Effects of Organic–Inorganic Nitrogen Deposition on Element Content and Stoichiometric Ratios in the Rhizospheric Soil of Torreya grandis
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript investigates how different organic-to-inorganic nitrogen (ON) ratios affect the elemental composition and stoichiometric ratios (C:N) of the rhizospheric soil in Torreya grandis. The topic is timely and relevant to ongoing research on nutrient cycling, nitrogen deposition, and forest soil stoichiometry. The manuscript is generally well organized, with a clear experimental design and detailed methodology. However, several aspects require clarification, refinement, or further discussion before it can be considered for publication.
The study contributes to understanding nitrogen deposition effects on an economically important tree species (T. grandis). While similar studies exist, the combined analysis of ON and IN ratios and their stoichiometric implications adds modest novelty. However, the ecological mechanisms underlying ON/IN interactions remain insufficiently explored in the discussion. The authors should clarify what conceptual gap this study specifically fills compared to previous works.
The experimental setup (five treatments, randomized block design) is appropriate.
The 2-year experimental duration is adequate for detecting soil responses but may not reflect long-term trends; this limitation should be emphasized more explicitly in the Discussion or Conclusions.
Details such as N addition rates (mg N m⁻² yr⁻¹) and the actual amount of ON/IN applied per treatment are missing. Quantitative details are necessary to compare results with other nitrogen deposition studies.
Soil sampling depth (0–15 cm) is reasonable, but the paper should mention whether samples were composited per plot or analyzed individually.
Figures are well structured, but the legends could better explain the statistical symbols (e.g., what the lowercase letters represent).
The results section tends to restate figure data without sufficient interpretation. The authors could emphasize patterns or mechanisms (e.g., acidification, microbial activity).
Correlation analysis (Figure 4 and 5) is valuable but should specify whether correlations are based on averaged treatment data or all replicates.
In several cases, the magnitude of changes (e.g., SOC +7%, AK −40%) should be discussed in ecological terms—are these changes minor or significant for forest nutrient cycling?
The discussion correctly connects ON/IN deposition to soil acidification and base cation loss, but it heavily cites secondary literature rather than linking results to new insights from this study.
The authors should integrate microbial or enzymatic processes to explain why ON and IN have divergent effects on P availability.
The linkage between rhizospheric soil chemistry and leaf physiology (Figure 5) is promising but underdeveloped. More detail on causal relationships (e.g., how N imbalance influences photosystem efficiency) would strengthen the argument.
Comments on the Quality of English LanguageThe English is clear overall but could be improved for conciseness. For instance, phrases like “ON/IN deposition not only significantly alters the contents of important elements and compounds, such as those in SOC, TN, and P…” can be simplified.
Minor grammatical and typographical errors (e.g., “1:1 urea blend as the source of ON” → “a 1:1 mixture of urea and glycine served as the ON source”) should be revised.
References are current and relevant, but some in-text citations are marked as [Error! Reference source not found.] — these must be corrected before submission.
Author Response
Response to Reviewer 1's Comments
Dear Reviewer 1,
We are truly grateful for your meticulous review and insightful suggestions on our manuscript. Your comments have been invaluable in helping us refine the work and enhance its scientific rigor. We have carefully addressed each of your points, and the detailed responses are as follows, with revised content highlighted in the manuscript where applicable.
Comment 1: This manuscript investigates how different organic-to-inorganic nitrogen (ON) ratios affect the elemental composition and stoichiometric ratios (C:N) of the rhizospheric soil in Torreya grandis. The topic is timely and relevant to ongoing research on nutrient cycling, nitrogen deposition, and forest soil stoichiometry. The manuscript is generally well organized, with a clear experimental design and detailed methodology. However, several aspects require clarification, refinement, or further discussion before it can be considered for publication.
The study contributes to understanding nitrogen deposition effects on an economically important tree species (T. grandis). While similar studies exist, the combined analysis of ON and IN ratios and their stoichiometric implications adds modest novelty. However, the ecological mechanisms underlying ON/IN interactions remain insufficiently explored in the discussion. The authors should clarify what conceptual gap this study specifically fills compared to previous works.
