Dear authors:

Thank you for contribution to Biogeosciences.
Your manuscript on soil carbon storage in the Sanjiang Plain of China
received enough number of comments and I examined your replies and
revisions. You made appropriate responses to most comments.
However, I thought that you did not reply adequately to the Comment23
from anonymous referee 3, i.e. CH4 emission as a result of land-use
conversion from dry farmlands to paddy fields. Please add more
explanations as carefully as suggested by the referee.
Additionally, in your manuscript, you used the word "ecosystems"
to represent "land-cover types" (e.g., Table 1). I think the latter
is more appropriate to indicate both natural biomes and croplands.
Anyway, these revisions may not be difficult, and I'm looking
forward to receiving your revised manuscript soon.

Best regards,
Akihiko Ito

Dear authors:

Thank you for contribution to Biogeosciences. Now, your manuscript received 4 reports from Dr. Ding and three anonymous referees, including a number of comments. I read these comments and your replies and conclude that the manuscript has been revised appropriately for most points. Additionally, as several referees concern about the English writing, you called for an English editing service.
I found requirement of more your clarification for one point: i.e., comment 13 by referee #3. In the revised manuscript, “SOC content”, “SOC storage”, and “SOCD” are still confusing for readers. In Table 1, SOCD of paddy field does not look significantly higher than that of dry farmland. If ‘SOCD is proportional to SOC content (your reply to this comment)’, I could not understand why the relationship found in Fig 8 occurs. Please provide additional explanation. One minor point: in the revised manuscript, you cited IPCC (2001). This is the Third Assessment Report of IPCC, and the latest one, the Fifth Assessment Report of WG1, was published in 2013. Why not cite the latest one?
These revisions may not take long time, and I’m looking forward to receiving your revised manuscript.

Best regards,
Akihiko Ito

Dear authors:

Thank you for contribution of Biogeosciences.
I examined your revised manuscript and found that it became clearer than the previous one. Also, I agree with you to delete Figure 8 in the previous manuscript, because this result slightly confused me. Finally, I conclude that this manuscript is acceptable for publication. I appreciate your long efforts.

Best regards,
Akihiko Ito