Rainfall Runoff and Nitrogen Loss Characteristics on the Miyun Reservoir Slope

Round 1

Reviewer 1 Report

The paper concerns an important topic - erosion changes and the associated losses of a nutrient - here, nitrogen. The research presents a typical approach to the subject and has a local dimension. These are one-time/one-year tests and without tests it is questionable. Moreover, the authors focused on quantitative changes - total nitrogen leaching - which is a bit surprising, especially when we assess the leachability of easily soluble/water-soluble forms in mineral forms. In my opinion, this would be more valuable information than giving the amount of N in general. The paper is in many places imperfect, general and based on certain speculations. I believe that if it were supplemented with the amount of mineral N, it would be more valuable, especially since a lot of attention was paid to it in the introduction. There is no statistical data documenting the observed changes. Without this information, the results are unreliable. In its current form it is not suitable for publication. Below are the most important comments that contributed to this opinion.
1. Keywords duplicate those in the title - need to be changed.
2. L. 53: fixation should be replaced by sorption
3. Lack of clearly formulated research hypotheses and research goals. The entire paragraph in lines: 97 to 103 should be thoroughly reworded to clearly specify the goals of the research
4. The soil classification according to WRB should be provided
5. The information in lines 123-124 will be easier to read in the form of a table. Also it should be supplemented with soil texture. The analytical methods used to determine these parameters should be provided. Citing the source is insufficient.
6. Lines 126-127 talk about physical properties - what are these properties? , where are the data/methods/results for them?
7. The author's method for determining bulk density should be given.
8. Line 205 - this cannot be stated (soluble nitrogen) because it was not tested in this study
9. Line 207 - why is this literature cited in the description of the results?
10. The paper contains information about statistical calculations, but there is no table with parameters or statistical data that would confirm or exclude the significance of the observed changes. Without this, it is difficult to refer to the results and treat the observed directions as a documented phenomenon
11. Lines 222-224 - speculation - this aspect has not been neglected
The  caption of Figure 5 has been lost and is located under Table 3.
12. The literature in lines: 335, 360, 272 should be different cited
13. The conclusions are very long and are definitely a summary of the results. It should be reworded.
14. The old literature that is over 10 years old needs to be updated.

Author Response

Dear reviewer, We are thankful for your constructive comments, which greatly helped us to improve the paper. We have carefully read all comments and followed. Specific responses to questions and comments are given below. We have applied all changes in the original manuscript file.

Point 1. Keywords duplicate those in the title - need to be changed.

Response 1. Thank you. We revised it.

Point 2.  L. 53: fixation should be replaced by sorption

Response 2. Thank you. We revised it.

Point 3. Lack of clearly formulated research hypotheses and research goals. The entire paragraph in lines: 97 to 103 should be thoroughly reworded to clearly specify the goals of the research

Response 3. Thank you. We revised it.

Point 4. The soil classification according to WRB should be provided

Response 4. Thank you. We revised it. The soil classification belongs to sandy loam soil.

Point 5. The information in lines 123-124 will be easier to read in the form of a table. Also it should be supplemented with soil texture. The analytical methods used to determine these parameters should be provided. Citing the source is insufficient.

Response 5. Thank you. We revised it.

Point 6. Lines 126-127 talk about physical properties - what are these properties? , where are the data/methods/results for them?

Response 6. Thank you. We revised it. Soil physical properties refer to soil texture, and the data is not reflected in the text. The data is only used to ensure that the filling of each layer of soil sample is consistent with the original soil.

Point 7. The author's method for determining bulk density should be given.

Response 7. Thank you. We revised it.

Point 8.  Line 205 - this cannot be stated (soluble nitrogen) because it was not tested in this study

Response 8. Thank you. We revised it.

Point 9.  Line 207 - why is this literature cited in the description of the results?

Response 9. Thank you. We revised it.

Point 10.  The paper contains information about statistical calculations, but there is no table with parameters or statistical data that would confirm or exclude the significance of the observed changes. Without this, it is difficult to refer to the results and treat the observed directions as a documented phenomenon

Response 10. Thank you. We revised it. We added surface runoff and surface runoff yield and TN losses under different treatments (slope and rainfall intensity).

