Excessive Nitrate Limits the Sustainability of Deep Compost Mulch in Organic Market Gardening

Round 1

Reviewer 1 Report

The work is good with strong review of literature and promising results from well planned experiments.

Introduction:

Line 65-67, page 2: The calculation mentioned in the sentence needs attention. Please justify your statement with some reference that is more practical in relation with crop requirement.

Material and Methods

Line 125, page 3, table 1: Write the complete words for MW and DM

Literature review: Line 151, page 4: Please mention the year from which 29 studies are referred

Conclusion: The conclusion needs changes. This section describes those parameters that has never been done by the authors like soil temperature, soil moisture, weed control measurements etc. Authors must focus the work being done during the study and conclude on the basis of those results.

Author Response

Dear Colleague,

Thank you for the detailed and helpful review. The objections are very good and understandable and help us to improve the article. Your suggestions for improvement, as well as those of the other reviewers, have been discussed and essentially implemented. The following is a list of your specific points:

“Line 65-67, page 2: The calculation mentioned in the sentence needs attention. Please justify your statement with some reference that is more practical in relation with crop requirement.”

• The statement was supplemented with the expected N mobilization during the first year and compared to the average fertilizer requirement of vegetable crops.

“Line 125, page 3, table 1: Write the complete words for MW and DM”

• The correction was implemented.

“Literature review: Line 151, page 4: Please mention the year from which 29 studies are referred”

• Please note that the years of publication of each study are given in the bibiliography.

“Conclusion: The conclusion needs changes. This section describes those parameters that has never been done by the authors like soil temperature, soil moisture, weed control measurements etc. Authors must focus the work being done during the study and conclude on the basis of those results.”

• Thank you for letting us know that this needs clarifying. Due to the unusual study design of complementing a literature review with field measurements and modeling, it is necessary to be more explicit in the conclusion about which conclusions are based on which aspect of the study. Therefore, we have revised the conclusion to more clearly separate the findings from each of the literature review, field data, and modeling elements, and hope to have addressed the ambiguity.

Reviewer 2 Report

I have quite a dilemma with the evaluation of the manuscript, although I generally find its content interesting. In my opinion, the manuscript is in fact a compilation of a literature review on the use of compost as mulch in agriculture and a presentation of the Authors' own research, with a rather narrow scope. The extensive "Literature review" section distracts from the interesting empirical results. This literature review could be expanded, refined and published separately, and a full, albeit concise, justification for undertaking the research should be included in the Introduction. In turn, the Authors' own research results could be published as a short communication.

After removing the literature review section, the title of the article and the objective of the research should be clarified, as both should relate to MW used as DCM, not DCM in general. Also, the conclusions and abstract will need to be revised (adjusted) accordingly.

In line 118, please add a more precise timing for the first application of MW mulch.

In the appropriate section (Materials and Methods, lines 146-148), please clearly describe the assumptions used to simulate scenarios where MW compost was replaced with “Green Compost” and “Woody Compost”.

In the main text of the manuscript, give full names when abbreviations are used for the first time.

I hope my suggestions will help Authors improve the article in terms of content and form.

Author Response

Dear Colleague,

Thank you for the detailed and helpful review. The objections are very good and understandable and help us to improve the article. Your suggestions for improvement, as well as those of the other reviewers, have been discussed and essentially implemented. The following is a list of your specific points:

“I have quite a dilemma with the evaluation of the manuscript, although I generally find its content interesting. In my opinion, the manuscript is in fact a compilation of a literature review on the use of compost as mulch in agriculture and a presentation of the Authors' own research, with a rather narrow scope. The extensive "Literature review" section distracts from the interesting empirical results. This literature review could be expanded, refined and published separately, and a full, albeit concise, justification for undertaking the research should be included in the Introduction. In turn, the Authors' own research results could be published as a short communication.”

• Your dilemma is very understandable due to the unusual design of the article, and we exchanged ideas on how to deal with it. Due to the fact that DCM application is hardly discussed in the scientific community, while it is widely used in practice, we were motivated to take a broad view on the subject. Hence, the approach chosen was to assess the advantages and disadvantages of compost as mulch based on a literature review, to make first statements about the specific N dynamics under DCM based on field data, and to propose a solution supported by modeling. In order to bring more coherence into the article despite these different approaches, which could also stand alone, as you consequently suggested, we have revised the abstract, introduction and conclusion and hope that it is now more stringent.

“In line 118, please add a more precise timing for the first application of MW mulch.”

• The mulching applications on the farm took place every year in February and the information was concretized.

“In the appropriate section (Materials and Methods, lines 146-148), please clearly describe the assumptions used to simulate scenarios where MW compost was replaced with “Green Compost” and “Woody Compost”.”

• We apologize for not making the modeling assumptions clear enough. Climate and soil conditions, application rate and crop rotation were the same as the original input data, i.e. the conditions of the sample farm (see chapter 2.2.), only the compost properties were changed according to Green & Woody compost (Vandecasteele et al. 2022). We have now clarified this aspect in the last paragraph of Section 2.3.

