Research & reports

Dieudonné E. Musibono, E.M. Biey, M. Kisangala, Camille Ipey Nsimanda, B.A. Munzundu, V. Kekolemba, J.J Palus · VertigO · Democratic Republic of Congo (Kinshasa)

Urban agriculture in Kinshasa, Democratic Republic of Congo, serves as a palliative solution for social survival constraints such as a lack of remunerative salaries and sustainable jobs. However, poorly supervised urban farmers cultivate along busy roads, exposing vegetables to various contaminations, including lead. This practice highlights issues with site selection and supervision.

I Kibona, SL Mkoma, IC Mjemah · International Journal of Biological and Chemical Sciences · Tanzania (Morogoro)

Groundwater samples were collected from 20 wells in six wards of Morogoro municipality, Tanzania, during March-April 2010, and nitrate concentrations were measured. Nitrate levels ranged from 1.4 mg/L to 32.5 mg/L, with an average of 7.76 mg/L. These concentrations were below the upper limits set by the Tanzania Bureau of Standards and the World Health Organization.

Mamadou Ndiaye, H.‐R. Pfeifer, S. Niang, Y Dieng, Mauro Tonolla, Raffaele Peduzzi · VertigO · Senegal (Dakar)

In Dakar's urban agriculture, untreated wastewater is used for irrigation due to shallow groundwater salinization. A study conducted at Pikine and Patte d'Oie sites evaluated the chemical and microbiological quality of irrigation water. Findings showed that total nitrogen in irrigation water exceeded WHO guideline values, Salmonella spp. was isolated from 35% of irrigation water, and a wastewater sample tested positive for Vibrio cholerae. This research indicates that irrigation with polluted water and the use of organic fertilizers can degrade groundwater quality and pose health risks.

Kohei Makita, Eric M. Fèvre, Charles Waiswa, Mark Bronsvoort, Mark C. Eisler, Susan C. Welburn · Land Use Policy · Uganda

This paper describes a spatial representation of the peri-urban interface (PUI) of Kampala, Uganda, and identifies socio-economic factors related to peri-urbanicity using rapid rural mapping. It notes that urban and peri-urban agriculture (UPA) in rapidly expanding cities carries public health risks, such as zoonotic disease transmission. The study provides a methodology for describing the PUI in developing countries.

Mamadou Ndiaye, S. Niang, H.‐R. Pfeifer, Raffaele Peduzzi, Mauro Tonolla, Y Dieng · Irrigation and Drainage · Senegal

Lettuces grown at two urban agricultural sites (Pikine and Patte d'Oie) near Dakar, Senegal, and sold in local markets were tested for microbial contamination linked to irrigation water. Salmonella spp. positivity was 6% at Pikine and 7% at Patte d'Oie farm sites, with lettuces irrigated by shallow 'Ceanes' groundwater most contaminated at both sites (8%), compared to wastewater irrigation (4% at Pikine) and well water (5% at Patte d'Oie); at market, Salmonella was isolated at every marketplace surveyed, with higher rates around Patte d'Oie (9% at Grand Yoff, 11% at Dalifort) than around Pikine (4% at Zinc, 2% at Sham) or the control site Rufisque (2%), and lettuces washed with Ceanes water before sale were more contaminated than those rinsed with tap water. Reusing wastewater for irrigation is presented as an alternative to animal manure, with the microbial contamination risk significantly reducible by washing vegetables with tap water before sale.

O. Muñiz, M. Ternero, Álvarez Montero, F. Martínez, T. Limeres, O. Jouber, M. Orphee, Julia Vidan Estevez, B. Calero, F. A. de Alcantara, Adriana María de Aguiar Accioly · Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) · Global

This paper situates its topic within the urban agriculture movement, which it describes as having successfully enabled low-input food production in cities, noting that organoponicos — plots focused on producing leafy vegetables and condiment crops in organic substrates — have driven up demand for organic material sources. The title indicates the study addresses the effect of using heavy-metal-contaminated compost on vegetable production, but the available abstract provides only this background context, with no results on contamination or crop impact stated.

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.

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.

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.

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.