Point 11. Lines 222-224 - speculation - this aspect has not been neglected.The caption of Figure 5 has been lost and is located under Table 3.

Response 11. Thank you. We revised it.

Point 12. The literature in lines: 335, 360, 272 should be different cited

Response 12. Thank you. We revised it.

Point 13. The conclusions are very long and are definitely a summary of the results. It should be reworded.

Response 13. Thank you. We revised it.

Point 14.  The old literature that is over 10 years old needs to be updated.

Response 14. Thank you. We revised it.

Author Response File: Author Response.pdf

Reviewer 2 Report

Rewiev

The authors examined the influence of rainfall intensity and slope slope on surface runoff processes and nitrogen losses. They conducted an indoor simulated rain experiment to understand the distribution characteristics of surface and subsurface runoff and nitrogen migration paths on the slopes of Miyun Reservoir.

The research results were presented reasonably, both in the text, tables and figures. The multi-aspect Discussion  is interesting and supported by a reasonable and extensive selection of literatures. This manuscript contains the current and practical aspects.

Comments:

If we determine total nitrogen, we only determine protein nitrogen of organic compounds and the ammonium form, we omit the mineral forms of nitrate nitrogen(V) and (III). The eutrophication of water reservoirs is mainly caused by nitrates, which are not subject to exchangeable physicochemical sorption and are very easily washed out of the soil. It would be worth extending such experiments to examine the leaching of mineral forms of nitrogen and phosphates(V). Together, these forms determine the pollution of catchment waters.

The introduction of these changes will allow for a more clear transfer of research results on the impact of rainfall and slope inclination on surface runoff processes and nitrogen losses.

Rewiever

Author Response

Dear reviewer, We are thankful for your constructive comments, which greatly helped us to improve the paper. We have carefully read all comments and followed. Specific responses to questions and comments are given below. We have applied all changes in the original manuscript file.

Point 1. If we determine total nitrogen, we only determine protein nitrogen of organic compounds and the ammonium form, we omit the mineral forms of nitrate nitrogen(V) and (III). The eutrophication of water reservoirs is mainly caused by nitrates, which are not subject to exchangeable physicochemical sorption and are very easily washed out of the soil. It would be worth extending such experiments to examine the leaching of mineral forms of nitrogen and phosphates(V). Together, these forms determine the pollution of catchment waters.

The introduction of these changes will allow for a more clear transfer of research results on the impact of rainfall and slope inclination on surface runoff processes and nitrogen losses.

Response 1. Your good advice was very much appreciated. We will analyze the impact of rainfall intensity and slope on nitrate nitrogen(V) and (III) in the next step.

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors

Thank you for the opportunity to review the manuscript.

The author's team conducted time-consuming experimental studies on nitrogen loss from soils on the slopes of the Miyun Reservoir. The results presented in the paper seem interesting and reliable. This type of research is very rarely performed and should be published. I only have two technical comments:

1. Both in the abstract and in the text of the article, the authors use the abbreviation TN, which is explained only in chapter 2.3 Experimental Design – line 152

2. Figure no. 5 should be placed after table no. 4.

Author Response

Response to Reviewer 3 Comments

Dear reviewer, We are thankful for your constructive comments, which greatly helped us to improve the paper. We have carefully read all comments and followed. Specific responses to questions and comments are given below. We have applied all changes in the original manuscript file.

Point 1. Both in the abstract and in the text of the article, the authors use the abbreviation TN, which is explained only in chapter 2.3 Experimental Design – line 152

Response 1. Thank you. We revised it.

Point 2. Figure no. 5 should be placed after table no. 4.

Response 2. Thank you. We revised it.

Author Response File: Author Response.pdf

Reviewer 4 Report

Material and Methods

- You should give a brief characterization of the climate, soil, and land use types of Miyun Reservoir Slope

- If possible, add a map with the geographic location of the study area

- Between what values does the apparent density of the soil vary or what is the average value?

