flame atomic absorption spectrophotometry. Concentrations ranged from 12-89 mg Cu kg-1 and 2.8-41 mg Zn kg-1 for Minna, and 2.4-6.5 mg Cu kg-1 and 0.57-36 mg Zn kg-1 for Bida. Apparent accumulation of Cu was found in Minna cultivated farmlands, with a mean Cu content of 24 ± 22 ppm, which was almost five times that of the control soils. Other mean values were similar to soil background averages.

Adedeji Adedeji, H Oludare, Ademiluyi · Journal of Geography and Regional Planning · Nigeria

This discussion of urban agriculture and urban land use planning in metropolitan Lagos, Nigeria, frames urban agriculture as a crisis response and survival strategy for the urban poor that contributes to food security, while stating that urban agriculture production systems can pose risks to public health and the environment through inappropriate or excessive use of agricultural inputs — including pesticides, nitrogen, and raw organic matter containing heavy metal residues. It recommends that urban land use planners promote multifunctional land use and greater community participation in managing urban open spaces.

Shazia Iram, Iftikhar Ahmad, Doris Stüben · Pakistan Journal of Botany · Asia

Soil samples were collected from peri-urban agricultural land in Lahore, Pakistan, irrigated by industrial and sewerage waste from the Hudiara drain, and from mine waste soil in Wiesloch, Germany, and analyzed for heavy metals by X-ray fluorescence and ICP-MS and for fungal diversity and frequency by a soil dilution method. X-ray fluorescence found higher Zn, As and Pb in the German mine waste soil, and the more sensitive ICP-MS found higher Fe, Mn, Cu, As, Sr, Mo, Cd, Sb, Ti, Zn and Pb there as well; the Pakistani peri-urban soils had lower heavy metal concentrations than the German mine waste but higher overall fungal frequency and diversity. Testing radial growth of isolated Aspergillus niger, A. flavus and A. nodulans against CdCl2, CuSO4, NiCl2 and ZnCl2 at 1-40 ppm, all tested fungi tolerated ZnCl2 (25 ppm) and NiCl2 (12 ppm) but none tolerated CdCl2 or CuSO4.

Abha Singh, Salahuddin Mohd. · National Geographical Journal of India · India

In-depth field research around the Iglas sewage pumping station on the Aligarh-Mathura road in Aligarh, India, surveyed 41 farming households and some consumers across five peri-urban villages — Bhojpura, Hari Narayan ki Sarai, Hajipur Chohata, Kheri Khwaja Buddha and Daurala Nirpal — that had used urban wastewater for irrigation for many years. Farmers and vegetable sellers reported suffering from ailments including diarrhoeal disease, typhoid fever, hookworm, amoebiasis and skin infections, yet their primary concern was securing enough water to sustain crop productivity and income, while consumers were more focused on getting a fresh, steady supply of vegetables than on the health risk.

Sophie Graefe, Eva Schlecht, Andreas Buerkert · Outlook on Agriculture · Niger (Niamey)

Semi-structured interviews with 130 households in Niamey, Niger, characterized urban and peri-urban agriculture (UPA) and assessed resource use. The study found high use of livestock manure and indiscriminate use of nutrient-loaded wastewater for irrigation, leading to significant nutrient surpluses in UPA gardens. Initial calculations suggested large gaseous emissions of nitrogenous compounds and and leaching of nitrogen, phosphorus, and potassium to groundwater.

Erastus K. Kang’ethe, Delia Grace, Thomas F. Randolph · East African Medical Journal · East Africa

This study synthesizes current knowledge on urban agriculture (UA) in East Africa, focusing on its human health impact. It identifies UA as an important source of food security, but notes that many zoonotic and food-borne diseases are associated with it, with a lack of evidence on human health impact and management. Major constraints include illegality and limited access to inputs and markets, indicating a need for more research to understand both positive and negative health impacts.

Seyed Esmaeil Mahdavian, R. Somashekar · ePrints@Bangalore University (Bangalore University) · India (Bangalore)

A study in Bangalore city, India, showed that urban consumers are at greater risk of purchasing fresh fruits with high levels of heavy metals beyond the legally permissible limits defined by the Indian Prevention of Food Adulteration Act, 1954. These national norms are less strict than international food safety standards.

