Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation

Round 1

Reviewer 1 Report

Summary:

This study looks at using vermicompost application methods and its impact on tree growth in a greenhouse study. It evaluates four different application methods including surface, “circular”, incorporated, and deep. They evaluated plant growth in terms of height, leaf matter, and roots growth. The study found that surface and circular application methods resulted in highest growth for three tree species and would be suitable for improving urban trees.

Overall comments:

While the study is interesting I believe it is very misleading and misses some key information due to methodology not being complete. Authors state that they are investigating vermicompost application methods for bettering urban tree growth and reduce mortality. However, this study is done in a green house, in a soil that does not appear to be at all similar to typical urban soils conditions (mainly compaction). Additionally, they simply just measured the tree growth information and provided no information on nutrient availability differences between application methods, which I think would have greatly enhanced the paper.  

If the authors want to publish this information I think they need to rethink the way they are setting up the paper. Based on most literature regarding urban tree mortality, the issue is not simply due to nutrients, that can be simply fixed with fertilizer application, but is due to soil characteristics primarily related to compaction. This study in no way looks at how these methods would influence these soil properties and improve urban tree root development and growth. Additionally, the two methods they conclude are the best, would do little to improve soil compaction issues so telling municipality planners that those methods would improve issues with mortality is misleading.  I think that this paper should remove the general idea of improving urban sustainability and focus simply just on the application method related to tree growth, which could be used for other purposes such as tree farms, orchards, landscapers, ect. I do not think it truly explores the issues related to urban tree planting.

Overall, while the study shows compost impacts to tree fertilization, I think it misses the mark regarding impacts to urban trees, and may not be suitable for this special issue. I have left general comments related to each section below, and have provided specific comments as well. I believe before publication this paper needs major revisions.

Introduction:

The introduction is all over the place and I suggest rewriting it to set up the problem more effectively. You seem to be just throwing all the information you can about vermicompost and urban trees and not getting into specifics about the problem you are trying to solve. You need to clearly lay out the problem, how vermicompost may be able to help , and how this study fills a gap in our knowledge. You definitely need to define what vermicompost is. Also soil bulk density and compaction play a major role in urban tree growth and mortality and compost could have a major influence on that, but it is not even mentioned in the introduction.

Methods:

After reading the methods I am not exactly sure how you are simulating urban tree environment. Seems you are just filling pots with soil and seeing the impact on growth. Thus I would say the title is very misleading if you are only looking at the impacts of fertilizer/vermicompost application method in regards to growth. The big issue with urban tree mortality I would say is not necessarily due to soil nutrients, we can easily supplement them, but due to soil properties such as impacts from compaction. I think in order to be considered for urban environment you would have needed to simulate typically urban soil conditions. Otherwise it is just a growth study with no real implementations to urban areas.

I do appreciate that you had a good number of replicates. There are some issues that need to be addressed though. First soil information you present results in L121-125 then methods later in the section, they should be together. Also did you not soil sample the pots after the study period? That seems like it would be important to analyze for plant available nutrients release form the compost.

Results:

Tables and figures need to be in order they appear. Table one is 5 pages below where it is first mentioned. All figures should be improved for quality and y-axis should be changed to better fit the data. To me table one makes no sense and needs to either be better defined what you are looking at or changed. I would rather see values for all the parameters rather than P values. Additionally in all figures and tables you are re-defining all abbreviations which is unnecessary. Overall the analysis is okay, but presented poorly. However, I do not really see the point in the vector analysis. You only mention it briefly in your results and I do not find it interesting. If you want to keep it I would move to the supplemental section.

Discussion:

The discussion is essentially just another literature review. You need to relate your data to past studies and how they are similar or different. There is very little of this happening in this section. Additionally, I have issue with claiming this has implications on urban environmental sustainability. You essentially just conducted a growth study of trees in a sandy loam soil. In no way did you simulate urban soil conditions. Additionally you find that surface and “circular” application results in best growth, but would this really have an impact in urban trees? The biggest issue with urban areas is compaction impacting root development. I do not believe either of these methods would have benefited soil bulk density much at all. I think if you want to publish this study, it needs to be framed differently, as I find it very misleading. If you want to say application changes nutrients and tree growth for tree farms, orchards, ect, I think that would be more suitable than saying it has implementations on urban trees.

Specific comments:

L18: Three contrasting species of what? Be specific

L21: “circular placement” seems like a very odd way to say it was placed just below the surface.

L37: delete “the”

L37-38: You need to define what vermicompost is and explain the general process before going into characteristics

L44-45: Seems unnecessary to use (1) and (2) here

L46-47: Okay that is true, but is this relevant to the study you are doing?

L54: Suggest instead of saying “at dumps” saying “off site”. The idea is you are not returning it to the soil in that location, may be many places it is disposed of.

