Properties of Humic Acids in Meadow Soils Irrigated with the Slope-and-Flooding System

Round 1

Reviewer 1 Report

After the authors revision, this manuscript has improved significantly. The authors replied convincingly to all reviewer requests. 

Author Response

Dear Reviewer,

Thank you very much for accepting the manuscript.

Best regards

Magdalena Banach-Szott

Reviewer 2 Report

The authors have conveniently restructured the paper and it has been improved from the previous version. It is a pity that it was not possible to include a control section to see the effect of irrigation on the properties of organic matter and to compare it with that of soils not irrigated by this system. Furthermore, it must be said that the number of samples is small, so the robustness remains low. On the other hand, the authors should revise the text and improve some aspects, e.g. delete lines 240-244 due to duplication, or add dots or dashes when listing.

Author Response

Dear Reviewer,

Thank you for all the comments. We have tried to apply all of them during the revision of the article. We agree that including a control area in the article would be a very good solution. In our case this was not possible, but we have added some information on the organic matter content of similar Brunic Arenosols, that have not been irrigated. We also agree that the number of soil samples is not very large, however we tried to select the most representative sites. The sampling sites were selected after long field and laboratory studies.

Other comments regarding the manuscript, incl. removal of duplicate lines or editorial correction were included in the revised version of the article.

Best regards

Magdalena Banach-Szott

Reviewer 3 Report

The current study entitled “Properties of humic acids in meadow soils irrigated with the slope-and flooding system” is good. For a better understanding in-depth, it is a need for time to work on this topic. Furthermore, the achievement of potential benefits by using current technology is also dependent on the extensive research work for more exploration. Although the experiment is well organized, yet I suggest a major revision due to the following deficiencies.

Major Concerns

Systematic abstract is missing.

• Introduce the need for study in 1-2 lines.
• Give a problem statement.
• Give reason for the selection of current strategy for the solution of the problem.
• Quantitative data is also important to support your conclusion. Would you please provide some quantitative data in terms of percentage significant increase or decrease in the abstract?
• Please provide a conclusive conclusion with is withdrawn through research in a single line. The statement “The results have demonstrated that many-year grassland irrigation affected the structure and the properties of humic acids.” is general. Please conclude with a statement that shows a knowledge gap covered, potential beneficiaries and specific recommendations as well.
• Give future prospective in a single line.
• As per standard suggestions, please avoid using title words as keywords
• Please follow the title in the introduction section, i.e., humic acids, then meadow soils, irrigation with the slope-and flooding system, knowledge gap, hypothesis and aims.
• Also, provide a novelty statement at the end. What new things authors have done or correlated in this research compared to old ones?
• Would you please give a single line about the knowledge gap which your research has covered?
• Please revise the results and give some quantitative data in terms of percentage increase or decrease.
• Please mechanistic approach as supporting evidence for discussion of results.
• Please give a conclusive conclusion.
• Major portions of the introduction and results are incorporated in the conclusion. Please remove that.
• If the authors are not sure, then give future recommendations for more research and investigation.
• Add the targeted beneficiary audience who will get benefits from this research.
• Also, give clear-cut recommendations and future prospective regarding this research.

Minor

The English language needs moderate editing from native English speakers.

 

Author Response

Dear Reviewer,

Thank You for all the comments. We tried to apply all of them during the revision of the article. The detailed list of changes has been placed below. Other comments from the reviewer have been included in the text; we have checked carefully and corrected the manuscript.

• Reviewer's comments on the abstract: The abstract has been corrected as suggested by the reviewer. Following the comments of the reviewer, a completely new abstract was created. We have added: the introduction of study, problem statement and reason for the selection of current strategy for solution to the problem. We've also added some quantitative data to support conclusion. We added more conclusive conclusion and at the end, we have provided perspectives for further research. 
• “As per standard suggestions, please avoid using title words as keywords” – We have changed the keywords. The new ones are: Meadow soil; TOC; Elemental composition; UV-VIS; HPLC.
• “Please follow the title in the introduction section, i.e., humic acids, then meadow soils, irrigation with the slope-and flooding system, knowledge gap, hypothesis and aims.” - We have changed the order of the issues raised in the introduction in line with the reviewer's suggestions. 
• “Also, provide a novelty statement at the end.” Information on the novelty can be found in the introduction, where it touches on the fact that the content discussed in the article refers to the lack of research on soil organic matter in arable poor sandy soils of wetlands so far. And these matters are closely related, inter alia, to the sequestration of organic carbon.
• “Please revise the results and give some quantitative data in terms of percentage increase or decrease.” - We took this reviewer's comment into account. Some missing data has been added.
• “Please mechanistic approach as supporting evidence for discussion of results.” - We have tried to organize our results in line with the mechanistic approach. Our main problem was divided into parts analyzed separately. The quality of soil organic matter was determined on the basis of a series of soil analysis results, both basic (e.g. TOC, Nt, particle size distribution, pH) and specialized (e.g. humic acids properties – their elemental composition, hydrophilic and hydrophobic properties, UV-VIS absorption spectra and the others).
• “Please give a conclusive conclusion” - We have added more conclusive conclusion.
• “Major portions of the introduction and results are incorporated in the conclusion. Please remove that.” – We have changed this part of manuscript.
• “Add the targeted beneficiary audience who will get benefits from this research.” And “give clear-cut recommendations and future prospective regarding this research.”– We have added this information: “The obtained results may allow for the development of, inter alia, models of agricultural practices that increase carbon sequestration in soils. In the long term, this will allow for environmental benefits, and thus also financial benefits.”
• The comments about the English language - The manuscript has been revised by a native speaker.

