Comparative Effects of Nitrogen Fertigation and Granular Fertilizer Application on Pepper Yield and Soil GHGs Emissions
Round 1
Reviewer 1 Report
Comments and Suggestions for Authorsplease see the attachment.
Comments for author File: Comments.zip
Comments on the Quality of English LanguageThe English could be improved to more clearly express the research.
There are quite a lot of long sentences, of which expression are not clear.
There are part of grammatical errors, such as subject-verb inconsistency and tense confusion.
Author Response
Reviewer 1
The content of this manuscript is relatively complete, and the research design has certain logic, However, the following specific problems need to be revised:
[Reviewer]: The introduction part is rather long and provides a lot of background descriptions, but it does not clearly focus on the scientific issues and research purposes of the study. Although the literature review was detailed, it did not highlight the shortcomings of the existing studies, nor did it clearly introduce the research motivation and innovation points of this manuscript. The introduction lacks a clear identification of the research gap, and the innovation of the study remains somewhat vague. clearer positioning of the research contribution in relation to current literature is needed.
[Authors]: Thank you for pointing this out. We tried to summarize the introduction, reducing background description but avoiding to give too much details, focusing on research gap and trying to state as clear as possible the goals and the value of this study, in the context of the Mediterranean pepper crop of the Campania region. The new version of the introduction is highlighted in yellow in the revised version of the manuscript, at the lines 38-127.
[Reviewer]: Line 137 “~3 months”, it is not a formal expression. I think it should be almost 3 months or about 3 months.
[Authors]: Thank you for this suggestion. In the revised version of the manuscript, because another reviewer asked to remove the mentioned part because sounded more like a Material & Methods section, the expression “3 months” it was removed.
[Reviewer]: Line 156-158, please revise the English writing of the highlighted part.
[Authors]: Thank you for pointing this out. We have corrected the English for this part, now in the revised and summarized introduction, that is globally changed.
[Reviewer]: Thank you for pointing out the lack of clarity. In paragraph 2.1, within the Materials and Methods section, we have included information regarding the methodology of fertilizer application, planting method, and irrigation."
[Reviewer]: Please separate the figures of rainfall and air temperature from Figure 1 to chapter 2. These are not the observed data of results; these are the basic experiment situation. The same as irrigation, pleased put it in the part of experiment design description.
[Authors]: Thank you for your valuable feedback. We have chosen to include the air temperature, precipitation, and irrigation data alongside the emission data, soil temperature, and WFPS in global graph of Figure 1, to provide a more comprehensive understanding of the environmental factors influencing the emissions. This approach helps in interpreting the data in a broader context, allowing for a clearer understanding of the trends throughout the entire study period. None of the other reviewers or the editor raised concerns about the inclusion of these variables in the first figure, as they are integral to providing a holistic view of the experimental conditions. We hope this clarification addresses your concern and look forward to any further suggestions you may have.
[Reviewer]: Expand the methodology section to clarify treatment definitions and measurement protocols. Usually, we use odd numbers of replicates, so why we use 4 here? The 1m is the line spacing? so how about the row spacing? please give out the specific spacing in the rows and spacing between rows.
[Authors]: We preferred to use 4 replicates to make the statistical analysis more robust. The distance among the plants on the row was 0,4m. We implemented also this information in section 2.1
[Reviewer]: We only have 2 treatments? They used the same fertilizer amount, while the different fertilization method, right? For the granular fertilizer treatment, how about its irrigation schedule? please give out more information about the experiment design.
[Authors]: Yes, we tested only two treatments, i.e. granular fertilizer and fertigation by using Urea (46% N) as N fertilizer and the same Urea amount in both treatments. Concerning the irrigation scheduling, both treatments received the same water amount at the same time. So, the irrigation scheduling was the same for the two treatments. Detailed information was added in M&M, Section 2.1 (lines: 145-164), highlighted in yellow in the revised manuscript.
[Reviewer]: The description of the Figure is rather wordy. It is suggested to be more concise.
[Authors]: Thank you for your suggestion. However, we believe the figure captions are appropriately concise and structured to be self-standing, providing all the necessary context for the figure without requiring additional explanations. The current length is intentional to ensure clarity and allow the figure to be fully understood on its own. However, we tried to modify them as much as possible.
[Reviewer]: Strengthen the discussion with more in-depth explanation and engagement with previous studies. During the discussion, the test results were not adequately interpreted. There was a lot of repetitive description and a lack of explanations for the causes of the phenomena as well as trend analysis. It is suggested to explore possible mechanisms or influencing factors, or to conduct a comparative analysis with existing research results. And try to correspond with the research purpose as well.
[Authors]: Thank you for this useful suggestion. We tried to rearrange the discussion part, summarizing it, in a more focused and concise way, improving results interpretation and explanation of proposed phenomena, adding some recent literature. The new discussion in the revised version of the manuscript now covers the lines 400-461, highlighted in yellow.
[Reviewer]: Avoid merely repeating the results in the conclusion part, focus on the main insight and impact of this study.
[Authors]: Thank you for this valuable suggestion. We revised the conclusion and now it is more focused on the impact and insights of these findings, at page 14, line 462-475, highlighted in yellow in the revised manuscript.
[Reviewer]: There is a lack of the latest research literature for the past two years. The references mostly date back to before 2017, and there is a shortage of information on the research progress in this field from 2022 to 2024. Besides, there are too many citations for one viewpoint, it should be avoided.
[Authors]: Thank you for pointing this out. We tried to add other point of view and a more recent literature from the past two years, mainly in the discussion.
For clarity we add below a list of the most recent cited articles:
Alasinrin, S.Y.; Salako, F.K.; Busari, M.A.; Sainju, U.M.; Badmus, B.S.; Isimikalu, T.O. Greenhouse gas emis-sions in response to tillage, nitrogen fertilization, and manure application in the tropics. Soil and Tillage Re-search 2025, Volume 245, 106296, ISSN 0167-1987. https://doi.org/10.1016/j.still.2024.106296.
Zhu, Y.; Houping, Z.; Li, R.; Wendong, Z.; Kang, Y. Nitrogen fertigation affects crop yield, nitrogen loss and gaseous emissions: a meta-analysis. Nutrient Cycling in Agroecosystems. 2023, 127. 1-15. 10.1007/s10705-023-10318-5.