Response 1: Thank you for pointing out the need to explicitly articulate the conceptual gap. We have revised the Introduction and Discussion sections to emphasize that prior studies on N deposition primarily focused on single forms (either ON or IN) or total N deposition, while neglecting the differential effects of ON:IN ratios on rhizospheric soil nutrients of economic tree species like *Torreya grandis*. Our study fills this gap by systematically investigating how mixed ON/IN deposition with varying ratios regulates soil elemental cycling and stoichiometry, particularly linking these changes to soil acidification, microbial activity, and plant physiological responses.
Comment 2:The experimental setup (five treatments, randomized block design) is appropriate.
The 2-year experimental duration is adequate for detecting soil responses but may not reflect long-term trends; this limitation should be emphasized more explicitly in the Discussion or Conclusions.
Response 2: Thank you. We agree with your comment and have strengthened the discussion on the limitation of the 2-year experimental duration in both the Discussion and Conclusions sections. We explicitly note that while short-term soil responses were effectively captured, long-term trends (e.g., cumulative P leaching, persistent soil acidification, and microbial community succession) may not be fully reflected. We also suggest that long-term monitoring is needed in future research to verify the sustainability of the observed effects.
Comment 3: Details such as N addition rates (mg N m⁻² yr⁻¹) and the actual amount of ON/IN applied per treatment are missing. Quantitative details are necessary to compare results with other nitrogen deposition studies.
Response 3: Thank you. As recommended, we have supplemented the specific N addition rates and ON/IN application amounts for each treatment in Section 2.2 (Experimental design). The total N addition rate is 30 kg N ha⁻¹ yr⁻¹ (equivalent to 3 mg N m⁻² yr⁻¹), and the actual ON/IN amounts for T1 (9:1), T2 (7:3), T3 (3:7), and T4 (1:9) are 2.7/0.3, 2.1/0.9, 0.9/2.1, and 0.3/2.7 mg N m⁻² yr⁻¹, respectively. This calculation follows standard methods in mixed N deposition experiments, ensuring comparability with global studies.
Comment 4: Soil sampling depth (0–15 cm) is reasonable, but the paper should mention whether samples were composited per plot or analyzed individually.
Response 4: Thank you. We have clarified in Section 2.3 (Sample processing and determination) that soil samples were collected from three randomly selected trees per plot and analyzed individually, without compositing. This approach was adopted to retain within-plot variability and enhance the statistical power of the results.
Comment 5: Figures are well structured, but the legends could better explain the statistical symbols (e.g., what the lowercase letters represent).
Response 5: We have revised the legends for Figures 1–5 to explicitly explain that different lowercase letters indicate significant differences among treatment groups (p < 0.05) based on Tukey’s multiple comparison test, making the statistical symbols more understandable for readers.
Comment 6: The results section tends to restate figure data without sufficient interpretation. The authors could emphasize patterns or mechanisms (e.g., acidification, microbial activity).
Response 6: To address the issue of over-reliance on data restatement, we have supplemented mechanistic interpretations in the Results section (3.1, 3.2, 3.3). For example, we explained that the higher SOC in T1 is driven by ON-induced microbial residue accumulation, and the decline in available P (AP) in high IN treatments is related to acidification-promoted metal-P complexation. We also emphasized ecological patterns, such as the threshold effect of the 7:3 ON:IN ratio on P limitation.
Comment 7: Correlation analysis (Figure 4 and 5) is valuable but should specify whether correlations are based on averaged treatment data or all replicates.
Response 7: Thank you. In Section 3.4 (Correlation analysis), we have specified that both soil-only (Figure 4) and plant-soil cross-correlations (Figure 5) were conducted using all replicate data (n = 15, 3 replicates per treatment). This avoids information loss from mean-value analysis and better reflects real-world variability, consistent with standard ecological correlation analysis practices.
