Sustainable Strategies for Raspberry Production: Greenhouse Gas Mitigation Through Biodegradable Substrate Additives in High Tunnels

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The research period is only one year, and it does not cover the degradation rate of biodegradable additives (such as biochar) over multiple growth cycles, the stability of nutrient release, and the impact of long-term use on substrate structure (such as bulk density and porosity), making it impossible to determine the long-term environmental and economic sustainability of this substrate improvement strategy;
2. The potential for emission reduction in tunnel construction has not been discussed in depth; research results show that tunnel construction is the largest source of emissions, but the paper focuses entirely on matrix improvement;
3. Some newest research work related with this paper can becited. In situ nuclear magnetic resonance observation of pore fractures and permeability evolution in rock and coal under triaxial compression. Diffusion evolution rules of grouting slurry in mining-induced cracks in overlying strata. Thermo-mechanical degradation and fracture evolution in low-permeability coal subjected to cyclic heating–cryogenic cooling.
4. The text only mentions that "The use of modified substrates leads to increased water and nutrient use efficiency within the production system." but does not quantify key economic indicators, such as the production cost of improved substrates, the input-output ratio per unit yield, and the economic benefit difference compared to traditional substrates, making it impossible to fully support the conclusion of balancing environmental and economic efficiency.

Author Response

Thank you for your kind review of our paper and for your comments. Please see your comments below (in bold) followed by our responses. We have tracked all changes in the resubmitted manuscript.

Comments 1: The research period is only one year, and it does not cover the degradation rate of biodegradable additives (such as biochar) over multiple growth cycles, the stability of nutrient release, and the impact of long-term use on substrate structure (such as bulk density and porosity), making it impossible to determine the long-term environmental and economic sustainability of this substrate improvement strategy;

Response 1: We fully acknowledge the limitation indicated by the Reviewer concerning the one-year scope of our study. The experiment was designed as a vegetation trial to provide a first, controlled assessment of the environmental performance of innovative substrates with biodegradable additives in raspberry production.
We agree that the long-term dynamics of biodegradable components (such as biochar degradation rate, stability of nutrient release, and changes in bulk density and porosity of the substrate across multiple production cycles) represent an important research gap.
We will emphasize this limitation more clearly in the revised manuscript and point out that future research will focus on long-term substrate stability and its implications for sustainability assessments.

 

Comments 2: The potential for emission reduction in tunnel construction has not been discussed in depth; research results show that tunnel construction is the largest source of emissions, but the paper focuses entirely on matrix improvement;

Response 2: We appreciate the Reviewer’s observation regarding the role of tunnel construction in the overall emission profile. Indeed, our results confirm that infrastructure construction - particularly steel and plastic used for tunnels - constitutes the dominant share of the carbon footprint in raspberry production. The present paper focused primarily on substrate modification strategies, as they are more directly manageable by producers in the short term and were the main object of our experimental design. However, we fully agree that mitigation options related to tunnel construction, such as the use of alternative covering materials with lower embodied emissions, extended tunnel lifespan, recycling strategies, or innovative lightweight structures, deserve more in-depth analysis.
As suggested, we have added a statement in the Limitations section noting that potential mitigation strategies for tunnel infrastructure were not analyzed in depth and should be addressed in future research.

 

Comments 3: Some newest research work related with this paper can be cited. In situ nuclear magnetic resonance observation of pore fractures and permeability evolution in rock and coal under triaxial compression. Diffusion evolution rules of grouting slurry in mining-induced cracks in overlying strata. Thermo-mechanical degradation and fracture evolution in low-permeability coal subjected to cyclic heating–cryogenic cooling.

Response 3: We thank the reviewer for bringing this latest research to our attention. We will address it in our future work.

 

Comments 4: The text only mentions that "The use of modified substrates leads to increased water and nutrient use efficiency within the production system." but does not quantify key economic indicators, such as the production cost of improved substrates, the input-output ratio per unit yield, and the economic benefit difference compared to traditional substrates, making it impossible to fully support the conclusion of balancing environmental and economic efficiency.

Response 4: We appreciate the Reviewer’s insightful comment. We agree that a full economic evaluation - including substrate production costs, input-output ratios, and comparative profitability - would strengthen the analysis of environmental-economic trade-offs. However, the primary aim of this study was to assess the environmental performance of biodegradable substrate additives using the LCA framework, while the economic analysis was limited to qualitative implications based on resource use efficiency. As suggested, we have clarified this limitation in the manuscript and emphasized that future research should include detailed cost-benefit assessments to complement the environmental findings and provide a comprehensive evaluation of sustainability.

 

Response to Comments on the Quality of English Language

We thank the Reviewer for this comment. We have reviewed the manuscript with attention to clarity and readability.

Reviewer 2 Report

Comments and Suggestions for Authors

The article submitted entitled “Sustainable Strategies for Raspberry Production: Greenhouse Gas Mitigation through Biodegradable Substrate Additives in High Tunnels” is in the middle way of Environmental Sciences and Agricultural Engineering. But the aims are closely to sustainable production. So, it can be considered in that way.