Ding, W.; Zhang, G.; Xie, H. et al. Balancing high yields and low N2O emissions from greenhouse vegetable fields with large water and fertilizer input: a case study of multiple-year irrigation and nitrogen fertilizer regimes. Plant Soil 2023, 483, 131–152. https://doi.org/10.1007/s11104-022-05730-9
Hamad, A.A.A.; Wei, Q.; Xu, J.; Hamoud, Y.A.; He, M.; Shaghaleh, H.; Wei’, Q.; Li, X.; Qi, Z. Managing Fer-tigation Frequency and Level to Mitigate N2O and CO2 Emissions and NH3 Volatilization from Subsurface Drip-Fertigated Field in a Greenhouse. Agronomy 2022, 12, 1414. https://doi.org/10.3390/agronomy12061414
Hall S.J.; Tenesaca C.G.; Lawrence N.C. et al. Poorly drained depressions can be hotspots of nutrient leaching from agricultural soils. J Environ Qual 2023, 52:678–690. https:// doi. org/ 10. 1002/ jeq2. 20461
Anthony, T.L.; Szutu, D.J.; Verfaillie, J.G.; et al. Carbon-sink potential of continuous alfalfa agriculture low-ered by short-term nitrous oxide emission events. Nat Commun 2023, 14, 1926. https://doi.org/10.1038/s41467-023-37391-2
Sourav, S.K.; Subbarayappa, C.T.; Hanumanthappa, D.C.; et al. Soil respiration under different N fertilization and irrigation regimes in Bengaluru, S-India. Nutr Cycl Agroecosyst 2023, 127, 333–345. https://doi.org/10.1007/s10705-023-10311-y
Wei, Q.; Xu, J.; Liu, Y.; Wang, D.; Chen, S.; Qian, W.; He, M.; Chen, P.; Zhou, X.; Qi, Z. Nitrogen losses from soil as affected by water and fertilizer management under drip irrigation: Development, hotspots and future perspectives. Agricultural Water Management 2024, Volume 296, 108791, ISSN 0378-377. https://doi.org/10.1016/j.agwat.2024.108791
Feng, Z-J.; Weibo, N.; Ma, Y.-P.; L., Y.; Ma, X-Y.; Zhu, H-Y. Effects of urea solution concentration on soil hy-draulic properties and water infiltration capacity. Science of The Total Environment 2023, 898. 165471. 10.1016/j.scitotenv.2023.165471.
Zhang, M.; Wu, Y.; Qu, C.; Huang, Q.; Cai, P. Microbial extracellular polymeric substances (EPS) in soil: From interfacial behaviour to ecological multifunctionality. Geo-Bio Interfaces 2024, 1, e4. https://doi.org/10.1180/gbi.2024.4
Ribeiro P.L.; Pitann B.; Banedjschafie S.; Mühling K.H. Effectiveness of three nitrification inhibitors on mit-igating trace gas emissions from different soil textures under surface and subsurface drip irrigation. Journal of Environmental Management 2024, 359, 120969. https://doi.org/10.1016/j.jenvman.2024.120969
Zhang P.; Liu J.; Zhang H.; Wang M.; Xu J.; Yu L.; Cai H. Deficit irrigation interacting with biochar mitigates Nâ‚‚O emissions from farmland in a wheat–maize rotation system. Agricultural Water Management 2024, 297, 108843. https://doi.org/10.1016/j.agwat.2024.108843
Reviewer 2 Report
Comments and Suggestions for AuthorsAbstract
The first sentence is too long; it should be divided into two parts to better understand the issue being studied.
Abbreviations should be explained the first time they are used. GWP - Global Warming Potential?
Keywords: It is not recommended to repeat the same words extensively in the title and keywords. This reduces the chances of finding the article in search engines. You could also use keywords like CO2 and N2O fluxes, high emission events, for example.
Introduction
Overall, the Introduction provides sufficient background information about the research topic and relevance, and the purpose and hypothesis of the research are clearly formulated. However, the Introduction is too long. This is not a review article, so the many examples from previous research results should be summarized to make the Introduction more focused and compact.
Materials and Methods
Although the M&M section is written quite clearly, some questions arose and need to be clarified.
2.1. Trial Materials and Experimental Design
How many plants were in one plot?
2.2. Biometrical determinations
Line 185. “The plant dry biomass production has been monitored during the whole crop growing season”.
How often was plant biomass determined during the growing season?
“Different plants per plot have been sampled” - Strange statement, better specify how many plants you collected, or was it an average sample.
Results
To make it clearer and more understandable, it is recommended to indicate the dates (days) of fertilizer application in the Figures. The text in the Results talks about them, but when looking at the Figure, you have to go back to the text.
Figure 2. No legend visible. What is the dotted line, what is the solid line?
Why is there no data on plant mass in the results, if you determined and monitored it throughout the season? Was this data used for other purposes, calculations? The results also do not contain any information about the pepper yield obtained.
Why is Figure 5 not in the Results section but posted in the Discussion?
Discussion
Overall, the Discussion section is written clearly and concisely, analyzing the research question.
However, there are some notes.
Line 470-471. “Moreover, urea fertilizer used in this study delivers ammoniacal N” – it is not quite correct; urea does not content ammonium nitrogen.
Don't make sentences that are too long. This will lose the idea you wanted to convey. A striking example:
“Fertigated plots recorded slightly fewer CO2 hot moments compared to the fertigated thesis (0.8% vs 1.0% of observations) and a small contribution to the total emission (2.6% vs 4.0%; Table 1); the largest single peak in G thesis (up to 15 μmol m—2 s—1, > 6 SD) occurred after granular N input (Figure 4), consistent with the pulse‑driven respiration that follow large, discrete inputs of carbon and moisture condition. “
Conclusions
The conclusions generally provide answers to the research objective and questions raised in the tasks, as well as outline future research directions.
Concluding remarks. The article is devoted to such an important issue as the potential use of various fertilization methods to reduce greenhouse gas emissions while maintaining vegetable yields. Although the hypothesis was not confirmed, interesting results and insights have been obtained that can also be used in horticultural practice.
Author Response
Reviewer 2
Abstract
[Reviewer]: The first sentence is too long; it should be divided into two parts to better understand the issue being studied.
[Authors]: Thank you for pointing this out. We agree to this comment to better understand this first introduction line. We have re-written almost all the abstract, in a more organic form as suggested by the Reviewer 3, and the tried to address this suggestion as well. In the abstract, page 1, line 16 to 19, we have modified this concept splitting it in two sentences marked in yellow in the revised manuscript.
