Effect of Thaw Depth on Nitrogen and Phosphorus Loss in Runoff of Loess Slope
Round 1
Reviewer 1 Report
The main aim of the paper is analysing the effect of thaw on Nitrogen and phosphorus loss in Less slope.
The study shows interesting information but some of the information is missing. It seems there are no repetitions with different samples of soil from different locations. There are no repetitions of the results, and no different conditions are tested (different slopes or different rains for example). Discussion of some parts of the paper are poor and should be redone. More conditions should be tested and results remade with the new data.
Specific comments
Line 25. Acronyms should be explained in the abstract (AN, TN, NN…)
Line 45. Reference needed.
Line 53 and 55. Reference needed.
Line 62. Reference needed.
Line 85. Reference needed.
Line 103. How many samples? All from the same location? Description of the location? Cultivated soil??
Line 107. The values are average of several measurements? Where is the error of the average? How ere measured?
Line 114. The quantity or strength of the rain could be modified? Size of the drops? It is similar to the kind of rain of the area studied? (line 125).
Line 125. Only one slope? Why not several? Why 15º? Why 0.9 mm-1 of simulated rain? Why not other values?
Line 128. One sample of soil or different samples were prepared?
Line 149. Method used to measure N and P?
Line 185. This result needs a proper discussion. Why 6 thaw deep is lower that 2 or 4?
Line 197. Values are averages? Where is the error? Statistical analysis to check differences?
Line 235. Acronyms should be explained in the text.
Line 238. How many measurements were done? How did you calculate the statistical differences if there were only one value per measurement?
Line 284. Quality of the figures should be improved.
Line 292. Why higher at 4 cm?
Line 293. Total loss from the initial N of the soil?
Line 333. These results need a proper discussion
Line 418. Conclusion should be based in the discussion and explain the results obtained.
Author Response
Dear editor and reviewers, please see the attachment, thanks.
Reviewer 2 Report
The article is practically important, based on lengthy laboratory experiments that require time and energy. The results obtained by the researchers are applicable not only for one type of soil, but can help maintain fertility in large areas, therefore, the relationship between erosion and temperature changes deserves further study on different types of soils.
However, the article has some defecrs, poor-quality design. I have noted the most notable ones, but the manuscript needs to be reworked by the authors and literary editors.
References to the results should not be formulated as separate sentences that do not carry any information, for example: “The regression analyzes of the runoff rate and the Nitrogen loss in runoff for the different thawing depths are shown in Fig. 5 and Tab. 3 ". “Runoff energy and runoff power of the different thawing depths are shown in Tab. 7 ". It is necessary to save the readers' time for reading: it is necessary to immediately describe in words the phenomenon you have established, and after that, in parentheses, give links to the table and figure.
The size of the fonts in all figures should be the same, equal to about 9 points.
If the quality of figure 4 is excellent, then in figure 5 all lines are of poor quality. The same remarks for other figures.
There should always be a space between the number and the unit of measure, for example in the legend of Figure 6.
There is no need to repeat the units of measurement several times, for example, on lines 278, 280, 330.
The header of table 7 is made incorrectly. In general, Table 7 does not contain any statistical processing of the data. I (probably like other readers) do not understand how “The T test showed that there were significant differences in runoff energy and runoff power at the different thawing depths (P <0.05).” (Line 363). Does this sentence refer to table 7? If yes, then the methodology and results of the statistical processing should be indicated in the table itself or in a note below it. Authors should remember that it is imperative to check the normality of the sample before performing the T test. I doubt that normality (lack of significant skewness and excess kurtosis) is achievable for such a small dataset.
It is better to edit the text, make the sentences more concise, for example: “The freeze-thaw cycle has a significant effect on the ammonia Nitrogen and nitrate Nitrogen proportions in inorganic Nitrogen” (lines 294-295). There are many similar places in the article.
