Greenhouse gas emissions in maize agroecosystems of Sub-Saharan Africa: evidence synthesis and mitigation insights

Résumé

Maize-based agroecosystems dominate food production across much of Sub-Saharan Africa (SSA) and are central to regional food security. At the same time, agricultural soils are important sources of greenhouse gas (GHG) emissions, particularly nitrous oxide (N 2 O), carbon dioxide (CO 2 ) and methane (CH 4 ), raising concerns about the climate impacts of maize intensification. Although a broad body of agronomic research in SSA has examined soil carbon dynamics, nitrogen cycling and productivity trade-offs, evidence based on field-measured GHG fluxes from maize systems remains limited. This review synthesises experimental, field-based studies that quantify CO 2 , N 2 O and CH 4 emissions from maize agroecosystems in SSA to characterise emission levels, identify key emission drivers and assess the mitigation potential of various management strategies. A PRISMA-guided systematic mapping and narrative synthesis was conducted using Web of Science and Scopus databases. Twenty-one field-based studies met the inclusion criteria and were analysed using bibliometric and thematic approaches. Across the reviewed studies, GHG emissions from maize systems in SSA were generally lower than those reported from high-input systems elsewhere, attributed to low nitrogen inputs and prevailing environmental conditions. Nitrogen management and soil moisture consistently emerged as dominant controls of N 2 O emissions, which typically contributed most to overall global warming potential. Carbon dioxide fluxes were strongly influenced by tillage practices and residue management, while soils commonly acted as net sinks for CH 4 , with episodic emissions during prolonged wet conditions. Evidence on conservation agriculture components points to context-dependent mitigation potential, with trade-offs among CO 2 , N 2 O and CH 4 varying by soil type, climate and management intensity. The review highlights the need for long-term, multi-site field experiments, particularly in underrepresented regions, to support the development of context-specific, climate-smart maize production strategies in SSA.

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