[Reviewer]: Abbreviations should be explained the first time they are used. GWP - Global Warming Potential?
[Authors]: Thank you for this comment. We have modified the abstract, page 1, lines 25-26, adding GWP in brackets and explained the abbreviation in the long form. The entire abstract, modified, is marked in yellow in the revised manuscript.
[Reviewer]: Keywords: It is not recommended to repeat the same words extensively in the title and keywords. This reduces the chances of finding the article in search engines. You could also use keywords like CO2 and N2O fluxes, high emission events, for example.
[Authors]: Thank you for this suggestion. We have modified the keywords at page 1, line 35, marked in yellow in the revised manuscript.
Introduction
[Reviewer]: Overall, the Introduction provides sufficient background information about the research topic and relevance, and the purpose and hypothesis of the research are clearly formulated. However, the Introduction is too long. This is not a review article, so the many examples from previous research results should be summarized to make the Introduction more focused and compact.
[Authors]: Thank you for this suggestion. We tried to summarize the introduction, reducing background description but avoiding to give too much details, focusing on research gap and trying to state as clear as possible the goals and the value of this study, in the context of the Mediterranean pepper crop of the Campania region. The new version of the introduction is highlighted in yellow in the revised version of the manuscript, at the lines 38-127.
Materials and Methods
Although the M&M section is written quite clearly, some questions arose and need to be clarified.
2.1. Trial Materials and Experimental Design
[Reviewer]: How many plants were in one plot?
[Authors]: Thank you pointing this out. There were 72 plants in each plot. We have added this information in the revised manuscript at page 4, line 161, highlighted in yellow.
2.2. Biometrical determinations
[Reviewer]: Line 185. “The plant dry biomass production has been monitored during the whole crop growing season”.
[Authors]: Thank you for this observation. Plant biomass has been determined five times during the growing season. We have added this information in the revised manuscript at page 4, line 176, highlighted in yellow.
[Reviewer]: How often was plant biomass determined during the growing season?
“Different plants per plot have been sampled” - Strange statement, better specify how many plants you collected, or was it an average sample.
[Authors]: Thank you for this observation. Two plants per plot were sampled. We have added this information in the revised manuscript at page 4, line 177, highlighted in yellow.
Results
[Reviewer]: To make it clearer and more understandable, it is recommended to indicate the dates (days) of fertilizer application in the Figures. The text in the Results talks about them, but when looking at the Figure, you have to go back to the text.
[Authors]: We appreciate the reviewer’s suggestion and the attention to clarity. Among four reviewers, this is the only request to add application dates directly onto every figure. We would like to point out that Figure 3 already presents both the fertilizer dose and the exact date of each application for every treatment method, thereby providing the information in a graphical form. Adding the same annotations to the remaining figures would—in our view—introduce visual congestion without conveying new data. Nevertheless, we are happy to implement additional graphical markers if the Editor believes they would improve readability for the journal’s audience.
[Reviewer]: Figure 2. No legend visible. What is the dotted line, what is the solid line?
[Authors]: Thank you for noticing this. It is just a mistake importing the image. There should be a legend. We added the correct image in the revised manuscript, where the dotted line represents fertigated treatment and the solid line the granular treatment.
[Reviewer]: Why is there no data on plant mass in the results, if you determined and monitored it throughout the season? Was this data used for other purposes, calculations? The results also do not contain any information about the pepper yield obtained.
[Authors]: We did not report biomass data because the goal of our study is to evaluate the effect of different fertilization managements on pepper yield and GHG emissions. Infact, we used only the fruit yield data to obtain the yield-scaled global-warming potentials (GWP/Y).
[Reviewer]: Why is Figure 5 not in the Results section but posted in the Discussion?
[Authors]: Thank you for noticing this. Figure 5 is it not there for a reason, but we just tried to insert the images among the sections interrupting the reading as less as possible. Now in the revised version of the manuscript, we moved Figure 5, right after Figure 4, both after the related Section 3.4.
Discussion
Overall, the Discussion section is written clearly and concisely, analyzing the research question.
However, there are some notes.
[Reviewer]: Line 470-471. “Moreover, urea fertilizer used in this study delivers ammoniacal N” – it is not quite correct; urea does not content ammonium nitrogen.
[Authors]: Thank you for underlying this important detail. We better explained this concept correctly, re-writing the sentence at lines 470-471 of the first version of the manuscript as the following:
Because urea in both treatments rapidly hydrolysed to NH4+
now at the line 406 in the revised version of the manuscript and highlighted in yellow.
[Reviewer]: Don't make sentences that are too long. This will lose the idea you wanted to convey. A striking example:
“Fertigated plots recorded slightly fewer CO2 hot moments compared to the fertigated thesis (0.8% vs 1.0% of observations) and a small contribution to the total emission (2.6% vs 4.0%; Table 1); the largest single peak in G thesis (up to 15 μmol m—2 s—1, > 6 SD) occurred after granular N input (Figure 4), consistent with the pulse‑driven respiration that follow large, discrete inputs of carbon and moisture condition. “
[Authors]: Thank you for suggesting to re-write this sentence in a simpler way, avoiding long periods. We modified the related section in the discussion, lines 444-461, as requested also by the other reviewers. so also this statament changed.
Conclusions
The conclusions generally provide answers to the research objective and questions raised in the tasks, as well as outline future research directions.
Concluding remarks. The article is devoted to such an important issue as the potential use of various fertilization methods to reduce greenhouse gas emissions while maintaining vegetable yields. Although the hypothesis was not confirmed, interesting results and insights have been obtained that can also be used in horticultural practice.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript by Manco et al. investigates the comparative effects of nitrogen fertigation versus granular fertilizer application on greenhouse gas (GHG) emissions and yield in a Mediterranean pepper crop (‘papaccella’). Using automated chambers and cavity ring-down spectroscopy, the authors provide high-resolution temporal data on COâ‚‚ and Nâ‚‚O fluxes. Their results show that fertigation, at low application frequency with urea, did not reduce cumulative GHG emissions or improve crop yield compared to granular application. Notably, they highlight the significant contribution of “hot moments” to overall GHG budgets, suggesting that excluding these events may lead to systematic underestimation of emissions in horticultural systems. The data presented here is interesting and contributes meaningfully to our understanding of GHG emissions from soil, particularly in Mediterranean horticultural systems. The use of continuous high-resolution gas flux monitoring adds valuable insight into the temporal dynamics of emissions, especially the role of hot moments. However, below are some suggestions the authors can consider to improve their manuscript.