Andréa Andreis, Graziela Maria Schuh, Rejane Giacomelli Tavares · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · Brazil (Novo Hamburgo)

An evaluation of parasite contamination in playground soils at Horta Comunitária Joanna de Angelis in Novo Hamburgo, RS, Brazil, detected rhabditoid larvae in 33% of soil samples. An enteroparasitological survey (n=22) confirmed parasitism in 59.10% of samples. However, it was not possible to establish a correlation between the presence of parasitosis in children and in the soil.

Bernard Keraita, Pay Drechsel, Flemming Konradsen · Journal of Risk Research · Ghana

A study in Ghana used participatory research methods to summarize farmers' perceptions of health risks and risk reduction measures in urban vegetable farming irrigated with untreated wastewater. Farmers were aware of health risks from wastewater, perceiving occupational skin infections as the greatest risk, while consumer health risks were rated very low. Many international risk reduction measures were deemed unsuitable by farmers, who preferred simple, low-cost alternatives.

Tamara García–Armisen, Josué Prats, Yociel Marrero, Pierre Servais · Water Science & Technology · Cuba (Havana)

The Almendares River in Havana, Cuba, receives wastewater from over 200,000 inhabitants, resulting in very poor microbiological water quality downstream due to high faecal bacterial indicators (FBIs). This water is used for urban agriculture and recreation, despite not meeting microbiological standards. This study compared FBI removal in three wastewater treatment plants (WWTPs): a conventional facility, a constructed wetland (CW), and a solar aquatic system (SAS). Natural systems (CW and SAS) showed approximately two log units higher FBI removal efficiency than the conventional plant. The large conventional WWTP was found to have a negative impact on the river's microbiological quality.

J.N. Hogard, Julius N. Fobil, Godfred K. Ofosu-Budu, D. Carboo, Nii‐Ayi Ankrah, Alexander K. Nyarko · · Ghana

This study in Ghana investigated the macro-nutrient content and heavy metal concentrations in solid waste composts to assess their potential for soil fertility amelioration and health implications in urban and peri-urban agriculture. Overall NPK concentration was low, with agricultural waste composts showing higher total N, K, and organic carbon than municipal solid waste (MSW) composts. Heavy metal concentrations for Ni, Zn, Cu, and Cd were generally low and within Australian standards. However, lead (Pb) concentration in mixed MSW composts was significantly high during the dry season, exceeding the Australian limit of 150 mg/kg Pb for unrestricted use. Seasons and composting processes were found to be important determinants of toxic metal concentrations in final compost products.

Bernard Keraita, Pay Drechsel, Flemming Konradsen · Water Science & Technology · Ghana (Kumasi)

A study in Kumasi, Ghana, assessed the use of on-farm ponds to reduce microbial contamination in wastewater-contaminated irrigation water, analyzing over 300 samples. It found that while ponds are common, their potential for pathogen removal via sedimentation is not fully optimized. Helminth eggs reduced by about 70% with careful water collection, but thermotolerant coliforms took six days in the dry season to meet WHO guidelines, indicating suboptimal performance for some pathogens.

Pay Drechsel, Olufunke Cofie, R. van Veenhuizen, Theophilus O. Larbi · Irrigation and Drainage · West Africa

Informal irrigation in urban and peri-urban agriculture (UPA) in West Africa offers benefits but is often hindered by water pollution, threatening public health. A multi-stakeholder process implemented since 2005 in six West African cities, including Accra, Ghana, aimed to integrate UPA into sustainable urban development. However, an internal lesson learned was that local partners may not prioritize every project, and capacity-building efforts might not provide expected incentives for commitment.

Euis Suryaningsih · Jurnal Hortikultura · Indonesia (Bandung)

From January to July 2001, a field experiment on vegetable disease control in a mosaic farming system in periurban agriculture was conducted at a farmer's field in Rancaekek, Bandung, Indonesia. Treatments included white plastic net cages, biorational pesticides, Bacillus subtilis, a mixture of Mancozeb and Bacillus subtilis, and an unsprayed control. All tested alternative control methods were very effective against major diseases of chili pepper, shallot, eggplant, beans, and cucumber, but the use of poisonous synthetic pesticides in periurban agriculture increases the likelihood of contaminating humans and the environment.

