Soil Quality Indicators and Water Erosion in Olive Groves (Olea europaea L.) Under Different Vegetation Cover Management

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments

The authors designed the article with hypothesis that cover management practices that maintain continuous soil cover enhance the physical, chemical, and biological properties of the soil and reduce water erosion in olive groves. In this paper, authors considered how different vegetation cover management systems influence soil quality indicators and water erosion in a tropical olive orchard. The research is good for soil and ultimately water conservation at the university farm UFLA. However, there are some questions that need to be clarified and improved.

Specific Comments

The research explains well structured study including all three types of indicators , physical. Biological and chemical regarding soil.

The main focus is only on soil health. If the authors could add olive growth, yield or olive production. The next step could be calculation of water productivity of olive. Otherwise it is okay with only soil erosion/productivity context.

The authors carried out research study for 6-7 years from 2015 to 2021, what are the climate change effects in this period on the study. If the authors add one paragraph on this because climate change would affect the erosion of soil.

However, the paper shows integrated soil management with some ecological benefits of soil cover management.

Some of the improvements are suggested in the pdf file attached.

 

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a well-written manuscript that evaluates the effects of cover crop on soil quality and water erosion in Olive Groves.

My detailed notes are provided below, hoping these will help the Authors when making revisions.

Line 19: change it to “Soil physical, chemical …….. and soil losses….

Line 104-109: Did you use this plot to collect any data?  If this information is just for history of the plot, then delete line 104-109 and present only the table 1.

Line 135: why upper and lower thirds of the plots were selected?

Line 275-277: move before/above Figure 4

Line 318: “Soil and water losses and aggregate stability”: change this to Aggregate stability and soil and water losses- aggregate stability figure is presented before soil and water loss- if you change the subheading move line 319-323 after line 344

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review Soil Quality Indicators

 

The investigators examined soil erosion and soil quality indicators in olive groves managed with increasing degrees of vegetative cover management. The greater the management, the greater the erosion control and the parameters associated with improved water quality. Benign vegetative cover was better than nothing at all.

The experiment design was straightforward. The work was generally clear and well written with only the occasional odd word choice and sentence construction. Overall, there were no big surprises in the results based on classical conservation theory and studies.

It would appear that the grove is relatively new, having been first planted in 2015. So, the contribution of olive growth to erosion control should be minimum and the study reflects the best management practices for early establishment.

Soil sampling occurred once and represented a single sample rather than a composite. The details of sampling with respect to distance from tree were not given. This is a serious limitation to the work as sampling at other times of the year might have given different results and the limited amount of sampling may not have been representative of each plot. These limitations should be explicitly discussed in the text.

Specific Comments

Table 3 is more complicated than it needs to be. The actual values for the F Test are largely irrelevant to the reader. What matters is whether it was significant, and to what degree it was significant or not.

Table 4 is a much better representation of the data and their significance. Note that decimal points rather than commas should be used to delineate place – unless the formatting conventions of the journal allow either.

Table 5 -  Given that nothing is significant except for pH, this Table is unnecessary and its results addressed solely in the text. The values are best left to a supplemental table given that the actual numbers are site specific for this work. The same can be said of Table 6, which needs to be reformatted so that the indicators for nonsignificance are the same.

l. 248 The values in the text should mirror those present in the table.

Table 8 Does superior and inferior refer to the upper third and lower third of the plots? Be consistent with how you express plot position.

Table 9 Avoid using too many significant figures for the real precision of your measurements.

Fig.7 The shading is nearly impossible to discern and would not be discernable in B&W.

l. 292- 293 Table 9 indicates that MBC, BSR, and qCO2 are not significantly different by aggregate size, so the text implying there is a difference is misleading.

l. 303-306 The text does not match the results shown in Fig. 5.

Table 11 should be repositioned to closely follow the text that refers to it.

l. 380-381 Given that you did not provide the original chemical analysis of the soil before the experiment started you cannot really say that bare soil ‘caused’ a reduction. Rather, in the ensuing period since the start of the study the other management treatments have increased relative to the bare soil. Some rephrasing is necessary to reflect cause and effect here.

l. 406-412 Other than the survey of species no data on diversity are presented. Hence, one cannot say diversity increased or decreased, only that composition changed. This section needs to be revisited to better correspond with what your data support.

l. 418-419 Same point as before. You have no control for what these values were before the treatments were imposed, so you do not know if they decreased. You only know treatments with vegetation had more.

l. 463 On a mass basis, true. But considering the distribution of aggregates, far more activity is in the larger aggregates. The statement almost implies it is better to have smaller aggregates from the perspective of enzyme activity.