The abstract, as currently written, lacks a coherent narrative structure and should be rewritten to stand alone as a complete summary of the study. At present, it reads as a sequence of fragmented results rather than a clear progression through the background, objectives, methods, key findings, and implications. To improve clarity and reader engagement, the authors are encouraged to follow a logical flow that includes: (1) context and rationale, (2) objectives, (3) experimental design, (4) key results, and (5) major conclusions or implications. Additionally, several minor typographical errors were noted. For example, Line 23: “thesis” is used where "treatment" or "approach" would be more appropriate. Line 26: “till to 4%” should likely be “up to 4%.” Line 31: “highlight that also in horticulture system” is grammatically awkward. Consider revising to “highlight that in horticultural systems...”. Moreover, the use of the word “thesis” throughout the abstract (e.g., Lines 23, 27, and 29) is incorrect in this context and should be replaced with “treatment,” “approach,” or “method.”
The introduction provides an adequate background on greenhouse gas (GHG) emissions from agricultural soils and the role of nitrogen fertilization and irrigation. However, several parts should be revised for clarity and focus. Lines 62–85, which discuss various fertigation studies, are overly detailed and can be significantly shortened by summarizing key findings rather than listing each study. Additionally, Lines 59–60 appear incomplete and should be combined with the preceding paragraph for coherence. Importantly, the discussion in Lines 54–56 should be expanded to include other critical soil parameters such as pH, redox potential (Eh), and microbial community composition, all of which strongly influence Nâ‚‚O dynamics. Lines 135–152 introduce method details about the automated chamber and gas analysis system that would be more appropriately placed in the Materials and Methods section. Furthermore, while the final paragraph (Lines 153–163) effectively states the study’s objectives, it could be refined to more clearly highlight the research gap in fertigation-based GHG studies in Mediterranean pepper systems and the underexplored role of hot moments.
The Results section is generally well-structured and clearly presents the data; however, there are a few minor concerns that should be addressed. First, the repeated use of the term “thesis” is inappropriate in this context and should be replaced with “treatment” throughout the section. Additionally, while statistical data are provided in tables, it could more consistently highlight whether observed differences are statistically significant. Some phrasing is also unnecessarily verbose; for example, the statement on Lines 296–297 regarding Nâ‚‚O flux differences could be made more concise.
First, the discussion would benefit from more concise synthesis rather than extended reiteration of results (check and correct throughout). There is some redundancy with the Results section, especially in the explanation of COâ‚‚ and Nâ‚‚O flux patterns, which should be minimized. Second, some speculative interpretations are presented without sufficient citation or evidence, for instance, the hypothesis about urea’s osmotic effects and microbial stimulation in Lines 515–518, which, while plausible, are not directly supported by the presented data and should be framed more cautiously or supported by stronger references. Third, continued use of “thesis” instead of “treatment” (e.g., Line 543). Lastly, while the role of hot moments is well-articulated, the discussion of their implications could be better linked to practical recommendations for management or future research directions (Lines 554–560).
Minor comments
The authors should review the entire manuscript for inconsistencies with abbreviations.
Author Response
Reviewer 3
Comments and Suggestions for Authors
The manuscript by Manco et al. investigates the comparative effects of nitrogen fertigation versus granular fertilizer application on greenhouse gas (GHG) emissions and yield in a Mediterranean pepper crop (‘papaccella’). Using automated chambers and cavity ring-down spectroscopy, the authors provide high-resolution temporal data on COâ‚‚ and Nâ‚‚O fluxes. Their results show that fertigation, at low application frequency with urea, did not reduce cumulative GHG emissions or improve crop yield compared to granular application. Notably, they highlight the significant contribution of “hot moments” to overall GHG budgets, suggesting that excluding these events may lead to systematic underestimation of emissions in horticultural systems. The data presented here is interesting and contributes meaningfully to our understanding of GHG emissions from soil, particularly in Mediterranean horticultural systems. The use of continuous high-resolution gas flux monitoring adds valuable insight into the temporal dynamics of emissions, especially the role of hot moments. However, below are some suggestions the authors can consider improving their manuscript.
[Reviewer]: The abstract, as currently written, lacks a coherent narrative structure and should be rewritten to stand alone as a complete summary of the study. At present, it reads as a sequence of fragmented results rather than a clear progression through the background, objectives, methods, key findings, and implications. To improve clarity and reader engagement, the authors are encouraged to follow a logical flow that includes: (1) context and rationale, (2) objectives, (3) experimental design, (4) key results, and (5) major conclusions or implications. Additionally, several minor typographical errors were noted.
For example, Line 23: “thesis” is used where "treatment" or "approach" would be more appropriate. Line 26: “till to 4%” should likely be “up to 4%.” Line 31: “highlight that also in horticulture system” is grammatically awkward. Consider revising to “highlight that in horticultural systems...”. Moreover, the use of the word “thesis” throughout the abstract (e.g., Lines 23, 27, and 29) is incorrect in this context and should be replaced with “treatment,” “approach,” or “method.”
[Authors]: Thank you for pointing this out. We agree to this comment to better improve abstract reading. We have re-written almost all the abstract, in a more organic form, as suggrsted. Page 1, line 16 to 34, marked in yellow in the revised manuscript. We also changed all the the words “thesis” with “treatment”, as suggested, as well as we replaced “till to” with “up to” at the line 28 of the revised abstract, and highlight that also in horticulture system” with “highlight that in horticultural systems” at line 33,
[Reviewer]: The introduction provides an adequate background on greenhouse gas (GHG) emissions from agricultural soils and the role of nitrogen fertilization and irrigation. However, several parts should be revised for clarity and focus. Lines 62–85, which discuss various fertigation studies, are overly detailed and can be significantly shortened by summarizing key findings rather than listing each study. Additionally, Lines 59–60 appear incomplete and should be combined with the preceding paragraph for coherence. Importantly, the discussion in Lines 54–56 should be expanded to include other critical soil parameters such as pH, redox potential (Eh), and microbial community composition, all of which strongly influence Nâ‚‚O dynamics. Lines 135–152 introduce method details about the automated chamber and gas analysis system that would be more appropriately placed in the Materials and Methods section. Furthermore, while the final paragraph (Lines 153–163) effectively states the study’s objectives, it could be refined to more clearly highlight the research gap in fertigation-based GHG studies in Mediterranean pepper systems and the underexplored role of hot moments.
