Optimizing Biodegradable Films with Varying Induction Periods to Enhance Rice Growth and Soil Carbon and Nitrogen Dynamics

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript describes two years field experiments to assess the impact of different induction periods on soil hydrothermal conditions, rice growth, yield, grain quality, irrigation water use efficiency (IWUE) and soil C, N. The field experiment has explored the effects of different induction periods on rice cultivation comprehensively. The results showed that BFs with longer induction periods (80 days) was more suitable for rice cultivation in this area. Because it can increase yield, IWUE and soil carbon than the no plastic film mulching treatment. This study is valuable for the rice cultivation because of the low temperature in this area and the importance to protect the black soil. However, the manuscript should be revised as follows:

1. 1. Lines19-21: Thesentence is too long and is not very clear. It can be “Results showed that mulching increased soil temperature and soil moisture. Across the growing season, the mean soil temperature at the 0–5 cm depth under PE was 5.5% and 2.2%–5.5% higher than that under CK and BFs, respectively.”
2. 2. Line 26: It should be “At 0–20 cm depth…”.
3. Lines37-40: The sentence“Rice (Oryza sativa L.) serves as the primary dietary staple for over half the global population, is among the most water-intensive cereals, requiring 1,200–1,500 mm of water per growing season—two to three times more water per unit yield than wheat or maize” should be “Rice (Oryza sativa L.) serves as the primary dietary staple for over half the global population and is among the most water-intensive cereals, requiring 1,200–1,500 mm of water per growing season—two to three times more water per unit yield than wheat or maize.”
4. Lines94: Thesentence should be “……water use efficiency; and (3) determine the changes……”
5. Line 99: The sentence is missing a period.
6. Line 104: The latitude and longitude values should be placed after “Experiment Research Center”.
7. It is preferable to use the passive voice in the Materials and Methods section. Forexample, “The rice variety Daohua Xiang No. 2 was used in the experiment. Planting was carried out on May 20, 2023, and May 23, 2024, with harvesting conducted on September 22, 2023, and September 24, 2024. The effects of black biodegradable film with varying induction periods—45 days (BF45), 60 days (BF60), and 80 days (BF80)—were investigated.”
8. Line 125: There is a redundant period.
9. Line 130: Actually, rice was transplanted, not directly planted in this study. It should be “Rice was planted in……”.
10. 1 Line 133: The greeningstageis not correct. Is regreening stage? Please check the whole manuscript.
11. Line172: The“heated” is better than “blanched” in this sentence.
12. 1 Lines 193-194: “layer-wise” is not very good. Thesentenceshould be “……and the samples from each layer were combined to form two composite samples corresponding to the 0–5 cm and 5–20 cm layers.”
13. 1 Lines 231-232: Whereisthe letters?
14. 1 Line 233: Intable1, the “Green-returning” is not correct. It should be “regreening”. The line between “Greeen-returning stage” and “Tillering stage” was missing.
15. Lines 240-248: It is bettertodescribe the results in 2023 firstly, and then the results in 2024.
16. 1 Lines 288-289: Theletters“a, b, c” in the figure should explain. Please check the whole manuscript.
17. 1 Lines 535-538: Thesentenceis too long. It should be two sentences because one is about rice quality and the other is about SOC and C:N.

Overall, I suggest the manuscript can be published in this journal after the minor revision.

Author Response

Dear Editor in Chief,

Many thanks for your letter regarding our manuscript (4089228). We are grateful for your valuable comments that can greatly enhance the quality of this paper. We have addressed all the comments raised by the reviewer in the revised manuscript to improve the quality of this paper. In what follows, we have made all the changes in detail for response to the comments.

1. Comment: Lines19-21: The sentence is too long and is not very clear. It can be “Results showed that mulching increased soil temperature and soil moisture. Across the growing season, the mean soil temperature at the 0–5 cm depth under PE was 5.5% and 2.2%–5.5% higher than that under CK and BFs, respectively.”

Response: Thank you for your comment. We have made the amendments in the manuscript. “Results showed that mulching increased soil temperature and soil moisture. Across the growing season, the mean soil temperature at the 0–5 cm depth under PE was 5.5% and 2.2%–5.5% higher than that under CK and BFs, respectively.” (Lines 19-21).

2. Comment: Line 26: It should be “At 0–20 cm depth…”.

Response: Thank you for your comment. We have made the amendments in the manuscript (Lines 221 and 393).

3. Comment: Lines37-40: The sentence “Rice (Oryza sativa L.) serves as the primary dietary staple for over half the global population, is among the most water-intensive cereals, requiring 1,200–1,500 mm of water per growing season—two to three times more water per unit yield than wheat or maize” should be “Rice (Oryza sativa L.) serves as the primary dietary staple for over half the global population and is among the most water-intensive cereals, requiring 1,200–1,500 mm of water per growing season—two to three times more water per unit yield than wheat or maize.”

Thank you for your comment. We have made the amendments in the manuscript. Rice (Oryza sativa L.) serves as the primary dietary staple for over half the global population and is among the most water-intensive cereals, requiring 1,200–1,500 mm of water per growing season—two to three times more water per unit yield than wheat or maize.” (Lines 38-41).

4. Comment: Lines94: The sentence should be “……water use efficiency; and (3) determine the changes……”

Response: Thank you for your comment. We have made the amendments in the manuscript (Line 89).

