The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript addresses an important topic at the intersection of agricultural sustainability and environmental regulation. The authors explore the effects of China's pilot policy on controlling nitrogen and phosphorus emissions (PCNPE) on agricultural total factor productivity (ATFP), utilizing a difference-in-differences (DID) approach with multidimensional fixed effects.

The study makes a contribution by assessing the differentiated effects of phosphorus and nitrogen controls and the mechanisms through which these policies affect productivity, especially through agricultural technological innovation (ATI).

The use of DID with city and year fixed effects is appropriate for estimating causal impacts in policy analysis. Parallel trend testing, propensity score matching (PSM-DID), and placebo tests strengthen the credibility of the empirical findings. Heterogeneity analysis underline regional differences in policy impact. The adoption of the Slack-Based Measure Data Envelopment Analysis (SBM-DEA) method to compute ATFP is also a good choice, since it allows for more precise efficiency estimation without requiring a predefined production function.

 This supports the Porter Hypothesis, which posits that well-designed environmental regulations can improve innovation and eventually enhance productivity is supported.

The literature review and theoretical framework sections sometimes repeat similar ideas. Make them more concise.

The use of agricultural invention patents as a proxy for ATI may not fully capture the breadth of technological progress or innovation adoption at the farm level. Explain how indicators such as R&D investment or adoption rates of modern machinery could strengthen the analysis.

The language used in the theoretical sections could be revised for clarity and precision.

The visibility of Figure 1 should be improved.

Table 1 should contain the sources and measurement units.

Author Response

Dear Reviewer and Editor:

 

First of all, we would like to thank once again the reviewer for reviewing our manuscript titled "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" (ID: sustainability - 3580231), and thank the editor for allowing us the opportunity to make revisions. The reviewer's comments are valuable for modifying and improving our manuscript and have important guiding significance for our research. We have carefully studied these opinions and made corrections, hoping for approval. We have re - uploaded the manuscript and made corresponding modifications. Our response to the reviewer's comments is as follows:

Comment 1: The manuscript addresses an important topic at the intersection of agricultural sustainability and environmental regulation. The authors explore the effects of China's pilot policy on controlling nitrogen and phosphorus emissions (PCNPE) on agricultural total factor productivity (ATFP), utilizing a difference-in-differences (DID) approach with multidimensional fixed effects.

 

Our Response: We appreciate your recognition of the importance of our topic. We have further emphasized the significance of our study in the introduction by highlighting the global relevance of balancing agricultural productivity with environmental sustainability.

 

Comment 2: The study makes a contribution by assessing the differentiated effects of phosphorus and nitrogen controls and the mechanisms through which these policies affect productivity, especially through agricultural technological innovation (ATI).

The use of agricultural invention patents as a proxy for ATI may not fully capture the breadth of technological progress or innovation adoption at the farm level. Explain how indicators such as R&D investment or adoption rates of modern machinery could strengthen the analysis.

 

Our Response: Thank you for your reminder. In the variable selection section (4.2.3), we have added a detailed discussion on the advantages of using agricultural invention patents as a proxy variable for ATI. We argue that while agricultural mechanization rates can reflect the level of agricultural automation, they do not capture innovations in agricultural fertilizers or other critical areas of agricultural technology. Agricultural invention patents, on the other hand, provide a comprehensive measure of technological innovation across various aspects of agriculture, including fertilizers, irrigation systems, and crop varieties. This makes them a more suitable proxy for assessing the impact of PCNPE on agricultural productivity.

 

Comment 3:The use of DID with city and year fixed effects is appropriate for estimating causal impacts in policy analysis. Parallel trend testing, propensity score matching (PSM-DID), and placebo tests strengthen the credibility of the empirical findings.This supports the Porter Hypothesis, which posits that well-designed environmental regulations can improve innovation and eventually enhance productivity is supported.

 

Our Response: Thank you for your professional review work, for your recognition of the methods used in our research, and for your constructive comments and valuable suggestions for our manual.

 

Comment 4: The literature review and theoretical framework sections sometimes repeat similar ideas. Make them more concise.The language used in the theoretical sections could be revised for clarity and precision.