Comment 8: In several cases, the magnitude of changes (e.g., SOC +7%, AK −40%) should be discussed in ecological terms—are these changes minor or significant for forest nutrient cycling?
Response 8: Thank you. We have added discussions on the ecological significance of key element changes in Sections 3.1 and 3.3. For instance, the 7–9% increase in SOC in T1 is ecologically significant for enhancing soil water-holding capacity and nutrient retention, while the 38–41% reduction in available K (AK) in T2–T4 pushes soil AK below the threshold for healthy *T. grandis* growth, potentially inhibiting root development and fruit formation.
Comment 9: The discussion correctly connects ON/IN deposition to soil acidification and base cation loss, but it heavily cites secondary literature rather than linking results to new insights from this study.
Response 9: Thank you. We have revised the Discussion section to reduce reliance on secondary literature and strengthen links between our results and new findings. For example, we emphasize that our study is the first to report a critical ON:IN ratio (~7:3) that amplifies P limitation in *T. grandis* rhizospheres, and we demonstrate that ON inputs strengthen soil C-N coupling (a stronger correlation in T1 than in T4), a pattern not observed in global studies that ignore ON:IN ratios.
Comment 10: The authors should integrate microbial or enzymatic processes to explain why ON and IN have divergent effects on P availability.
Response 10: Thank you. We fully agree that these processes are critical for unraveling the underlying mechanisms of soil nutrient transformations. However, due to the focus of this study on soil elemental content and stoichiometric ratios, we did not measure key microbial parameters or enzymatic activities during the experimental design and data collection phase. Therefore, we are unable to directly link ON/IN differences to microbial/enzymatic responses in the current manuscript.We recognize the importance of this research direction and plan to address it in our future follow-up studies.
Comment 11: The linkage between rhizospheric soil chemistry and leaf physiology (Figure 5) is promising but underdeveloped. More detail on causal relationships (e.g., how N imbalance influences photosystem efficiency) would strengthen the argument.
Response 11: Thank you. We have expanded the discussion in Section 4.2 to clarify the causal chain between soil nutrient status and leaf physiology. For example, AP reduction limits leaf TP accumulation, which impairs chlorophyll synthesis and photosystem II function (reflected by reduced Fv/Fm). Additionally, AK deficiency exacerbates this effect by limiting CO₂assimilation, creating a feedback loop that reduces photosynthetic efficiency.
Comment 12: Comments on the Quality of English Language
The English is clear overall but could be improved for conciseness. For instance, phrases like “ON/IN deposition not only significantly alters the contents of important elements and compounds, such as those in SOC, TN, and P…” can be simplified.
Minor grammatical and typographical errors (e.g., “1:1 urea blend as the source of ON” → “a 1:1 mixture of urea and glycine served as the ON source”) should be revised.
Response 12: Thank you. We revised the full text using the MDPI system. For example, we thoroughly revised the manuscript for conciseness and grammatical accuracy. For instance, we simplified phrases like ”ON/IN deposition not only significantly alters the contents of important elements and compounds, such as those in SOC, TN, and P...” to “ON/IN deposition significantly alters the contents of key elements (SOC, TN, P)”. We have also corrected minor typographical errors such as ensuring consistent notation for the ON source as “a 1:1 mixture of urea and glycine”).
Comment 13: References are current and relevant, but some in-text citations are marked as [Error! Reference source not found.] — these must be corrected before submission.
Response 13: Thank you. We have carefully checked all in-text citations and the reference list to resolve the “Error! Reference source not found” issues, ensuring all citations are correctly linked to the reference list and adhere to the journal’s formatting guidelines.
Once again, we sincerely appreciate your time and efforts in reviewing our manuscript. Your constructive feedback has greatly improved the quality and clarity of our work. We hope the revised version meets the journal’s publication standards. Please feel free to contact us if you have any further questions or suggestions.
Sincerely,
Yang Liu
Reviewer 2 Report
Comments and Suggestions for AuthorsAlthough it addresses a relevant topic and conducts its research using clear and robust methods, the article fails to explicitly highlight what is new about it: whether in terms of novel approaches, applied technologies, or discoveries with the potential to redirect scientific practices or paradigms.