I disagree with the authors about statistical processing. In the figures where it is advisable to calculate the regression equation, the authors do not do it. Where it is not correct to draw any trend lines, the authors draw them and calculate the regression equations by four points (Figures 3, 9, 10 and 11). Authors need to either add data points (at least the same number) and build a new regression equation from them, or they need to remove any regression equations and trend lines.
The names of all pictures should be self-contained. For example, in the title of Figure 3, you need to add a repetition of the study and 3-4 more parameters that will help to understand the essence of the image.
Line 230. It is necessary to draw trend lines on the plot (by increasing its size) and compare them with each other for these curves.
I believe the article will benefit if Results and Discussion become separate sections. The weak side of the manuscript in its current form is the lack of a detailed comparison of the data obtained for this experiment with the literature data. The article will benefit if the authors show readers what is new in their results compared to previous experiments.
I do not understand why there is a “[J]” after the title of each article in the bibliography.
Despite the indicated defects, the article contains interesting results and can be recommended for publication after revision.
Author Response
Dear editor and reviewers, Please see the attachment, thanks
Author Response File: 
Author Response.docx
Reviewer 3 Report
Dear Authors,
The topic of the article is interesting and intelligible. The manuscript has certainly potential to improve. In my humble opinion, if the manuscript is thoroughly revised and reorganized, it can make a fine publication. To help improve the quality of this manuscript, I have added more comments bellow:
General Comments:
- Please replace the abbreviations in "Abstract" with the full name.
- Please highlight the listings from the "Abstract" with concrete numbers. In paper it is not uncommon in "Abstract" to have enumerations. Please rephrase.
- Please change the word "study" in the sentences to "paper”.
- Add more concrete results (numbers) that confirm the hypotheses in the conclusions.
- Correct the "References" section in accordance with the "Instructions for Authors".
Line-by-line comments:
L100 The introductory text for "2. Materials and methods" is missing. Please add.
L181 The introductory text for " 3. Results and discussion" is missing. Please add.
L188 “[31,32,33]” -> [31-33]
L190 “Fan[7] et al. (2010),” -> Fan et al. [7],
L212 “R2 = 0.9692” -> Please delete and insert in the text.
L217 “Hua et al. [35] (2017)” -> same like L190
L243 Improve the quality of Figure 5.
L256 Improve the quality of Figure 6.
Kind regards,
Reviewer
Author Response
Dear editor and reviewers, Please see the attachment, thanks
Author Response File: Author Response.docx
Reviewer 4 Report
The article deals with an interesting research topic.
The following facts were not clear from the article:
What was the design of the experiments, what was the order of the experiments, how was the uniformity of the soil samples used in the experiment guaranteed.
Respectively, what soil samples were used in the experiment.
It needs to be added to the experimental design section.
I consider the following to be errors in interpretation:
1. Some graphs and equations are set for 4 results, which is too little to draw any relation between the indicators.
2. Table 2. Statistical analysis results for runoff at the different thawing depths does not contain statistical analysis, but only the values ​​of indicators.
3. Line 219 contains the text: The correlations between the runoff rate and the TN, AN, and NN loss rates were significant, but there is no correlation indicator on which to base this claim.
4. Line 221 contains the text: significant difference between the total runoff rate and the slope of the regression equations, which does not make sense, as the significant difference should be between the 2 populations and not between the population and the regression equation.
The other text is also quite unintelligible.
The authors present regression equations, but their graphical representation on empirical data does not correspond in some thaw depth sessions.
It would be appropriate to distinguish more significantly between thaw depth 4 cm and thaw depth 6 cm, as it is very difficult to distinguish them in pictures of this size.
Given the large amount of research, I would recommend the authors to try to find a multiple linear regression equation to explain the relations.
If they decide to present the equations given in the publication, I recommend them to focus on the residue analysis in addition to the R squared indicator. In terms of assessing the suitability of the equation, the residues should be above and below the regression line. A graphical evaluation or a residue independence test will suffice.
The article needs to be corrected, to use the correct statistical terminology.
