Research & reports

Mekonnen Getahun, Yihenew G. Selassie · Journal of Agricultural Science · Ethiopia

A study investigated the extent of contamination of soil, water, and vegetables from wastewater used for irrigation in urban agriculture in Bahir Dar and Kombolcha, Ethiopia. Soil, water, and vegetable samples were collected and analyzed. While heavy metal concentrations in soil were within permissible levels, wastewater samples showed high nitrate and phosphate levels, and boron concentrations in Borkena River and Lake Tana exceeded permissible limits for irrigation. Wastewater drained to Lake Tana exhibited high turbidity and very high BOD, and lettuce and Swiss chard accumulated higher levels of iron, manganese, and zinc.

Teferi Daba Lemma, M. S. A. Rao · · Ethiopia

This study assessed the social and environmental sustainability of urban and periurban agriculture (UPA) in selected towns of Ethiopia, using primary data from 280 households via questionnaires and interviews. The findings indicate that the environmental and health aspects of UPA sustainability are compromised by extensive use of chemical inputs. Furthermore, UPA is inclined to be unsustainable from a social and political perspective.

Dlamini Magagula, Khathi Khumalo, Nombuyisilwe Sithole, Kgosiwe Maseko · Zenodo (CERN European Organization for Nuclear Research) · South Africa (Cape Town)

This study in Cape Town, South Africa, investigated the impact of community gardens on food security among the urban poor using mixed methods, including ten years of household food expenditure surveys. Participating households showed an average 20% increase in fresh produce consumption compared to non-participants, directly impacting nutrition levels. The review concluded that community gardening projects can enhance food security and quality of life, but further research is needed on best practices, scalability, long-term sustainability, and the impact of diverse crop cultivation.

Nhamo Makhuwa · Zenodo (CERN European Organization for Nuclear Research) · Mozambique

A 2013 study presented a theoretical framework underpinning the impact of school gardens on nutrition and academic outcomes in developing countries like Mozambique, where school gardens are recognized as a potential intervention. This framework, built upon existing literature on environmental education, agriculture-based interventions, and their impact on nutritional status and cognitive development, emphasized the need for further empirical research to validate these insights and inform policy recommendations for integrating school gardens into educational curricula.

Dominique Rossi Breetzke, Christina Breed · Suid-Afrikaanse tydskrif vir kunsgeskiedenis · South Africa (Pretoria)

This paper explores using abandoned urban land for allotment community gardening in Sunnyside, Pretoria, South Africa, through a case study along the Walker Spruit. It tests the hypothesis of increasing food security and social capital through urban ecology design. Findings suggest that allotment culture and permaculture can reconnect people with urban nature, proposing a design concept to unite neighborhoods and provide social and biophysical services sustainably.

Evaristo Mwaba Kapungwe · Open Journal of Metal · Africa

Water, soil, and crop samples were analyzed by atomic absorption spectrometry for lead, copper, cobalt, nickel, and chromium at two peri-urban wastewater-irrigation farming sites in Zambia: New Farm Extension in Mufulira Town, Copperbelt Province, and Chilumba Gardens in Kafue Town, Lusaka Province. Heavy metal levels in wastewater, soil, and food crops exceeded acceptable limits at both sites, confirming contamination and a potential human health risk from consuming the crops grown there.

Léon W. Nitièma, Boubacar Savadogo, Dramane Zongo, Aminata Kaboré, Poda Jean Noël, Alfred S. Traoré, Dayéri Dianou · Journal of Environmental Protection · Africa

This study examined the microbial quality of wastewater used for truck farming in Ouagadougou, Burkina Faso, testing for bacterial and parasitological fecal indicators during the dry-hot season (May) and the wet season (July) of 2012. Wastewater from three water reservoirs and two canals intensively used for truck farming was analyzed, and the same indicators were tracked through waste stabilization ponds at three treatment plants in the city. Concentrations of microbial indicators were significantly higher in the dry-hot season than the wet season across all sampling sites, with levels reaching up to 53,800 CFU/100ml for E. coli, 8,200-108,400 CFU/100ml for fecal coliforms, 650-45,000 CFU/100ml for fecal streptococcus, and 0-2.4 eggs/l for helminths. Through the waste stabilization ponds, significant microbial concentration drops of 82-100%, 78-98%, 60-100%, and 82-88% respectively were recorded between the anaerobic and maturation ponds. The results indicate that improving the refining performance of waste stabilization pond technology could help reduce the health risks associated with wastewater reuse in urban agriculture in developing countries.