Evan Green · · United States (California)

A literature meta-analysis on lead contamination in urban farms was applied to Alemany Farm in San Francisco, California, where soil lead concentrations range from 60 to 720 ppm. It found that every food crop except tree fruits may pose a health risk if grown in Alemany Farm's soil. A phytoremediation plan using Indian mustard (Brassica juncea) to remove lead was found to exceed the farm's available budget, and its timescale made it impractical. The study concludes that phytoremediation is generally not feasible for small-scale urban farms and that other measures are needed to reduce lead exposure for urban farmers.

XU Yong-xian, Biao Huang · Soils · China

A study of a small-scale vegetable farming system in peri-urban Nanjing, China, monitored heavy metal balances and pollution potential from July 2003 to July 2004. Heavy metals entered the soil mainly through fertilization and irrigation, with organic manure application accounting for more than 98% of inputs. Annual heavy metal input in the area was significantly higher than in European farmland, while annual output was very low, under 10% of input, leading to accumulation of heavy metals in the plots; long-term vegetable cultivation had already caused heavy metal buildup in the soils. Copper, lead, zinc, and cadmium concentrations in vegetables and soil were still below national safety standard limits, so the vegetable farming system was assessed as currently safe. However, an evaluation that incorporated atmospheric deposition showed the region carries a high risk of copper, zinc, and cadmium contamination, and the study concludes that intensive vegetable cultivation will aggravate soil heavy metal pollution, potentially pushing the soil to Second Grade of the National Soil Environment Quality Standard within several decades.

Do Thuy Trang, Kåre Mølbak, Phung Dac Cam, Anders Dalsgaard · Tropical Medicine & International Health · Vietnam (Hanoi)

A cross-sectional study in a peri-urban area of Hanoi, Vietnam, surveyed 400 agricultural households and examined 807 stool samples from 620 adults and 187 children for helminth infections. The study found that 39% of samples were infected with helminths, with Ascaris sp. at 21.6%, Trichuris sp. at 9.8%, and hookworm at 21.8%. Wastewater exposure was not a major risk, but lack of sanitation facilities and use of fresh or inadequately composted human excreta in agriculture were important risk factors for infection.

Barbara Matthys, Andres B. Tschannen, Norbert T. Tian‐Bi, Hermann Comoé, Salia Diabaté, Mahamadou Traoré, Penelope Vounatsou, Giovanna Raso, Laura Gosoniu, Marcel Tanner, Guéladio Cissé, Eliézer K. N’Goran, Jürg Utzinger · Tropical Medicine & International Health · Côte d'Ivoire

A cross-sectional survey was conducted in urban farming communities in Man, western Côte d'Ivoire, involving 113 farming households (586 individuals) and 21 non-farming households (130 individuals). The prevalences of S. mansoni and hookworm in farming households were 51.4% and 24.7%, respectively. Risk factors for S. mansoni included close proximity to the Kô River, water contact with irrigation wells and ponds, and low education attainment, while risk factors for hookworm included living in smallholder irrigated rice plots or large rice perimeters, using domestic well water, and low socioeconomic status.

Bernard Keraita, Flemming Konradsen, Pay Drechsel, Robert Clement Abaidoo · Tropical Medicine & International Health · Ghana

The effectiveness of low-cost irrigation methods (drip irrigation kits, furrow irrigation, and watering cans) in reducing contamination of lettuce irrigated with untreated wastewater in urban farming in Ghana was assessed. Analysis of 396 lettuce, 72 soil, 15 poultry manure, and 32 water samples revealed that lettuce irrigated with drip irrigation kits had the lowest contamination levels, with an average of 4 log units per 100g fewer thermotolerant coliforms than those irrigated with watering cans. However, drip kits often clogged, required lower crop densities, and restricted other routine farm activities.