 

Our Response: Thanks for your recommendation. We have carefully reviewed the literature review and theoretical framework sections to identify and eliminate redundant content. We have merged overlapping discussions and streamlined the presentation of key concepts to ensure clarity and conciseness.

 

Comment 5: The visibility of Figure 1 should be improved.

 

Our Response: Thanks for your recommendation. We've re-uploaded the image to improve the clarity of the image.

 

Comment 6: Table 1 should contain the sources and measurement units.

 

Our Response: Thanks for your reminder. We have carefully considered your suggestion regarding Table 1 and have made the necessary revisions to ensure that it now includes the sources and measurement units for all variables.

 

Special thanks to you for your good comments!

 

Yours sincerely

Reviewer 2 Report

Comments and Suggestions for Authors

1. Summary and Overall Evalution

The paper under review which is entitled as "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" has employed, based on the dataset covering a total of 164 prefecture-level cities in China, an empirical strategy combining the Difference-in-Differences (DID) framework with multidimensional fixed efects model over the period from 2003 to 2022, aiming to uncover whether and how China's pilot policy, which is related to the nitrogen and phosphorus emission control, has actually influenced agricultural total factor productivity (ATFP), with a further extension to explore the mechanism channel via Agricultural Technological Innovation (ATI), and this is indeed a research topic that is not only important but also policy-relevant, though still several critical issues need further attention.

 

2. Detailed Comments by Section

Abstract (Lines 7–23)

• The abstract as it is now composed, especially in Lines 12 through 14, seems to include excessive detail which may reduce the communicative effectiveness of the abstract itself, and it may not necessarily help the reader grasp the overall contribution.
• The sugestion here is that the authors should consider rewriting this part in a way that it could be more condensed and conceptually centralised, with all minor numerical results and side findings removed.

Introduction (Lines 25–78)

• In Lines 26–44, although several important facts and reports have been mentioned, it remains unclear when exactly those references were published and whether their sources are official, and also the citation style does not always following standard convention.
• In the paragraph that stretches from Line 65 to 77, the extensive elaboration on China’s agricultural governance characteristics, while being informative, actually weakens the focus of this section on the policy under investigation, namely PCNPE.
• It might be better if the authors could remove or move part of that paragraph into another section, and instead use the space to more clearly state why this study is needed, what gaps it intends to fill, and how it relates to ongoing debates regarding environmental policy and productivity.

Literature Review (Lines 171–255)

• In Lines 221–240, the authors wrote quite extensively about the biochemical functions of nitrogen and phosphorus, but it almost feels like textbook knowledge, and it is somewhat disconnected from empirical or policy-focused literature.
• Besides, many cited works, as in Line 182 and also Line 233, they are Chinese studies which is understandable given the case context, however, without international references, it will makes the argument looks parochial.
• So, my sugestion will be that authors keep a shorter version of biological discussion and instead highlight what has not been done in prior studies regarding environmental regulation and agricultural productivity.

Theoretical Framework and Hypothesis (Lines 256–320)

• The theoretical narrative between Line 269 and 279, while seemingly logical, is lacking clarity in causal transmission, and the link between policy restriction and innovation suppression is not always robustly substantiated.
• Line 291–293 directly draws a hypothesis regarding short-run decline of ATFP due to policy, but the support is not solid enough and may be seen as premature or speculative.
• To fix this, one good way is perhaps using some flowchart or conceptual diagram, so that all elements of the mechanism—policy, innovation, productivity—can be visually mapped and logically connected.

Research Design (Lines 321–474)

• Though the model described in Line 344–346 seems standard, but the source and construction method of some control variables like government intervention and rural labor force level was not clearly documented.
• The DEA part, especially Line 391 to 399, present detailed equations which are mathematically correct but stylistically might distract readers, because such technical notations are more suitable for appendix or supplementary materials.
• Therefore, some re-organization here would makes the narrative easier to follow and more accessible to interdisciplinary audiences.

