Intelligent Analysis Strategy for the Key Factor of Soil Nitrogen and Phosphorus Loss via Runoff under Simulated Karst Conditions
Round 1
Reviewer 1 Report
The objective of the study exposed in the manuscript is clear and precise, detaching the importance of N and P as essential elements for plant nutrition and which are the mechanisms and factors that impacts on the loss of these nutrients under a rock-exposed karst slope with synchronous existence of surface runoff and subsurface leakage. For this it is proposed an analysis strategy based on a Random Forest (RF) regression algorithm.
The manuscript is clear and comprehensive.
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Reviewer 2 Report
Review Report
Manuscript ID: forests-2618912
Title: Intelligent analysis strategy for the key factor on soil nitrogen and phosphorus loss via runoff under simulated karst conditions
Authors: Yuqi Zhang , Rongchang Zeng , Tianyang Li , Lan Song , Binghui He *
Dear Authors,
I found several shortcomings in the work submitted for review that should be corrected. There are also many incomprehensible terms. I am aware that this is the first round of reviews that will allow the authors to improve this manuscript to make it readable and understandable.
I included some of the comments in the PDF version, but I would like to share my comments with the authors in this review.
The most important note is the incomprehensible N/P entry. What does it mean and how was it determined? Is it some kind of indicator, or is it the N:P ratio? Is it the sum of N and P content? If it is NP value you should explain what it means, and how you obtained the NP value. Then, do not use slash (N/P) use just NP value.
In the methodology, authors must write about it! What is soluble nitrogen? After all, N-NO3, N-NH4, and TN are the forms marked in the runoffs you study (surface runoff, underground runoff, and drainage through underground fissures). All these forms are soluble. Were the water samples previously filtered or centrifuged? How was the suspension removed? Were water samples mineralized to determine the total forms of nitrogen and phosphorus?
Please provide literature sources with a description of the research methods used. Please also include the literature in the references section.
Please think about the nomenclature. Once a term is used, it should be used consistently. Don't use synonyms!
In the figure (schema), the authors wrote: surface runoff, underground runoff, and underground fissures.
I suggest using the terms surface runoff, subsurface runoff, and fissures runoff.
In the 2.3 Experimental Process Section the authors use the terms soil surface water, interflow, and soil percolating water. Why? Please use earlier defined terms throughout the whole manuscript, check also figures!
I suggest making a professional diagram, which should be made to an appropriate scale and reflect the actual appearance of the experimental equipment. It would also be good to attach a photo of this research equipment.
The angle between the rock stratum and slope is incomprehensible. I understand the angle of inclination 30, 60, and 90° but 120, 150, and 180°! It's upside down after all!
Please prepare a second figure and indicate these angles!
α is OK, but β is difficult to understand.
In Figure 1, the authors showed a diagram showing that they were used:
v1, v2, v3 what means: 5, 7.5 i 10 dm3 min-1
α1, α2, α3 what means: 10°, 15°, and 20°
β1, β2, β3 what means: 30°, 60°, and 90° what about 120°, 150°, and 180°? Were there any more betas?
There is a spelling error in the description of the Y-axis in Figure 3.
Please pay attention to the readability of figures, especially numbers 4 and 6
The review is done partially. After making needed corrections according to the reviewer’s suggestions please resend the manuscript for final review.
Yours sincerely
Reviewer
Comments for author File: Comments.pdf
Author Response
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Reviewer 3 Report
Specific comment and suggestions to the authors are included in order to improve the final version of the manuscript.
General comments:
- Why are runoff, interflow and drainage data not included in the paper?
- The authors do not provide information on the number of combinations they have tested, how many they have used to train the algorithm and how many to validate the results.
Specific remarks:
- Line 27: 18.88 kg
- Line 27: What do these values refer to? China? worldwide?
- Lines 30 – 33: This statement should be supported by some references.
- Lines 79 -91: This paragraph should not be in the Introduction section; it should be before heading 2.1 of the Material and methods section. Instead, the authors should state their hypothesis and the objectives of the work.
- Scheme 1: The figure does not show whether the system has a soil layer and its thickness.
Use alpha and beta symbols in slope description and the angle between the rock stratum and the slope.
- Table 1: Other soil properties, such as the content of particles larger than 2 mm, organic matter content, or hydraulic properties, are of interest in the study.
- Line 115: 10, 15, and 20°
- Line 117: and 180°
- Line 135: What references?
- Line 137: Shouldn't they measure ammonium (NH4+), instead of NH3?
- Lines 138 -144: Analytical methods must be referenced
- Line 156: Supporting Information Where is it?
- Line 179: The description of the measuring apparatus could go together with the analytical methods.
- Line 194: Figure 1 or Figure 2?
- Figure 2: Please include in the legend the description of each plot (A-I)
- Line 227: How is the "importance" value obtained? Please indicate the possible range of values and their significance.
-Lines 56 – 271: It is not necessary to keep repeating the variable names; you can use the abbreviations.
- Line 185 – 186: NP value? Please provide more details of this new index, its calculation, significance and importance.
- Line 293: You talk here about ammonium...(see comment Line 137).