L57: What are these “stressful urban site conditions” please explain. Need to set up the problem you are trying to fix better.

L73: Suggest saying “broadcasting (or surface) application methods”

L121-125: How did you fill the pots? What was the soil bulk density? What method did you use to determine soil characteristics?

L129-139: Do not like this circular placement definition. Very confusing. After seeing Figure 2 it makes a little more sense.

L142: Need to define what kind was used.

L178: cite method

L174-182: What are the soil properties? Is it just what you discussed in L121-124? Because if so this needs to go up there. Also did you not do any soil sampling after? I would think that would have been very important to do.

L231: I should not have to scroll down five pages to see table one if you mention it here.

L243-280: Overall the figure quality could be improved. Also please change the y axis so it is more clear. Not sure why in e and f you still have it set to 200, when it does not go above 300%. Also in figure description you do not need to define all the abbreviations again, you already did that and it just takes up space.   

L282-319: same comment as above.

L335-354: same figure comment as before

L391-401: First of all, this table should come much earlier. Also I find table one very confusing and I am not sure I understand what you are trying to tell me. I would rethink the way you are presenting whatever you are trying to present. I would rather see the values for everything rather than just he p-values. Would be more beneficial and easier for readers to understand. I would denote significant difference then with letter annotations. Also you say significant p-values are in bold, but nothing is bolded. So nothing was significant?

L396-400: Remove the big gap between table and caption. Do not need to define abbreviations again.

L412-414: Yes this is true, but you did not seem to measure any of this. I think that is an issue with this paper.

L448-450: How? All you have shown here is that adding fertilizer improves growth and that different application methods may result in better growth, but I would argue that you did not really look at actual urban soil conditions.

L490-492: How does this impact soil properties though? I think should have been the main point of this study.

L501-519: Do not need to define again. Why are letters only present in the N column? I would put them for all, even if they are not significantly different, just have the same letter.

Author Response

Dear Editors

We are very thankful for the editors and reviewers for their helpful comments on the manuscript entitled “Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation”. We have tried to address all their comments and suggestions in a proper way and believe that our paper has improved considerably.

We would be happy to make further corrections if necessary and look forward to hearing from you soon.

Sincerely,

Byung Bae Park

Associate Professor

Department of Environment and Forest Resources

College of Agriculture and Life Sciences

Chungnam National University

99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Tel: +82-42-821-5747

Fax: +82-42-825-7850

Email: [email protected]

On behalf of all authors.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors, you should address my recommendations highlighted across the text, tables and figures.

Comments for author File: Comments.pdf

Author Response

Dear Editors

We are very thankful for the editors and reviewers for their helpful comments on the manuscript entitled “Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation”. We have tried to address all their comments and suggestions in a proper way and believe that our paper has improved considerably.

We would be happy to make further corrections if necessary and look forward to hearing from you soon.

Sincerely,

Byung Bae Park

Associate Professor

Department of Environment and Forest Resources

College of Agriculture and Life Sciences

Chungnam National University

99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Tel: +82-42-821-5747

Fax: +82-42-825-7850

Email: [email protected]

On behalf of all authors.

Reviewer 3 Report

Dear Authors,

The article investigated the effects of different vermin compost (VC) application placements on the growth and nutrient uptake of three contrasting species [fast-growing Betula platyphylla and Larix kaempferi and slow-growing Chamaecyparis obtusa] to provide implications for urban environmental sustainability. The article is within the scope of Sustainability journal and of current interest to the readers. However, it should be thoroughly revised before publication, especially the discussion section.

Below are some comments and suggestions. Find more comments posted on the pdf file.

Introduction

Please check the objectives and hypotheses and reorganize to be in a stand alone paragraph.

Materials and methods

Was inorganic fertilizer applied or basal fertilizer to all treatments? If not, please specify that no inorganic fertilizers were added, except the amendment.

Results

Please check in table 1, revise the tittle beginning with the dry weight or growth and followed by nutrient concentrations. 

Discussion

The discussion is still inadequate. More and detailed explanations should be provided to support the results.

In Lines 405-414, it is too early to introduce the discussion on available nutrients in vermicompost and the improvement in the physical properties of soil such as bulk density and porosity. This paragraph should be brought after discussing the results presented in the paper. Discuss according to the data presented here such as the improvement in the growth, indicated by improvement in heights that could attributed to the dense roots that allow absorption (for example). Then later, add the general information on what the compost does which were not measured here in this study such as improving bulk density and porosity, infiltration, nutrients etc.

For the discussion on N, please provide evidence by citing some of your important results into the discussion. For example, enhanced N uptake occurred in all species, especially in B…., as indicated by the high foliar N compared to other species (Table…).

Discuss how N increases growth of the tree species, using the dataset, did it promote growth through the increase in stem length (for example), and cite some papers that show N is important in tree growths or plants highlight some few mechanisms wherever possible.