It would be interesting if the work:
1. Highlighted in a separate section (preferably in the abstract and discussion) the innovative differences in relation to previous research with Torreya grandis, rhizosphere soil, or atmospheric deposition of nutrients.
2. Emphasize the practical implications of the results: for example, how the findings can support new agricultural strategies, forest management, or environmental policies for tropical and subtropical systems.
3. Explain the limitations arising from the short experimental period and suggest how long-term approaches could improve understanding of the sustained effects of nitrogen deposition, also considering variables such as microbial functional group, climate, and biodiversity.
Author Response
Response to Reviewer 2
Dear Reviewer 2,
Thank you for your valuable comments and suggestions on our manuscript. Your insights have been highly instructive in enhancing the quality of this research. We have carefully revised and improved the manuscript based on your recommendations. Below is our point-by-point response to your comments:
Comment 1: Although it addresses a relevant topic and conducts its research using clear and robust methods, the article fails to explicitly highlight what is new about it: whether in terms of novel approaches, applied technologies, or discoveries with the potential to redirect scientific practices or paradigms.
It would be interesting if the work:
- Highlighted in a separate section (preferably in the abstract and discussion) the innovative differences in relation to previous research with Torreya grandis, rhizosphere soil, or atmospheric deposition of nutrients.
Response 1: Thank you. We fully agree with your suggestion to further clarify the innovative aspects of our study in the abstract and discussion sections.Although we attempted to highlight the novelty in the initial draft, the expression may not have been sufficiently prominent. In the revised manuscript, we have added dedicated paragraphs in both the Abstract and Discussion sections to explicitly state the innovative findings of this study regarding the differential mechanisms of organic vs. inorganic nitrogen deposition on the elemental stoichiometry of T. grandis rhizospheric soil. Specifically, we emphasize the distinct effects of different nitrogen forms on carbon sequestration and phosphorus limitation, which have not been adequately explored in previous studies.
Comment 2: Emphasize the practical implications of the results: for example, how the findings can support new agricultural strategies, forest management, or environmental policies for tropical and subtropical systems.
Response 2: Thank you. We appreciate this constructive suggestion.We have added a new subsection titled "Practical Implications" at the end of the Discussion section, which elaborates on the potential application value of our findings in the following aspects:
- Providing guidance on the form and ratio of fertilization for T. grandis economic forests.
- Offering a theoretical basis for regulating forest soil nutrients under the context of nitrogen deposition.
- Informing the development of sustainable forest management policies in subtropical regions.
Comment 3: Explain the limitations arising from the short experimental period and suggest how long-term approaches could improve understanding of the sustained effects of nitrogen deposition, also considering variables such as microbial functional group, climate, and biodiversity.
Response 3: Thank you. We completely agree with your view on the limitations of the experimental duration.In the revised Discussion section, we have added a paragraph explicitly stating that the main limitation of this study stems from the relatively short experimental period, which could not capture the long-term cumulative effects of nitrogen deposition. Furthermore, we have expanded on future research directions, recommending the implementation of long-term monitoring studies that integrate multidimensional variables such as microbial functional groups, climatic factors, and biodiversity to systematically assess the sustained ecological effects of nitrogen deposition.
Once again, we sincerely thank you for your valuable comments, which have significantly contributed to the refinement and improvement of our study. We hope that the revisions meet your expectations and look forward to your acceptance of our manuscript.
Sincerely,
Yang Liu
Reviewer 3 Report
Comments and Suggestions for AuthorsUnderstanding the dynamics between nutrients in soils is important to ensure the optimal growth of various species, including T. grandis.
This species is economically relevant, so ensuring the best conditions for its growth is crucial.
The article attempts to find a rationale between the various nutrients in the soil and the addition of ON:IN in different proportions.
The problem proves to be complex and without a linearity. The addition of ON:IN is an operation that alters several nitrites in the soil, with positive effects on some of them but also with negative effects.