- Lines 312 – 313: This sentence is not correct or the idea that the authors want to convey is not well expressed. The chemical forms in which soil C, N and P are usually found in the soil are known, as well as the processes that lead to one form or another. Also how these processes are affected by factors such as moisture, temperature, etc...
Author Response
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Reviewer 4 Report
This is research can be viewed as aimed at exploring new ways of processing experiments or obtaining new data through experimental modeling. In both directions, the scientific significance of the article is difficult to assess because the elements of a simple scheme are missing - what was previously and what the problem is - what is new proposed and how it works - a comparison with what was previously and what’s next. In my opinion, the article needs significant revision for a clearer presentation of the methodology, results, discussion of the results and comparison of the results with the literature.
Point 1. Are the applied model and the proposed method promising for studying the influence of various factors on the content of nitrogen and phosphorus in karst slope soils?
- perhaps this is too general a question to require an answer, but if the authors believe that it should be answered in the affirmative, it is advisable to clarify why this is so for readers of the article.
Point 2. The presence in the model of additional hydrodynamic traps caused by the addition of a certain amount of stones is interesting and raises the following questions:
A) did the authors decide to add the stones themselves or do they continue following someone else's ideas?
B) the parameters of the stone/soil ratio, the size of the stones, and the distance between the stones are not indicated. Do the authors consider other parameters besides angle b to make no or less significant contribution to the process of leaching of nutrients?
C) were the stones natural or were they artificial objects with a clearly defined geometry. If the stones are artificial, how was the geometry set?
Point 3. The "/" sign, like the ":", is the most common sign for the arithmetic division operation. Thus "N/P loss" is read as a decrease in the ratio of N content relative to P content.
Point 4. Lines 24-30. The problem of loss of essential plant nutrients - nitrogen and phosphorus - is reported, but the problem of protecting valuable water resources is kept silent. For example, Xia et al., 2020 - https://doi.org/10.1186/s13765-020-0493-6: "Eutrophication of natural water is a universal problem. Nitrogen (N) and phosphorus (P) from agricultural runoff are the main sources of nutrient input, provided that emissions from industrial point sources are under control. Therefore, it is of great environmental importance to reduce pollution associated with agricultural runoff as a means of regulating eutrophication levels in natural water."
Upon closer examination of the literature used in the manuscript, one gets the impression that the authors should be well acquainted with this side of the problem of leaching of nutrients from the soil, but for some reason they do not consider it worthy of mention.
Point 5. I do not have the opportunity to comment on the correspondence of each reference used in the manuscript, but it seems obvious to me that the authors did not check the correspondence of the references used and the text of the manuscript before submission. For example, Lines 30-34 - a description of the relationship between the loss of nitrogen and phosphorus in the soil and the method of leaching by chemical or physical weathering is reported [references 4-7]. The reference to [5] does not correspond to the text, and does not support any aspect discussed in it.
Point 6. Lines 39-42 should provide links to the publications "few studies have presented such experiments and fundamental mechanisms of interactions among various features in the complex soil N & P loss system".
Point 7. Lines 54-59. It is not obvious from the text that in this case the various characteristics and factors include not only the angle of flow velocity and the angles between the soil and the rock, since in the text of the previous paragraph the authors concentrated attention on them. However, references to the literature, in particular [12], do not correspond to the text in the context of the previous paragraph. It is necessary to either rewrite the text for greater clarity or double-check references to the literature.
Point 8. Lines 74-77 should provide links to the publications "few studies have reported the use of the RF regression algorithm for estimating the key factors on soil N & P loss under simultaneous rock-exposed karst conditions with the existence of surface runoff and subsurface leakage."
Point 9. Lines 109-110. It may be preferable to use "was conducted using a custom designed experimental equipment" or "was carried out using specially designed experimental equipment" instead of "was conducted using a customer-designed experimental equipment".
Point 10. Line 113. This phrase is unclear and raises questions - "customer-designed". Who is your customer? This is probably just a unsuccessful translation into English.
Point 11. Line 145. Figure 1. Flow velocity v and angle a, as described in lines 115-118, each had three set values. Thus, the ellipsis after v3 and a3 should be removed.
Point 12. Instead of or in addition to Figure 1, provide a diagram work flow of the model processing.
Point 13. Line 194. Figure 2.
Point 14. Lines 194-196. There is not clear correlation between the concentration of N and inflow rate, ..
The authors have the right to independently determine the meaning of correlation or clear correlation. Please note that the text is not yet supported by graphics or is not interpreted as intended.
Point 15. Lines 196-198. Figure 2a demonstrates either the absence of a statistically significant difference between N contents in surface runoff depending on 3 pressure modes 5, 7.5, 10 L/min, or indicates a nonlinear relationship. It is unclear why interpolated values are presented in the graph. It is unclear whether each dot marker on the graph represents the average nitrogen concentration of 14 solutions collected over 18 different experiments. What should the fill area demonstrate - the spread of data or the standard deviation or some kind of confidence interval?
Point 16. Line 198. "Specially," this opening word is not appropriate here, since the second sentence does not reveal any aspect of the first sentence.