[Authors]: Thank you for this suggestion. We tried to summarize several parts of this introduction, as pointed out, with a new completely revised version of the introduction now at lines 38-127, highlighted in yellow in the revised version of the manuscript.
[Reviewer]: The Results section is generally well-structured and clearly presents the data; however, there are a few minor concerns that should be addressed. First, the repeated use of the term “thesis” is inappropriate in this context and should be replaced with “treatment” throughout the section. Additionally, while statistical data are provided in tables, it could more consistently highlight whether observed differences are statistically significant.
Some phrasing is also unnecessarily verbose; for example, the statement on Lines 296–297 regarding Nâ‚‚O flux differences could be made more concise.
[Authors]: Thank you for pointing out this details that could help to improve Results section. We replaced all the term “thesis” in the manuscript with “treatment”, as suggested, in all the section, not only in the Results, and highlighted in yellow in the revised manuscript.
Moreover, about the statistically significant differences we are not sure to have correctly understood the reviewer request. If the reviewer is requesting to add statistically significant differences in the text and not only in the table, when some comparison is recalled in the text, we already did this. So, we can ask the reviewer to be more specific, maybe indicating us some specific line o section in the manuscript.
Than we also tried to re-write the statement at the lines 296-297 of the previous version of the manuscript, in a more concise expression. We rephrase as the following:
Both treatments showed transient N2O spikes shortly after fertilization (Figure 1D). The granular treatment averaged 0.12 ± 0.10 nmol m—2 s—1 versus 0.13 ± 0.10 nmol m—2 s—1 under fertigation, but this difference was not significant (Table 1)
now at the lines 288-291 of the revised version of the manuscript, highlighted in yellow.
[Reviewer]: First, the discussion would benefit from more concise synthesis rather than extended reiteration of results (check and correct throughout). There is some redundancy with the Results section, especially in the explanation of COâ‚‚ and Nâ‚‚O flux patterns, which should be minimized.
Second, some speculative interpretations are presented without sufficient citation or evidence, for instance, the hypothesis about urea’s osmotic effects and microbial stimulation in Lines 515–518, which, while plausible, are not directly supported by the presented data and should be framed more cautiously or supported by stronger references. Third, continued use of “thesis” instead of “treatment” (e.g., Line 543). Lastly, while the role of hot moments is well-articulated, the discussion of their implications could be better linked to practical recommendations for management or future research directions (Lines 554–560).
[Authors]: Thank you for this useful suggestion. We tried to rearrange the discussion part, summarizing it, in a more focused and concise way, improving results interpretation and explanation of proposed phenomena, adding some recent literature. We also tried to suggest practical recommendations for management e future research, The new discussion in the revised version of the manuscript now covers the lines 400-461, highlighted in yellow. Moreover, as mentioned also before, we remove all “thesis” from the test and replaced with “treatment”.
Minor comments
[Reviewer]: The authors should review the entire manuscript for inconsistencies with abbreviations.
[Authors]: Thank you for this suggestion. We have read again all the manuscript and explained all the abbreviations, when they compared for the first time, as also the other reviewers have requested.
Reviewer 4 Report
Comments and Suggestions for AuthorsComments and Suggestions for Authors:
The article "horticulturae-3683639" must be revised for publication due to several errors. This study analyzes the impact of two methods of fertilizing pepper crops: granular fertilization and fertigation, with greenhouse gas emissions and crop yield as outcomes. Important observations include the position of tables and figures, some references, correcting some chemical formulas, improving the wording in materials and methods, and restructuring the discussions.
Specific comments follow:
Review CO2 and N2O throughout the text, since the number 2 does not appear as a subscript in all of them. Please standardize.
Abstract
- L 24. The acronym has not been described previously, describe the acronym GWP.
Introduction
- L 60-61. I believe that more details should be given about this study to give a better overview and relate it to the present study.
- L 85-87. References for this statement.
Materials and methods
I consider the design to be somewhat simple, since to have a better overview of the behavior it would have been better to have the treatments at least two levels.
In the materials and methods section, the methodology for determining WFPS is omitted, please include it.
- L167-170. I think it would help to place a map of the region indicating the area where the experiment was carried out and the area where the meteorological station is located. This gives us a more accurate picture of the proximity between the two.
- L178-180. Why wasn't the fertilizer applied on the same days in both fertilization modes? Could this alter the results?
- L186-187. What does it mean to monitor biomass production? At what time intervals or on what days during the crop? These lines are unclear, as they are somewhat ambiguous. Furthermore, biomass results were not reported in the results section.
- L186-187. Reference of this technique
- L178. I think it is important to mention the supplier of the urea (Enter the city and country of the company)
- L195-194. The parenthesis needs to be closed
Results
I consider that section 3.1 should be divided into several paragraphs, and once the temperature and rainfall have been described, add figure 1.
- L 260, 287, 309, Write only the acronym Ts
- L 290-291 Write only the acronym WFPS
- Figure 1. I think it should go in section 3.1.
- Table 1- I think it should go in section 3.1 and Figure 2 mentions ± standard error, please homogenize
- Figure 2. Write only the acronym Ts. Indicate what the dotted lines and the solid lines represent
- Figure 3. I think it should go in section 3.3
- Figure 5. I think it should go in section 3.4
Discussion
Divide the discussions according to the sections in the results section, i.e., daily CO2 and N2O fluxes, daily trends in CO2 and N2O fluxes by fertilization period, cumulative fluxes of the growing season and global warming potential at the yield scale and importance of the contribution of warm moments throughout the season.
Conclusions
I think the conclusion addresses the most relevant aspects of the study, as well as the results and perspectives.
Comments for author File: Comments.pdf
Author Response
Reviewer 4
The article "horticulturae-3683639" must be revised for publication due to several errors. This study analyzes the impact of two methods of fertilizing pepper crops: granular fertilization and fertigation, with greenhouse gas emissions and crop yield as outcomes. Important observations include the position of tables and figures, some references, correcting some chemical formulas, improving the wording in materials and methods, and restructuring the discussions.
Specific comments follow:
[Reviewer]: Review CO2 and N2O throughout the text, since the number 2 does not appear as a subscript in all of them. Please standardize.
