Simulating the Long-Term Effects of Fertilizer and Water Management on Grain Yield and Methane Emissions of Paddy Rice in Thailand

Comments and Suggestions for Authors

Revision / Answers

Form suggestions

English must be carefully revised in some paragraphs and check the entire manuscript: Please avoid using the personal manner of addressing “we”, “our”, and use the impersonal one; the text will sound much more professional (i.e. in a single paragraph L519-527, 2 "we" and one "our).

Thank you for comment and suggestion in the revision. We have rewritten the personal manner as followed your comments which are listed below.

-        “We used the Denitrification-Decomposition(DNDC) model to simulate grain yield…” was changed to “The Denitrification-Decomposition (DNDC) model was used to simulate grain yield…” (Page 1)

-        “…., we collected the field management data from RF…” was changed to “….., the field management data were collected from RF…” (Page 4)

-        “…, we compiled the soil data from the Land Development Department of Thailand.” was changed to “…..,the soil data were compiled from the database of the Land Development Department of Thailand” (Page 6)

-        “We then analyzed the effects of three fertilizer managements (F, M and F+M) with three water managements (CF, MD and AWD) on the simulated grain yield and emissions of CH₄.” was changed to “The effects of three fertilizer managements (F, M and F+M) with three water managements (CF, MD and AWD) on the simulated grain yield and emissions of CH₄ were then analyzed.” (Page 8)

-        “Therefore, we focused on grain yield and CH₄emissions…” was changed to “Therefore, this study focused on grain yield and CH₄emissions…” (Page 10)

-        “…., we considered the simulated grain yield only in the wet season.” was changed to “…, only the simulated grain yields in the wet season were considered.” (Page 11)

-        “As compared with CF, we found that AWD irrigation increased the rice grain yields…” was changed to “As compared with CF, it was found that AWD irrigation increased the rice grain yields…” (Page 12)

-        “We used the “irrigation” option…” was changed to “The “irrigation” option with a marginal flooding (water layer thickness varying be-tween –5 and 5 cm) for 15 to 60 days after planting in AWD irrigation was used in the present study” (Page 18)

-        “…., we found that the wet and dry soil conditions…” was changed to “it was found that the wet and dry soil conditions…” (Page 18)

-        “Our study highlights that additional management….” was changed to “This study highlights that additional management….” (Page 19)

-        “However, we also noted that….” was changed to “This study also noted that….” (Page 19)

Table 1. Please revise the head of the Table. First column has no head of the table - please reposition it. Agement not agement. What is Man- column? it is empty.

We were sorry for the lack of clarity. It was an error in the table header preparation.

I have edited the table header in the first column to“Management practices”.

Under the Table, please explain in full all abbreviations used in the Table (according to the Instructions to the authors that you will find at the link: https://www.mdpi.com/journal/agriculture/instructions)(RF, RR, etc.)

Thank you for comment and suggestion. We have added all abbreviations under the table. They are listed below.

-        RF is the single rice cropping system of fallow land in the dry season and rice in the wet season.

-        RR is the double rice cropping system in the dry and wet seasons.

-        NPK is a compound fertilizer of N: P₂O₅: K₂O (15:15:15).

-        Urea is 46:0:0 of nutrient (NPK) contents.

References must be written in the consecrated MDPI style. i.e. for Journal Articles:
1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range. I suggest to check the same Instructions of Authors mentioned above, in this regard, providing all and just the information requested. Please do not forget adding the accession date for the links used.

Thank you very much for comment and suggestion.

We have rewritten the references by downloading the file of MDPI ACS Journals style for Endnote.

Content suggestions

Keywords must to reflect the main characteristic words of the paper (usually reflected also by the title. So, I suggest the following keywords: long-term effects; fertilisers and water management; grain yield; methane emission; paddy rice; Thailand; DNDC model; GHG mitigation.  

Thank you very much for suggestion in the keyword modification.

We have changed the keywords as followed your suggestion.