Results and Robustness (Lines 475–549)

• The argument made in Line 499, claiming that phosphorus is more intensively relied upon in agriculture than nitrogen, is not completely convincing as there are no supporting agronomic evidence cited to back that.
• In addition, the formatting style for Figures (like Figure 3 and also Figure 5) is not fully consistent, and it does not always match with text flow.
• It may be helpful to add short interpretive paragraphs following each figure instead of just plotting it without narrative.

Heterogeneity Analysis (Lines 596–668)

• In Lines 601–617, the finding that the PCPE had smaller effect in environmental protection zones was interpreted as being due to prior adaptation or technology reserves, but there is no quantitative evidence offered to substantiate this claim.
• My sugestion is that authors try to bring in environmental expenditure statistics or some green patent density data for different cities to make this claim more reliable.

Mechanism Analysis (Lines 670–732)

• There is quite a lot of repetition between Lines 695 and 717 which were already stated earlier in the paper, and this redundancy could easily bore readers.
• More importantly, the validity of using patent counts to measure ATI is assumed but not discussed; whether these patents translate into actual production innovation is something readers might ask.
• So it would be good to add some caveats or complementary explanations to justify this proxy.

Conclusions and Policy Suggestions (Lines 736–783)

• The policy recommendations, while sounding reasonable, in Lines 766 to 777, they seems to lack specific operationalizable detail; e.g., how exactly should central government support western regions?
• It is suggested that the authors may consider tailoring policies to the different regional findings they already uncovered—such as enhancing subsidies for ATI in the west, or supporting technology diffusion in the east.

Limitations and Future Work (Lines 784–802)

• Although it is mentioned in Lines 792–794 that spatial spillovers were not captured, the reason why spatial econometrics was not used is not fully elaborated.
• The authors could say more about potential data limitations or sample coverage issues that prevented the use of such models.

 

3. Language and Expression

• The manuscript contain some excessive repetition such as the phrase “agricultural total factor productivity” appearing over 30 times.
• The sentence structure especially from Lines 137 to 143 is quite dense and should be split or rephrased, because it cause dificult to understand for readers who is not fluent.
• Words like “maximize structure of key agricultural input” in Line 313 is also unclear and awkwardly constructed.
• Figures and tables are generally useful but need to be more tightly integrated into the text, not just displayed.

Author Response

Dear Reviewer and Editor:

 

First of all, we would like to thank once again the reviewer for reviewing our manuscript titled "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" (ID: sustainability - 3580231), and thank the editor for allowing us the opportunity to make revisions. The reviewer's comments are valuable for modifying and improving our manuscript and have important guiding significance for our research. We have carefully studied these opinions and made corrections, hoping for approval. We have re - uploaded the manuscript and made corresponding modifications. Our response to the reviewer's comments is as follows:

Comment 1: The paper under review which is entitled as "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" has employed, based on the dataset covering a total of 164 prefecture-level cities in China, an empirical strategy combining the Difference-in-Differences (DID) framework with multidimensional fixed efects model over the period from 2003 to 2022, aiming to uncover whether and how China's pilot policy, which is related to the nitrogen and phosphorus emission control, has actually influenced agricultural total factor productivity (ATFP), with a further extension to explore the mechanism channel via Agricultural Technological Innovation (ATI), and this is indeed a research topic that is not only important but also policy-relevant, though still several critical issues need further attention.

 

Our Response: Thank you for your comprehensive evaluation of our manuscript. We appreciate your recognition of the importance and policy relevance of our research topic. We have taken your comments seriously and have made the necessary revisions to address the critical issues you have identified.

 

Comment 2: The abstract as it is now composed, especially in Lines 12 through 14, seems to include excessive detail which may reduce the communicative effectiveness of the abstract itself, and it may not necessarily help the reader grasp the overall contribution.

The suggestion here is that the authors should consider rewriting this part in a way that it could be more condensed and conceptually centralised, with all minor numerical results and side findings removed.

 

Our Response: Thank you for your insightful suggestion on the abstract of our manuscript. We appreciate your suggestion to make the abstract more concise and conceptually centralized. We have carefully revised the abstract to remove minor numerical results and side findings, focusing on the core contributions and main findings of our study.