F Ortega Sastriques, Rosa Orellana Gallego · Revista ciencias técnicas agropecuarias · Global

In many cities, the high price and limited availability of potable water necessitate considering irrigation with poor quality water, such as saline or alkaline waters, in urban agriculture. This paper considers aspects of irrigation with poor quality water, including risks like contamination.

F Ortega Sastriques, Rosa Orellana Gallego · Revista ciencias técnicas agropecuarias · Global

In many cities, potable water is expensive, and its availability is limited and will decrease in the future. Urban agriculture is an aspect to consider in this context.

F Ortega Sastriques, Rosa Orellana Gallego · · Global

Due to high prices and limited availability of drinking water in many cities, urban agriculture will require the use of alternative water sources. Groundwater and surface currents near cities are typically polluted, and this paper points out aspects to consider for safe irrigation using sewage water.

Stephanie Buechler, Gayathri Devi Mekala, B. Keraita · Victoria University Research Repository (Victoria University) · Global

This 2006 global study from Victoria University discusses wastewater use in urban and peri-urban agriculture for crop production and aquaculture, noting its role in generating livelihoods and providing cheap produce. However, the study emphasizes that clear policy guidelines and careful research are needed to prevent potential negative impacts on human health and the environment from wastewater reuse.

Astrid Mendez, Paulo Cseri Ricardo, P Jeny Pérez, Callejas Hernández, Osvaldo Campos · DOAJ (DOAJ: Directory of Open Access Journals) · Cuba

This introductory study in Arroyo Naranjo municipality, Cuba, examined the use of Luyanó effluent wastewater for irrigation in urban agriculture. The wastewater was classified as low contamination based on BOD5 and COD values and posed no toxic contamination risk to soil or environment. However, it should not be used without prior treatment for direct consumption crops due to its microbial load. Experimental plots with carrot, radish, and marigold showed high agricultural yields, and radish harvests had no bacterial contamination.

Martin Krauß, J. Moering, Walther Amelung · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · Global

This study aimed to assess whether local soil contamination contributes to PCB contamination in apples (Malus domestica Borkh.) at an allotment garden site, in addition to background atmospheric deposition. The importance of the soil-air-plant pathway for persistent organic pollutants like PCBs has been rarely studied, and it is unknown if volatilization from contaminated soils or deposition of contaminated soil dust is a significant source compared to background deposition. The research sought to clarify this potential contamination route for apples.

F.P. Huibers, O. Moscoso, Álvaro Ocampo Durán, J.B. van Lier · CABI Publishing eBooks · Bolivia

A study examining wastewater use in urban and peri-urban agriculture in Cochabamba, Bolivia. Both vegetable and fodder crops are irrigated with polluted water — diluted or partly treated municipal and industrial sewage — containing high concentrations of pathogens, heavy metals, and salts. In the downstream La Mayca area, where farmers have an agreement with the municipal water and sewerage company, soil degradation has forced them to increasingly replace vegetable crops with more salt-tolerant fodder crops. In other areas around the city, cultivators deny using wastewater and point to nearby wells as their water source, but many of these wells are likely also polluted and do not yield enough water for the irrigated area they serve. Farmers report no specific health problems related to using polluted water, which contradicts reports from local health workers. Because surface water flow and rainfall are low while industrial pollution is high and wastewater treatment capacity is limited, most of the water available to farmers is of poor quality. Options identified for improvement include reducing industrial pollution, increasing treatment capacity, and adopting integrated water management that blends good-quality groundwater with wastewater — but strong traditional water rights, lack of urban planning, and weak institutions are cited as constraints on improving wastewater management in Cochabamba.

G. B. Luilo, Othman C. Othman · Journal de Physique IV (Proceedings) · Tanzania (Dar es Salaam)

This study measured heavy metal levels (cadmium, manganese, lead, and zinc) in Cynodon grasses near roads in Dar es Salaam City, Tanzania. Mean levels of lead and zinc varied exponentially with distance from the road up to 15m and correlated with average daily traffic, suggesting vehicular sources. For public health reasons, it is recommended that pasture grasses in road vicinities not be used for foraging dairy cattle and goats.