The abstract is quite good. I wonder if you can add the name of the substrate variant which was “the most efficient variant achieving nearly a 40% decrease”.

The keywords are ok.

The introduction gives a nice a overview to present the objectives of this work However, I think that some comments regarding the substrate origin, the transport and the economic cost and the effects on GHG emissions would be comment. As much as I know, no coconut production in Poland and no fiber from coconut to prepare substrates.

Please, check the section 2. For instance, “LERGO” or “Legro” (compare line 207 and table 1).

In table 2: Max. water holding capacity kg/kg ????? Data?

References about the methods used to measure the physical parameters of the substrates would be desirable.

Please indicate in section 2 the statistical treatments applied to the data obtained.

In general, the section 2, methods, should give enough information for the reproducibility of the experiment. Moreover, it is important to indicate how the results were obtained, were they from the use of emissions factors from literature? Were they measured directly? and how?

In my opinion, this should be clarified to understand the results, their origin and how they were calculated.

The results, considering that they are correct and the sources and measurements incorporated to the section 2, are well presented and discussed.

A consequence of that is that conclusions response to the objectives of the work, although they seem a bit long.

Finally, as a minor consideration to improve the paper and facilitate the reading, check the end of the sentences when a word is cut. In line 25, it is written “represent-“and in the following line “ing”. I suggest that it is better “represen-ting”. Of course, in this case and other, I understand that this is a question of the template.

Author Response

Thank you for your kind review of our paper and for your comments. Please see your comments below (in bold) followed by our responses. We have tracked all changes in the resubmitted manuscript.

Comments 1: I wonder if you can add the name of the substrate variant which was “the most efficient variant achieving nearly a 40% decrease”. 

Response 1: Thank you for your valuable comments, which have contributed to improving this manuscript. The suggested change has been made.

 

Comments 2: The introduction gives a nice overview to present the objectives of this work However, I think that some comments regarding the substrate origin, the transport and the economic cost and the effects on GHG emissions would be comment. As much as I know, no coconut production in Poland and no fiber from coconut to prepare substrates.

Response 2: Thank you for this valuable suggestion. We have revised the introduction accordingly to address the points you raised.

 

Comments 3: Please, check the section 2. For instance, “LERGO” or “Legro” (compare line 207 and table 1).

Response 3: The mistake was improved.

 

Comments 4: References about the methods used to measure the physical parameters of the substrates would be desirable.

Response 4: We appreciate your suggestion. In the revised manuscript, appropriate references have been included to support the description of the measurement methods.

 

Comments 5: In table 2: Max. water holding capacity kg/kg ????? Data?

Response 5: This mistake has been corrected. Thank you for bringing it to our attention.

 

Comments 6: Please indicate in section 2 the statistical treatments applied to the data obtained.

Response 6: Thank you for this valuable suggestion. In the revised manuscript, we have added a description of the statistical analysis at the end of section 2.

 

Comments 7: In general, the section 2, methods, should give enough information for the reproducibility of the experiment. Moreover, it is important to indicate how the results were obtained, were they from the use of emissions factors from literature? Were they measured directly? and how?

Response 7: Information regarding the data sources used to calculate greenhouse gas emissions is presented in the Results and Discussion section. The calculation of greenhouse gas emissions resulting from production was based on literature data. References 39-48 are the input data sources for calculating GHG levels.

Reviewer 3 Report

Comments and Suggestions for Authors

1. Line 314: In Table, it is necessary to explain in more detail for the calculation of amount of water used.
2. Line 332: Irrigation was carried out using groundwater pumped from a depth of 25 meters. The authors should clarify the average energy input required for these irrigation systems and quantify the associated greenhouse gas emissions.
3. Line 337: The operational lifespan of the tunnel structures was assumed to be 25 years. It is necessary to cite relevant research to justify the chosen time span of 25 years. The appropriate duration could be shorter or longer, which may lead to different results.
4. Line 361: In Figure 2, the lowest share - below 1% - was attributed to emissions from pesticide use and fuel combustion during crop cultivation. The authors should verify whether this result is reasonable and recheck the complete set of calculations, as such a low value may indicate an error or an overlooked emission source.
5. Line 464: the greatest reduction in greenhouse gas emissions per unit of yield was achieved in variants where both biochar and insulation material were applied simultaneously. This is an interesting point. Could you explain it in more detail?
6. Line 561: Based on this research, the highest contribution to total GHG emissions originated from tunnel construction activities, ranging from 2.92 to 3.27 kg CO₂-eq per kg of fruit, which accounted for 66.86-75.07% of the total emissions. In the conclusion section, it is necessary to discuss how tunnel construction can be improved to reduce total GHG emissions.

Author Response

Thank you for your kind review of our paper and for your comments. Please see your comments below (in bold) followed by our responses. We have tracked all changes in the resubmitted manuscript.

Comments 1: Line 314: In Table, it is necessary to explain in more detail for the calculation of amount of water used.