5. Comment: Line 99: The sentence is missing a period.

Response: Thank you for your comment. We have made the amendments in the manuscript (Line 95).

6. Comment: Line 104: The latitude and longitude values should be placed after “Experiment Research Center”.

Response: Thank you for your comment. We have made the amendments in the manuscript (Line 99).

7. Comment: It is preferable to use the passive voice in the Materials and Methods section. For example, “The rice variety Daohua Xiang No. 2 was used in the experiment. Planting was carried out on May 20, 2023, and May 23, 2024, with harvesting conducted on September 22, 2023, and September 24, 2024. The effects of black biodegradable film with varying induction periods—45 days (BF45), 60 days (BF60), and 80 days (BF80)—were investigated.”

Response: Thank you for your comment. We have made the amendments in the manuscript. “The rice variety Daohua Xiang No. 2 was used in the experiment. Planting was carried out on May 20, 2023, and May 23, 2024, with harvesting conducted on September 22, 2023, and September 24, 2024. The effects of black biodegradable film with varying induction periods—45 days (BF₄₅), 60 days (BF₆₀), and 80 days (BF₈₀)—were investigated.” (Lines 113-116).

8. Comment: Line 125: There is a redundant period.

Response: Thank you for your comment. We have made the amendments in the manuscript.

9. Comment: Line 130: Actually, rice was transplanted, not directly planted in this study. It should be “Rice was planted in……”.

Response: Thank you for your comment. We have made the amendments in the manuscript (line 122).

10. Comment: The greening stage is not correct. Is regreening stage? Please check the whole manuscript.

Response: Thank you for your comment. We have made the amendments in the manuscript (line 156).

11. Comment: Line172: The “heated” is better than “blanched” in this sentence.

Response: Thank you for your comment. We have made the amendments in the manuscript (line 174).

12. Comment: Lines 193-194: “layer-wise” is not very good. The sentence should be “……and the samples from each layer were combined to form two composite samples corresponding to the 0–5 cm and 5–20 cm layers.”

Response: Thank you for your comment. We have made the amendments in the manuscript. “samples from each layer were combined to form two composite samples corresponding to the 0–5 cm and 5–20 cm layers”, Lines 188_189.

13. Comment: Lines 231-232: Where is the letters?

Response: Thank you for your comment. We have made the amendments in the manuscript (Figure 1).

14. Comment: Line 233: Intable1, the “Green-returning” is not correct. It should be “regreening”. The line between “Greeen-returning stage” and “Tillering stage” was missing.

Response: Thank you for your comment. We have made the amendments in the manuscript (Table 1).

15. Comment: Lines 240-248: It is better to describe the results in 2023 firstly, and then the results in 2024.

Response: Thank you for your comment. We have made the amendments in the manuscript (Lines 235-242).

16. Comment: Lines 288-289: The letters“a, b, c” in the figure should explain. Please check the whole manuscript.

Response: Thank you for your valuable reminder. We would like to clarify that the letters in the figures of this manuscript are only used for two purposes: (1) marking different years and (2) indicating the subfigure serial numbers. Both of these two types of letter annotations have been clearly explained in the corresponding figure captions (i.e., the notes of each figure). In addition, we have thoroughly checked the entire manuscript and confirmed that all letter annotations in all figures have complete and unified explanations in their respective captions, with no omissions or ambiguities.

17. Comment: Lines 535-538: The sentence is too long. It should be two sentences because one is about rice quality and the other is about SOC and C:N.

Response: Thank you for your comment. We have made the amendments in the manuscript. “BFs had little effect on milling and nutritional quality but improved appearance and eating quality. BF treatments—especially BF₈₀—raised SOC and C:N in the 0–20 cm layer, indicating greater soil carbon accumulation” (Lines 539-543). We appreciate your help in improving the rigor of our manuscript.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Comments and Suggestions for Authors

 

Title: Optimizing biodegradable films with varying induction periods to enhance rice growth and soil carbon and nitrogen dynamics

Dear Authors and Editors

The research results presented in the manuscript fall within the publishing profile of the journal Plants. The research topic is original and relevant to the field of agricultural sciences.

Manuscript presents research results of local importance.

The methodology section requires some clarification and additions. The results obtained from the 2023-2024 study are clearly presented in tables and figures and are well-documented. The conclusions are consistent with the results obtained. The references used are appropriate.

In order to increase the usefulness of the article, Authors must refer to the following points. Additions should be made to increase the scientific value of the manuscript.

Comments:

1. Keywords: The important macronutrient "total nitrogen" should be added.
2. Introduction: Why were the studies conducted using very good quality soils (black soils)?
3. Materials and Methods: Subsection 2.1. Please provide soil classification according to IUSS Working Group 2014, 2022. Line 136 - Please provide the name and dose of the pesticide. Please provide the doses of all ingredients (in kg of pure ingredient per hectare). What fertilizer mixture with humic acids was used (add dose). Please include the composition of the Xin Balok fertilizer and the names of the enzyme bacteria. You should add the sources for the formulas listed in subsection 2.3 and the sources for the methods listed in subsection 2.3.5.
4. Results and Analysis: Table 3 and Table 5 - The same yield data has been provided (repeated). Yields should be reported in t ha^-1. Table 4 - Missing units need to be completed. Figure 6a - the description of the results presented in figure 6a is missing.
5. Discussion: Lines 440-442 This sentence needs clarification. What are the other soil nutrients? (Fig. 6a). Lines 523-524 should also be included and expanded in subsection 3.3.
6. Conclusions: Can the obtained results be used in agricultural practice in times of sustainable agricultural production? Do the authors see a need for further thematic research? If so, please indicate directions for further research.