l. 496 You will need to further explain why you are suggesting the numerical values reflect reality rather than the statistical reality, which was noted in Table 11 to be nonsignificant because of variability.

l. 541 I think the discussion is lacking if it does not include some assessment of the relative differences between mowing and herbicide treatments as well as the controlled weeding, each of which has erosion control and soil quality effects, yet are not entirely similar.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The topic of the article - preventing/reducing soil erosion on sloped terrain in olive groves using cover crops - is timely and important. The experimental setup is well-designed, and the selected physicochemical and microbial indicators serve as good markers of unfavourable impacts on the soil and its microbial community. The results clearly demonstrate the usefulness and necessity of using cover crops, while also highlighting the potential dangers of herbicide application.

Comments and suggestions:

C1: Line 5: Please check the journal's formatting requirements (missing comma between 1 and *).

C2: Regarding the references: I recommend increasing the number of independent English-language references. The article currently includes an high number of self-citations, some repeated multiple times (16 self-citations appearing in 29 locations), many of which are in Portuguese-language. A significant portion of the independent references are also in Portuguese-language. I suggest reducing the number and frequency of self-citations and increasing independent English-language references.

Introduction:
C3: Lines 34–35: Please specify the exact source of the FAO data and include it in the reference list. References [1] and [2] appear to be identical—does [1] actually refer to the FAO data? Please clarify both in the text and reference list.
C4: Line 42: Reference [4] is not relevant here; it examines the mineral composition of olive leaves to assess plant nutrition and potential phytotoxic effects of pesticide use.

Materials and Methods:

C5: Line 92: The coordinates provided are not accessible in this format.
C6: Figure 1: I suggest enlarging the section showing the layout of the experimental plots and indicating the slope direction in this Figure.

C7: Lines 130–140 would fit better in the previous section (2.1.) because of the logical order, before line 104.

C8: Line 136: (iii) three soil aggregate size classes: 8–4 mm, 4–2 mm, and <2 mm. Why these size ranges? Please provide classification criteria and support with an independent reference.
C9: In section 2.2., I would retain only the information related to sampling and preparation (Lines 141–147).

C10: Line 148: Suggest revising the section title: "Investigation of…"
C11: Table 2., Lines 149–154: This section is unnecessarily repetitive - suggest deletion or, if the table remains, revise and clarify the content while shortening the associated text. For ß-glucosidase, we use p-nitrophenol, not “r.”

C12: Line 162: Aquino et al., 2012 – incorrect citation format ([number]); also missing from the reference list.

C13: Line 166–167: Please indicate slope direction in Fig. 1.

C14: Line 174: "Three (3)" – redundant to write the number both in digits and words.
C15: Line 177: Please include an(more) independent reference(s) that supports the methodology used.

Results:
C16: The presentation of results is disorganized—the text doesn’t follow the logical order of the tables/figures and often references data presented several pages later or mixes content from different tables.

C17: Numerical precision is not unified- data in the text often show two decimal places, while Tables 4–7 mostly show one decimal place. Additionally, the same parameter presented with varying precision within the same table. Please ensure consistency for better clarity.

C18: Tables 4, 5, 6, 8, 11: The "Unit" column is unnecessary. Units can be indicated using superscripts next to parameters (e.g., K⁺ (i)), then explained below the table. This would improve readability.

C19: Lines 195–196: In case of the K⁺, Mg²⁺, Al³⁺, and SOM, correlation with cultivation is not significant, which I do not accept. I suggest you divide the parameters into two groups, list which parameters had a significant correlation, and which parameters had a difference between the treatments, but it was not statistically proven.

C20: Table 3: The superscript "+" is missing for K; CO₂ is missing the subscript "2" in both the table and its caption.

C21: Lines 202–208: The figure caption does not define significance levels (*, **, ns, etc.).
C22: Previously, Lines 184–186. state that Tukey's test was applied only when ANOVA showed significance. However, this section includes parameters like K⁺, Mg²⁺, Al³⁺, and SOM, which don’t belong here according to Table 3. Please resolve this contradiction.
C23: Table 4: K⁺ and H₂O lack proper superscripts. Why are particle size fractions included in this table if not discussed? Were they not subjected to ANOVA and Tukey's test?

C24: Line 212: H+Al is not in Table 4. but appears in Table 7. Avoid referencing data not yet presented.

C25: Line 213: The "m" value and saturation index of 15 are in Table 4., not Table 3.
C26: Table 5: Why was a t-test not used?

C27: Lines 235–241: Refers to Table 7. data before it's presented. In Line 238, I suggest using of "were higher" instead of "increased."