Best regards

Magdalena Banach-Szott

Round 2

Reviewer 3 Report

i recommend to accept the manuscript in current form

Author Response

Dear Reviever,

Thank you for accepting the manuscript in current form. The article has been proofread by native speaker during previous revision.

Best regards,

Magdalena Banach-Szott

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The work deals with the study of humic acid properties in soils irrigated with the slope-and-flooding system in the Czersk Meadow Complex. This is a topical issue, especially because of the role of organic matter in soil functionality and climate change mitigation. The authors have extensive experience in the analysis of these compounds. However, I am afraid that the paper is not sufficiently prepared for publication in the journal. I suggest that the authors restructure the article before undertaking a further revision. Also, revise the numbering of the headings, especially Section 3 and Conclusions. Include the Figures referred to in the text; it is not possible to evaluate the paper properly without them.

1. The paper refers to a unique case of soil management: irrigation with the slope-and-flooding system. Please include more information about this technique and its influence on the main soil parameters. What advantages are obtained in the soils, e.g. from an agronomic point of view, with this management? What is the current soil exploitation regime?
2. It is stated that "the aim of the present paper has been to determine the impact of many-year irrigation of unique grasslands on the properties of humic acids determining the quality of organic matter". However, in the paper there is no control population, i.e. nearby soils with similar characteristics to those studied (Albic Brunic Arenosol), not subjected to irrigation. Therefore, I believe that with the proposed methodology, the objective of the study cannot be addressed, since we cannot know the added impact of irrigation, as we cannot compare with other non-irrigated soils. What could be established is a characterisation of the humic acids in the soils of these irrigated grasslands. 
3. The sample volume is very small, with only 9 soils sampled in total, 3 at each site, and only one at each of the 3 proposed distances from the irrigation ditch. This is a serious problem for the robustness of the work.
Please justify the rationale for sampling at different distances from the irrigation ditch, as well as at different depths. On what assumptions is this based? How will the different soil parameters related to organic matter vary accordingly? In particular, the variations in the data due to the distances to the irrigation ditch are not clear, logically, there must be a series of edaphic or environmental parameters that determine the different composition of humic acids according to the distance. What are they and to what extent do they affect? This is another of the points that most raises doubts in my mind, because although the authors reflect these differences in composition according to distance, they do not determine the real reason, the causes, of these differences. Perhaps the failure to study in depth the different soil parameters or environmental conditions of the sector is behind this. 
5. Provide the results of the cluster, it is not possible to analyse the work without these figures. I am afraid they were omitted unintentionally, as they are cited in the text. 

Reviewer 2 Report

The article entitled "Properties of humic acids in meadow soils irrigated with the slope-and flooding system" investigate the effect of many-year irrigation of unique grasslands on the properties of humic acids defining the quality of organic matter. The reserch topic has lot of potential and the paper is generally interesting, but the manuscript in its current state presents some minor problems. The first refers to the introduction. I suggest the authors to make this paragraph more interesting by eliminating the many theoretical aspects related to humic acids and inserting more references to the case study using. The bibliography present not only in the introduction but also in the other sections of the manuscript would require more recent publications, there are many before 2010. Secondly, regarding the section of materials and methods, it would be important to include the reference for the extraction of humic acids. In addition, some suggestions related to the discussion of the results. The results referred to the organic matter dynamics in the experimental soils, even if very interesting, are not discussed and argued . For example, why does the SOM increase with depth? The basic characterization of humic acids, all the figures and letters indicating significance in the tables are also absent in the manuscript. In this state, paragraph 3 is really very difficult to read. Given the particular soil texture and high presence of water, it would be very interesting to study the relationship between the organic matter (in its the different forms, not only humic acids but also weom) and the high percentage of sand. In the end, I recommend improving the quality of the paper by rewriting the conclusion. I agree that irrigation strongly affects the high degree of humification but should be considered as an indirect factor. Irrigation could positively affect the root system, increase microbial activity and biomass and therefore the organic matter humification.

Reviewer 3 Report

I have indicated a number of specific issues in the attached file using 'sticky notes' but these are the main points that need addressing:   In the abstract I was not quite sure what is meant by the term 'irrigated continuously' - does this really mean constant irrigation year round or that the has been the same irrigation management for 150 years? I think that even in the body of the paper there could have been a better explanation of the location of the experiment. Are the meadows grazed or cut etc? How far apart were the sampling sites and why were three sites chosen?    Why was separate data not presented in Table 2 for depth and site? Presumably deeper soils are wetter - ideally data would be presented regarding this!   No figures are included, although they are mentioned in the text! These obviously need to be included in any resubmission and without seeing them it is difficult to comment on the later parts of the paper.   Some differences between the sites are mentioned - the reasons for these could have been better discussed.  

Comments for author File: Comments.pdf