Research & reports

Oso Adeola Abiola · Zenodo (CERN European Organization for Nuclear Research) · South Africa

This review discusses vegetable production in South Africa, focusing on the impacts of root-knot nematodes (Meloidogyne species) on small-scale farming communities. The review highlights that these nematodes are a primary pest, causing delayed crop maturity, reduced yields, poor quality produce, and escalating production costs. This leads to substantial income losses for farmers and the abandonment of community gardens, intensifying challenges for vegetable production and food security.

Delphine Manka’abusi, Désiré Jean‐Pascal Lompo, Christoph Steiner, Mariko Ingold, Edmund Kyei Akoto-Danso, Steffen Werner, Volker Häring, George Nyarko, Bernd Marschner, Andreas Buerkert · Journal of Plant Nutrition and Soil Science · Sub-Saharan Africa

To quantify carbon and nitrogen losses in urban and peri-urban agriculture soils in West Africa, this study measured CO2-C, N2O-N, and NH3-N fluxes from irrigated fields in Ouagadougou, Burkina Faso, and Tamale, Ghana, under different fertilization and (waste)water regimes. Compared with unamended controls, fertilizer application increased average cumulative CO2-C emissions by 103% over eight cropping cycles in Ouagadougou and by 42% over seven cropping cycles in Tamale. Total emissions across all cropping cycles reached 14 t C/ha in Ouagadougou — 73% of the carbon applied as organic fertilizer over two years at that site — and 9 t C/ha in Tamale. Fertilizer application increased N2O-N emissions in Ouagadougou by 37-360% across cropping cycles and NH3-N losses by an average of 670%, but had no significant effect on N2O-N losses in Tamale. Wastewater irrigation did not significantly raise CO2-C emissions in Ouagadougou, but in Tamale CO2-C emissions were 71% higher on wastewater plots (1.6 t C/ha) than on controls (0.9 t C/ha); wastewater had no significant effect on N2O-N or NH3-N emissions at either site. Biochar did not affect N2O-N or NH3-N losses but could help reduce CO2-C emissions from urban garden soils.

Cosmos C. Alamanjo, Abimbola O. Adepoju, H. Martin, R.N. Baines · Zenodo (CERN European Organization for Nuclear Research) · Nigeria (Jos)

This mixed-methods study investigated farmers' perceptions, willingness, and capacity to use household sewage sludge as organic resources for peri-urban agriculture around Jos, Nigeria. Farmers were found to use a complex mix of fertilizers and were keen to utilize household sewage sludge for soil fertility, though constrained by accessibility. A critical finding was that household sewage sludge observed in the field is heterogeneous due to its proximity to urban refuse disposal, raising concerns for possible cross-contamination of pollutants and indicating a lack of extension guidance.

Hendrick J. Bruins · · Africa

This paper discusses drought mitigation in urban and peri-urban Africa, where severe droughts threaten food production under rainfed agriculture. It argues that while urban and peri-urban farming's informal private sector should not be government-controlled, the treatment and use of urban wastewater in agriculture requires government planning, investment, and extension services. Participatory development is suggested to integrate central wastewater planning with private farmer use.

Nicolette Tamara Jonkman, Esmee D. Kooijman, Karsten Kalbitz, Nicky Pouw, Boris Jansen · SOIL · Kenya (Kisumu)

This study in Nyalenda urban gardens, Kisumu, Kenya, investigated how female farmers' knowledge and practices influence soil nutrient status. Soil analysis revealed that intercropped fields had significantly lower total soil nutrients than fields with only manure, despite cowpeas theoretically increasing soil N. Female farmers' knowledge was limited to practical and sensory aspects, and intercropping did not increase soil nutrient content due to socioeconomic factors like poverty.

Solomon Tulu Tadesse, O. Oenema, Christy van Beek, Fikre Lemessa Ocho · Nutrient Cycling in Agroecosystems · Ethiopia

This study investigated the diversity and nutrient balances of urban and peri-urban agriculture (UPA) systems in three Ethiopian cities, using data from 425 households (Addis Ababa: 175, Adama: 126, Jimma: 124). It identified six farm types, including commercial livestock (cLS) and subsistence field crop (sFC) systems. The study found that cLS systems accumulated significant nutrients (450 kg N, 85 kg P, 260 kg K ha−1 year−1) with low use efficiency (26% N and P, 15% K), while sFC systems depleted nutrients (−30 kg N, −17 kg K ha−1 year−1) with high use efficiency.