[Authors]: Thank you to have noticed this. We have checked the entire manuscript and modified the number 2 as subscript.
Abstract
[Reviewer]: L 24. The acronym has not been described previously, describe the acronym GWP.
[Authors]: Thank you for this comment. We have modified the abstract, page 1, lines 25-26, adding GWP in brackets and explained the abbreviation in the long form. The entire abstract, modified, is marked in yellow in the revised manuscript.
Introduction
[Reviewer]: L 60-61. I believe that more details should be given about this study to give a better overview and relate it to the present study.
[Authors]: Thank you for pointing this out. We tried to summarize and explain in few concise sentences this and other concepts, as the other reviewer pointed out in their comments. 3 of 4 reviewers, asked to reduce and summarize the introduction, avoiding sounding as a review. No the new version of the introduction is highlighted in yellow in the revised version of the manuscript a the lines 38-127
[Reviewer]: L 85-87. References for this statement.
[Authors]: Thank you for this observation. In the new revised version of the manuscript, we tried to reduce and summarize all the literature review, as the other 3 reviewers asked to us, so this detail stated in these lines was removed. Anyway, this statement was always referring to the reference [33], cited above:
“Tian, H., Xu, R., Canadell, J.G., Thompson, R.L., Winiwarter, W., Suntharalingam, P., Davidson, E.A., Ciais, P., 699 Jackson, R.B., Janssens-Maenhout, G., Prather, M.J., Regnier, P., Pan, N., Pan, S., Peters, G.P., Shi, H., Tubiello, 700 F.N., Zaehle, S., Zhou, F., Arneth, A., Battaglia, G., Berthet, S., Bopp, L., Bouwman, A.F., Buitenhuis, E.T., 701 Chang, J., Chipperfield, M.P., Dangal, S.R.S., Dlugokencky, E., Elkins, J.W., Eyre, B. D., Fu, B., Hall, B., Ito, A., 702 Joos, F., Krummel, P.B., Landolfi, A., Laruelle, G.G., Lauerwald, R., Li, W., Lienert, S., Maavara, T., MacLeod, 703 M., Millet, D.B., Olin, S., Patra, P.K., Prinn, R.G., Raymond, P.A., Ruiz, D.J., van der Werf, G.R., Vuichard, N., Wang, J., Weiss, R.F., Wells, K.C., Wilson, C., Yang, J., Yao, Y. A comprehensive quantification of global nitrous 705 oxide sources and sinks. Nature 2020, 586, 248–256. https://doi.org/10.1038/s41586-020-2780-0”
Materials and methods
[Reviewer]: I consider the design to be somewhat simple, since to have a better overview of the behavior it would have been better to have the treatments at least two levels.
In the materials and methods section, the methodology for determining WFPS is omitted, please include it.
[Author]: We provided detailed information about WFPS calculation in M&M (lines 211-213), highlighted in yellow in the revised manuscript.
[Reviewer]: L167-170. I think it would help to place a map of the region indicating the area where the experiment was carried out and the area where the meteorological station is located. This gives us a more accurate picture of the proximity between the two.
[Author]: We thank the reviewer for the suggestion. Among the four reviewers and editor, this is the only request for an additional map. In the Materials and Methods, we already provide precise geographical coordinates and explicitly state that the meteorological station is ~100 m from the trial plot (lines 131–135):
The trial was carried out at an experimental site near Naples (Acerra, Italy; 40 °57′ N, 14 °25′ E), equipped with a meteorological station managed by the Campania Region (link), located in a field very close to the experimental site (about 100 m).
Because the station is effectively adjacent to the experimental field, a regional map would not convey additional information and could distract from the core figures. For this reason, we respectfully consider the map unnecessary. Nevertheless, should the Editor deem it advantageous for readers, we will gladly prepare a simple inset map or schematic indicating both points.
[Reviewer]: L178-180. Why wasn't the fertilizer applied on the same days in both fertilization modes? Could this alter the results?
[Author]: The two schedules were intentionally different because they replicate the way each fertilization mode is used in commercial practice:
In fertigation, the same total nutrient dose was split into multiple small aliquots and delivered at every irrigation event. This higher frequency is essential for fertigation, ensuring that nutrients move with the waterfront, remain in solution, and are available in the rhizosphere when roots are actively taking up water.
In granular application, the identical cumulative dose of N was supplied in three discrete dressings, reflecting the standard protocol when fertilizer is broadcast or banded on the soil surface.
Because the cumulative nutrient input over the growing season was identical in both modes (see Figure 3). Splitting the dose in fertigation therefore does not bias the comparison; it simply reproduces the characteristic management strategy of that technique.
[Reviewer]: L186-187. What does it mean to monitor biomass production? At what time intervals or on what days during the crop? These lines are unclear, as they are somewhat ambiguous. Furthermore, biomass results were not reported in the results section.
[Author]: We did not report biomass data because the goal of our study is to evaluate the effect of different fertilization managements on pepper yield and GHG emissions. In fact, we used only the fruit yield data to obtain the yield-scaled global-warming potentials (GWP/Y).
[Reviewer]: L186-187. Reference of this technique.
[Author]: Thank you for your comment. The technique described in lines 186-187, now line 177-178 in the revised version of the manuscript, highlighted in yellow, is referred to the following article:
Caccavello, G.; Giaccone, M.; Scognamiglio, P.; Mataffo, A.; Teobaldelli, M.; Basile, B. Vegetative, Yield, and Berry Quality Response of Aglianico to Shoot Trimming Applied at Three Stages of Berry Ripening. American Journal of Enology and Viticulture 2019, 70. 10.5344/ajev.2019.18079.
[Reviewer]: L178. I think it is important to mention the supplier of the urea (Enter the city and country of the company).
[Author]: Thank you for this comment. We added information of the Urea supplier, Fertilsud, Spinazzola (BT), Italy, at page 4, lines 152-153, in a new part added in the material and methods section of the revised manuscript, highlighted in yellow, as requested by the Editor.
[Reviewer]: L195-194. The parenthesis needs to be closed
[Author]: Thank you for noticing this. It was just a typo. We modified it in the revised version of the manuscript, now the lines 185-186, highlighted in yellow.
Results
[Reviewer]: I consider that section 3.1 should be divided into several paragraphs, and once the temperature and rainfall have been described, add figure 1.
