Dear Mathieu,

Thank you very much for your comments to the reports of 4 reviewers. These provided quite a number of concerns with your MS to which I agree. Though most of your answers seem logical, I am not so happy with them as it is often unclear to me what, or if at all, you intend to change/modify. This should normally be provided (…thus, I'm modifying the text in the following way... thus, I refrain from changing the text) as it is otherwise rather difficult for the editor to assess as to whether a contribution is likely to improve sufficiently to meet the journal's standards.
I trust that you intend to modify more than you stated in the rather few instances where you clearly outlined modification plans - for the revised version, this would not be enough. In particular with respect to some methodology, the bubble method, I kindly ask you to provide a solid discussion in the revised text as previous publications showed that determining kinetics from incubations with large volume bubble methods can be problematic because of reservoir effects. If you have data that show that this is negligible, then they should be shown/cited.
Hereby, I invite you to provide a revised MS, but I expect that the concerns of the reviewers will be addressed appropriately. Please use the 'track changes' mode of your text editor, so that the reviewers and I can better assess the progress of your MS.

Best wishes, Helge

Dear Mathieu,

thank you again for submitting your interesting work to Biogeosciences. There are only a few points that need clarification / an extension of the discussion, before I can accept the MS.

Reviewer 1 gave some specific suggestions, and I kindly ask you to address these. Please pay particular attention to the question regarding potential N-contamination of your samples when exposed to atmospheric N, and the bias induced by measuring d15N at the end of the incubation.

Dear Mathieu,

thank you very much for considering BG as a journal for your interesting work, which I hereby would like to accept for publication in BG. The copy/print editorial board will contact you soon regarding the further steps necessary for production.

With the best wishes, Helge