EPIC perhaps? E.g. Izaurralde et al., 10.1016/j.ecolmodel.2005.07.010. See http://epicapex.tamu.edu. I'm not sure but think it does N2O.

Maybe DNDC model. It aim at modling N2O emission from agricultual soils at any time step scale

Hi Marcus, the two most recognised models for N2O simulation from agricultural soils would be DNDC and Daycent. I am no modeller but as far as I know the daily time step is the most popular and I don't think these two models could use hourly data input. However they would be appropriate tools for estimating fluxes. I hope this helps.

About the two models:

http://www.globaldndc.net/information/about-us-i-1.html

http://www.nrel.colostate.edu/projects/daycent/

I am workin in a model where the metereological variables are included with the traditional variables considered in a Coob Douglas model.