Research & reports

Aminu Zakariyau, Murtala Rabiu · International Journal of Advances in Engineering and Management · Nigeria (Katsina City)

The potential ecotoxicological impacts of municipal solid waste compost (MSWC) on soil, plants, and humans in urban Katsina, Nigeria, were assessed. Analysis of soil mixtures and plant biomass (maize and beans) revealed high phytotoxicity in beans, while maize considered MSWC as phytonutrients. No statistical difference in non-biodegradable substance concentrations in soils and plants was found, and ecological risk index (ERI) indicated low risk; however, Target Hazard Quotients (THQ) suggested a likelihood of non-carcinogenic effects to the ecosystem.

Abrham Kassa Ejigu, Kumelachew Yeshitela · Frontiers in Sustainable Cities · Ethiopia (Arba Minch City)

A study assessed Arba Minch City's governance capacity to integrate resource-oriented sanitation technology with urban agriculture. The findings indicated that the city's capacity is hindered by a lack of systematic monitoring, fragmented policy tools, and inadequate public sector participation. There is no single government body responsible for integration, and a behavioral gap exists among users in adapting to new technologies and recovered organic fertilizer.

Sani Abubakar Mashi, Samuel Yakubu, Sofia Yuniar Sani · Asian Research Journal of Agriculture · Africa

A study in the Kubanni basin of Zaria, Africa, evaluated the quality of wastewater used for irrigating urban agriculture soils. The wastewater contained arsenic, iron, chromium, copper, zinc, manganese, and lead. Although concentrations were generally below Nigeria's permissible limits for irrigation, the study noted the metals' tendency to accumulate in soils, raising concerns about potential heavy metal buildup in irrigated soils and crops.

Anne-Louise Fritz, Ramia Jannoura, René Beuschel, Christoph Steiner, Andreas Buerkert, Rainer Georg Joergensen · Chemical and Biological Technologies in Agriculture · Africa

This 2-year study in semi-arid Ouagadougou and sub-humid Tamale, West Africa, measured the effects of biochar and N fertilization on soil microbial biomass carbon, fungal ergosterol, and functional diversity. Sole biochar addition did not affect soil chemical or biological properties, but biochar with N fertilization increased microbial respiratory response. N fertilization decreased soil pH by 1.1 units in both cities, and a pH of 4.7 led to reduced microbial biomass carbon and ergosterol contents in Tamale. An N fertilizer-induced decline in soil pH below 5 should be avoided, as it decreased microbial biomass carbon and microbial functional diversity.

Mary Njoki Mwaura, Sabina Mukoya-Wangia, Japheth Ododa Origa, O.L.E. Mbatia, Evans Chimoita · Journal of Agricultural Extension · Kenya

A study of 149 respondents in Nairobi County examined urban and peri-urban agricultural practices, finding composting and open field farming popular but not the most profitable. More profitable practices like cattle rearing and mushroom farming were unpopular due to expensive inputs and specialized skills. The study indicates that popular practices are less profitable, highlighting a need for transformation towards controlled environment agriculture with policy support.

Solomon Tulu Tadesse, O. Oenema, Christy van Beek, Fikre Lemessa Ocho · Frontiers of Agricultural Science and Engineering · Ethiopia

This study in Jimma, Ethiopia, from 2015-2050, used an N mass flow model and field experiments to explore manure recycling from urban livestock farms under four scenarios. It found that livestock manures are the main organic wastes in urban areas, and manure production in urban and peri-urban agriculture (UPA) is projected to increase 3 to 10 times. Critically, only 13% to 38% of manure nitrogen will be recycled in croplands, and intensification of urban livestock production greatly increased nitrogen surpluses, indicating a significant environmental tradeoff.

Hillary A. Craddock, Elisabeth Fost Maring, Stephanie Grutzmacher · African Journal of Food Agriculture Nutrition and Development · Ethiopia

A mixed-methods pilot survey of 21 teachers and parents in Debre Berhan, Ethiopia, investigated household agricultural practices to understand foodborne illness risks. The study found that half of respondents using manure applied uncomposted manure as fertilizer, and many kept multiple animal species. This suggests a high risk of pathogen exposure for children and adults through contact with uncomposted manure and animals.

F. Waswa, M. Mwamburi, I. I. C. Wakindiki, Roseline Chemutai · Journal of applied science and environmental management · Kenya

This study focused on soil physicochemical properties and fertility management in Ruiru Sub County, a peri-urban area in Kiambu County, Kenya. Soil samples from ten small contact farms (~0.1 ha) were analyzed, revealing that most farmers were tenants growing leafy vegetables, maintaining soil fertility with organic manures, and performing tillage by hand. These practices signal limitations imposed by small farm size and lack of land ownership, with soil fertility primarily limited by the interaction of soil pH, K, and Ca.

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.

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.

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.

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.

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.

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.

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.

Andreas Buerkert, Eva Schlecht, Martina Předotová, Rodrigue V.C. Diogo, Katja Kehlenbeck, Jens Gebauer · eScholarship (California Digital Library) · Sub-Saharan Africa

This study analyzed urban and peri-urban agriculture (UPA) systems in major Sub-Saharan African cities, measuring carbon, nitrogen, phosphorus, and potassium fluxes and conducting biodiversity studies. In Niamey, low-input gardens showed annual gaseous carbon emissions of 20-25 t ha-1, predominantly CO2, and high-input gardens irrigated with wastewater had annual CO2-C emissions of 27 t ha-1, with N2O as a major nitrogen loss contributor. Animal manure stored in the open was subject to large carbon and nitrogen losses, indicating environmental tradeoffs. However, UPA gardens in Niamey maintained a large variety of fruit and vegetable species, with richness increasing with garden and household size and commercialization.

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.

Halidou Koanda · Infoscience (Ecole Polytechnique Fédérale de Lausanne) · Sub-Saharan Africa

In Sub-Saharan Africa, faecal sludge management practices are often financially unviable due to widespread lack of municipal involvement, paucity of legal provisions, and absence of stakeholder coordination. This leads to indiscriminate dumping of faecal sludge in urban areas or its untreated use in urban agriculture. These practices pose permanent and serious health risks and contaminate scarce ground and surface water. This research aims to develop an innovative strategic planning approach for sustainable urban faecal sludge management to minimize public health and environmental risks.