Detailed comments:

Citations should be numbered consecutively, e.g. Lines 37 and 40 are: ..(Rosegrant and Cline, 2003); ...(Bouman et al., 2007)... Should be: [1]; [2] etc.

Line 117 - It should be: May 20, 2023, and May 23,  2024…….

References – Record references in the order they are cited in the manuscript. In addition, the References section should be adapted to editorial requirements. References no. 30 was not cited in the body of the manuscript. References no. 30 - Please check the correct spelling of the authors' names. References: 41 and 42; 46 and 47; 61 and 62 should be additionally marked with the letters a and b.

Best regards

 

Author Response

Dear Editor,

Many thanks for your letter regarding our manuscript (4089228). We are grateful for valuable comments made by yours that can greatly enhance the quality of this paper. We have addressed all the comments raised by the reviewer in the revised manuscript to improve the quality of this paper. In what follows, we have made all the changes in detail for response to the comments.

1. Comment: Keywords: The important macronutrient "total nitrogen" should be added

Response: Thank you for your comment. We have made the amendments in the manuscript.

2. Comment: Introduction: Why were the studies conducted using very good quality soils (black soils)?

Response: This study was conducted in black soils because our experimental site is located in the Northeast China black soil region, a strategic grain production base currently facing severe degradation, water scarcity, and a critical research gap in bio-based film application for paddy rice systems. All these rationales are elaborated in the introduction.

3. Comment: Materials and Methods: Subsection 2.1. Please provide soil classification according to IUSS Working Group 2014, 2022. Line 136 - Please provide the name and dose of the pesticide. Please provide the doses of all ingredients (in kg of pure ingredient per hectare). What fertilizer mixture with humic acids was used (add dose). Please include the composition of the Xin Balok fertilizer and the names of the enzyme bacteria. You should add the sources for the formulas listed in subsection 2.3 and the sources for the methods listed in subsection 2.3.5.

Response: Thank you for your precise suggestion. (1) We appreciate your suggestion. As required, the soil at the experimental site is classified as Haplic Phaeozem (Loamic) in accordance with IUSS Working Group (2014, 2022). This classification, based on the provided soil properties, has been supplemented in the relevant section of the manuscript (lines 105-106). (2) We have supplemented the details as follows: After pesticide application (Acephate, total active ingredient content 30%; 450–675 g ha⁻¹), a 4 cm water layer was maintained for 3 days. Fertilizers applied included: urea (N 46%) at 190 kg/hm², slow-release fertilizer (N 44%, with a 60-day release period) at 200 kg/hm², and a mixture of humic acid fertilizer, enzyme bacteria, and Xin Balok fertilizer at 750 kg/hm², all applied as a one-time base application (Enzyme-activated organic compound fertilizer (N+P2O5+K2O≥30%; organic matter≥10%); Humic acid bio-organic fertilizer (Fulvic acid≥12%; Organic matter ≥40%; Bacillus megaterium+ Paenibacillus mucilaginosus ≥ 0.5 100M/g); X-Balok (Organic matter content≥ 30%; Nitrogen, phos-phorus and calcium content≥ 5%) Enzymes 375 kg/hm2+ Organic fertiliser 300 kg/hm2 + Xin Balok 150 kg/hm2)(Lines 133-143).

 (3) We sincerely appreciate your insightful comment. As recommended, we have supplemented the specific literature sources for each formula presented in Subsection 2.3 and every research method detailed in Subsection 2.3.5 at their relevant locations in the manuscript. Additionally, we have carefully checked these citations to ensure their accuracy, completeness, and consistency with the journal’s citation format guidelines.

4. Comment: Results and Analysis: Table 3 and Table 5 - The same yield data has been provided (repeated). Yields should be reported in t ha-1. Table 4 - Missing units need to be completed. Figure 6a - the description of the results presented in figure 6a is missing.
5. Response: Thank you for your careful review and constructive suggestions. We have addressed all the issues raised as follows:
6. Table 3 and Table 5: The identical yield data was intentionally retained rather than deleted for specific scientific purposes, and all yield data have been uniformly reported in t ha⁻¹. Specifically, the yield data in Table 3 is presented to intuitively reflect the changes in yield components and their corresponding final grain yield. In contrast, the same yield data in Table 5 is retained for the direct calculation and presentation of irrigation water use efficiency (IWUE), which avoids readers having to cross-reference data between different tables and improves the readability and analytical convenience of the results.
7. We sincerely appreciate your insightful suggestion regarding the standardization of the yield unit. We have taken into account that after modifying the unit, the IWUE value will correspondingly decrease, which may reduce the accuracy of the IWUE (e.g., 10.4 becoming 0.10), and after careful consideration and checking of relevant references ([1,2]), we would like to respectfully request to retain the original yield unit kg/hm² in the revised manuscript, instead of converting it to t ha⁻¹. The detailed and reasonable reasons are as follows: Clear unit equivalence: First, we would like to clarify that the unit kg/hm² is completely equivalent to kg ha⁻¹, because 1 hm² (hectare) is the same as 1 ha (hectare) in terms of area measurement. The conversion relationship between kg/hm² and the suggested unit t ha⁻¹ is very clear: 1 t ha⁻¹ = 1000 kg/hm² = 1000 kg ha⁻¹. Therefore, retaining kg/hm² will not cause any ambiguity in data understanding, and readers can easily convert the yield data to the desired unit if necessary.