 

Comment 3: In Lines 26–44, although several important facts and reports have been mentioned, it remains unclear when exactly those references were published and whether their sources are official, and also the citation style does not always following standard convention.

 

Our Response: Thank you for your detailed feedback on the manuscript.We have reviewed the references in Lines 26–44 and ensured that each reference includes the publication year and is sourced from official documents or reputable sources. We have also added specific citations to clarify the origin of the data and reports. For example, we have included references to official reports from the United Nations, World Bank, and other authoritative sources to support the facts mentioned.

 

Comment 4: In the paragraph that stretches from Line 65 to 77, the extensive elaboration on China’s agricultural governance characteristics, while being informative, actually weakens the focus of this section on the policy under investigation, namely PCNPE.

It might be better if the authors could remove or move part of that paragraph into another section, and instead use the space to more clearly state why this study is needed, what gaps it intends to fill, and how it relates to ongoing debates regarding environmental policy and productivity.

 

Our Response: In the paragraph that stretches from Line 65 to 77, the extensive elaboration on China’s agricultural governance characteristics, while being informative, actually weakens the focus of this section on the policy under investigation, namely PCNPE.

It might be better if the authors could remove or move part of that paragraph into another section, and instead use the space to more clearly state why this study is needed, what gaps it intends to fill, and how it relates to ongoing debates regarding environmental policy and productivity.

 

Comment 5: In Lines 221–240, the authors wrote quite extensively about the biochemical functions of nitrogen and phosphorus, but it almost feels like textbook knowledge, and it is somewhat disconnected from empirical or policy-focused literature.

Besides, many cited works, as in Line 182 and also Line 233, they are Chinese studies which is understandable given the case context, however, without international references, it will makes the argument looks parochial.

So, my suggestion will be that authors keep a shorter version of biological discussion and instead highlight what has not been done in prior studies regarding environmental regulation and agricultural productivity.

 

Our Response: Thank you for your detailed feedback on the manuscript. We have revised the section to provide a more concise overview of the biochemical functions of nitrogen and phosphorus, focusing on the aspects most relevant to our study. We have removed detailed textbook-like descriptions and instead highlighted the key points that are crucial for understanding the impact of nitrogen and phosphorus on agricultural productivity and the environment. This change helps to maintain the focus on the empirical and policy implications of our research.

We have added relevant international references to provide a more comprehensive and balanced view of the literature. This includes studies from other countries that have examined the impact of environmental regulations on agricultural productivity. By incorporating these international references, we aim to situate our study within the broader global context and highlight the universal relevance of our findings.

 

Comment 6: The theoretical narrative between Line 269 and 279, while seemingly logical, is lacking clarity in causal transmission, and the link between policy restriction and innovation suppression is not always robustly substantiated.

Line 291–293 directly draws a hypothesis regarding short-run decline of ATFP due to policy, but the support is not solid enough and may be seen as premature or speculative.

To fix this, one good way is perhaps using some flowchart or conceptual diagram, so that all elements of the mechanism—policy, innovation, productivity—can be visually mapped and logically connected.

 

Our Response: Thank you for your insightful comments on the theoretical narrative and the clarity of the causal transmission in our manuscript.We have revised the theoretical narrative to provide a clearer and more detailed explanation of the causal mechanisms linking policy restrictions to innovation and productivity. We have added intermediate steps and logical connections to ensure that the causal transmission is robustly substantiated. We have strengthened the support for our hypothesis by providing additional empirical evidence and theoretical justification. We have included references to studies that have observed similar short-term declines in productivity due to environmental regulations. We have also added a detailed discussion on the potential reasons for this decline, such as increased compliance costs and the time required for technological adaptation. We have created a conceptual diagram (Figure 2) that visually maps the key elements of our theoretical framework, including policy restrictions, agricultural technological innovation (ATI), and agricultural total factor productivity (ATFP). This diagram clearly illustrates the causal relationships and intermediate steps between these elements, providing a visual representation of the mechanisms we discuss in the text. We have also added a detailed caption to explain each component of the diagram.

 

Comment 7: Though the model described in Line 344–346 seems standard, but the source and construction method of some control variables like government intervention and rural labor force level was not clearly documented.