- In all treatments, was the soil bare? This situation represents the maximum potential of erosive processes in each treatment! This information should be placed in the article.

- What laboratory methods were used to analyze sediment and runoff? Were the sediments dried before analysis?

Results

-  Lines 167-169: The tests were carried out with a bare soil surface, right?

- Figures 1 and 2 - you should increase the font size

-  Lines 189-190: “At 60 mm/h, for example, average surface runoff of 5, 10 and 15° slopes was 2.90, 3.2 and 3.6L”. I have difficulty reading this data in Figure 2!!!

-  Figure 5 is missing

Discussion

-  The Discussion can be improved.

Author Response

Response to Reviewer 4 Comments

Dear reviewer, We are thankful for your constructive comments, which greatly helped us to improve the paper. We have carefully read all comments and followed. Specific responses to questions and comments are given below. We have applied all changes in the original manuscript file.

Point 1. You should give a brief characterization of the climate, soil, and land use types of Miyun Reservoir Slope

Response 1. Thank you. We revised it.

Point 2. If possible, add a map with the geographic location of the study area

Response 2. Thank you. We added it.

Point 3. Between what values does the apparent density of the soil vary or what is the average value?

Response 3. Thank you. We added it.

Point 4. In all treatments, was the soil bare? This situation represents the maximum potential of erosive processes in each treatment! This information should be placed in the article.

Response 4. Thank you. We revised it.  In all treatment, soil was bare.

Point 5. What laboratory methods were used to analyze sediment and runoff? Were the sediments dried before analysis?

Response 5. The total nitrogen (TN) in runoff was detected by potassium persulfate oxidation–ultraviolet spectrophotometry, and TN in sediment was examined by semi-micro Kjeldahl assay. This paper did not analyze sediment, only analyzed surface runoff and subsurface runoff.

Point 6. Lines 167-169: The tests were carried out with a bare soil surface, right?

Response 6. Yes. In all test treatment, soil was bare surface.

Point 7. Figures 1 and 2 - you should increase the font size

Response 7. Thank you. We revised it.

Point 8. Lines 189-190: “At 60 mm/h, for example, average surface runoff of 5, 10 and 15° slopes was 2.90, 3.2 and 3.6L”. I have difficulty reading this data in Figure 2!!!

Response 8. We have added Table 3 to supplement illustrate the data in Figure 2.

Point 9.  Figure 5 is missing

Response 9. Thank you. We revised it.

Point 10.  The Discussion can be improved.

Response 10. Thank you. We revised it.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has been mostly revised in accordance with given by me suggestions. However, it is still necessary to correct and specify: 1. clearly indicate the goals of the study; 2. there are no methods for determining organic matter and available forms of P and K - this should be supplemented
3. lack of systematic names of the soil used in the tests according to WRB, 4. the readability of figures 2, 3, 5 and 6 should be improved

Author Response

Dear reviewer, We are thankful for your constructive comments, which greatly helped us to improve the paper. We have carefully read all comments and followed. Specific responses to questions and comments are given below. We have applied all changes in the original manuscript file.

Point 1. clearly indicate the goals of the study;

Response 1. Thank you. We revised it. The research goal of this paper is to clarify the impact mechanism of rainfall intensity and slope on runoff nitrogen loss.

Point 2. there are no methods for determining organic matter and available forms of P and K - this should be supplemented

Response 2. Thank you. We revised it. The soil organ organic matter is determined using the dichromate volumetry–outside heating method, available phosphorous is determined using the sodium hydroxide melting–Mo-Sb colorimetry, and available potassium is determined sodium hydroxide melting–flame pho-tometry.

Point 3. lack of systematic names of the soil used in the tests according to WRB,

Response 3. Thank you. We revised it. The soil in trial areas mainly belongs to cinnamon soil.

Point 4. the readability of figures 2, 3, 5 and 6 should be improved

Response 4. Thank you. We revised it.

Author Response File: Author Response.pdf

Reviewer 4 Report

I consider that the article can be published in its present form.

Author Response

Dear reviewer, Thank you very much for your support.