References

1. Sun, D.; Li, H.; Wang, E.; etc. An overview of the use of plastic-film mulching in China to increase crop yield and water-use efficiency. Natl Sci Rev 2020, 7, 1523-1526. https://doi.org/10.1093/nsr/nwaa146.
2. Chen, L.; Wang, R.; Xiao, W.; etc. Optimizing irrigation and mulching strategies to improve root–water relations, water use efficiency, and yield in apple–soybean alley cropping systems on the Loess Plateau, China. Eur J Agron 2025, 168, 127586. https://doi.org/10.1016/j.eja.2025.127586.

 

4. Consistency with relevant references and field academic conventions: A large number of classic and recent references in our research field (i.e., cold-region paddy rice production on black soils, plastic film mulching technology, and crop yield and water use efficiency research) widely adopt kg/hm² as the standard unit for reporting rice yield. Retaining this unit in our manuscript ensures consistency with the existing research results in the field, which is conducive to the comparison and reference of subsequent studies. More intuitive and clear data presentation: In our study, the rice yield values of different treatments are all in the range of 7000–9500 kg/hm². Using kg/hm² can present these values as integers, which makes the data more intuitive and easier to read and compare. If we convert them to t ha⁻¹, the yield values will be presented as decimals (e.g., 7.0–9.5 t ha⁻¹), which may reduce the readability of the data to a certain extent. We hope that you can understand and approve our request to retain the yield unit as kg/hm². We have ensured that all yield data in the manuscript are accurately reported and the unit is clearly marked in all relevant tables and text sections.
5. Table 4: We sincerely appreciate your careful reminder. We have fully addressed the issue of missing units in Table 4: all missing units for the measured indicators in the original Table 4 (now adjusted to Table 5 in the revised manuscript) have been supplemented and clearly marked in the table. For the specific indicators, the standard unit (%) (on a dry weight basis) has been added for Protein Content, which is consistent with the measurement method described in the Materials and Methods section; Sensory Evaluation Score is a dimensionless relative rating index based on a predefined scoring system, so no unit is required, and this has been clearly presented in the table. Additionally, we have conducted a thorough check to ensure that all units in the table are standardized and consistent with the relevant research methods.
6. Figure 6a: A detailed description of the results presented in this subfigure has been added in the corresponding part of the Results and Analysis section (Line 354).
7. Comment: Discussion: Lines 440-442 This sentence needs clarification. What are the other soil nutrients? (Fig. 6a). Lines 523-524 should also be included and expanded in subsection 3.3.

Response: (1) “It is noteworthy that temperature had a greater positive effect on production-related indicators, such as tiller number, biomass and yield than other soil nutrients (S0C, TC, Org-N, TN, C.N) (Fig. 6a)” Lines 436-438. (2) Thank you for your valuable suggestion. We have made the required revision. Please refer to Lines 353-359 in the revised manuscript for the content that includes and expands Lines 523-524 in Subsection 3 (“To explore differences among samples from different years and reveal relationships between key variables, we conducted correlation analysis and a principal component analysis (PCA). Temperature and irrigation volume are positively correlated with yield (Fig. 6a). Fig. 6b displays the PCA results, where PC1 and PC2 explain 51.6% and 28.4% of the total variance in the data, respectively. Soil organic carbon (SOC) and total carbon (TC) showed positive correlations with rice growth and quality, indicating that abundant soil organic matter positively influences rice development.”) (Lines 353-359).

6. Comment: Conclusions: Can the obtained results be used in agricultural practice in times of sustainable agricultural production? Do the authors see a need for further thematic research? If so, please indicate directions for further research.

Response: Thank you for your insightful suggestions. We have supplemented the conclusions section to address your questions as follows:

Applicability in sustainable agricultural production: The obtained results are directly applicable to agricultural practice in the context of sustainable agricultural production. Specifically, biodegradable films (BFs) with longer induction periods (especially BF₈₀) can be used as a practical alternative to conventional polyethylene (PE) films in the cold-region paddy rice system on black soils. They not only achieve comparable agronomic performance (slightly lower yield but higher irrigation water use efficiency (IWUE) and improved rice quality) but also reduce long-term plastic pollution and enhance soil carbon accumulation, which are consistent with the core requirements of sustainable agriculture.

Further thematic research: We recognize a clear need for further thematic research to promote the wider application of BFs. The main directions for future research are proposed as follows: (1) Adaptability of BFs with different induction periods in various climatic zones and soil types; (2) Long-term effects of consecutive BF application on soil ecological environment and crop productivity; (3) Combined application of BFs with other agronomic measures (e.g., nitrogen management, water-saving irrigation) to optimize sustainable production efficiency; (4) Development of low-cost BFs with tailored induction periods to meet the needs of different crop systems.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Brief Summary. This study evaluates the effects of biodegradable films (BFs) with varying degradation induction periods (45, 60, and 80 days) compared to polyethylene (PE) and control (CK) on soil temperature, moisture, rice growth, yield, irrigation water use efficiency (IWUE), grain quality, and soil C/N dynamics in Northeast China's black soils. The authors conducted two-year field experiments and found that BFs—especially BF80—can closely match PE in improving yield, IWUE, and soil carbon levels, while mitigating plastic pollution risks. The manuscript offers valuable agronomic insights and supports the broader transition to sustainable rice production systems.