 

Our Response:Thank you for your detailed feedback on the manuscript.We revised the manuscript to explain in more detail the origin and construction method of each control variable, including government intervention and rural labor levels. This information is now included in the 4.2 Variable Selection section, ensuring that the reader has a clear understanding of the data source and how those variables are structured.

 

Comment 8: The DEA part, especially Line 391 to 399, present detailed equations which are mathematically correct but stylistically might distract readers, because such technical notations are more suitable for appendix or supplementary materials.

Therefore, some re-organization here would makes the narrative easier to follow and more accessible to interdisciplinary audiences.

 

Our Response: Thank you for your valuable feedback on the presentation of the DEA (Data Envelopment Analysis) section in our manuscript.We have taken your suggestion to heart and have reorganized the DEA section to enhance readability and accessibility. The detailed equations and technical notations have been moved to an appendix section, where they can be referenced without disrupting the flow of the main text. In the main text, we have provided a concise overview of the DEA method, focusing on its conceptual framework and how it is applied in our study. This approach ensures that readers with different backgrounds can follow the narrative without being overwhelmed by technical details.

 

Comment 9: The argument made in Line 499, claiming that phosphorus is more intensively relied upon in agriculture than nitrogen, is not completely convincing as there are no supporting agronomic evidence cited to back that.

 

Our Response: Thank you for your insightful feedback on the manuscript.We have revised the manuscript to include specific agronomic evidence supporting the claim that phosphorus is more intensively relied upon in agriculture than nitrogen. We have added references to studies that provide empirical data on the differential reliance on these nutrients in various agricultural contexts. This additional evidence strengthens the argument and provides a solid basis for our claim.

 

Comment 10: In addition, the formatting style for Figures (like Figure 3 and also Figure 5) is not fully consistent, and it does not always match with text flow.

It may be helpful to add short interpretive paragraphs following each figure instead of just plotting it without narrative.

 

Our Response: Thanks for your reminder.We have revised the formatting of all figures to ensure consistency in style and presentation. Additionally, we have added short interpretive paragraphs following each figure to provide context and explain the key findings illustrated in the figures. This approach enhances the readability and coherence of the manuscript, ensuring that the figures are well-integrated with the narrative.

 

Comment 11: In Lines 601–617, the finding that the PCPE had smaller effect in environmental protection zones was interpreted as being due to prior adaptation or technology reserves, but there is no quantitative evidence offered to substantiate this claim.

My suggestion is that authors try to bring in environmental expenditure statistics or some green patent density data for different cities to make this claim more reliable.

 

Our Response: Thank you for your detailed feedback on the manuscript.We have taken your suggestion to heart and cited relevant green patent documents to support our interpretation. 

 

Comment 12: There is quite a lot of repetition between Lines 695 and 717 which were already stated earlier in the paper, and this redundancy could easily bore readers.

More importantly, the validity of using patent counts to measure ATI is assumed but not discussed; whether these patents translate into actual production innovation is something readers might ask.

So it would be good to add some caveats or complementary explanations to justify this proxy.

 

Our Response: Thank you for your suggestions on the manuscript.We've reviewed the section and removed the redundant to ensure the narrative is concise and engaging.We have revised the section on the selection of mechanism variables to provide a more comprehensive rationale for the use of agricultural invention patents as agents for ATI. This includes a detailed discussion of the definition of agricultural invention patents and their relevance to agricultural productivity.

 

Comment 13: The policy recommendations, while sounding reasonable, in Lines 766 to 777, they seems to lack specific operationalizable detail; e.g., how exactly should central government support western regions?

It is suggested that the authors may consider tailoring policies to the different regional findings they already uncovered—such as enhancing subsidies for ATI in the west, or supporting technology diffusion in the east.

 

Our Response: Thank you for your valuable feedback on the policy recommendations section of our manuscript. We have revised the policy recommendations section to include more specific and operationalizable details. We have tailored the recommendations to address the unique challenges and opportunities identified in different regions, particularly the western and eastern regions of China. This approach ensures that the recommendations are practical and can be effectively implemented.

