Changing soil degradation trends in Senegal with carbon sequestration payments

Abstract

In Sudo-Sahelian Africa, erosion and nutrient mining are prominent causes of soil degradation. In Senegal, harvesting grains and crop residue from the land impact heavily on soil carbon content, while the insufficient replacement of soil nutrients with fertilizers contributes to negative nutrient balances. Given the economic perspective of the rational farmer and the dynamic nature of crop and soil management issues, this thesis used a regional case study in the Groundnut Basin of Senegal to do the following: describe and assess economic incentives specific the to the case study region; model the farmer's production and decision making process; design carbon contract policies and model them within the farmer's decision making process; simulate the interaction between the current agricultural marketplace and potential carbon policies; and to assess the role that carbon sequestration could play in helping the region deal with soil degradation problems, if and when international action is taken to reduce greenhouse gas emissions.

Information from farmers in the region indicates that several factors constrain fertilizer use, including financial constraints and market imperfections. The result of these constraints is to reduce the productivity and increase the farm gate cost of fertilizers. The results of the simulation supported this hypothesis. Using data from the Groundnut Basin in Senegal, and employing an econometric-process simulation model, this study found that some carbon contracts could be used to reduce losses in soil carbon and productivity; however, only at high carbon prices ($180 USD/t carbon and higher). Transactions costs, the additional labor costs associated with residue incorporation, and groundnut residues prices all strongly influenced the results of the carbon contract policies, particularly where carbon prices are less than $100/t.