Kh. N. Shaaban, M. Abul-Soud, OSAMA A. EL-BEHAIRY · Journal of Environmental Science · Africa

On the rooftop of the Central Laboratory for Agriculture Climate, Agriculture Research Centre, Egypt, tomato was grown over two summer seasons and strawberry over two winter seasons during 2014-2015 to test vermicompost-perlite substrate mixes (10%, 20%, 30% vermicompost, and a perlite-only control) combined with chemical, vermi-liquid, or combined nutrient solutions. Vegetative growth, yield and leaf N/P/K content were highest with chemical or combined chemical/vermi-liquid solution paired with the 30% then 20% vermicompost mixes, and applying or increasing vermicompost reduced heavy metal content in the tomato and strawberry fruit.

Dominique Massé, Moussa N’Diénor, Edmond Hien, Tovonarivo Rafolisy, Yacine Badiane Ndour, Alfonse Bilgo, Serge Houot, Christine Aubry · IRD Éditions eBooks · Sub-Saharan Africa

This chapter reviews research since 2006 on composting urban waste and using municipal landfill screenings in Sub-Saharan Africa. In Ouagadougou, urban waste compost significantly increased sorghum yields (2 to 5 times higher than controls) over two years, with phosphorus content being crucial when concentrated at plant level, and mineralization rate determining yield when spread. In Madagascar, soil from the Andralanitra landfill showed value as an amendment or fertilizer for tomato cultivation, though application principles and safety need definition. However, municipal landfill screenings from Dakar did not achieve yields comparable to horse manure when tested on tomato crops.

Upite Joseph Tshala, Misonga Alain Kitabala, Mwamba Jean-Pierre Tunda, Kayakez Michel Mufind, Miji Arsene Kalenda, Kanyimbu Georges Kapele, Kimuni Luciens Nyembo · Journal of Applied Biosciences · Africa

This study, conducted from May 2015 to April 2016 in Kolwezi, assessed the agronomic characteristics of compost from household waste and determined its biodegradable fraction for agricultural use. Waste was collected from 100 households, revealing biodegradable and non-biodegradable fractions, with quantities varying by season and commune. The biodegradable fraction represented 53% of the average monthly waste of 1001.5 kg per household. Major element concentrations were relatively high compared to Cameroon, while heavy metal concentrations were well below international standards.

Volker Häring, Delphine Manka’abusi, Edmund Kyei Akoto-Danso, Steffen Werner, Kofi Atiah, Christoph Steiner, Désiré Jean‐Pascal Lompo, S.G.K. Adiku, Andreas Buerkert, Bernd Marschner · Scientific Reports · Sub-Saharan Africa

This 2-year study in Tamale (Ghana) and Ouagadougou (Burkina Faso) investigated the effects of biochar, wastewater irrigation, and fertilization on sandy, nutrient-depleted soils in urban vegetable production. Biochar addition (2 kg m⁻²) initially doubled soil organic carbon (SOC) stocks, but 35% SOC losses occurred afterward. Both biochar types had no effect on soil pH, phosphorus availability, or cation exchange capacity, though rice husk biochar retained nitrogen. The study found that the effects of biochar and waste water were less pronounced than reported elsewhere.

S. A. Materechera · Journal of Soils and Sediments · South Africa (Mahikeng)

Properties of subsoil in soils used for urban and peri-urban agriculture in Mahikeng city, South Africa, were investigated. Measurements of physical, chemical, and biological properties in four soil profiles (topsoil 0-20cm, subsoil 20-40cm) revealed high bulk density (mean 2.06 Mg m−3) and high penetrometer resistance (1.89 MPa) in the subsoil, indicating potential impedance to root growth. Low hydraulic conductivities at saturation and low plant-available boron levels were also found, leading to the conclusion that subsoil constraints to root growth are widespread in these soils.

Hilary Bambrick, Stefano Moncada · QUT ePrints (Queensland University of Technology) · Ethiopia

A photo-documentation report on a water point installed in 2012 as part of a biogas development initiative in an informal urban community of 200 households in Shashemene, Ethiopia. The facility comprises four latrines, an inlet for animal waste, a fermentation chamber, and a communal kitchen with four stoves; the fermented slurry by-product is used as fertiliser for the community garden. The report states that the system improved management of human and animal waste, reducing gastroenteric disease; provided cleaner cooking fuel than wood, dung, or charcoal, reducing indoor air pollution and respiratory disease risk; lowered household fuel costs; and increased food production and income through the fertiliser it generates.

M. G. Dahiru, Onaiwu Idahosa Enabulele · · Nigeria (Kano)

Microbiological and physicochemical parameters of urban wastewater from the Jakara Canal in Kano were analyzed to assess its potential for irrigation. Mean fecal coliform counts ranged from 64.43 ± 63.20 MPN 100/ml to 216.85 ± 350.16 MPN 100/ml, increasing along the canal. All physicochemical parameters were within FEPA and WHO/FAO acceptable limits, but conductivity needed monitoring to avoid salinity.