In the introduction, It would be important to present the main reactions involving nitrogen in soils. Namely, the transformations that this element undergoes in soils.
The main interactions between nitrogen and the most important nutrients present in the soil (C, P, K, Ca, Mg...) could also be the subject of further development in the introduction.
The effects on N addition on the leaves of T. grandis are used in this study for correlations and other data analysis but are not explained in this article. A paragraph should be included explaining which effects on leaves were studied and considered in this article.
Suggested corrections:
Line 34: Check [Error! Reference source not found.]
Line 51: Check [Error! Reference source not found.]
Line 90: "...along with other leaf performance parameters, was analyzed." These parameters should be explicitly stated here. The other effects studied, responses of soil to N addition, are clearly explained in the previous sentence. However, the effects on the leaves of T. grandis are used in this study for correlations and other data analysis but are not explained in this article.
Line 97: "... site of this study lies in Zhuji city, Zhejiang province, China". It would be interesting to present a figure as the location of the study marked on a map of China and Asia.
Line 102: Briefly explain what a "...slightly acidic red soil" is, specifically referring to its high iron oxide content which can interact with the nitrogen cycle.
Line 111: Are the ratios used and designated T1 to T4 mass ratios of ON and IN compounds, or are they mass ratios of nitrogen in both forms (organic and inorganic)? Or a molar ratio? This should be explained.
Line 130: Was air-drying the soil sufficient for sieving? For how long was the air-drying process carried out? Generally, the soil is oven-dried at around 65ºC after air drying. Air drying does not eliminate all moisture from the soil. The option of air drying only must be justified.
Figure 2: Adjust the size of the three graphs uniformly. Labels A, B, and C should be placed in the upper right corner and in a larger font for better readability.
Figure 3: Labels A, B, C and D should be placed in the upper right corner and in a larger font for better readability.
In Figures 4 and 5, the font size of the correlation coefficients presented should increase. They are very difficult to read.
Line 298: Introduce the meaning of "leaf Chl content".
Line 297 and figure 5: The terms and concepts associated with TN, TP, a+b, Fv:Fm ratio, PIabs, and N:P ratio in the leaves (L) of T. grandis are not clearly introduced. They should be explained and their measurement method in the plants described.
Line 360: Don't leave the subtitle orphaned.
Comments on the Quality of English LanguageThe results are not easy to explain. Shorter, more direct sentences could better systematize the results.
Author Response
Response to Reviewer 3's Comments
Dear Reviewer 3,
We sincerely appreciate your thoughtful review and constructive suggestions on our manuscript. Your insights have helped us identify key areas for improvement, particularly in clarifying concepts, enriching background information, and optimizing figure presentation. We have carefully addressed each of your comments, and the detailed responses are as follows :
Comment 1: Understanding the dynamics between nutrients in soils is important to ensure the optimal growth of various species, including T. grandis.
This species is economically relevant, so ensuring the best conditions for its growth is crucial.
The article attempts to find a rationale between the various nutrients in the soil and the addition of ON:IN in different proportions.
The problem proves to be complex and without a linearity. The addition of ON:IN is an operation that alters several nitrites in the soil, with positive effects on some of them but also with negative effects.
In the introduction, It would be important to present the main reactions involving nitrogen in soils. Namely, the transformations that this element undergoes in soils.
The main interactions between nitrogen and the most important nutrients present in the soil (C, P, K, Ca, Mg...) could also be the subject of further development in the introduction.
Response 1: Thank you for your insightful suggestion to elaborate on soil nitrogen transformation reactions and nutrient interactions in the Introduction. We carefully evaluated this recommendation against the core focus and structure of our manuscript, and after thoughtful consideration, we have decided to retain the current framework of the Introduction—though we fully acknowledge the scientific value of your input.