If the VCb N concentration or uptake was higher in the Betula platyphylla tree species, but its growth was higher in the treatments VCs and VCc, then could it be concluded that this growth was not due to N uptake, but another factor?

Please provide further explanation in the discussion about N uptake and growth.

If the uptake of P and K was not significantly different among the treatments, it could mean that the soil had sufficient amount of K and P. Please add this explanation. There are a number of literature that show that if the soil is limiting in some important nutrients, crops will respond positively to the application of the amendment.

I suggest adding discussion that the vermicompost contained more N (5.45 g per pot N) compared to the P (1.05 g per pot P) and K (2.92 g per pot K). With this composition, it is expected that N responses will be more than P and K. This also means this kind of compost is suitable in soils where N is limiting factor. Include references about responses of amendments where a nutrient is limiting. In fact, this explanation will be supported by the soil data provided in the M & M section which shows that N is low (0.10g per kg).

Furthermore, if this paper had the soil data after harvesting the trees (after experiment), the quality would be much improved. We could know whether or not the amendment improved/increased the contents of N, P, and K in the soil. Sometimes amendments are added but it will not release available nutrients. For instance, you could have measured inorganic N (NO3-N and NH4-N) which would help to know the available N in the soil.

In addition available P and exchangeable K including Ca and Mg could show us that nutrients were readily released into the soil. Soil pH would also show whether pH was decreased leading to nutrient fixation (P) or not. We could also tell from the data whether these nutrients were increased and available but the tree species could not uptake them evidenced by low uptake. Having soil data would avoid “speculations” that available nutrients increased in the soil. Of course previous studies say soil nutrients will increase upon such amendments but if the original research data shows it, it makes the paper speak on its own.

I suggest authors add the limitation of this research and future research. For instance, the growing period under the experiment was short and longer (more than a year) experiment will be required to find the long term effect of these vermicompost application method. This could be added towards the end of the discussion or conclusion.

Finally, I suggest adding Table S1 into the manuscript, not as a supplementary data because it is important. Perhaps, the problem is that n=3, and not n=9 as in the other data?

Thank you very much.

Comments for author File: Comments.pdf

Author Response

Dear Editors

We are very thankful for the editors and reviewers for their helpful comments on the manuscript entitled “Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation”. We have tried to address all their comments and suggestions in a proper way and believe that our paper has improved considerably.

We would be happy to make further corrections if necessary and look forward to hearing from you soon.

Sincerely,

Byung Bae Park

Associate Professor

Department of Environment and Forest Resources

College of Agriculture and Life Sciences

Chungnam National University

99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Tel: +82-42-821-5747

Fax: +82-42-825-7850

Email: [email protected]

On behalf of all authors.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I would like to thank the authors for taking the time to revise the document. I believe it has been improved significantly. I only have a few minor comments below that should be addressed before publication. 

L55-69 This is much better.

L100-103: Not sure figure 1 is necessary. Maybe move it to a supplemental file.

L110: I would say “commercial compost”

L116-117: Convert to mg/kg as you did for N and P.

L172-175: I would move to supplemental.

L191: You already defined VC

L259-260: Move up into table caption.

L317: should be “plants”

L318: change “is” to “are”

L324:: reword. Maybe… “trees grown using VCc application method may be…”

L324-329: This paragraph seems strange. I would maybe just remove it. Not exactly sure how it fits.

L332: You did not prove the physicochemical and biological properties in the soil though.

L359: Generally, supplementary material is put in a separate file.

Author Response

Dear Editors and Reviewer

We are very thankful to the editors and reviewers for the additional comments on the manuscript entitled “Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation.” We have tried to address all the comments and suggestions in a proper way and believe that the scientific rigor of the paper has improved further.

We would be happy to make further corrections if necessary and look forward to hearing from you soon.

Sincerely,

Byung Bae Park

Associate Professor

Department of Environment and Forest Resources

College of Agriculture and Life Sciences

Chungnam National University

99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Tel: +82-42-821-5747

Fax: +82-42-825-7850

Email: [email protected]

On behalf of all authors.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have addressed all my concerns and the manuscript has considerably improved.. I have no additional comments. Thank you very much.

Author Response

Dear Editors and Reviewer

We are very thankful to the editors and reviewers for the additional comments on the manuscript entitled “Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation.” We have tried to address all the comments and suggestions in a proper way and believe that the scientific rigor of the paper has improved further.

We would be happy to make further corrections if necessary and look forward to hearing from you soon.

Sincerely,

Byung Bae Park

Associate Professor

Department of Environment and Forest Resources

College of Agriculture and Life Sciences

Chungnam National University

99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Tel: +82-42-821-5747

Fax: +82-42-825-7850

Email: [email protected]

On behalf of all authors.