Many Results part, but in my opinion, some tables presented in the 2nd sections must be also moved in the Results part - they describing results/observations during their research!). Additionally, I suggest dividing the actual section 3. Results and Discussion in 2 separate sections, according to the same Instructions for authors.  

Discussion: Authors should discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible and limitations of the work highlighted. Future research directions may also be mentioned. 

We were sorry for unclear discussion. As your suggestion, we have modified this section by dividing the section 3. Results and Discussion in two separate sections, according to the “Instructions for Authors “including

Section 3. Results

Section 4. Discussion

If the authors chose to keep the combined section 3.Results and Discussion (which Agriculture journal allows), the Discussion part (which is poor in the actual manuscript) must be much better developed, including some similarities/differences between the results obtained in this research and other papers in the topic. From a total of 51 references, less than 10 are used for sustaining the Discussion part, which usually is the best referenced part of a study. Few ideas I suggest to be added in order to develop the part of Discussion:

·       maybe a Table summarising comparative data with other papers, having as last column the Ref.  (References used)

·       a paragraph about the water management in general, in Thailand, in the case of grain crops;

·       a paragraph about fertilisation/long-term fertilisation, its importance/role and its inevitable consequences (maybe correlated with Thailand climate). In this regard, please check and refer to Bungau et al. Expatiating the impact of anthropogenic aspects and climatic factors on long term soil monitoring and management. Environ Sci. Pollut. Res. 2021, 202, 30528-30550. https://doi.org/10.1007/s11356-021-14127-7

·       soil proprieties and changes under water and fertilisers management - as it is presented in Samuel A.D. et al.., Enzymological and physicochemical evaluation of the effects of soil management practices,  Rev. Chim. 2017,  68(10),  2243-2247.  https://doi.org/10.37358/RC.17.10.5864      

·       at the final of Discussion, please highlight in a separate paragraph the strengths and the weakness (if there is one)  of the present study.

Thank you for good suggestion. We have modified this section based on your suggestions above.

Question: can simulation from a model help improving rice yield and sustainability?

Due to this study applied the DNDC model to investigate the effects of fertilizer and water management practices on rice yield and CH₄ emission in the long-term. The finding showed appropriate options for many rice varieties and cropping systems. These finding could be promising options for sustainable rice production in Thailand.

The strong point of the manuscript is the quality of the writing and the relevance that these preliminary results may have for Thai rice cultivation. The weak point is that the results are pretty poor. However, the topic is interesting for the agricultural communities.

Thank you very much for comment in our manuscript.

Introduction: it is pretty complete, but the objectives must be re-arranged and clearly defined

Thank you for good comment. So, we have re-arranged and clearly defined the objectives in the last paragraph of Introduction section.

Methodology: well described, check the specific comments for minor changes

We have checked the specific comments and revised.

Results and Discussion: the results presented in Figure 3 are poor. It is true for grain yield, you have a high correlation, but looking at the plot, there are two values (RF (F) and RR (M+F)) which drive a regression line that doesn’t represent what’s going on. The explanation of the results and their Discussion is well written.

Thank you very much for comment in our data. Because it was a field experiment in a short-term, these data are quite limited.

Conclusions: these are probably a bit too sharp. Your work did not show terrific results, but your finding may help develop more sustainable and efficient rice cultivation in Thailand. This is worth emphasising! Stress that irrigation and fertilisation practices may follow the advice that can be retrieved from your findings, although further research will be needed. Second, stress that your findings may be the basis for setting up future experimentation based on field trials,…

Thank you for good comment. As you indicated, we have rewritten the paragraph of conclusion to be more clearly and suitable for our findings.

Last, I warmly suggest including a table of the acronyms as there are so many acronyms in the manuscript that it is pretty complicated to follow it.

Thank you for good suggestion. We have added list of acronyms at the last section.

Here are some specific comments:

Line 49: pleas, keep tons as the rest of the manuscript

Thank you for comment. The “7 million metric tons”was changed to “7 million tons” (page 2).