General Comments. The study addresses a timely and relevant topic by exploring sustainable alternatives to plastic mulching in paddy fields, with strong alignment to climate resilience and environmental conservation goals. The experimental design is sound, well-controlled, and replicated over two seasons, enhancing the robustness of the conclusions. The integration of physiological, agronomic, and soil parameters is a notable strength. However, the manuscript would benefit from a clearer hypothesis statement and a more detailed discussion on the biodegradation behavior of the films under local soil–climate conditions.

 

Comments on Scientific Content and Methodology. The hypothesis that BFs with different induction periods would differentially influence hydrothermal conditions, rice growth, and soil C/N dynamics is sound but not explicitly formulated in the introduction. Consider clearly stating a testable hypothesis.

The use of a randomized block design with triplicates and appropriate controls (PE, CK) is commendable. The selection of a widely used rice cultivar and realistic field conditions increases the relevance of the findings.

While variance analyses are mentioned, more detail is needed about the specific tests used (e.g., ANOVA, post hoc tests) and assumptions checked. Some statistical significance markings in figures (e.g., Fig. 1, Fig. 4) need clearer explanations in captions.

The manuscript lacks quantitative data on the actual degradation rate or physical integrity loss of the biodegradable films over time. Including such data (e.g., weight loss, visual scoring, or microscopy) would strengthen the conclusions about BF80’s superior performance.

Although PE and CK are included, a degradation-inert biodegradable film (e.g., BF with no induction period) could have served as an additional control to decouple the induction vs. material effects.

 Figures and tables are mostly clear, but some legends (e.g., Table 1 and Fig. 2) are overly technical and would benefit from simplification or brief definitions of terms (e.g., “effective accumulated temperature”).

 

Specific Comments

The hypothesis is only implied and not clearly formulated. It is advisable to explicitly state the hypothesis in a testable form—for example: “We hypothesize that biodegradable films with longer induction periods more effectively improve soil thermal-moisture conditions, enhance rice productivity, and promote soil C and N cycling compared to short-period BFs and CK.” (Lines 91–99)

While statistical significance is shown with letters, it is unclear which comparison is made (e.g., among treatments or across years). Specify in the caption that the differences are within each stage and year. (Figure 1)

The table includes effective soil accumulated temperatures, but no statistical tests are mentioned directly. Add a row or note explaining the statistical method used (e.g., Duncan's multiple range test) and whether differences are year-specific. (Table 1)

The vertical color bars lack clear units and thresholds for each soil depth. Consider simplifying the legend and clarifying color gradients. Also, label growth stages directly on the x-axis. (Figure 2)

The standard deviations for LAI are relatively high in some treatments, particularly in CK. This should be briefly discussed—does this reflect higher inter-plot variability or physiological instability under CK? (Table 2)

The grouping and naming of “Stage 1–Stage 4” for tillering are not clearly explained in the Methods. Clarify how each stage was defined (e.g., by days after transplanting or phenological markers). (Lines 275–286)

Stage labels are inconsistent between the figure and caption. Either spell out or number stages consistently throughout. Also, visually separate PE and BFs bars using shading or patterns to improve contrast. (Figure 4)

The distinction between above- and belowground dry matter is clear, but the use of small fonts and dense legends makes interpretation difficult. Enlarge the y-axis label fonts and move legends outside the plot area. (Figure 5)

There is no indication of significance (e.g., a, b, c) for 1000-grain weight, despite moderate variation. This could be important for assessing quality. Please clarify. (Table 3)

The discussion states “no significant differences” but omits p-values or confidence levels. Including these would clarify whether effects were trending or negligible. (Lines 337–351)

There is no visual highlight of which BF treatment showed the most favorable balance of SOC and TN. Consider summarizing this trend in a concluding sentence or adding bold font to best-performing values. (Table 6 and Table 7)

The PCA plot (b) shows overlap between years but lacks sample loadings or treatment grouping ellipses. Consider improving readability by labeling clusters with treatment codes (CK, PE, BF45, etc.). (Figure 6)

The statement “high nitrogen levels may inhibit rice development” contradicts conventional agronomy unless excessive. Clarify whether this refers to excessive N supply, poor C:N balance, or physiological trade-offs. (Lines 357–364)

 

Additional Questions to the Authors

Did you visually or chemically monitor the actual degradation progress of the biodegradable films during the experiment (e.g., integrity scoring, weight loss, or surface morphology)? Can you provide supplementary evidence to confirm that BF45, BF60, and BF80 degraded according to their induction periods?

Given that soil carbon and nitrogen dynamics were assessed, did you consider evaluating how different mulching treatments may have influenced microbial activity or composition, especially in relation to nitrogen cycling?

Have you estimated the comparative cost-effectiveness or economic feasibility of using BF80 versus PE in terms of input cost per kg of yield or per unit of IWUE improvement?

Were there any differences in greenhouse gas emissions (e.g., CH₄ or N₂O fluxes) observed or expected among treatments, particularly given changes in soil moisture and C/N ratios?

Can you comment on the scalability of BF80 deployment in large-scale rice systems under mechanized planting and harvesting conditions? Are there any known operational constraints (e.g., film handling, timing of degradation) from the perspective of farmers or technicians?