 

Comment 14:Although it is mentioned in Lines 792–794 that spatial spillovers were not captured, the reason why spatial econometrics was not used is not fully elaborated.

The authors could say more about potential data limitations or sample coverage issues that prevented the use of such models.

 

Our Response: Thank you for your insightful feedback on the manuscript.We have revised the manuscript to provide a more detailed explanation of the non-use of spatial econometric models. Because the distribution of the pilot samples is relatively scattered, there is no way to construct a geographic weight matrix to use the spatial econometric model.

 

Comment 15: The manuscript contain some excessive repetition such as the phrase “agricultural total factor productivity” appearing over 30 times.

The sentence structure especially from Lines 137 to 143 is quite dense and should be split or rephrased, because it cause dificult to understand for readers who is not fluent.

Words like “maximize structure of key agricultural input” in Line 313 is also unclear and awkwardly constructed.

Figures and tables are generally useful but need to be more tightly integrated into the text, not just displayed.

 

Our Response:Thank you for your valuable feedback on the language, expression, and presentation of figures and tables in our manuscript. We have reviewed the manuscript and reduced the repetition of the phrase “agricultural total factor productivity” (ATFP). We have replaced some instances with synonyms or rephrased sentences to maintain variety and avoid redundancy.We have revised the sentence structure in the specified lines to make it more concise and easier to understand. We have split long sentences into shorter ones and rephrased complex sentences to improve readability. Moreover, We revised the phrase "structure for maximizing key inputs in agriculture" to a clearer and more natural structure. We've replaced it with "force reconfiguration of production factors" to improve clarity and readability.Finally, we added explanatory paragraphs after each chart to provide context and explain the main findings. This approach ensures that the diagram is well integrated with the narrative and enhances the overall coherence of the manuscript.

 

Special thanks for your kind comments!

Sincerely

 

Reviewer 3 Report

Comments and Suggestions for Authors

This paper evaluates the effects of nitrogen and phosphorus emission control policies on agricultural total factor productivity (ATFP) using a DID model across 164 Chinese cities. The topic is timely and policy-relevant, and the empirical strategy is generally sound. However, the paper would benefit from clearer positioning, improved explanation of mechanisms, and stronger international contextualization. A major revision is recommended.

Comment 1: The abstract outlines the findings but lacks clarity on the study’s originality. The authors should better highlight the research gap and main contributions. In the introduction, the motivation is clear, but the core research questions and theoretical positioning need sharpening.

Comment 2: The literature review is relevant but overly domestic in focus. It lacks sufficient reference to international work on environmental regulation and agricultural productivity. Some recent and relevant contributions should be cited and discussed.

Heterogeneity of urban‒rural responses to multigoal policy from an efficiency perspective: An empirical study in China. Habitat International 2025, 158, 103341.

Crop switching can enhance environmental sustainability and farmer incomes in China. Nature, 2023, 616, 300–305.

Comment 3: The DID approach is appropriate, and the robustness checks are well done. Still, more detail is needed on variable definitions, the rationale for treatment/control group classification, and how potential endogeneity (especially of ATI) is addressed.

Comment 4: The results are clearly presented but need stronger interpretation. Differences between nitrogen and phosphorus effects should be more clearly explained, and heterogeneity findings would benefit from linkage to regional characteristics. Visual aids (maps or timelines) could help enhance clarity.

Comment 5: The ATI mechanism is well proposed, but the policy discussion could go further. The authors should offer actionable recommendations—e.g., how to accelerate ATI adoption or support regions facing short-term productivity losses. Referring to international policy practices would enhance this section.

Comment 6: The manuscript is readable but occasionally dense, especially in the theoretical and empirical parts. Some expressions are unclear or awkward and need polishing. A round of language editing is advised to improve overall clarity and flow.