Our study specifically focuses on the effects of varying organic-inorganic nitrogen (ON:IN) ratios on rhizospheric soil elemental content and stoichiometry of Torreya grandis, rather than on the mechanisms of soil nitrogen transformations themselves. The existing Introduction already establishes the contextual relevance of nitrogen deposition to forest soil nutrient dynamics (e.g., links between N addition, microbial activity, and soil C/P cycling [8,10,15]) and highlights gaps in understanding ON:IN ratio effects on economic tree species like T. grandis. Adding detailed descriptions of nitrogen transformations (e.g., mineralization, nitrification) would shift the focus toward process-based nitrogen cycling, which is not the primary objective of our work. Moreover, key connections between N deposition-induced changes (e.g., soil acidification) and nutrient availability (e.g., P, Ca, Mg) are already addressed in the Discussion section [4.1 and 4.2], where we link our results to mechanisms such as metal-P complexation and cation leaching [33,54]—ensuring these critical interactions are still thoroughly covered.
We hope this explanation clarifies our decision, and we remain grateful for your attention to strengthening the manuscript’s theoretical foundation. We have refined minor phrasing in the Introduction (e.g., Line 42: revised "N addition alters plant root nutrient uptake" to "N addition modulates plant root nutrient uptake and rhizospheric microbial activity") to enhance clarity regarding N-soil interactions, without expanding into transformation processes.
Comment 2: The effects on N addition on the leaves of T. grandis are used in this study for correlations and other data analysis but are not explained in this article. A paragraph should be included explaining which effects on leaves were studied and considered in this article.
Line 90: "...along with other leaf performance parameters, was analyzed." These parameters should be explicitly stated here. The other effects studied, responses of soil to N addition, are clearly explained in the previous sentence. However, the effects on the leaves of T. grandis are used in this study for correlations and other data analysis but are not explained in this article.
Response 2: Thank you. We agree that leaf-related parameters and their effects need explicit explanation.
We have made two key revisions:
In the Introduction, we added a paragraph specifying that the leaf parameters studied include total nitrogen (L.TN), total phosphorus (L.TP), chlorophyll content (Chl a+b), maximal photochemical efficiency of photosystem II (Fv/Fm), and photosynthetic performance index (PIabs). These parameters reflect leaf nutritional status and photosynthetic capacity, which are closely linked to soil nutrient supply.
Comment 3: Line 34: Check [Error! Reference source not found.]
Line 51: Check [Error! Reference source not found.]
Response 3: Thank you. We have thoroughly checked the in-text citations and resolved the "Error! Reference source not found" issues in Lines 34, 51, and other relevant positions. All citations are now correctly linked to the reference list, adhering to the journal’s formatting guidelines.
Comment 4: Line 97: "... site of this study lies in Zhuji city, Zhejiang province, China". It would be interesting to present a figure as the location of the study marked on a map of China and Asia.
Response 4: Regarding your suggestion to include a location map, we have added a Figure 1 showing the experimental site (Zhuji City, Zhejiang Province) marked on maps of China and Asia.
Comment 5: Line 102: Briefly explain what a "...slightly acidic red soil" is, specifically referring to its high iron oxide content which can interact with the nitrogen cycle.
Response 5: Thank you. As recommended, we have expanded the description of "slightly acidic red soil" in Section 2.1. We specified that this soil type is characterized by a pH of 5.5–6.5, high iron oxide content (which gives it the red color), and that iron minerals can interact with nitrogen compounds (e.g., forming complexes with NH₄⁺) and regulate carbon-nitrogen cycling. This clarification helps readers understand the soil’s inherent properties and their potential impacts on experimental results.We have added supporting references to the relevant section to justify our choice. Please find relevant studies below.
Liao, Y.W.; Liao, P.; Liu, J.X.; et al. Short-term effects of straw biochar on soil aggregate composition and carbon and nitrogen distribution in red soil vegetable fields. J. Yangzhou Univ. (Agric. Life Sci. Ed.) 2023, 44(05), 41–48. Available online: https://doi.org/10.16872/j.cnki.1671-4652.2023.05.005 [In Chinese]
Comment 6: Line 111: Are the ratios used and designated T1 to T4 mass ratios of ON and IN compounds, or are they mass ratios of nitrogen in both forms (organic and inorganic)? Or a molar ratio? This should be explained.