Author Response

Dear Editor,

Many thanks for your letter regarding our manuscript (4089228). We are grateful for your valuable comments that can greatly enhance the quality of this paper. We have addressed all the comments raised by the reviewer in the revised manuscript to improve the quality of this paper. In what follows, we have made all the changes in detail for response to the comments.

1. Comment: The hypothesis is only implied and not clearly formulated. It is advisable to explicitly state the hypothesis in a testable form—for example: “We hypothesize that biodegradable films with longer induction periods more effectively improve soil thermal-moisture conditions, enhance rice productivity, and promote soil C and N cycling compared to short-period BFs and CK.”(Lines 91–99).

Response: Thank you for your comment. We have made the amendments in the manuscript “We hypothesize that biodegradable films with longer induction periods more effectively improve soil thermal-moisture conditions, enhance rice productivity, and promote soil C and N cycling compared to short-period BFs and CK.” (Lines 85-88).

2. Comment: While statistical significance is shown with letters, it is unclear which comparison is made (e.g., among treatments or across years). Specify in the caption that the differences are within each stage and year.(Figure 1).

Response: Thank you for your valuable suggestion. We have revised the caption of Figure 1 as follows: We deleted the original statement "Different letters within the same growth stage indicate significant differences between treatments (p < 0.05)"; The reasons for this revision are twofold: (1) The original statement was ambiguous and failed to clarify the comparison dimension of statistical significance, which is inconsistent with your comment pointing out that it is unclear whether the comparison is among treatments or across years; (2) The figure actually shows the dynamic changes of soil temperature during the entire growth stage in two separate years (2023 and 2024). The original description of "within the same growth stage" was not applicable to the continuous observation data, and the statistical comparison was actually conducted among treatments at the same observation time point within each year. The revised statement fully complies with your request to specify that the differences are within each stage and year, ensuring the accuracy and clarity of the statistical annotation.

3. Comment: The table includes effective soil accumulated temperatures, but no statistical tests are mentioned directly. Add a row or note explaining the statistical method used (e.g., Duncan's multiple range test) and whether differences are year-specific.(Table 1).

Response: Thank you for your valuable suggestion. We have added a note to Table 1 in the revised manuscript “Note: Statistical analysis was conducted using Duncan’s multiple range test (p < 0.05). Different letters within the same growth stage and column indicate significant differences between treat-ments (p < 0.05), and the same applies hereafter.” (lines 236-239). (2) We would like to clarify that differences between years were not statistically tested in this study—our experimental design was a 2-year repeated trial, and statistical analysis was independently conducted within each year (i.e., comparing treatments in the same phenological stage of the same year). To avoid misunderstanding, we have added a note to Table 1 in the revised manuscript: it specifies that the statistical method used is Duncan’s multiple range test (p < 0.05), and clarifies that the reported differences (marked by lowercase letters) only refer to treatment differences within the same year and the same rice phenological stage (with year-to-year differences not tested). This revision ensures the statistical scope of the table is clearly defined, consistent with our current analytical design.

4. Comment: The vertical color bars lack clear units and thresholds for each soil depth. Consider simplifying the legend and clarifying color gradients. Also, label growth stages directly on the x-axis.(Figure 2).

Response: Thank you for your insightful suggestions. We would like to clarify and optimize Figure 2 based on your comments:

1. Explanation of the heatmap and color bar:

This figure is a heatmap (the “hot map” you mentioned) used to visualize soil-water content dynamics. The vertical color bar (color gradient) represents the soil-water content (unit: g/g): different colors correspond to specific moisture values (e.g., dark blue = ~0.24 g/g, red = ~0.31 g/g), which allows readers to intuitively identify moisture differences across different soil depths (y-axis) and different rice growth stages (x-axis). We have added the unit “(g/g)” next to the unified global color bar (to replace repeated subplot color bars) and clarified the numerical thresholds of the color gradient, making this correspondence clearer.

2. Adjustment for x-axis stage labels:

We note your suggestion to label growth stages directly on the x-axis. However, the full names of the growth stages (e.g., “Jointing-booting stage”) are too long: horizontal labeling would cause text overlap (reducing readability), while vertical labeling would make the labels hard to recognize. Thus, we retained “stage 1–4” on the x-axis (for clarity) and strengthened the figure note (placing it directly below the x-axis) to explicitly link each “stage” to its full name (e.g., “stage 1 = Tillering stage”), ensuring readers can quickly match the labels to the actual growth stages. These revisions clarify the color bar, maintain the intuitive visualization of moisture dynamics, and balance readability with label clarity, fully addressing your concerns.

5. Comment: The standard deviations for LAI are relatively high in some treatments, particularly in CK. This should be briefly discussed—does this reflect higher inter-plot variability or physiological instability under CK?(Table 2).

Response: Thank you for your careful observation of the LAI standard deviations. We appreciate your suggestion, but we have decided not to add additional discussion on this point in the current manuscript. The high standard deviations (especially in CK) may be driven by multiple intertwined factors (e.g., field microenvironmental heterogeneity, individual crop growth differences, etc.), but our study design was focused on comparing the effects of different mulching treatments, and we did not conduct targeted experiments to distinguish the specific drivers of this variability. Given the lack of direct data to clarify the exact cause, we prefer to avoid speculative discussion here. We will consider investigating the drivers of such variability in our follow-up studies.

6. Comment: The grouping and naming of “Stage 1–Stage 4” for tillering are not clearly explained in the Methods. Clarify how each stage was defined (e.g., by days after transplanting or phenological markers).(Lines 275–286).