Dominique Rossi Breetzke, Christina Breed · UpSpace Institutional Repository (University of Pretoria) · South Africa

A landscape architecture study centered on Sunnyside, Pretoria, South Africa, using an abandoned stretch of land along the Walker Spruit as a case study to test the hypothesis that allotment-style community gardening designed around urban ecology can increase food security and social capital. It examines Guerrilla Gardening and allotment cultures in Britain, Canada, and Switzerland, and applies the green infrastructure concept of a "Continuous Productive Urban Landscape," concluding that allotment culture and permaculture can be ways of reconnecting people with urban nature. It proposes a "three natures" design concept intended to unite the neighboring Clydesdale and Sunnyside East areas. The work is a design proposal and case study rather than a study with measured outcome data.

G. N. Egwu, John O. Agbenin · Archives of Agronomy and Soil Science · Nigeria

A study in northern Nigeria assessed cadmium, lead, and zinc contamination in soils and leaf vegetables (amaranthus, lettuce) irrigated with untreated wastewater. Total cadmium and zinc concentrations in soils exceeded safe limits, and lead and cadmium in edible portions of amaranthus and lettuce exceeded safe limits for human consumption by 7–17 times. The permissible limit for lead established for agricultural lands may not be suitable to ensure produce safety in urban and peri-urban agriculture in Kano.

Nancy Karanja, Mary Njenga, G.K. Mutua, Carl Johan Lagerkvist, E. Kutto, JJ Okello · Journal of Agriculture Food Systems and Community Development · Kenya (Nairobi)

A study in three peri-urban sites in Nairobi, Kenya, assessed heavy metal, nitrate, and pesticide residue levels in wastewater-irrigated kale. Elevated levels of boron, cobalt, chromium, copper, lead, zinc, and nickel were found in vegetables at two sites, with high soil loadings of nickel, arsenic, lead, chromium, copper, and zinc attributed to chicken manure. Pesticide residues of diazinon, cypermethrin, biternol, and profenofos exceeded permissible limits in kale at one site, suggesting consumers may ingest significant amounts of contaminants.

Sebastian U. Ugbaje, John O. Agbenin · International Journal of Environmental Studies · Nigeria

A pot experiment in Zaria, northern Nigeria, evaluated the chemical forms and phytoavailability of Cr, Ni, and Pb in savannah soil amended with two urban wastes and planted with sorghum. While urban waste application increased total metal concentrations in the soil, only Pb uptake by sorghum increased, with no corresponding increases for Cr and Ni. A single application of urban wastes significantly increased Pb uptake by sorghum, raising concerns about the long-term consequences of such applications in urban and peri-urban agriculture, especially regarding children's exposure to Pb.

Catherine Rwamba Githuku · Abstracts of postgraduate thesis · Kenya (Nairobi)

This study investigated soil and crop pollution levels resulting from untreated wastewater reuse for irrigation in Kibera and Mailisaba wastewater irrigation farms in Nairobi, Kenya. Analysis of irrigation water, soil, and crop samples (maize, kales, black nightshade, arrowroots) revealed that the Electrical Conductivity (EC) of irrigation water at Mailisaba exceeded recommended levels. Farmers reported adverse effects on crops due to wastewater quality, and despite awareness of health risks, many farmers confessed to not using protective clothing.

John Jacob, Samuel E. Kakulu · American Journal of Chemistry · Nigeria

Soil and vegetable samples (spinach, jute mallow, and tomato) were collected from farms and gardens across 20 zones within Kaduna, Nigeria, plus two rural control villages about 30 km from the city, and analyzed for heavy metals by Flame Atomic Absorption Spectrophotometer. Pollution Load Index results showed soils in the city farms were moderately enriched with cadmium and chromium and strongly enriched with lead and nickel from anthropogenic sources. Mean soil concentrations of lead and cadmium exceeded WHO/FAO permissive limits for agricultural soil (nickel and chromium did not), while vegetable metal concentrations exceeded the permissive limits for every metal except nickel — a finding flagged as concerning given the toxicity of lead and cadmium in particular, which have no known biological use.