“In the main text of the manuscript, give full names when abbreviations are used for the first time. “

• We have now also added it to the main text.

Reviewer 3 Report

Research is relevant and interesting.

1. No research hypothesis is presented in the introduction.

2. I recommend presenting the discussion in a separate chapter.

3. Literature analysis should be more related to the topic of the article.

4. In the chapter „Materials and Metods“ the used statistical analysis methods are not described.

 

5. In the figure No. 1 significant differences between the treatments are not marked (asterisk or different letters).

6. The conclusions could be more concrete.

 

7. I recommend not to use old literature sources.

Author Response

Dear Colleague,

Thank you for the detailed and helpful review. The objections are very good and understandable and help us to improve the article. Your suggestions for improvement, as well as those of the other reviewers, have been discussed and essentially implemented. The following is a list of your specific points:

“No research hypothesis is presented in the introduction.“

• The aim and purpose of the study have been clarified in the abstract and introduction. Since the article is not based on an experimental design to validate a hypothesis, there is no explicit thesis.

„I recommend presenting the discussion in a separate chapter.“

• For ease of reading, we decided to combine results and discussion in one chapter.

„Literature analysis should be more related to the topic of the article.“

• Since limited literature on compos mulch is available, we included literature not only focusing on nutrient dynamics. We do this in order to present the current body of literature with their respective scopes and to point out their limitations and needs for future research topics.

“In the chapter „Materials and Metods“ the used statistical analysis methods are not described.” & “In the figure No. 1 significant differences between the treatments are not marked (asterisk or different letters).”

• Please excuse the lack of clarity. The data collected are measurements made under real field conditions, where the sampling of the individual beds and measurement times were each examined as a composite sample in the laboratory. Thus, unfortunately, the data situation does not allow a statistical evaluation. The article was revised accordingly to clarify this aspect.

“The conclusions could be more concrete.”

• Thanks for the objection, the Conclusion has been revised.

 “I recommend not to use old literature sources.“

• I think that the old literature is mainly studies from the literature review, maybe sporadic studies on basic correlations (e.g. Fink and Scharpf 1993), whose results are still state of the art in our opinion. Regarding the literature on compost mulch: The literature review revealed that the topic has not been widely studied in the scientific community, and thus the study base is thin. In our opinion, the studies from the 1990s in particular provide important basic knowledge on the use of compost mulch and were therefore included, even though they were published quite some time ago.

Reviewer 4 Report

Dear Editor and authors, the manuscript is very good and interesting and should be published after some adjustments listed below:

Some paragraphs of introduction, material and methods and discussion are long, authors can rewrite these in short paragraphs.

In Figure 1, the authors must provide the mean error bar, in order to evaluate of data variation, as it may be that the studied factors may have different variations, which I believe did. Also, how do the authors compare the different Growing Seasons? – If it is only in the observed data, this is incorrect, the authors need to make some statistical approach to make this comparison, otherwise the inferences are speculations without support by statistics. Furthermore, a statistical approach must be taken to allow comparison of one area with another, otherwise the article is simply based more on an informational text than a scientific article. Thus the whole approach to the data in section 3.2 On-farm soil sampling must be revised! And after that, the authors need to discriminate in the Material and Methods section, the statistical approach used.

Authors must place as a supplementary document and cite in the text this supplementary document the list of works used in the literature review

 

The article is good.

Author Response

Dear Colleague,

Thank you for the detailed and helpful review. The objections are very good and understandable and help us to improve the article. Your suggestions for improvement, as well as those of the other reviewers, have been discussed and essentially implemented. The following is a list of your specific points:

“In Figure 1, the authors must provide the mean error bar, in order to evaluate of data variation, as it may be that the studied factors may have different variations, which I believe did. Also, how do the authors compare the different Growing Seasons? – If it is only in the observed data, this is incorrect, the authors need to make some statistical approach to make this comparison, otherwise the inferences are speculations without support by statistics. Furthermore, a statistical approach must be taken to allow comparison of one area with another, otherwise the article is simply based more on an informational text than a scientific article. Thus the whole approach to the data in section 3.2 On-farm soil sampling must be revised! And after that, the authors need to discriminate in the Material and Methods section, the statistical approach used.”

• Please excuse that the data type was not clear enough. As these are field data under real conditions and the soil samples of a sampling date were sent to the laboratory as a composite sample of the respective bed, there are no replicates and no experimental design on which to base a statistical evaluation of the collected data. Please note, however, that due to the frequency of the measurements, the change in Nmin-N levels under DCM during the year is presented under practical conditions, and we refer in our conclusions only to the specific farm during the observation period. Thank you for pointing this out, and we have made appropriate additions to the relevant sections, to clarify this point.

“Authors must place as a supplementary document and cite in the text this supplementary document the list of works used in the literature review”

• This is a good point, and we had already discussed a table listing the studies for the first manuscript. In the end, we decided against it because it would have been redundant to the text and bibliography.

Round 2

Reviewer 3 Report

No comments.