Response 6: Thank you. We have clarified in Section 2.2 (Line 111) that the ON:IN ratios (T1–T4) refer to the mass ratio of nitrogen in organic and inorganic forms. Specifically, the ratios are based on the total nitrogen content of the applied materials: ON from the 1:1 urea-glycine mixture, and IN from ammonium nitrate. This avoids ambiguity about whether the ratios reflect compound mass or nitrogen mass.
Comment 7: Line 130: Was air-drying the soil sufficient for sieving? For how long was the air-drying process carried out? Generally, the soil is oven-dried at around 65ºC after air drying. Air drying does not eliminate all moisture from the soil. The option of air drying only must be justified.
Response 7: Thank you. In Section 2.3 (Line 130), we added a justification for air-drying the soil: "Soil samples were air-dried under natural conditions for 7 days to stabilize moisture content prior to analysis. Air-drying was chosen over oven-drying to preserve the integrity of soil organic matter and avoid altering the availability of labile nutrients (e.g., available P, exchangeable cations)—a standard practice in rhizospheric soil nutrient analysis." This explains the rationale and aligns with established methodologies in soil science.
Comment 8:
Figure 2: Adjust the size of the three graphs uniformly. Labels A, B, and C should be placed in the upper right corner and in a larger font for better readability.
Figure 3: Labels A, B, C and D should be placed in the upper right corner and in a larger font for better readability.
In Figures 4 and 5, the font size of the correlation coefficients presented should increase. They are very difficult to read.
Response 8: Thank you. We have revised Figures 2–5 as requested:
For Figures 2 and 3: Adjusted the size of subgraphs to be uniform, moved labels A/B/C (Figure 2) and A/B/C/D (Figure 3) to the upper right corner, and increased the font size for better readability.
For Figures 4 and 5: Increased the font size of correlation coefficients to improve legibility, ensuring all values are clearly visible without compromising the overall layout of the correlation heatmaps.
Comment 9: Line 298: Introduce the meaning of "leaf Chl content".
Response 9: Thank you. Done as suggested.
Comment 10:Line 297 and figure 5: The terms and concepts associated with TN, TP, a+b, Fv:Fm ratio, PIabs, and N:P ratio in the leaves (L) of T. grandis are not clearly introduced. They should be explained and their measurement method in the plants described.
Response 10: Thank you. Done as suggested.
Comment 11: Line 360: Don't leave the subtitle orphaned.
Response 11: Thank you. We have corrected the formatting of the subtitle in Line 360 to ensure it is properly aligned with the text, eliminating the "orphaned" issue.
Comment 12: Comments on the Quality of English Language
The results are not easy to explain. Shorter, more direct sentences could better systematize the results.
Response 12: Thank you. We revised the full text using the MDPI system. Following your suggestion to use shorter, more direct sentences, we have revised the Results section to simplify complex expressions. For example, we split lengthy sentences describing nutrient changes into concise statements that emphasize key trends and mechanisms, making the results more systematic and easier to follow.
Once again, we are grateful for your time and efforts in reviewing our manuscript. Your feedback has significantly enhanced the clarity, completeness, and readability of our work. We hope the revised version meets the journal’s publication standards. Please feel free to contact us if you have any further questions or suggestions.
Sincerely,
Yang Liu
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAll revisions have been carefully reviewed and fully incorporated into the revised manuscript.
Comments on the Quality of English LanguageThe English is clear overall but could be improved for conciseness. For instance, phrases like “ON/IN deposition not only significantly alters the contents of important elements and compounds, such as those in SOC, TN, and P…” can be simplified.
Minor grammatical and typographical errors (e.g., “1:1 urea blend as the source of ON” → “a 1:1 mixture of urea and glycine served as the ON source”) should be revised.
References are current and relevant, but some in-text citations are marked as [Error! Reference source not found.] — these must be corrected before submission.
Reviewer 2 Report
Comments and Suggestions for AuthorsAfter reviewing the revised version, I believe the paper is clear enough to be published.