Vide Adedayo · Journal of Research in National Development · Nigeria (Lagos)

This study investigated poultry waste management in urban vegetable farms in Metropolitan Lagos from an ecosystem to human health perspective. Using a transdisciplinary approach, community participation, and socio-cultural, physiochemical, microbiological, and clinical information, the research revealed negative impacts and health problems associated with poultry waste management due to poor storage, composting, and packaging techniques. Consequently, adverse effects on users were identified.

Carol Posthumus · SABI Magazine - Tydskrif · South Africa (Cape Town)

Abalimi Bezekhaya, a community-supported agricultural organization in Cape Town, operates a network of approximately 5000 small-scale organic farmers across various areas of the Cape Flats. The organization views the city as a farm, contributing to fresh food security.

Alain Peoule Kouhouyiwo GOMGNIMBOU, Birjees Hassan, A. Sanon, P.M. Sedogo, Martinez, J. · HAL (Le Centre pour la Communication Scientifique Directe) · Africa

A study evaluating the effect of pig and cattle manure application on soil chemical parameters of Lixisols in the Bobo-Dioulasso area of Burkina Faso, framed around the potential for organic waste fertilizers in urban and peri-urban agriculture to maintain soil fertility and support food security. Eight farms using animal waste and some non-cultivated plots were identified in 2012, and soil samples were taken for chemical analysis. Pig manure use lowered soil pH (H2O) by 0.46 units at 0-10 cm depth and 0.51 units at 10-20 cm, while increasing organic carbon and nitrogen content and easily absorbed phosphorus at both depths. Cattle manure use raised total potassium to 1,210 ppm at 0-10 cm and 1,351 ppm at 10-20 cm, and cation exchange capacity (CEC) to 7.18 meq/100g, about three times that of unmanured plots. The study concludes animal manure could be an alternative to costly chemical fertilizers.

Messay Mulugeta · DOAJ (DOAJ: Directory of Open Access Journals) · Ethiopia

This study assessed the need for a policy framework for urban/peri-urban agriculture (UPA) in Ethiopia. It was based on a desk review of other countries' experiences and policy frameworks, supplemented by primary and secondary data from Ethiopia and interviews with legislators, experts, urban farmers, and urban planners. The study's synthesis indicates that formulating a policy framework and by-laws for UPA in Ethiopia is imperative for the country to fully utilize the sector's potential.

Diana Lee-Smith · City · Africa

This paper reviews a synthesis from late 2010 on Urban and Peri-urban Agriculture (UPA) data from East and Central Africa, identifying major issues such as UPA's relationship to food security and poverty, its waste recycling effectiveness, and policy responses. The analysis is updated with data from Southern Africa, suggesting UPA's capacity to recycle nutrients, particularly on efficient crop-livestock backyard farms, signifies its potential role in making cities sustainable.

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.

Vide Adedayo · · Nigeria

A study of poultry waste management and utilization techniques in urban vegetable farms in metropolitan Lagos revealed that poultry waste is poorly collected, packaged, and transported. Proper knowledge on treatment is lacking due to insufficient skill, space, time, and capital. Furthermore, a significant difference was found between poultry waste utilization, crop yield, and revenue in the study area.

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.

Oranjezicht City Farm · Oranjezicht City Farm (OZCF) · South Africa

Founded in 2012, Oranjezicht City Farm (OZCF) is an organic urban farm and market in Cape Town, South Africa. Alongside a weekend market selling certified organic produce, it runs volunteer programmes, workshops and farm tours to build local food culture and community. In December 2025 the market relocated to the V&A Waterfront.

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.

Sarah Ward · · South Africa (Cape Town)

This article features an interview with Christina Kaba, who works for Abalimi, an urban agriculture and environmental action association operating in socio-economically neglected townships on the Cape Flats near Cape Town, South Africa. Kaba assists individuals, groups, and community-based organizations in initiating and maintaining permanent organic food growing and nature conservation projects, which serve as a basis for sustainable lifestyles, self-help job creation, poverty alleviation, and environmental renewal.

S. A. Materechera · African Journal of Agricultural Research · Africa

A study of soil salinity in irrigated fields used for urban agriculture in a semi-arid region of South Africa. It compares sodium levels (19.3 vs. 9.8), pH (7.13 vs. 6.3) and electrical conductivity ECe (22.1 vs. 7.9 dS/m) between topsoil and subsoil layers, finding that calcium, magnesium and potassium (unlike sodium) were higher in the top than the subsoil layer, while pH and ECe did not differ significantly by depth overall. By irrigation method, basin irrigation produced the highest accumulation of calcium, magnesium, potassium and sodium, followed by drip and then sprinkler irrigation, with the same ranking (basin > drip > sprinkler > control) for pH and ECe; sprinkler irrigation was the only method showing higher pH and ECe at 10-20 cm depth than at 0-10 cm. The study concludes that irrigation is increasing soil salinity and points to the need for sound irrigation water management, particularly appropriate irrigation scheduling.