Interactive comment on "N 2 O release from agro-biofuel production negates global warming reduction by replacing fossil fuels" by P. J. Crutzen et al.

Crutzen, Mosier, Smith and Winiwarter claim that the nitrous oxide (N2O) emissions from energy crop production have been underestimated in existing studies of the greenhouse gas (GHG) balances of biofuels. We agree that N2O emissions are an important and often neglected issue in the debate on biofuels. However, there are several aspects of the calculations presented by Crutzen et al. that may cause a substantial overestimation of their N2O emissions from energy crops, particularly the N2O emission factor.