Anthonia N. Asadu, E. M. Igbokwe, Jane M. Chah, I A Enwelu · DOAJ (DOAJ: Directory of Open Access Journals) · Nigeria

A study of Enugu Urban, Nigeria, examining farmers' perceptions of the health and environmental hazards posed by keeping livestock in urban areas, and the implications for climate change mitigation. Seventy-five heads of household were freely sampled and interviewed, with data analyzed using percentages and means. Most farmers kept improved chicken breeds under an intensive system. All respondents were aware of health and environmental implications of urban livestock keeping, but only 4.0% were aware that livestock could contribute to climate change. Reported environmental issues included crop destruction (89.3%), filth in urban areas (89.3%) and noise (88.0%); health issues included disease spreading (50.7%), accidents (46.7%) and bad smell (86.7%). Perceived control measures included proper waste disposal (mean 1.79), seeking veterinary services (mean 1.85), regular shed cleaning (mean 1.80) and provision of extension services (mean 1.85). The study recommends integrating urban agriculture into urban health and environmental policy and having extension services raise awareness of livestock's climate impact among urban keepers.

Chinedu Agbakoba, Funmilayo Olayiwala · Zenodo (CERN European Organization for Nuclear Research) · Nigeria

A paper framed as addressing a research gap on eco-friendly pesticide use strategies among urban farmers in Lagos State, Nigeria, health impacts, and environmental protection (2012) states that it conducted a structured literature review with thematic synthesis of key findings. However, the abstract's actual content is limited to generic mathematical-formalism language — establishing "bounded error under perturbation," a "convergent estimation process under stated assumptions," a "stable link between the proposed metric and observed outcomes," and an empirical specification described as a linear regression form (Y expressed as a linear function of X plus an error term) — and does not report specific data or results on actual pesticide practices, measured health impacts, or environmental protection outcomes among Lagos urban farmers. It closes by calling on stakeholders to prioritize inclusive, locally grounded strategies and improve data transparency.

Ferdinan Dos Santos · Zenodo (CERN European Organization for Nuclear Research) · Sub-Saharan Africa

This study examines the impact of school garden programmes on nutrition knowledge and food security among primary school students in rural Mozambique. While such programmes have been implemented across various regions with mixed results, this study used a mixed-methods approach combining qualitative interviews and quantitative surveys with primary school students and their parents or guardians. Students showed a statistically significant improvement (p<0.05) in nutrition knowledge, with an average score increase of 20% on the post-intervention survey compared with pre-test results. The findings indicate that the school garden programmes positively influenced students' nutritional knowledge and contributed to their families' food security in Mozambique's rural areas. The authors state that further studies should examine long-term impacts and potential barriers to implementation.

Stephen Odede. Shisanya, Sheryl L. Hendriks · Development Southern Africa · South Africa

This study evaluated the contribution of community gardens to alleviating food insecurity for 53 community gardeners in Maphephetheni, KwaZulu-Natal, South Africa. Using the Household Food Insecurity Access Scale, it was found that 89% of these households were anxious about food supplies, consumed insufficient food, and were severely food insecure. Additionally, 72% consumed poor quality food. Community gardens were unable to solve the problem of food insecurity, but their contribution to consumption cannot be entirely ignored.

Nafiu Abdu, John O. Agbenin, Andreas Buerkert · Journal of Plant Nutrition and Soil Science · Nigeria (Kano)

A study evaluated the distribution and origin of trace elements (Ti, Fe, Nb, Pb, Rb, Sr, Y, and Zr) in five long-term wastewater-irrigated urban vegetable gardens in Kano, Nigeria. Surface soil concentrations of Ti, Fe, Pb, and Y were high compared to comparable soils elsewhere, but soil pollution assessment yielded no evidence of anthropogenic input of the studied trace elements. Enrichment factor, contamination factor, and geoaccumulation index (Igeo) revealed little to no contamination with trace elements.

