Carbon for farmers: Assessing the potential for soil carbon sequestration in the old peanut basin of Senegal

Carbon sequestration in soil organic matter of degraded Sahelian agro-ecosystems could play a significant role in the global carbon (C) uptake through terrestrial sinks while, simultaneously, contributing to sustainable agriculture and desertification control. The paper documents the results of a two-year pilot project in Senegal assessing real project opportunities with main emphasis on the West-Central Agricultural Region ("Old Peanut Basin"). Current total system C content in this region, calculated on the basis of in situ soil and biomass carbon measurements, amounted to 28 t ha ^-1 with 11 t C ha^-1 in soils (0-20 cm) and 6.3 t C ha ^-1 in trees. Potential changes in soil C, simulated with CENTURY for a 25-year period, ranged from -0.13 t C ha^-1 yr^-1 under poor management to +0.43 t C ha^-1 yr^-1 under optimum agricultural intensification. Simulated changes in crop yields varied from -62% to +200% under worst and best management scenarios respectively. Best management practices that generate the highest sequestration rates are economically not feasible for the majority of local smallholders, unless considerable financial support is provided. Especially when applied on a larger scale, such packages risk to undermine local, opportunistic management regimes and, in the long run, also the beneficiaries' capacity to successfully adapt to their constantly changing environment.