Response: Thank you for your suggestion. We have clarified the definition of each growth stage in the Methods section (Lines 137). Each stage was defined based on phenological markers (combined with specific calendar dates in the experimental years), and the corresponding periods for each growth stage in 2023 and 2024 are specified in supplementary table 1.

7. Comment: Stage labels are inconsistent between the figure and caption. Either spell out or number stages consistently throughout. Also, visually separate PE and BFs bars using shading or patterns to improve contrast.(Figure 4).

Response: Thank you for your suggestions. We first clarify the issue of stage label consistency: Figure 4 focuses on the dynamic change of rice tiller number (a key indicator of tiller development), so we subdivided the “Tillering stage” (used in other figures/tables) into 4 specific sub-stages (Early/Mid/Late tillering stage, plus effective tillers at maturity) and labeled them as “Stage 1–4” in this figure. In contrast, other figures/tables use “Tillering stage” to refer to the entire tiller period (which includes these 4 sub-stages), leading to the apparent label difference. (2) In the current version of Figure 4, different treatments (including PE and BFs) are represented by distinct, contrasting colors, and the corresponding legend (below the figure) clearly matches each color to its treatment. We have confirmed that these color distinctions allow readers to easily identify and distinguish PE from BFs bars.

8. Comment: The distinction between above- and belowground dry matter is clear, but the use of small fonts and dense legends makes interpretation difficult. Enlarge the y-axis label fonts and move legends outside the plot area.(Figure 5).

Response: Thank you for your valuable suggestion. We have revised Figure 5 as requested: we enlarged the font size of the y-axis labels to improve readability, and moved the legends from the plot area to the outer area (next to the figure). These adjustments make the figure clearer and easier to interpret.

9. Comment: There is no indication of significance (e.g., a, b, c) for 1000-grain weight, despite moderate variation. This could be important for assessing quality. Please clarify.(Table 3).

Response: Thank you for your follow-up. The lack of significant differences in 1000-grain weight among treatments is likely because 1000-grain weight is primarily determined by grain filling conditions in the late growth stage, and all treatments (including CK) provided relatively sufficient basic resources (e.g., light, nutrients) during this period. Our mulching treatments mainly regulated soil hydrothermal conditions in the early-to-mid growth stages (which affected traits like productive panicles and grains per panicle), but did not create large enough differences in the late-stage microenvironment (or nutrient supply for grain filling) to alter 1000-grain weight significantly—resulting in only moderate numerical variation without statistical significance.

10. Comment: The discussion states “no significant differences” but omits p-values or confidence levels. Including these would clarify whether effects were trending or negligible.(Lines 337–351).

Response: Thank you for your observation. To clarify: In our manuscript, significant differences among treatments are denoted using lowercase letters (based on Duncan’s multiple range test, p < 0.05). When treatments share the same letter (as seen for soil C/N and nutrient content in Table 6), this directly indicates no significant differences between those groups—so we did not additionally report p-values or confidence levels, as the letter notation already conveys this statistical result.

11. Comment: There is no visual highlight of which BF treatment showed the most favorable balance of SOC and TN. Consider summarizing this trend in a concluding sentence or adding bold font to best-performing values.(Table 6 and Table 7).

Response: Thank you for your valuable suggestion. We have added a concluding sentence in the corresponding discussion section: “Mulching had little effect on soil C and N in the very surface layer, at 0–5 cm, SOC, TC and N fractions did not differ significantly among CK, PE and BF treatments. By contrast, clear effects emerged in the 0–20 cm plough layer (Table 7), where SOC was consistently higher under BFs than under CK (BF₈₀ > BF₆₀ > BF₄₅), and generally not lower than under PE. In 2024, Org-N was slightly higher and TN slightly lower under BFs than under CK and PE, resulting in a modestly higher C:N ratio, especially under BF₈₀, indicating relatively greater C accumulation under biodegradable mulching.” (Lines 488-494)

12. Comment: The PCA plot (b) shows overlap between years but lacks sample loadings or treatment grouping ellipses. Consider improving readability by labeling clusters with treatment codes (CK, PE, BF45, etc.).(Figure 6)

Response: Thank you for the suggestion! Let me clarify why we’re keeping the plot as-is: The core goal here is to show how soil nutrients, yield, and quality traits connect across the two years (which is what this PCA is meant to highlight). If we added grouping ellipses for each treatment (CK, PE, BF₄₅, etc.), two issues pop up: It’d make the plot way more cluttered—we’d lose the clear view of how 2023/2024 samples (and their linked traits) relate to each other. Our sample size for each treatment is pretty small, so adding treatment ellipses would actually make the plot less readable: the ellipses would be overly variable (since there’s not enough data to define tight clusters), and that noise would overshadow the year-trait relationships we’re trying to show. Since we already detail treatment-specific patterns for these traits in other tables/sections, this plot is focused on its original job: keeping the focus on year-to-year trait connections, without extra complexity that muddles the key message.

13. Comment: The statement “high nitrogen levels may inhibit rice development” contradicts conventional agronomy unless excessive. Clarify whether this refers to excessive N supply, poor C:N balance, or physiological trade-offs.(Lines 357–364).