Comments on the Quality of English Language

none

Author Response

Dear Reviewer and Editor:

 

First of all, we would like to thank once again the reviewer for reviewing our manuscript titled "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" (ID: sustainability - 3580231), and thank the editor for allowing us the opportunity to make revisions. The reviewer's comments are valuable for modifying and improving our manuscript and have important guiding significance for our research. We have carefully studied these opinions and made corrections, hoping for approval. We have re - uploaded the manuscript and made corresponding modifications. Our response to the reviewer's comments is as follows:

 

Comment 1: This paper evaluates the effects of nitrogen and phosphorus emission control policies on agricultural total factor productivity (ATFP) using a DID model across 164 Chinese cities. The topic is timely and policy-relevant, and the empirical strategy is generally sound. However, the paper would benefit from clearer positioning, improved explanation of mechanisms, and stronger international contextualization. A major revision is recommended.

 

Our Response: Thank you for your comprehensive evaluation of our manuscript. We appreciate your recognition of the timeliness and policy relevance of our research topic, as well as the soundness of our empirical strategy. We have taken your suggestions for clearer positioning, improved explanation of mechanisms, and stronger international contextualization very seriously and have made the necessary revisions to enhance the quality and impact of our study.

 

Comment 2: The abstract outlines the findings but lacks clarity on the study’s originality. The authors should better highlight the research gap and main contributions. In the introduction, the motivation is clear, but the core research questions and theoretical positioning need sharpening.

 

Our Response: Thank you for your insightful feedback on the manuscript. We have revised both the abstract and the introduction to more clearly state the innovation of our study and how it addresses existing research gaps. Specifically, we have:

Abstract: Added a sentence that succinctly captures the innovation and contributions of our study.

Introduction: Enhanced the section on research gaps to focus on the lack of studies examining the impact of restricting essential agricultural inputs, such as nitrogen and phosphorus, on agricultural production. We have also sharpened our theoretical positioning by emphasizing the unique angle of our study, which examines the effects of input restrictions in environmental regulation.

 

Comment 3: The literature review is relevant but overly domestic in focus. It lacks sufficient reference to international work on environmental regulation and agricultural productivity. Some recent and relevant contributions should be cited and discussed.

 

Heterogeneity of urban‒rural responses to multigoal policy from an efficiency perspective: An empirical study in China. Habitat International 2025, 158, 103341.

 

Crop switching can enhance environmental sustainability and farmer incomes in China. Nature, 2023, 616, 300–305.

 

Our Response:Thank you for your suggestions on the manuscript. We have revised the literature review section to include a broader range of international studies, ensuring that our review is more comprehensive and globally representative. Specifically, we have added references to the two articles you suggested, which are highly relevant to our study. We have also included a discussion on how these international studies contribute to our understanding of the impact of environmental regulation on agricultural productivity.

 

Comment 4: The DID approach is appropriate, and the robustness checks are well done. Still, more detail is needed on variable definitions, the rationale for treatment/control group classification, and how potential endogeneity (especially of ATI) is addressed.

 

Our Response:  Thank you for your in-depth feedback on our manuscript. We have added more details about variable definitions and the rationale for treatment/control group classification. Furthermore, to address the potential endogeneity issue, we have conducted a PSM-DID analysis for agricultural technological innovation. This approach can help alleviate the endogeneity problem caused by sample bias. However, we currently have not found a suitable instrumental variable.

 

Comment 5: The results are clearly presented but need stronger interpretation. Differences between nitrogen and phosphorus effects should be more clearly explained, and heterogeneity findings would benefit from linkage to regional characteristics. Visual aids (maps or timelines) could help enhance clarity.

 

Our Response: Thank you for your valuable feedback on the presentation and interpretation of our results. We have revised the results section to provide a more detailed interpretation of the differences between nitrogen and phosphorus effects. We have also linked the heterogeneity findings to regional characteristics, providing a clearer understanding of the regional differences in the impact of the Phosphorus and Nitrogen Control Policy (PCNPE) on agricultural total factor productivity (ATFP).

 

Comment 6: The ATI mechanism is well proposed, but the policy discussion could go further. The authors should offer actionable recommendations—e.g., how to accelerate ATI adoption or support regions facing short-term productivity losses. Referring to international policy practices would enhance this section

 

Our Response:Thank you for your valuable feedback on the policy discussion section of our manuscript. Thank you for your feedback. We have revised the policy discussion section to include recommendations that could be made and international policy practice.