[Author]: Thank you for this comment. We think that information in this section needs to be discussed organically, to have an overall view of the variables and gases in the studied period, since all the variables are correlated ad interacts.
[Reviewer]: L 260, 287, 309, Write only the acronym Ts
[Author]: Thank you for this suggestion. We corrected leaving only the acronym, now at the lines 252, 280 and 343, in the new version of the revised manuscript, highlighted in yellow.
[Reviewer]: L 290-291 Write only the acronym WFPS
[Author]: Thank you for this suggestion. We corrected leaving only the acronym, now at the line 283 in the new version of the revised manuscript, highlighted in yellow.
[Reviewer]: Figure 1. I think it should go in section 3.1.
[Author]: Thank you for this suggestion. Because this figure is big and takes a whole page, we have been forced to place it in the first entire blank page empty and available, without splitting the text too much. Now we moved as close as possible to the Section 3.1, right after, in the first blank page available, splitting the text of the section in half.
[Reviewer]: Table 1- I think it should go in section 3.1 and Figure 2 mentions ± standard error, please homogenize
[Author]: Thank you for this suggestion. The reasons were the same as for the Figure 1 in the previous comment. Now we moved Table 1 as close as possible to the Section 3.1, right after Figure 1. Moreover, as suggested, we homogenized how we referred to the standard error, writing “± standard error” in all captions of figures and tables. We have highlighted it in yellow in Table 1, where we changed it.
[Reviewer]: Figure 2. Write only the acronym Ts. Indicate what the dotted lines and the solid lines represent
[Author]: Thank you for this observation. We replaced Soil Temperature with only the acronym Ts in the Figure 2 description, highlighted in yellow in the revised version of the manuscript. Moreover, the meaning of the dotted and solid lines should be explained by the legend that was missing in the previous version of the manuscript by mistake. Please see the new version of the image in the revised version of the manuscript, where the meaning of the dotted and solid line is clearly explained by the legend.
[Reviewer]: Figure 3. I think it should go in section 3.3
[Author]: Thanks for this suggestion. Now in the revised version of the manuscript the Figure 3 is placed as close as possible after the Section 3.3. At the end of the page there is a portion of the Section 3.4, occupying a space not big enough to contain Figure 3, that was placed immediately in the next page.
[Reviewer]: Figure 5. I think it should go in section 3.4.
Thanks for this observation. Figures 4 and 5 are placed right after the end of the Section 3.4, as close as possible, in the first empty page that can contain the figures with their captions.
Discussion
[Reviewer]: Divide the discussions according to the sections in the results section, i.e., daily CO2 and N2O fluxes, daily trends in CO2 and N2O fluxes by fertilization period, cumulative fluxes of the growing season and global warming potential at the yield scale and importance of the contribution of warm moments throughout the season.
[Author]: Thanks for this comment, while is contrasting with the suggestion of the other reviewers, that asked us to be more concise and summarize. In fact, we tried to rearrange the discussion part, summarizing it, in a more focused and concise way, improving results interpretation and explanation of proposed phenomena, adding some recent literature. The new discussion in the revised version of the manuscript now covers the lines 400-461, highlighted in yellow.
Conclusions
I think the conclusion addresses the most relevant aspects of the study, as well as the results and perspectives.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsPlease revise this manuscript again according to the comments.
- There are still many long sentences, and the expressions tend to be rather verbose. And the Introduction part is still long. From Line 48 to Line 104, too many literatures were listed there, I think it is important to list what previous researchers have done, and more important thing is to analyze and summarize the shortcomings of their previous studies, and then find the basis for this research.
- The English writing still need to be improved. For example, “p < 0.05”, the letter p should be in Italic.
- Please double check, is the expression of “~30%” right? What does this mean? about 30%? I pointed this issue in the last review, while they are still there in this version.
- Line 280,” both treatment shows….”, Line 288, “both treatments….”, ???
- Line 382-384, “Nâ‚‚O increase 382 of daily emission due hot moments contribute was much higher, even though 452 without 383 any significantly difference among the two theses (Figure 5B; p < 0.05).” please revise this sentence, what does two theses mean?
- Line 407, “NO3- fertilizers” should be “NO3- N fertilizers”?
- Line 414, “CO2fluxes” should be “CO2 fluxes”
- In discussion part, the results were fully explained, it would be better to add some comparison explanation with former studies.
The English expression of this manuscript needs extensive revision .
Author Response
Reviewer 1
[Reviewer]: There are still many long sentences, and the expressions tend to be rather verbose. And the Introduction part is still long. From Line 48 to Line 104, too many literatures were listed there, I think it is important to list what previous researchers have done, and more important thing is to analyze and summarize the shortcomings of their previous studies, and then find the basis for this research.
[Authors]: Dear reviewer thank you for your comment. We tried again to summarize even more the introduction as suggested, and to reduce verbose expressions. The listed literature is needed to put the basis and the state of the art in the different sector of this multidisciplinary work. Neither the other reviewers nor the editor told us to reduce literature, and we, respectfully, do not think it is a problem. We tried to summarize their findings and key concept, without removing or reducing the literature. Now the new version of the introduction is highlighted in yellow in the new revised version of the manuscript, at the lines 38-90.
[Reviewer]: The English writing still need to be improved. For example, “p < 0.05”, the letter p should be in Italic.
[Authors]: Thank you for this observation. We wrote all the letter p in “p < 0.05” in Italic every time it appears in the text as suggested.
[Reviewer]: Please double check, is the expression of “~30%” right? What does this mean? about 30%? I pointed this issue in the last review, while they are still there in this version.
[Authors]: Thank you for this comment. It is right, you already pointed out this, but it was in another section, in the Material & Methods, related to the expression “~3 months”. We think you are referring to the line 254, where we are stating:
WFPS showed values ~30% at beginning of the experiment for both treatments, with smaller values to 18% for the fertigated treatment and raised up after the first showing higher values for the F treatment (Figure 1E).
Here, we are trying to describe the WFPS trend at the beginning of the experiment, stating that is among 30%, because WFPS is a parameter expressed in % and we wanted to say that, among the tow treatments and the several days, in this period initial WFPS fluctuate around that value.
If you need a more specific correction, please let us know. For now, we just removed the form “~” and replaced with “around”, highlighted in yellow in the revised version of the manuscript at the line 274
[Reviewer]: Line 280,” both treatment shows….”, Line 288, “both treatments….”,???