I. K. Adewumi, Adebanji Samuel Ogbiye, E. O. Longe, David O. Omole · Covenant University Repository (Covenant University) · Nigeria (Ota)

This study assessed the impact of industrial wastewaters discharged into River Atuwara in Ota, Nigeria, on water quality using standard physical and chemical analyses and QUAL2K software. The majority of water quality parameters exceeded maximum permissible concentrations, with BOD at ≥ 31 mg/L, COD at ≥ 181 mg/L, and alkalinity at ≥ 138.4 mg/L. High concentrations of heavy metals, including Cadmium, Pb, Zn, Fe, and Mn, were detected, indicating an environmental hazard for riparian users.

Ardjouma Dembélé, Oumarou Badini, Alessandro Abbà · InTech eBooks · Africa

A book chapter surveying the state of urban agriculture in African cities. As rural-to-urban migration increases demand for food quantity and quality, urban agriculture is described as able to contribute to livelihoods and economic growth; horticulture is called a vital economic sector, citing figures such as Côte d'Ivoire's fruit and vegetable exports to the EU exceeding 360,000 tons, Burkina Faso's 2007 green bean exports of over 925,000 tons, and Mali's tomato and okra production reaching over 17,000 tons and 8,600 tons respectively. The chapter also notes that the horticultural sector, including urban agriculture, faces pest attacks and phytosanitary problems and must comply with pesticide regulations and quality-control (traceability) standards required by export markets.

Haruna Haruna · · Africa

A study of soils irrigated with sewage water on Fadama floodplain land in northern Nigeria used sequential extraction to determine the mobility and availability of cadmium, copper, nickel, lead and zinc. The residual fraction held the largest pool of all five metals, but 2.7-70.2% was present in the potentially available, non-residual fraction. Contamination by cadmium and nickel was less severe than by lead, copper and zinc, and mobility/bioavailability ranked Pb > Zn > Cu > Ni > Cd.

Chabalani Ndlovu, Shethile Simelane, Kgosiwele Mngeni · Zenodo (CERN European Organization for Nuclear Research) · South Africa

In Cape Town's high-rise neighborhoods, South Africa, where geographic constraints and socio-economic disparities limit access to fresh produce, a mixed-methods study using surveys, interviews and observation compared participants who regularly used community garden spaces with a control group who did not. Community gardens yielded an average of 50% more fresh produce per square meter than traditional urban plots, contributing to local food security, and garden users showed health changes including better nutrition and lower obesity rates.

Wycliffe Cherono Nyaga · Zenodo (CERN European Organization for Nuclear Research) · Kenya (Nairobi)

This study in Nairobi, Kenya, investigated the impact of urban agriculture community gardens on elderly food security, health outcomes, and social support. Surveys and interviews with participants in four gardens revealed a significant improvement in dietary variety (p < 0.05) among elderly residents, with a 25% average increase in vegetable intake. Social support networks within and outside the gardens were also crucial for health maintenance.

Nancy Karanja, Fiona Yeudall, S Mbugua, Mary Njenga, Gordon Prain, Donald C. Cole, Alexandra L. Webb, Daniel Sellen, Christopher Gore, Jennifer Levy · International Journal of Agricultural Sustainability · Kenya (Nakuru)

This paper outlined the conception, design, and implementation of a project aimed at strengthening technical, environmental, financial, and social capacity for urban agriculture (UA) among HIV-affected households in Nakuru, Kenya. Key lessons learned included the value of multi-stakeholder partnerships, the crucial role of self-help group organizations, and the importance of institutional commitments to support farming by vulnerable persons. The usefulness of mixed-methods evaluative tools for monitoring progress was also highlighted.

Hygin Faust Kakai, Alban Gilles Kakai, Armelle Grey Tohouegnon · VertigO · Benin (Cotonou)

This study in Benin examined urban agriculture and waste valorization in Cotonou, Abomey, and Abomey-Calavi. In Cotonou, overexploitation of sandy, organic-poor soil in market gardening led to soil impoverishment, forcing gardeners to use chemical fertilizers with negative environmental impacts. However, some market gardeners adopted compost use, transitioning to organized organic urban agriculture after a waste management project supported waste valorization. This dynamic was not observed in Abomey, where urban agriculture is practiced in family spaces and public areas, unlike Cotonou's developed sites. Abomey-Calavi, despite rapid demographic growth, was almost devoid of urban agriculture practices.