C28: Table 6.: K⁺, H₂O – missing indices. Table 6. takes up half a page, but is discussed in only one sentence. Since no parameter shows significant differences, consider moving it to Supplementary Materials. Retain only Lines 227–228 in the main text.
C29: Table 7., Lines 255–257: Unclear explanation. If lowercase letters indicate row differences and uppercase indicate columns, state this clearly. Improve clarity by consistently using and displaying both letter types.

C30: Lines 275–277: This text separate the figure from its figure caotion, so move it after Lines 278–282.

C31: Figure 4.: Disproportionately large compared to Figure 3. Suggest resizing the figure,and updating the Y-axis label to "EE-GRSP." Consider merging Figures 3, 4, and 5 into one figure with panels a–e for consistent layout:

a

b

c

d (Fig 4)

e (Fig 5)

 

 

 

 

C32: Lines 292–296: Only ß-gluc and EE-GRSP showed significant effects. MBC, BSR, and qCO₂ varied with aggregate size but the differences were not statistically significant. Please revise the text accordingly.

C33: Table 9.: Why not use the "upper third"/"lower third" terminology from Lines 283–285 and elsewhere? "Superior" and "Inferior" are confusing. You should strive for uniformity for the sake of better transparency.

C34: Row 3. of Table 9. the qCO₂: format of "2" is not subscript; in the unit column: the superscript is used incorrectly.

C35: Table 9: Incorrect unit for MBC. The word "soil" is in Portuguese ("solo"), and superscript "-1" is missing after "g."

C36: Lines 303–312 + Figure 5: This belongs earlier (after Fig. 4.), where cultivation effects on MBC, BSR, qCO₂, and EE-GRSP are discussed, Figure is too large. Tukey-b categories are misaligned—please revise the figure layout.

C37: Table 10: Define the abbreviation "EI30" below the table.

C38: Lines 319–323: It does not fit here logically—refers to a figure three pages back and a table two pages ahead.

C39: Line 319–320: Please explain the high CV values - include this in the Discussion.
C40: Lines 320–323: This belongs in section 3.6.

C41: Lines 331–332: "WAD" appears twice - it should be "WMD." This mistake also appears in the abbreviation table. Please correct.

C42: Line 339–340: This section cannot be evaluated because the figure is unreadable, even with significant zoom. Please provide a higher resolution PCA figure.

C43: The reference list is inaccurate. For example, references [1] and [2] are identical, and the FAO data mentioned in lines 34–35 are missing entirely. Several sources are presented as English-language publications when only the abstract is in English. After revision, please ensure compliance with the journal's style guidelines.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

The quality of the paper has improved significantly, and most of the suggested changes have been implemented. However, there are still some parts that need to be revised:

C1: The number and proportion of self-citations are still unreasonably high compared to independent English-language references. I will accept the paper only if the number of self-citations has been reduced to two, or at most three, and the number of relevant, independent English-language references has been increased.

C2: Line 112: I suggest inserting the appropriate reference you provided in your previous response and including it in the bibliography.

C3: Line 159: I do not accept replacing the previous literature with a self-citation; please include that or another independent source in the bibliography.

C4: Line 175: I do not accept listing two self-citations here, only reference [39].

C5: Line 195: “Financial indicators” — what exactly do you mean by this? Could this be a typo?

C6: Table 3: While in the first version, the correlation analysis for some parameters yielded non-significant results, in the revised version these same values are now marked with a strong significance level (***). In your previous response, you wrote that the “ns” label had been incorrectly indicated earlier; please include the statistical output in the Supplementary Materials.

C7: Table 4: The K⁺ values have been changed in several places compared to the previous version. Please explain how this is possible.

C8 (former C23): The value of sand, silt, and clay are not chemical parameters.

C9 (former C24), lines 205–206: H⁺Al still appears in Table 7, much later in the paper, so this is not the appropriate place to present this parameter.

C10 (former C26): I do not accept the response, since according to the caption under the figure, you did perform a Tukey-b test, and for pH and K⁺ the Tukey-b categories are also indicated there. I suggest running a t-test and showing its results in the table.

C11 (former C29): Please indicate the capital letters in all rows/columns, as it is distracting that they are visible only in some places.

C12 (former C36): This figure is still disproportionately large; please reduce its size and simultaneously enlarge the labels.

C13 (former C39): You still do not justify or explain the high CV values.

C14: The quality of the PCA figure has improved a lot, but the font size is still too small; please enlarge it.

C15: Line 358: “NO PRINTED FORM”???

C16: For the tables, the abbreviations were previously correctly indicated below the tables; please do not omit them and update them with the new relevant information.

