Soil carbon sequestration in small-scale farming systems: A case study from the Old Peanut Basin in Senegal.

摘要

Carbon sequestration in small-scale farming systems in semi-arid regions offers the possibility to increase local soil fertility, improve crop yields, enhance rural people's wellbeing, and strengthen the resilience of agricultural systems while reducing CO₂ accumulation in the atmosphere and, thus, contributing to climate change mitigation. A variety of management practices and land use options have been proposed to increase carbon uptake and reduce system losses. So far, less attention has been paid to local smallholders, the ultimate agents of anticipated community carbon projects, and the complexity, diversity, and dynamics of their livelihoods in a highly variable and risk-prone environment.; A hybrid research approach, combining biophysical, economic, cultural, and institutional analysis, was used to assess the potential for soil carbon sequestration in the Old Peanut Basin of Senegal. In situ soil and biomass measurements provided current carbon accounts. Historic carbon changes and future sequestration rates under various management practices were simulated with CENTURY, a biogeochemical model. The simulation results well represented general historic trends and carbon storage potential. However, they did not accurately reflect variable and flexible site-specific management strategies as farmers adapt to stress, shock, and crises over time. To account for these, distinct pathways of agricultural and environmental change were examined in Wolof and Serer villages and viable options for carbon sequestration were evaluated. Systems analysis was used to explore the various components that influence farmers' perceptions, choices, and decisions with respect to land management. Results showed that resource endowment and institutional and policy incentives determine which carbon sequestration activities might be most appropriate for different groups of farmers. Finally, a cost-benefit analysis and a cash-flow analysis (using STELLA) were performed to assess the financial profitability and economic feasibility of proposed management strategies. The study reveals large differences in these measures between farmers with low and high resource endowments. In most cases, local smallholders are not likely to have the investment capital necessary to implement the alternative management practices. A farmer-centered approach to carbon sequestration, as proposed by the study, can be used to more effectively address the needs and capacities of smallholders in dryland carbon offset programs.