A simple two-equation model is proposed for soot formation and oxidation. It is based on measurements of the maximum soot volume fraction, experimentally observed in all premixed hydrocarbon-air laminar flames, and depends on the fuel composition. The model is validated on laminar diffusion flames, and then introduced in an Eulerian-Lagrangian approach to predict turbulent flames. The proposed set of constants has been adapted to ethylene-air atmospheric flames, although the newly developed approach may be applied to any hydrocarbon-air diffusion flame. The major parameters have been tested and the present study emphasizes the effects of turbulent fluctuations on the soot yield. The comparison of the computed results and experimental published data shows good agreement with the predictive trends provided.