 

Comment 7: The manuscript is readable but occasionally dense, especially in the theoretical and empirical parts. Some expressions are unclear or awkward and need polishing. A round of language editing is advised to improve overall clarity and flow.

 

Our Response: Thank you for your feedback on the readability and clarity of our manuscript.We have carefully reviewed these sections to eliminate redundancy and improve clarity. Additionally, we have revised the language to make it more concise and clear, addressing any awkward or unclear expressions.

 

Special thanks for your kind comments!

 

Sincerely

 

Reviewer 4 Report

Comments and Suggestions for Authors

Guo et al conducted a study about the impact of nitrogen and phosphorus emission control policies (PCNPE) on agricultural total factor productivity (ATFP) in China using panel data from 164 prefecture-level cities (2003–2022). They employed a difference-in-differences (DID) framework with robustness checks, including PSM-DID, placebo tests, and heterogeneity analyses. They found phosphorus control policies (PCPE) reduced ATFP in the short term but stimulated agricultural technological innovation (ATI), which might offset initial productivity losses in the long run. The article is written in well language and is properly illustrated. At the same time, there are several weaknesses that need to be resolved in order for the article to be published. Unfortunately, I did not know what the principle was for the authors to choose these 164 prefecture-level cities? In addition, model validation and sensitivity analysis require more detailed information. A more detailed discussion of the timeline and mechanisms through which these long-term effects might materialize would strengthen the conclusions.

Author Response

Dear Reviewer and Editor:

 

First of all, we would like to thank once again the reviewer for reviewing our manuscript titled "The Impact of Nitrogen and Phosphorus Emission Control on Agricultural Total Factor Productivity" (ID: sustainability - 3580231), and thank the editor for allowing us the opportunity to make revisions. The reviewer's comments are valuable for modifying and improving our manuscript and have important guiding significance for our research. We have carefully studied these opinions and made corrections, hoping for approval. We have re - uploaded the manuscript and made corresponding modifications. Our response to the reviewer's comments is as follows:

Comment 1: Guo et al conducted a study about the impact of nitrogen and phosphorus emission control policies (PCNPE) on agricultural total factor productivity (ATFP) in China using panel data from 164 prefecture-level cities (2003–2022). They employed a difference-in-differences (DID) framework with robustness checks, including PSM-DID, placebo tests, and heterogeneity analyses. They found phosphorus control policies (PCPE) reduced ATFP in the short term but stimulated agricultural technological innovation (ATI), which might offset initial productivity losses in the long run.

 

Our Response: Thank you very much for your positive evaluation and constructive feedback on our manuscript.We appreciate your concise and accurate summary of our study.  We are pleased that you acknowledge the robustness of our approach and the significance of our results.

 

Comment 2: The article is written in well language and is properly illustrated. At the same time, there are several weaknesses that need to be resolved in order for the article to be published. Unfortunately, I did not know what the principle was for the authors to choose these 164 prefecture-level cities?

 

OUR RESPONSE: Thank you for your positive feedback on the language and illustrations in our manuscript. We have revised 4.2 Variable Selection and Construction to clearly explain the selection of the 164 prefecture-level cities. Specifically, we included detailed rationale for selecting these cities as the control and experimental groups.

 

Comment 3: In addition, more detailed information is needed for model validation and sensitivity analyses. A more detailed discussion of the timelines and mechanisms by which these long-term impacts may be realised would strengthen the conclusions.

Our response: thank you for your detailed feedback on our manuscript. We have revised the Analysis of Results section to include more detailed information on model validation and sensitivity analysis. Specifically, we added a discussion of the R-squared value of the model, highlighting how the inclusion of control variables and the application of propensity score matching (PSM) improves model fit. We also provide detailed information on placebo tests and other robustness checks.

Special thanks for your kind comments!

Sincerely

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I am pleased to see that the authors have respected and revised the manuscript based on my review comments, significantly improving its quality. I recommend accepting and publishing the paper immediately.

Reviewer 3 Report

Comments and Suggestions for Authors

Accept.

Comments on the Quality of English Language

None.