Response 1: We would like to thank the Reviewer for drawing our attention to this aspect. The comment was taken into account.

 

Comments 2: Line 332: Irrigation was carried out using groundwater pumped from a depth of 25 meters. The authors should clarify the average energy input required for these irrigation systems and quantify the associated greenhouse gas emissions. 

Response 2: We are grateful for your remark, which has been taken into account in the revision.

 

Comments 3: Line 337: The operational lifespan of the tunnel structures was assumed to be 25 years. It is necessary to cite relevant research to justify the chosen time span of 25 years. The appropriate duration could be shorter or longer, which may lead to different results.

Response 3: Thank you for this valuable comment. The assumed lifespan of 25 years reflects the average operational duration of tunnels in Poland, specifically in the study area, based on data obtained from companies producing soft fruit in tunnel structures.

 

Comments 4: Line 361: In Figure 2, the lowest share - below 1% - was attributed to emissions from pesticide use and fuel combustion during crop cultivation. The authors should verify whether this result is reasonable and recheck the complete set of calculations, as such a low value may indicate an error or an overlooked emission source.

Response 4: The results are correct. This is a potted crop, with planting occurring every few years and the substrate also being replaced every few years.

 

Comments 5: Line 464: the greatest reduction in greenhouse gas emissions per unit of yield was achieved in variants where both biochar and insulation material were applied simultaneously. This is an interesting point. Could you explain it in more detail?

Response 5: Thank you for this helpful comment. The manuscript has been revised accordingly.

 

Comments 6: Line 561: Based on this research, the highest contribution to total GHG emissions originated from tunnel construction activities, ranging from 2.92 to 3.27 kg CO₂-eq per kg of fruit, which accounted for 66.86-75.07% of the total emissions. In the conclusion section, it is necessary to discuss how tunnel construction can be improved to reduce total GHG emissions. 

Response 6: Thank you for pointing this out. Relevant clarifications have been added to the revised manuscript.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The language of the paper could benefit from further editing for clarity and coherence.

Author Response

Thank you for your kind review of our paper and for your comments. Please see your comments below (in bold) followed by our responses.

Comments 1: The language of the paper could benefit from further editing for clarity and coherence.

Response 1: We sincerely thank the Reviewer for drawing our attention to this important point. A thorough language revision has been carried out to improve the clarity and coherence of the manuscript, ensuring that the research is expressed more clearly. We hope that these revisions meet the Reviewer’s expectations.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for improving the article.

Although I think that the methods used could be better described (it is not enough to add at the end of a table but not linked with any part of the text "*The physical properties of the substrates were determined according to Polish Standard [42]" (I supposse that this is the same like UNE-EN 13041:2001), and the statistical analysis used needs previously to check the normality of the data (not done as it seems). The article in my opinion, can be accepted after a minor revision. But surely, you can improve both in section 2.

However, please check the references. At the end, it is mentioned a reference with the number 1 International Fertilizer Association (IFA). Energy Efficiency and CO₂ Emissions in Ammonia Production 2008–2009: Summary Report; 820 International Fertilizer Association: Paris, France, 2009. 

Probably these minor mistakes can be revised.

Author Response

Thank you for your kind review of our paper and for your comments. Please see your comments below (in bold) followed by our responses. We have tracked all changes in the resubmitted manuscript.

Comments 1: Although I think that the methods used could be better described (it is not enough to add at the end of a table but not linked with any part of the text "*The physical properties of the substrates were determined according to Polish Standard [42]" (I supposse that this is the same like UNE-EN 13041:2001), and the statistical analysis used needs previously to check the normality of the data (not done as it seems). The article in my opinion, can be accepted after a minor revision. But surely, you can improve both in section 2.

Response 1: 

We thank the Reviewer for this valuable comment and for pointing out the need to better clarify the methods used. In response, we have revised Section 2 and supplemented the description of the methods applied to the data presented in Tables 2 and 3. Specifically, the following explanations have now been included in the manuscript:

• Bulk density was determined using gravimetric analysis (ratio of the fresh mass of the solids to the volume of the substrate).
• Moisture content was determined using gravimetric analysis (oven-drying to measure weight loss).
• Angle of repose was determined using the fixed funnel method.
• Coefficient of friction was determined using a direct shear test.
• Porosity was determined using the water absorption test.
• Compressibility was determined using confined compression.

In addition, we have clarified the description of the statistical analysis. Prior to conducting ANOVA, the normality of the data distribution was verified using the Shapiro–Wilk test, and the assumption was confirmed.
We hope that these additions clarify the applied methods and meet the Reviewer’s expectations.

 

Comments 2: At the end, it is mentioned a reference with the number 1 International Fertilizer Association (IFA). Energy Efficiency and CO₂ Emissions in Ammonia Production 2008–2009: Summary Report; 820 International Fertilizer Association: Paris, France, 2009. 

Response 2: We thank the Reviewer for pointing out this issue. A thorough correction has been implemented accordingly.