[Authors]: Thank you for noticing this. We think you are referring to the grammatic error “both treatment shows”. It was a typo. Now in the revised version we have corrected it in “both treatments show”, at line 251, highlighted in yellow in the revised version of the manuscript.
[Reviewer]: Line 382-384, “Nâ‚‚O increase 382 of daily emission due hot moments contribute was much higher, even though 452 without 383 any significantly difference among the two theses (Figure 5B; p < 0.05).” please revise this sentence, what does two theses mean?
[Authors]: Thank you so much to noticing this. We think that through the process of coping and pasting, reducing, and rephrasing, we included some meaningless numbers:
The correct sentence, now at the lines 352-354 of the revised manuscript, highlighted in yellow, is:
Nâ‚‚O increase of daily emission due hot moments contribution was much higher, even though without any significantly difference among the two treatments (Figure 5B; p < 0.05).
[Reviewer]: Line 407, “NO3- fertilizers” should be “NO3- N fertilizers”?
[Authors]: Thank you so much to noticing this. It was corrected, now at the line 377 of the revised manuscript.
[Reviewer]: Line 414, “CO2fluxes” should be “CO2 fluxes”
[Authors]: Thank you so much to noticing this. It was a typo, now corrected at the line 384 of the revised manuscript
[Reviewer]: In discussion part, the results were fully explained, it would be better to add some comparison explanation with former studies.
[Authors]: Dear Reviewer, thank you for your comment. Your request to expand this part of the Discussion contrasts with guidance from the other reviewers, who asked us to shorten the section, add more recent references (which we have done), and avoid lengthy comparative digressions. In the current revision we have aimed to satisfy those earlier requests while still covering the key points you highlight. If specific details are still missing, please indicate them and we will incorporate them without unduly lengthening the manuscript. Considering the differing opinions of the referees, we kindly ask the editor for guidance on how to proceed
Reviewer 3 Report
Comments and Suggestions for AuthorsI have read the revised version of the manuscript by Manco et al., and the authors have addressed all of my concerns and have greatly improved the manuscript.
Author Response
Reviewer n. 3 seems approve our previous version
Reviewer 4 Report
Comments and Suggestions for AuthorsComments and Suggestions for Authors:
The article "horticulturae-3683639" shows improvement compared to the first revision; it still needs to be reviewed for publication due to minor errors. This study analyzes the impact of two fertilization methods on pepper crops: granular fertilization and fertigation, with results on greenhouse gas emissions and crop yield.
Specific comments follow:
Abstract
I consider that the summary meets the specifications and gives us an adequate overview of the study and results.
Introduction
The introduction was adapted according to the recommendations and adequately addresses the preamble of the study
Materials and methods
- L252. Indicate the supplier of the seeds used
- L252. Use only the acronym WFPS
- L176-180. Why determine the biomass of the parts of the plant? If only the fruit is used to determine the yield. Please indicate in greater detail the purpose of this determination.
Results
I consider that section 3.1 should be divided into several paragraphs.
- L 291, 351, 356. Indicate the level of significance
- Figure 2. Write mean outside the parentheses to homogenize in tables and figures.
Discussion
- L 402. Enter the number of studies in this meta-analysis
Conclusions
I think the conclusion addresses the most relevant aspects of the study, as well as the results and perspectives.
NEW COMMENTS
Authors have to put in the text the answer they put in the cover letter.
Comments for author File: Comments.docx
Author Response
Reviewer 4
The article "horticulturae-3683639" shows improvement compared to the first revision; it still needs to be reviewed for publication due to minor errors. This study analyzes the impact of two fertilization methods on pepper crops: granular fertilization and fertigation, with results on greenhouse gas emissions and crop yield.
Specific comments follow:
Abstract
I consider that the summary meets the specifications and gives us an adequate overview of the study and results.
Introduction
The introduction was adapted according to the recommendations and adequately addresses the preamble of the study
Materials and methods
[Reviewer]: L252. Indicate the supplier of the seeds used
[Authors]: Thank you for this observation. We added a line, with the specification of the supplier, in the Material & Methods, at the lines 112-113, highlighted in yellow in the revised version of the manuscript
[Reviewer]: L252. Use only the acronym WFPS
[Authors]: Thank you for this observation. At Line 252 there is only the acronym WFPS, now at the live 228 highlighted in yellow in the revised version of the manuscript.
[Reviewer]: L176-180. Why determine the biomass of the parts of the plant? If only the fruit is used to determine the yield. Please indicate in greater detail the purpose of this determination.
[Authors]: The reviewer is right. Since we did not discuss biomass, it is unnecessary to explain the method for its determination. Thank you.
Results
[Reviewer]: I consider that section 3.1 should be divided into several paragraphs.
[Authors]: Thank you for this suggestion. We divided the section in paragraphs, as suggested. Now, in the revised version of the manuscript, the Paragraph 1 goes from L 231-235, Paragraph 2 from L 266-270, Paragraph 3 from L271-277, Paragraph 4 from L278-289, Paragraph 5 from L290-292
[Reviewer]: L 291, 351, 356. Indicate the level of significance
[Authors]: Thank you for this observation. In the lines you indicated, we have now added the significance level in brackets (p > 0.05), as these differences are not statistically significant. If the reviewer instead wishes to see the exact ANOVA p-values, please let us know. Including all of them in the main text or in Figure 3 could be confusing: the figure reports point-by-point comparisons on 81 days for two gases, which would require presenting 162 individual significance values.
[Reviewer]: Figure 2. Write mean outside the parentheses to homogenize in tables and figures.
[Authors]: Thank you for this observation. We apologize, but we did not fully understand what the reviewer means. There are not mean inside parentheses in the image or in the caption. Please give us more details because we can not recognize the correction that the reviewer underline.
Discussion
[Reviewer]: 402. Enter the number of studies in this meta-analysis
[Authors]: Thank you for this comment. We added the number of the studies, 139, as request, at the line 372 of the discussion, highlighted in yellow in the revised manuscript.
Conclusions
I think the conclusion addresses the most relevant aspects of the study, as well as the results and perspectives.
NEW COMMENTS
[Reviewer]: Authors have to put in the text the answer they put in the cover letter.
[Authors]: When the answer was a correction or an addition, we put the answer in the text. When was an explanation of some information or details that we delivered, or if we have just corrected English, phrasing, pedis and similar formatting/writing details, we do not have something specific to write in to the text, beyond the correction itself.