Dear Drs. You and Zhuang,

Thank you for submitting your paper to Biogeosciences. Two expert reviewers provided comments on your paper and thank you for your responses to them in the interactive discussion. Based on your responses and the reviewer’s recommendation I now ask you to revise your paper and resubmit it for a second round of review. The paper will likely go to the same reviewers but additional suggestions for reviewers are appreciated.

If you have any questions let me know.

Best,
Denise Akob

Dear Drs. Yu and Zhuang.

Thank you for revising the manuscript based on the previous rounds of reviewer comments. One of the previous reviewers and I read over the revised manuscript and we both agree that the paper is a nice contribution to the debate on how much nitrogen is fixed globally through microbial activity, and provides a further approach towards modeling BNF. However, the paper does have some grammatical issues and would benefit from having a professional editor to smooth over the language by improving sentence structure and grammatical flow of the manuscript.

In addition, I made some suggestions for edits that are in the marked up manuscript. One place that I see a need for improvement is at the end of the introduction-- I suggest adding a statement there about why the work needs to be done. This is stated in the abstract but not in the introduction. Further, when referring to nitrogen fixation please use "N2" instead of N-- I marked all of the places this needs to be fixed. Since my notes are handwritten on the PDF please let me know if you have any questions.

Best,
Dr. Denise Akob

Dear Drs. Yu and Zhuang,

Thank you for making the requested revisions. I am pleased to accept your paper for publication in Biogeosciences!

Sincere apologies for the delay in returning a decision.

All the best,
Denise