Only then will the conclusions be understandable and clear.
Author Response
Response to Reviewer 4 Comments
Dear editor and reviewers:
We would like to thank the editor very much for giving us a chance to revise the paper, and also thank the reviewers so much for the constructive suggestions which help us significantly to improve the quality of the paper. According to the comments and suggestions, we have made a thorough revision and resubmit the new version of the manuscript entitled “Effect of Thaw Depth on Nitrogen and Phosphorus Loss in Runoff of Loess Slope” (ID: sustainability-1508661). In the revised manuscript, we highlighted all the changes in red. Should you have any query for the revision, the authors are pleased to make further revisions.
With best regards
Yuting Cheng, corresponding author
Point 1: What was the design of the experiments, what was the order of the experiments, how was the uniformity of the soil samples used in the experiment guaranteed. Respectively, what soil samples were used in the experiment. It needs to be added to the experimental design section.
Response 1: Thanks for your comments. The experiments design is in lines 126-129, and line 136. The order of the experiments is in lines 140-149. In this experiment, only one kind of loess soil was used as soil sample from Suide. The soil source and the same stratum were screened. Before each experiment, the soil was sieved and filled by the same processes to ensure that the bulk density deviation was small.
Point 2: Some graphs and equations are set for 4 results, which is too little to draw any relation between the indicators.
Response 2: Thanks for your suggestion. This test is only a preliminary basic research. Due to the long test time cycle, only four thawing depths have been done at present. Due to the calculation method of indicators, one test can only calculate one result, and the process result cannot be calculated. This paper makes a basic analysis of the existing test results. In the later period, according to the opinions of experts, the amount of data will be increased, the test in this area will be strengthened, and the in-depth analysis will be carried out. Thanks again.
Point 3: Table 2. Statistical analysis results for runoff at the different thawing depths does not contain statistical analysis, but only the values of indicators.
Response 3: Thanks for your comments. We can see the trend from the values of indicators of the runoff yield. Therefore, soil thawing depth had significant effects on runoff under the slope. When the thawing depth was 2 and 4 cm (32.84 and 33.35 mm), runoff a were greater than that were 0 and 6 cm (24.41and 12.95 mm).
Point 4: Line 219 contains the text: The correlations between the runoff rate and the TN, AN, and NN loss rates were significant, but there is no correlation indicator on which to base this claim.
Response 4: Thanks for your comments. We can use the linear equations to prove that the correlation between runoff rates and TN, AN and NN loss rates are significant.
Point 5: Line 221 contains the text: significant difference between the total runoff rate and the slope of the regression equations, which does not make sense, as the significant difference should be between the 2 populations and not between the population and the regression equation.
Response 5: Thanks for your comments. Line 221 is a difference between slopes and may have a description problem, which we have modified in this article.
Point 6: The other text is also quite unintelligible. The authors present regression equations, but their graphical representation on empirical data does not correspond in some thaw depth sessions. It would be appropriate to distinguish more significantly between thaw depth 4 cm and thaw depth 6 cm, as it is very difficult to distinguish them in pictures of this size. Given the large amount of research, I would recommend the authors to try to find a multiple linear regression equation to explain the relations. If they decide to present the equations given in the publication, I recommend them to focus on the residue analysis in addition to the R squared indicator. In terms of assessing the suitability of the equation, the residues should be above and below the regression line. A graphical evaluation or a residue independence test will suffice.
Response 6: Thanks for your comments. Residual analysis has been added as required.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The main aim of the paper is analysing the effect of thaw on Nitrogen and phosphorus loss in Less slope.
The study shows interesting information but some of the information is missing, and the authors have made some improvements, but the main concern (It seems there are no repetitions with different samples of soil from different locations. There are no repetitions of the results, and no different conditions are tested (different slopes or different rains for example) is not solved and it seems that there are no repetitions. Without repetitions the results cannot be compared, and no strong conclusions can be made. In my humble opinion with more data the paper can be resubmitted.
Author Response
Response to Reviewer 1 Comments
Dear editor and reviewers:
We would like to thank the editor very much for giving us a chance to revise the
paper, and also thank the reviewers so much for the constructive suggestions which
help us significantly to improve the quality of the paper. According to the comments
and suggestions, we have made a thorough revision and resubmit the new version of
the manuscript entitled “Effect of Thaw Depth on Nitrogen and Phosphorus Loss
in Runoff of Loess Slope” (ID: sustainability-1508661). In the revised manuscript,
we highlighted all the changes in red. Should you have any query for the revision, the
authors are pleased to make further revisions.
With best regards
Yuting Cheng, corresponding author
Point 1: Line 25. Acronyms should be explained in the abstract (AN, TN, NN…)
Response 1: Thanks for your suggestion and we have revised in Line 26,27,29,30.
Point 2: Line 45. Reference needed.
Response 2: Thanks for your suggestion and we have added.
Point 3: Line 53 and 55. Reference needed.
Response 3: Thanks for your suggestion and we have added.
Point 4: Line 62. Reference needed.
Response 4: Thanks for your suggestion and we have added.
Point 5: Line 85. Reference needed.
Response 5: Thanks for your suggestion and we have added.
Point 6: Line 103. How many samples? All from the same location? Description of
the location? Cultivated soil?
Response 6: Thanks for your comments, all the tested soil comes from the same
place, the tested soil is carried out from the Suide in Losses Plateau. The soil type
was collected below cultivated layer.
Point 7: Line 107. The values are average of several measurements? Where is the
error of the average? How ere measured?
Response 7: Thanks for your comments, the indexes were measured by Malvern
3000 laser particle size analyzer based on light scattering principle and the
results were output based on average measured value.
Point 8: Line 114. The quantity or strength of the rain could be modified? Size of the
drops? It is similar to the kind of rain of the area studied? (line 125).
Response 8: Thanks for your comments, a needle tube assembly moving device
for simulating rainfall by the Institute of Water Resources at the Xi'an
University of Technology was used for the simulated rainfall test. The effective
rainfall height was 5.2 m, the rainfall area was approximately 4.5 m × 4.5 m, and
the rainfall uniformity was more than 85%. Thanks.
Point 9: Line 125. Only one slope? Why not several? Why 15º? Why 0.9 mm-1 of
simulated rain? Why not other values?
Response 9: Thanks for your comments, this experiment was designed based on
the local soil type, slope and rainfall data.
Point 10: Line 128. One sample of soil or different samples were prepared?
Response 10: Thanks for your comments, this experiment has four thawing
depths (0, 2, 4, and 6 cm), and the filling method is the same.
Point 11: Line 149. Method used to measure N and P?
Response 12: Thanks for your comments, The Nitrogen and Phosphorus indexes
in runoff were designed using the intermittent chemical analyzer Clever Chem
200 + (Dechem-Tech. GmbH, Germany). It's a test instrument. Thanks.
Point 12: Line 185. This result needs a proper discussion. Why 6 thaw deep is lower
that 2 or 4?
Response 12: Thanks for your comments, I have analyzed it in the discussion
section.
Point 13: Line 197. Values are averages? Where is the error? Statistical analysis to
check differences?
Response 13: Thanks for your comments. In this paper, the process of rainfall
runoff generation and Nitrogen migration under the thawing depth of 0, 2, 4 and
6cm was analyzed experimentally. Each scenario was repeated only once, so it
was not an average and there was no error.
Point 14: Line 235. Acronyms should be explained in the text.
Response 14: Thanks for your suggestion, the acronyms have been explained in
the Table 1. Thanks.
Point 15: Line 238. How many measurements were done? How did you calculate the
statistical differences if there were only one value per measurement?
Response 15: Thanks for your comments. In each experiment, we measured a
value of ammonia Nitrogen, nitrate Nitrogen and total Nitrogen every five
minutes. Then, the AN, NN and TN values in an experiment were 12, and the
differences were analyzed based on the data measured every five minutes.
Point 16: Line 284. Quality of the figures should be improved.
Response 16: Thanks for your suggestion and we have revised.
Point 17: Line 292. Why higher at 4 cm?
Response 17: Thanks for your comments. I have analyzed it in the discussion
section.
Point 18: Line 293. Total loss from the initial N of the soil?
Response 18: Thanks for your comments, the total amount of Nitrogen lost in
this paper is relative to the initial amount in the soil.
Point 19: Line 333. These results need a proper discussion
Response 19: Thanks for your comments. I have analyzed it in the discussion
section.
Point 20: Line 418. Conclusion should be based in the discussion and explain the
results obtained.
Response 20: Thanks for your suggestion and we have revised.
Author Response File: Author Response.docx
Reviewer 4 Report
According to the abstract, the publication deals with the effects of thawing depth on runoff, Nitrogen and Phosphorus loss by the simulation of rainfall erosion.
1. In section 2.1 on line 122 it is stated for the permafrost system: The temperature range was from –40 ° C ~ –30 ° C (± 1 ° C).
The same chapter on line 141 states: temperatures that were between -18 ~ -22 ° C.
This is confusing.
2. From the authors' responses to my comments, I learned that the research consists of analyzing the results of 4 measurements. This fact is not mentioned in the experimental design.
Based on that, I have to say that It is not correct to estimate the parameters for regression from 4 results, nor to test statistical hypotheses, because with such a small number of measurements we do not obtain information about the experimental error. This would require more measurements. These can be measurements for different input parameters set, but also repeated measurements for the same settings. Only by repeating the measurements we get information about the natural variability of the results caused by the experimental error.
Out of respect for the work done by the authors, these estimates could be accepted, but it is not possible to approach the results differently from the preliminary estimates.
Other inconsistencies in the publication are:
3. Table 2 does not contain a statistical analysis, so it should be renamed. The discussion of the results presented in Table 2 can be named as a statistical analysis, but in that case the statistics (minimum, maximum, range, median and others) should be discussed.
4. Line 221 The authors did not state the calculated correlation coefficient, they claim that the correlation is significant, but on the basis of the graph it is not possible to correctly assess it.
5. Line 223 states: The T test showed that there was a significant difference. Neither the null nor the alternative hypothesis nor the calculated p value or test criterion is given for the test.
Therefore, it is not clear what t test is and what was actually verified by the test.
6. Residue analysis Figure 5 suggests that a linear equation is not sufficient to describe the relationship between the variables. The measured and theoretical values are not around the diagonal along the entire length, but they do make a wavy line, which means that it would be good to add a quadratic dependence to the equation.
7. The presented results and the type of estimated equation leave me in doubt whether the measurement for a thaw depth of 6 cm was carried out using a standardized procedure.
8. In the conclusion, the research results are presented in a weakly exact way.
Discussion in the form: 4 cm> 0 cm> 6 cm> 2 cm, without specifying specific values is insufficient.
This section should include the observed values of phosphorus and nitrogen losses and the impact of the loss on the environment, together with practical guidance on how the research results can be used.
Author Response
Dear reviewer, please check the attachment, thank you
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
The main aim of the paper is analysing the effect of thaw on Nitrogen and phosphorus loss in Less slope.
The study shows interesting information but some of the information is missing. The authors have made some improvements, but the main concern stills is missing. No improvements have been made in this aspect and no explanations given. It seems there are no repetitions with different samples of soil from different locations. There are no repetitions of the results, and no different conditions are tested (different slopes or different rains for example). This aspect is not solved, and it seems that there are no repetitions. Without repetitions the results cannot be compared, and no strong conclusions can be made. In my humble opinion with more data the paper can be resubmitted.
Author Response
Dear reviewer, please check the attachment, thank you
Author Response File: Author Response.docx