Response: Thank you for this critical observation. We apologize for the ambiguity in the original statement "high nitrogen levels may inhibit rice development", which gave the false impression of contradicting conventional agronomy. We have revised this sentence to clarify its exact meaning, and the key points are as follows:

To directly address your question: this statement does not refer to a general "high nitrogen level" (which would conflict with agronomic principles that appropriate nitrogen promotes rice growth). Instead, it specifically refers to two closely related scenarios in the context of our study: excessive nitrogen supply, and the subsequent poor soil carbon-to-nitrogen (C:N) balance (not independent physiological trade-offs). Conventional agronomy clearly recognizes that while moderate nitrogen supply is beneficial for crop growth, excessive nitrogen input will disrupt the optimal nutrient balance in the soil, leading to a poor C:N ratio—this, in turn, can cause issues such as reduced nutrient use efficiency, altered rhizosphere microbial communities, or imbalanced plant nutrient allocation, ultimately resulting in inhibitory effects on rice development. This is the exact connotation we intended to express in the original sentence. We have revised the relevant sentence in Lines 359–370, “Soil organic carbon (SOC) and total carbon (TC) showed positive correlations with rice growth and quality traits, indicating that abundant soil organic matter plays a beneficial role in rice development. Meanwhile, organic nitrogen (Org-N) exhibited a negative correlation with rice growth. It should be emphasized that this does not imply that high nitrogen levels per se inhibit rice development, but rather that excessive Org-N supply, which can disrupt the optimal soil C:N balance, may induce physiological trade-offs in rice plants (e.g., altered nutrient allocation or reduced resource use efficiency) and thus potentially exert an inhibitory effect on growth. The C/N ratio and total nitrogen (TN) content are also closely related to rice yield and quality, which requires further in-depth study to systematically elucidate the complex relationships between soil properties, yield, and quality throughout the entire rice growth process.”

 

Additional Questions to the Authors

Comment: Did you visually or chemically monitor the actual degradation progress of the biodegradable films during the experiment (e.g., integrity scoring, weight loss, or surface morphology)? Can you provide supplementary evidence to confirm that BF45, BF60, and BF80 degraded according to their induction periods?

Response: We greatly appreciate the reviewers’ insightful questions, which help to improve the completeness and depth of our study. We address each question as follows:1. Biodegradable film degradation progress monitoring. During the experiment, we did conduct quantitative determinations of the degradation progress of biodegradable films (BF₄₅, BF₆₀, and BF₈₀) at different rice growth stages (e.g., tillering stage, jointing-booting stage, and maturity stage). However, these data were not included in the original manuscript due to space constraints and our initial focus on soil nutrient and crop trait analysis.

Table 1 Degradation rates of different biodegradable films at the tillering stage in 2023 and 2024
Treatments	Degradation rate (%)
	2023		2024
	Mid-tillering stage	Mid-tillering stage	Mid-tillering stage	Mid-tillering stage
PE	5.8±1.2e	10.2±5.2c	3.7±0.6d	8.7±4.1c
BF45	18.7±5.7a	37.6±16.4a	8.2±1.5b	17.3±7.2b
BF60	11.3±2.3b	22.4±6.2b	10.2±3.4a	26.8±8.6a
BF80	9.5±0.8c	19.8±2.3b	6.1±1.8c	15.8±5.3bc

 

Comment: Given that soil carbon and nitrogen dynamics were assessed, did you consider evaluating how different mulching treatments may have influenced microbial activity or composition, especially in relation to nitrogen cycling?

Have you estimated the comparative cost-effectiveness or economic feasibility of using BF80 versus PE in terms of input cost per kg of yield or per unit of IWUE improvement?

Response: (1) Thank you for this insightful question. We did not conduct in-depth research on soil microbial activity, overall community composition, or their links to nitrogen cycling in this study, only analyzing soil fungal community structure. Inspired by your suggestion, we will carry out targeted follow-up studies to address this gap. (2) Thank you for this forward-looking inquiry. We did not estimate the comparative cost-effectiveness or economic feasibility of BF80 and PE in this study (including input cost per kg yield or per unit IWUE improvement). In light of your valuable suggestion, we will launch in-depth follow-up research to fill this critical gap.

Comment: Were there any differences in greenhouse gas emissions (e.g., CH₄ or N₂O fluxes) observed or expected among treatments, particularly given changes in soil moisture and C/N ratios?

Response: Thank you for this insightful question. We did not investigate differences in greenhouse gas emissions (e.g., CH₄ or N₂O fluxes) among treatments in this study, despite the potential associations with altered soil moisture and C/N ratios. This important research direction will be addressed in our follow-up studies.

Comment: Can you comment on the scalability of BF80 deployment in large-scale rice systems under mechanized planting and harvesting conditions? Are there any known operational constraints (e.g., film handling, timing of degradation) from the perspective of farmers or technicians?

Response: Thank you for this practical inquiry. BF₈₀ holds certain scalability potential in large-scale mechanized rice systems, as it can basically match the operational requirements of existing mechanized planting and harvesting equipment. Nevertheless, there are notable operational constraints: (1) Film handling: BF₈₀ has lower mechanical strength than PE film, making it more prone to breakage during high-speed mechanized laying; (2) Degradation timing: Its degradation rate is highly sensitive to soil moisture and temperature, with premature degradation reducing mulching effects and delayed degradation potentially interfering with mechanized harvesting; (3) Farmer/technician perspective: Limited awareness of its degradation characteristics and optimal operation parameters may hinder its on-field promotion and standardized application.

Author Response File: Author Response.docx