Point 17. Lines 199-200. Can you say - similar to the sine function? It is interesting that the model includes the factor of a hydrodynamic trap, caused, among other things, by the rotation of the guide stones, and at the output a response is visible in a form close to a trigonometric function.
Comments for author File: 
Comments.docx
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Review Report 2
Manuscript ID: forests-2618912
Title: intelligent analysis strategy for the key factor on soil nitrogen and phosphorus loss via runoff under simulated karst conditions
Authors: Yuqi Zhang, Rongchang Zeng, Tianyang Li, Lan Song, Binghui He
Dear Authors
Most of my comments have been taken into account by you. I found a few more details that need to be improved. I described these details in the reviewer's comments, in a pdf file.
After taking them into account, I recommend submitting the manuscript for printing in the MDPI Journal - Forests.
Yours sincerely
Reviewer
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
I thank the authors for their answers and clarifications to my doubts raised in the previous review.
Still, I have some minor issues to raise with the authors:
- Line 86: inflow rate (n)
- Line 120: Vaseline
- Line 125: angle
- Figure 2: surface runoff (A-C), subsurface runoff (D-F) and fissures runoff (G-I)
- Line 270: has the greatest effect on the SN concentration in the different water flows.
- Figure 5: replace NH3-N with NH4-N
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
As far as I understand, the authors claim that in some aspects the results of their work are the first of their kind. Since it's always hard to be first, I wish the authors good luck! The results of the labor-intensive experiment presented by the authors are not obvious to me. Perhaps the reasons I have given for misunderstanding the manuscript will allow the authors to gain another point of view and somehow improve their work.
Point 18. The authors do not discuss the time scale and diversity of the simulated processes. The model experiment is limited to 18 minutes, and in nature, leaching of nutrients can occur over time intervals that are several orders of magnitude larger. The influence of what factors is limited in the experiment due to the discrepancy in the time scale? Is it possible to consider that 18 minutes is not enough to get a response from the biochemical processes occurring in the soil? How could the competition of various factors change during the implementation of the model of the runoff process?
Point 19. The authors did not consider the additive effect of the removal result. If the concentration of nitrogen in the collected solutions practically did not change when the flow rate was doubled, then the amount of washed (extracted) nitrogen was also doubled. Thus, flow rate is one of the most important factors when studying nutrient loss.
Point 20. The angle between rock and soil is probably an incomplete characteristic of stream bed geometry. Depending on the tortuosity of the channel, you will get different hydrodynamic characteristics of the flow. The experiment may have been able to record a local increase in flow velocity or the creation of turbulence as a result of adding “dampers” of varying degrees of openness, but the position of the dampers relative to each other was not studied. One can expect a significant difference in the influence on the hydrodynamic characteristics of the flow when the stones are positioned either in a line or in a checkerboard pattern. It should be noted that the study of individual patterns of distribution of stones along the path of a flow is no more divorced from real conditions in nature than the study of the angle between stones and soil.
Point 21. Since in the first version of the manuscript I did not see linear correlation where the authors spoke of clear correlation, in paragraph 14 of the review I assumed that the authors could independently determine the meaning of correlation and clear correlation. I did not expect that the authors would change existing terms and laws of mathematics. It can be expected that in connection with the phrase on lines 201-204 “a clear correlation between .. , due to the linear relationship was with a correlation coefficient about 1 and a slope about 0”, many readers will not be ready to further consider any information presented in this manuscript from a scientific point of view.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 4 Report
Compared to the first version of the manuscript, the phrase “As shown in Figure 2, there was a correlation between the SN concentration and v, α, and β in the soil surface runoff, subsurface runoff, and fissures runoff, respectively”, has not changed fundamentally. Like last time, I cannot see the reliability of the correlation between the variable v, α and the measured parameter SN. Perhaps the authors should specify the meaning of the word correlation. Do the authors mean a functional relationship or a statistical one? As an example for Figure 2A, we can propose to consider the hypothesis that the linear Pearson correlation coefficient is different from 0. I take this particular indicator because it is well-known and simple, but the authors, of course, could consider the hypothesis that some other relationship indicator differs from 0. Since I don't have the data itself, but I do have information about indicators like mean, standard deviation, and sample size, I can do a series of reconstructions of the original data. Having calculated the correlation coefficient in each case, I can analyze its distribution relative to the boundary values. According to the description, the number of analyzed solutions is 3 * (3 * 6 * 14) = 3 * 252 = 756. The quantile Student distribution for n - 2 degrees of freedom for probability 1 - 0.01 / 2 is equal to 2.58 and the critical value of the correlation coefficient is 0.0936. In two series of experiments, I received an estimate that in more than 9 cases out of 10 (90-97%), the correlation coefficient does not exceed the threshold values, that is, it will not significantly (with a type I error level of 0.01) differ from 0. Of course, these estimates of the possible significance of linear correlation coefficients may poorly correspond to both the data presented in the manuscript and the meaning given by the authors to the term correlation. Probably, the manuscript should still present a judgment about the presence or absence of connections between the data more justifiably, so as not to cause confusion among readers.
Comments for author File: Comments.pdf
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