Carbon Mineralization under Different Saline—Alkali Stress Conditions in Paddy Fields of Northeast China

Round 1

Reviewer 1 Report

Wang and coauthors have described that the effects of soil organic carbon mineralization under four different saline-alkali conditions which were obtained from western Jilin Province of northeast China. They have concluded that higher the degree of salinization and alkalinity leads weaker mineralization and decomposition of the soil organic carbon using 70-day incubation experiment. They have also shown that the decomposition was consistent with the first-order kinetic equation.

I think this manuscript is based on well designed experiments and the results and discussions are clearly presented. I would like to recommend acceptance after minor revision.

Comments:

1. Please increase the text size in Figure 1 and Figure 2.
2. In figure 5, from day 7 to day 10, there are increment of the mineralization rate of soil organic carbon for all 8 samples. Please discuss on this in the result or discussion part.
3. Line 256, authors described that P2>P1>P3>P4, however, based on the figure 5, it is not clear to determine P1>P3. Please include the raw data to make sure they are clear.
4. Line 257, the trend P1>P2>P3 is not clear from the figure 5. Please include the raw data.
5. Line 258, please make sure table 2 includes SOC contents.
6. Line 271, the slope is not becoming negative after a period of time based on the presented data on Figure 6. Please double check whether this is a appropriate description.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

• I believe that reference number 15 is not complete.
• Citation number 35 does not correspond to Marklein AR et al.
• There are some minor technical errors in the text. For example:  line 90 - instead of "hm²" it should be "km²"; line 126 - three time "the, the, the"; line 261 - double paranthesis; line 271 - double dash; line 335 - missing dot after sentence; line 365 - number "(320627 yr)" is correct? Is there a missing decimal point?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript “Carbon Mineralization …” by Wang et al. is important research and presents logical conclusions that will be very interesting to soil scientists. Other earth scientists, geologists, and chemists will find it very hard to follow because of the fact that the soil science community has redefined a few terms such as “carbon mineralization” (conversion of carbonaceous material to carbon dioxide) so that other scientists have no idea what they are talking about. The vast majority of science defines mineralization as the precipitation of minerals out of solution including the precipitation of carbonates that sequester carbon dioxide from the solution and atmosphere. The results are the opposite and lead to confusion, so my first suggestion is for Wang et al. to indicate very early in the text and perhaps in the abstract that they use the soil science definition and simply add the phrase “conversion of carbonaceous material to carbon dioxide” where “carbon mineralization” is first used (lines 15 and 59). There are several additional changes that I would recommend. On line 19 of the abstract “the incubation period” is first introduced with any clue as to what is being incubated or how or why. That is unacceptable. The manuscript is based on the results of a controlled experiment involving the exposure of saline-alkaline soil to sodium hydroxide fumes but absolutely no chemistry is provided or any clear reason for the experiment. There needs to be some presentation of a balanced chemical reaction involving sodium hydroxide with carbonaceous material to yield carbon dioxide and whatever else is generated. I find the total lack of chemistry to be very frustrating. In addition, I would expect saline-alkaline soils to contain significant quantities of carbonates particularly calcite and perhaps some sodium or potassium salts. How can you accurately measure carbon dioxide emission and sodium activity without any consideration of such minerals? How can you assume that all the carbon dioxide is sourced from the organic material in the soil and not from the calcite? A few additional line by line items follow.

Line 136 Where is the CEC data?

Line 147 Where is the BD data?

Line 151 Why did you measure EC?

Line 247 What happened at 10 days that caused the anomaly?

Line 248 The lines are so close together that it gives the impression that the four samples acted the same at both depths. Some detail at the 0 to 10 day level should be presented.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf