Urban Organic Waste for Urban Farming: Growing Lettuce Using Vermicompost and Thermophilic Compost
Round 1
Reviewer 1 Report
The authors investigated the fertilizer value of vermicomposts and composts. The study showed that the urban waste-derived vermicomposts and fecal composts displayed a high delivery rate of plant-available nutrients. Overall, the approach of the study in the manuscript is good and could be useful in the public domain, but the manuscript needs considerable revision to reach the public domain.
* The significance of the study should be mentioned clearly in the abstract section.
* The change in physicochemical characteristics of the urban organic waste-derived composts should be written in brief in the abstract section.
* The abstract should also be revised with the benefits of the study findings and recommendations as a way forward.
* Provide significant words which are more relevant to the work in a logical sequence as ‘keywords’. Also, use keywords that are not present in the title.
* What is the current level of understanding in relation to the urban organic waste-derived composts on lettuce plants? What are the knowledge gaps?. These should be included in the introduction section. The introduction is insufficient to provide the state of art in the topic. The originality and novelty of the paper need to be further clarified. What progress against the most recent state-of-the-art similar studies was made in this study?
*It would be interesting to use more recent references in the introduction.
*Line no 153; In the materials and method section, any background information on why authors used lettuce plants, variety? Need to mention the reason for choosing. Any background information?
* Line no 259; for the compost analysis section, authors must give references.
* Line no 340; Don’t use the notion like ‘we’ or ‘our’ etc., as these are the redundant words (not the research words) for the standard journal manuscripts.
* Authors are suggested to add discussion by explaining trends in the obtained results along with the possible mechanisms behind the trends.
* Why authors have not analyzed the heavy metal analysis in urban organic waste-derived composts?
*Under section, discussion, it is recommended to discuss and explain what should be the appropriate policies based on the findings of this study.
*Pls. conclude with more focus on the major outcomes of the paper.
Author Response
We appreciate the general positive evaluation of the work we provided and thank the anonymous reviewer for the valuable comments that were provided to us. Below we provide point-by-point answers to the reviewer's comments. In the revised manuscript we used the following color-code to mark changes:
Green: text that was newly inserted in the manuscript, compared to the first submission;
Blue: thoroughly revised text parts.
Point-by-point answers to the reviewer's comments:
Point 1: The significance of the study should be mentioned clearly in the abstract section.
Response 1: Thank you for calling attention to that. We adapted the abstract to mention the significance of the study (p. 1, lines 12-13).
Point 2: The change in physicochemical characteristics of the urban organic waste-derived composts should be written in brief in the abstract section.
Response 2: Thank you for the comment. Due to a limited word number, we could not include a description of the change in physicochemical characteristics of the urban organic waste-derived composts. This part however is included in chapter 2 of the paper.
Point 3: The abstract should also be revised with the benefits of the study findings and recommendations as a way forward.
Response 3: Thank you for this feedback, we agree. We revised the abstract to point out the benefits of the study (p. 1, lines 24-26).
Point 4: Provide significant words which are more relevant to the work in a logical sequence as ‘keywords’. Also, use keywords that are not present in the title.
Response 4: We agree thank you for pointing this out. We added the relevant keywords coconut fiber, lettuce, organic wate, urban waste, and thermophilic compost.
Point 5: What is the current level of understanding in relation to the urban organic waste-derived composts on lettuce plants? What are the knowledge gaps?. These should be included in the introduction section. The introduction is insufficient to provide the state of art in the topic. The originality and novelty of the paper need to be further clarified. What progress against the most recent state-of-the-art similar studies was made in this study?
Response 5: We thank you for this valuable comment. We want to explain, however, that lettuce was mainly used as one representative sample crop for horticultural production, which is also often grown in modern urban cultivation systems. The focus of our research was on the assessment of new types of composts from urban waste with regards to their fertilization potential. Research on the suitability of the recycled products for use as fertilizer in horticulture and agriculture is still needed to support policy development at a European and national level (i.e. originality and novelty of the paper). Moreover, in our study we did not only focus on Nitrogen and/or Phosphorus as main nutrients, but also studied the effect of other macronutrients (i.e. progress against the most recent state-of-the-art as described in similar studies). We elaborate on this point in the revised manuscript on p. 3, lines 136-142.
Point 6: It would be interesting to use more recent references in the introduction.
Response 6: We agree. Thank you for pointing this out. We reacted on this valuable comment and added more recent references to the introduction while also revised and sharpened the introduction.
Point 7: Line no 153; In the materials and method section, any background information on why authors used lettuce plants, variety? Need to mention the reason for choosing. Any background information?
Response 7: Thank you for this feedback. we agree and added the reason for cultivar choice to the material and methods section (p. 4, lines 171-172).
Point 8: Line no 259; for the compost analysis section, authors must give references.
Response 8: Thank you for this helpful comment. We added the missing descriptions of the compost analysis methods on page 7. The compost analyses were based on national or international compost analysis standards. For each measurement, the method is indicated, e.g., "DIN EN 15933:2010". To improve the comprehensibility of the text, we add the sentence. "Unless otherwise stated, all compost analyses were based on national or international compost analysis standards." at the beginning of the chapter (p. 7, lines 271-272).
Point 9: Line no 340; Don’t use the notion like ‘we’ or ‘our’ etc., as these are the redundant words (not the research words) for the standard journal manuscripts.
Response 9: Thank you for the comment. We are aware that there are different approaches to the usage of active or passive language in journal manuscripts. We decided to use active language in the parts of our manuscript, which represent our findings and work and we changed active to passive language in parts where this is not the case (line no. 556).
Point 10: Authors are suggested to add discussion by explaining trends in the obtained results along with the possible mechanisms behind the trends.
Response 10: Thank you for your suggestion to rework on certain trends and mechanisms. We carefully revised the discussion and found some relations and processes that have not been mentioned:
(1) In section 3.1.1, we discuss compositional variations in relation to oxygen status, input and bedding material, and pH. We added the process which we forgot to add: nitrification in aerobic composting as main cause for the larger share of NO3- -N in the compost compared to NH4+-N. We also added NH3 volatilization in relation to the alkaline pH in faecal compost (TC-F), which lead to the lack of NH4+ in the compost (p. 9, lines 392-394)
(2) In section 3.1.3, we now mentioned the relation of EC with nutrient and salt concentration, explaining the high EC of coir-based vermicompost (VC-C) and faecal compost (TC_F). Moreover, the high Na concentration in TC-F explains the relatively high EC. We found a strong positive correlation with EC, which has been added to the discussion (p. 11, lines 435-456).
We also checked the section 3.2. for forgotten trends and mechanisms. We discuss dilution effects of nutrient tissue concentrations, nutrient availability and solubility, nutrient ratios and uptake rates correlated to nutrient concentration, as well as potential antagonistic effects by cationic imbalances. Fertilizer value and plant growth in relation to these aspects was discussed and explained. Moreover, we carefully compared all composts and ranged them, indicating trends for each nutrient. We could not find missing explanations.
Point 11: Why authors have not analyzed the heavy metal analysis in urban organic waste-derived composts?
Response 11: Thank you for highlighting this issue. We measured the content for As, Cd, Cr, Cu, Ni, Zn, and Pb and displayed it in table 2 (p. 9). All composts met the quality criteria of the German Federal Compost Quality Association. However, because of financial restrictions we could not analyse the content of heavy metals in plant tissue or root material.
Point 12: Under section, discussion, it is recommended to discuss and explain what should be the appropriate policies based on the findings of this study.
Response 12: Thanks for pointing this out. We added a short paragraph at the end of the discussion on p. 17, lines 714-718.
Point 13: Pls. conclude with more focus on the major outcomes of the paper.
Response 13: To this point, we considered the major outcomes: compost benefits and deficiencies as well as urban waste circulation in the conclusion.
Reviewer 2 Report
page 1, line 42: considering urban waste as ....
page 1, line 43: production of organic fertilizer....
page 2, line 58: potential resource....
The reason for use of sand instead of soil in pot experiments should be explained. Decomposition of bio-fertilizers in soil takes place by involvement of microorganisms and soil enzymes which would not be present in sand. Also, the chemical properties of soil such as Cation Exchange Capacity and Buffering Capacity, pH, etc. would affect the availability of nutrients released from bio-fertilizers.
Author Response
We appreciate the general positive evaluation of the work we provided and thank the anonymous reviewer for the valuable comments that were provided to us. Below we provide point-by-point answers to the reviewer's comments. In the revised manuscript we used the following color-code to mark changes:
Green: text that was newly inserted in the manuscript, compared to the first submission;
Blue: thoroughly revised text parts.
Point-by-point answers to the reviewer's comments:
Point 1: page 1, line 42: considering urban waste as ....
Response 1: Thank you for the comment. the proposed words were added (p. 2, line 49).
Point 2: page 1, line 43: production of organic fertilizer....
Response 2: Thank you for the comment. the proposed words were added (p. 2, line 50).
Point 3: page 2, line 58: potential resource....
Response 3: Thank you for the comment. the proposed words were added (p. 2, line 66).
Point 4: The reason for use of sand instead of soil in pot experiments should be explained. Decomposition of bio-fertilizers in soil takes place by involvement of microorganisms and soil enzymes which would not be present in sand. Also, the chemical properties of soil such as Cation Exchange Capacity and Buffering Capacity, pH, etc. would affect the availability of nutrients released from bio-fertilizers.
Response 4: We are thankful for this valuable comment and adapted the material and methods section according to your proposition (p. 4, lines 177-178). A further reason for the usage of sand not stated in the manuscript was the examination of the influence of the compost on mycorrhiza development in the pots. External influences of soil properties were excluded through our approach. Since no mycorrhiza growth was observed, we excluded this part of the experiment from our manuscript.
Round 2
Reviewer 1 Report
The authors have addressed all the comments with full justification, therefore the article may be accepted in the present form.
Author Response
Thank you for your time and effort to review our manuscript. Your input was a valuable contribution to the paper.
Reviewer 2 Report
Thank you for addressing my comments.
Author Response
Thank you for your time and effort to review our manuscript. Your input was a valuable contribution to the paper.
