<p>Soil carbon flux is the main source of atmospheric CO₂. An accurate understanding of the soil CO₂ transport process is of substantial significance for the study of global carbon flux and the prediction of future climate change. In this study, data on CO₂ concentrations over time in five media under the influence of surface winds and pore air pressure fluctuations were analysed using (1) an analytical solution of the dispersive transport model and (2) a numerical solution of the advection transport model to accurately delineate the transport mechanisms that control soil gas transport. For loam and sandy soils, gas transport is mainly dominated by diffusion, and in highly permeable sand, gas transport changes from diffusion–dispersion transport to advection transport dominated by wind speed and pore air pressure fluctuations. The effects of surface wind and pore pressure fluctuations on advection velocity differed with depth. The pore pressure fluctuations had a stronger penetrating power. The ratio of the enhanced diffusion coefficient (<i>D</i>_<i>e</i>) to advection velocity(<i>v</i>) was effective in determining the transport mechanism driving gas transport within the medium, which is conducive to accurately modelling the release of CO₂ from soils to improve the understanding and assessment of the global carbon cycle.</p>