Fallow Land Simulations to Fight Against Soil Degradation: Engaging Stakeholders with Model Exploration

This methodological paper forms part of a modelling approach conducted in the Senegalese groundnut basin. It addresses two key aspects: (1) the process of co-constructing the model with local stakeholders; and (2) the use of calibration to account for non-measurable elements, which stakeholders needed to describe and evaluate their system effectively. Thematically, the study examines the relationship between social solidarity and agro-pastoral systems in Diohine, a Senegalese village where communal fallow lands are a vital indicator of socio-ecological resilience. Using the co-constructed, agent-based "Me re Diam" model, we examine the dynamics of soil fertility, population growth and agricultural yields over a 25-year period, integrating local knowledge and ecological data. Our findings emphasise the pivotal role of social solidarity mechanisms, such as parcel lending and food sharing, in stabilising agro-pastoral systems amidst resource scarcity. Calibrating the model demonstrates its ability to reproduce historical dynamics and test alternative practices. Without these mechanisms, the system collapses, revealing their indispensable nature for long-term sustainability. This work emphasises the importance of collaborative modelling in bridging the gap between empirical data and local practices, providing actionable insights for addressing soil degradation and demographic pressures.