In this article a soil-vegetation-atmosphere transfer model is implemented to estimate amongst other variables, sensible and latent heat fluxes, in crop fields and other vegetated areas. Two distinct sub-models for carbon fluxes were implemented. We compared the models with each other and with heat flux measurements over a soy field. The results show the impact of the different stomatal response implementations on the surface heat fluxes. We found that the model has good predictive potential for operational applications or for evaluation of potential climate changes resulting from land-use modifications.