Soil Carbon Management for Climate-Smart Agriculture in the Derived Savanna Zone of Ogun State, South West Nigeria

This study evaluates soil carbon management practices and their integration into climate-smart agriculture (CSA) programming in the derived savanna zone of Ogun State, located in Nigeria's South West geopolitical zone. The derived savanna of Ogun State is characterised by accelerated soil organic carbon depletion under conventional farming, and the adoption of CSA practices that simultaneously improve food productivity and enhance soil carbon sequestration represents both an adaptation and mitigation opportunity. Using a professional programme evaluation and design methodology, 35 smallholder farms in Yewa North, Ijebu North, and Obafemi-Owode local government areas were assessed for current soil organic carbon levels, farming practices, and willingness to adopt CSA technologies. Soil carbon stocks were measured at 0 to 30 cm Soil Scienceh using the IPCC Tier 1 approach. Five CSA practices (cover cropping, minimum tillage, agroforestry integration, compost application, and improved fallow) were evaluated for their soil carbon improvement potential using a meta-analysis of experimental trials from comparable West African agroecological contexts. Findings revealed mean soil organic carbon of 0.92 percent across surveyed farms, representing 42 percent depletion from estimated natural savanna levels. Farmers expressing willingness to adopt CSA practices were primarily motivated by yield improvement rather than carbon sequestration per se, underscoring the importance of productivity co-benefits for farmer adoption. The study designs an ISFM-based CSA programme for Ogun State's derived savanna, prioritising agroforestry and cover cropping as the most adoptable and carbon-effective practices. Keywords: soil carbon management, climate-smart agriculture, Ogun State, derived savanna, carbon sequestration.