Research & reports

Alemseged Gerezgiher Hailu, daniel girmay, samuel ataklti · Discover Food · Sub-Saharan Africa

This scoping review analyzed 155 sources (2009–2024) on urbanization's impact on food security in Sub-Saharan Africa. Findings showed rapid urban expansion converted 30% of peri-urban agricultural land in some regions, increasing dependence on imported staples, and low-income households spend 60–80% of income on food. A policy gap was identified, with only 12% of countries having supportive policies and 19% of cities designating land for farming.

Mugabo Kalisa G. · Idosr Journal of Computer and Applied Sciences. · Sub-Saharan Africa

A review article addresses how, in Sub-Saharan Africa (SSA) where malaria transmission is increasing in urban and peri-urban areas due to rapid urbanization and inadequate infrastructure, urban agriculture — a vital livelihood strategy in peri-urban SSA — often intersects with poor water management practices, creating favorable breeding grounds for malaria vectors, particularly Anopheles mosquitoes. It examines the complex relationship between urban agriculture, water management and mosquito breeding in peri-urban areas, including how irrigation systems, water storage and waste management contribute to malaria transmission, and discusses the implications for malaria control. It also reviews emerging technologies such as remote sensing, GIS and mobile health platforms that can enhance mosquito surveillance and community involvement, and calls for a multi-sectoral approach spanning urban planning, vector control and community-based interventions, along with sustainable urban agricultural practices to mitigate malaria risks in SSA.

A. K. Ahmed, Rasheed Abiodun KURANGA, Oluwadara Latifat ISOLA-MUYIDEEN · International Journal of Research and Innovation in Social Science · Nigeria (Ilorin)

This study assessed the sustainability of environmental management practices among peri-urban rice farmers in Ilorin, Nigeria, using a sustainability index. It found that many practices were less sustainable, with 69.51% of farmers relying on chemical sprays and 69.85% using chemical fertilizers. The overall Environmental Management Practices Sustainability Index (EMPSI) for all farmers was 0.492, placing them in the moderately sustainable category.

Fuchaka Waswa, Duncan Gichabe, Ruth Kahuthıa-Gathu · Journal of the Kenya National Commission for UNESCO · Kenya (Ruiru)

This study investigated land use changes in Ruiru Sub-County, Kenya, from 1988 to 2024 using GIS. By 2024, agricultural land had decreased by 45.62%, while urban land use increased by 509%, and bare/rocky areas rose by 133% due to abandoned stone mining. The decline in agricultural land leads to reduced industrial crop areas and a shift to leafy vegetables, with an expected increase in agro-chemical use in intensive peri-urban farming.

F.E. Awoyelu, R.A. Mebo · Agro-Science · Nigeria (Osun State)

This study assessed the effects of artisanal sand mining on peri-urban agriculture in Ife East and Ife Central Local Government Areas, Osun State, Nigeria, from 2015 to 2019. Data from 120 respondents (landowners, cultivators, residents) showed that cultivated land area decreased by 24.8% (from 48% to 23.2%), while sand-mined area substantially increased by 20.4% (from 14.6% to 35%). Landowners' decision to part with land for sand mining increased with age, household size, and farming as primary occupation, but decreased with higher education levels.

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.

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.

Achamyeleh Gashu Adam · IntechOpen eBooks · Ethiopia

A case-study and desk-review analysis of how new urban built-up properties form in the transitional peri-urban areas of Ethiopia. These areas are described as sites of intense competition between agricultural and non-agricultural land use, where rural agricultural land rights are vanishing. The study finds that both formal and informal actors play a significant role in converting peri-urban agricultural land into non-agricultural urban built-up property, and that these properties result from land-use conversion through both formal and informal channels.

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.

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.

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.

Ekaete Francis Asuquo · · Nigeria (Calabar)

The impact of urban expansion on agricultural land in Calabar and its environs, Nigeria, was investigated. A survey of 150 questionnaires and comparative assessment revealed a decrease in agricultural land in the fringes as urban expansion persists and increases. Before 2013, more farmers owned larger plots, but much of this agricultural land has been converted to housing estates, roads, leisure resorts, and schools, indicating that urban expansion has negatively impacted agricultural land, reducing food productivity and leading to farmer unemployment.

CDR Aza-Gnandji, Yongxin Xu, Lincoln Raitt, Jonathan Levy · Water SA · South Africa (Cape Town)

This study explored the salinity of irrigation water from the Cape Flats aquifer in the Philippi farming area of Cape Town, South Africa, collecting water samples from boreholes and ponds in summer and winter. Concentrations of chloride, nitrate, potassium, and sodium exceeded target maximum limits set by DWAF and FAO guidelines. Groundwater and pond water were found to be brackish in most parts of the research area, with salinization primarily attributed to agricultural activities. The water is generally suitable for irrigation but requires caution for salt-sensitive vegetables.

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.

E. Mensah, Philip Amoah, Pay Drechsel, Robert Clement Abaidoo · CABI Publishing eBooks · Sub-Saharan Africa

This work, presented as case studies from Accra and Kumasi, addresses environmental concerns of urban and peri-urban agriculture. It focuses on waste composting for urban and peri-urban agriculture, aiming to close the rural-urban nutrient cycle in Sub-Saharan Africa.