Author Response

Dear Reviewer,

We sincerely thank you for your thoughtful evaluation and for recommending our manuscript for publication.  In response to your suggestions and comments provided directly in the text, we have made the following revisions:

C1: The number and proportion of self-citations are still unreasonably high compared to independent English-language references. I will accept the paper only if the number of self-citations has been reduced to two, or at most three, and the number of relevant, independent English-language references has been increased.

Response: The request was granted, leaving only three self-citations in the manuscript.

C2: Line 112: I suggest inserting the appropriate reference you provided in your previous response and including it in the bibliography.

Response: Thank you for your observation. The request has been granted.

C3: Line 159: I do not accept replacing the previous literature with a self-citation; please include that or another independent source in the bibliography.

Response: Thank you for your observation. The request has been granted.

C4: Line 175: I do not accept listing two self-citations here, only reference [39].

Response: Thank you for your observation. The request has been granted.

C5: Line 195: “Financial indicators” — what exactly do you mean by this? Could this be a typo?

Response: Thank you for your observation. Yes, there was a typo and it has been corrected.

C6: Table 3: While in the first version, the correlation analysis for some parameters yielded non-significant results, in the revised version these same values are now marked with a strong significance level (***). In your previous response, you wrote that the “ns” label had been incorrectly indicated earlier; please include the statistical output in the Supplementary Materials.

Response: Thank you for your observation. Statistical outputs will be added in the supplementary material.

C7: Table 4: The K⁺ values have been changed in several places compared to the previous version. Please explain how this is possible.

Response: Thank you for your observation. While attempting to correct the previously requested decimal places, some errors occurred. However, these have been resolved in this new version of the manuscript, which is compatible with the statistical output data and supplementary material.

C8 (former C23): The value of sand, silt, and clay are not chemical parameters.

Response: Thank you for your observation. The topic has been changed to reference soil characteristics related to sand, silt, and clay.

C9 (former C24), lines 205–206: H⁺Al still appears in Table 7, much later in the paper, so this is not the appropriate place to present this parameter.

Response: Thank you for your observation. The text has been duly edited to better understand the information we want to convey through our data.

C10 (former C26): I do not accept the response, since according to the caption under the figure, you did perform a Tukey-b test, and for pH and K⁺ the Tukey-b categories are also indicated there. I suggest running a t-test and showing its results in the table.

Response: Although the comparison between two positions could have been performed using a t-test, we opted to apply ANOVA followed by Tukey’s test for all variables in the study. This approach ensures consistency in the statistical procedures and reduces the risk of type I error, since multiple comparisons among different soil indicators were conducted.

C11 (former C29): Please indicate the capital letters in all rows/columns, as it is distracting that they are visible only in some places.

Response: Thank you for your observation. The request has been granted.

C12 (former C36): This figure is still disproportionately large; please reduce its size and simultaneously enlarge the labels.

Response: Thank you for your observation. The request has been granted.

C13 (former C39): You still do not justify or explain the high CV values.

Response: Thank you for your comment. The high CV is mentioned in the discussion between lines 477-484.

C14: The quality of the PCA figure has improved a lot, but the font size is still too small; please enlarge it.

Response: Thank you for your observation. The request has been granted.

C15: Line 358: “NO PRINTED FORM”???

Response: Thank you for pointing that out, and please forgive the formatting error.

C16: For the tables, the abbreviations were previously correctly indicated below the tables; please do not omit them and update them with the new relevant information.

Response: Thank you for your observation. The request has been granted.

Round 3

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

I recommend the article for publication with minor revisions, namely:
•    In Table 3, the significance level of some values is still not correct; I suggest checking these once again (based on attached Supplementary file).
•    The references need formatting; for [21], I would provide the link.
I wish you good health for your future research!

Author Response

Dear Reviewer,

We sincerely thank you for your thoughtful evaluation and for recommending our manuscript for publication.  In response to your suggestions and comments provided directly in the text, we have made the following revisions:

 

C1: In Table 3, the significance level of some values is still not correct; I suggest checking these once again (based on attached Supplementary file).

Response: Thank you for your comment. Based on the significance codes (Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1), we made adjustments to Table 3 and the Supplementary Material to ensure greater clarity in the presentation of the results. We emphasize that the numerical values remain unchanged; only the significance codes have been revised for standardization and better understanding."

 

C2: The references need formatting; for [21], I would provide the link.

Response: Thank you for your comment. The request was granted. All references were thoroughly checked.

 

Thank you once again for recommending our article for publication. I wish you good health as well.

Author Response File: Author Response.pdf