  Carbon sequestration is the process of capture and long-term storage of
atmospheric carbon dioxide (CO2) with the aim to avoid dangerous climate
change. In this paper, we propose a simple mathematical model (a coupled system
of nonlinear ODEs) to capture some of the dynamical effects produced by adding
charcoal to fertile soils. The main goal is to understand to which extent
charcoal is able to lock up carbon in soils. Our results are preliminary in the
sense that we do not solve the CO2 sequestration problem. Instead, we do set up
a flexible modeling framework in which the interaction between charcoal and
soil can be tackled by means of mathematical tools.
  We show that our model is well-posed and has interesting large-time
behaviour. Depending on the reference parameter range (e.g. type of soil) and
chosen time scale, numerical simulations suggest that adding charcoal typically
postpones the release of CO2.