Line 70: is instead of was. Moreover, the acronym should always be explained, although very popular. You explain it in line 83, but it should be clarified the first time you use it.

As you suggested, we have changed the sentence of “…the second source of GHG emissions was the agriculture sector”  to  “…the second source of greenhouse gas (GHG) emissions was the agriculture sector” (page 2).

Line 104: specify here it is the denitrification-decomposition model and not in line 123

As you suggested, we have rewritten the sentence in Line 104 to “The denitrification-decomposition (DNDC) model is a computer simulation….” and deleted “denitrification-decomposition” in line 123 (page 3).

Line 120: is it 2011-2050 or 2010-2050? Please, compare with the abstract

Thank you very much. As you indicated, we haverevised the years in abstract to “ 2011-2050”.

Line 133: useless statement, you say the same thing later

Thank you for comment.  We have modified the original sentence and paragraph in section 2.1 to be clearer (page 3).

Lines 148-149: “under the different fertiliser management options and cropping systems.” Information about this statement is needed; refer to Table 1

Thank you for comment.  We have referred this statement to Table 1.

Line 282: experiments

We have revised “experimants” to “experiments”

Line 286-287: you can’t state this with such a low correlation

We have deleted this sentence.

Line 382: SOC was also found to be the best predictor for subsoil of bulk density. (https://doi.org/10.1016/j.scitotenv.2021.146609). Therefore, your results may also be driven by the efficiency of the irrigation practice. Please, speculate about this.

Thank you very much for suggesting this article. It is important for our study.

For more clarity, we have revised the discussion part of SOC and irrigation practice on grain yields.

Line 519: please, rephrase this statement as it is very vague

Sorry for unclear statement. We have deleted this statement.

Line 520: yield

We have revised “yiled” to “yields” (page 19).

Even the paper have been improved in some parts, the authors avoided to respond punctually to my requests, regarding Discussion section (as it can be seen from their letter also) - which now is separately but having same missing points. From my previous report, please respond to the points bellow, none of them addressed in the actual shape:

Sorry for missing discussion points. It is my misconception that when I have revised according to the first suggestion, it is fine.

However, I have revised and improved the discussion part based on your comments.

From a total of 51 (now 52) references, less than a quarter are used for sustaining the Discussion part, which usually is the best referenced part of a study. Few ideas I suggest to be added in order to develop the part of Discussion:

Thank you for comment and suggestion. We have added more references (now total 58 references) and improved this section followed your comments which are listed below.

·       maybe a Table summarising comparative data with other papers, having as last column the Ref.  (References used)

Thank you very much for good suggestion. According to make the discussion section clearer. We have made a Table 6 for summarizing comparative simulated data of the DNDC model performance with other papers.

·       a paragraph about the water management in general, in Thailand, in the case of grain crops;

We have added a paragraph about the water management in general, in Thailand and in the case of grain yield at the end of section 4.2

·       a paragraph about fertilisation/long-term fertilisation, its importance/role and its inevitable consequences (maybe correlated with Thailand climate). In this regard, please check and refer to Bungau et al. Expatiating the impact of anthropogenic aspects and climatic factors on long term soil monitoring and management. Environ Sci. Pollut. Res. 2021, 202, 30528-30550. https://doi.org/10.1007/s11356-021-14127-7

Thank you for suggesting a good paper. This paper was used to discuss in section 4.2.

·       soil proprieties and changes under water and fertilisers management - as it is presented in Samuel A.D. et al.., Enzymological and physicochemical evaluation of the effects of soil management practices,  Rev. Chim. 2017,  68(10),  2243-2247.  https://doi.org/10.37358/RC.17.10.5864      

Thank you very much for suggesting a good paper.

Because the research in this paper was studied in crop rotation of wheat, soybean and oats-clover with maize fields. This may not be consistent with our study, which mainly focuses on the rice field system. So, we do not use this paper for discussion.

·       at the final of Discussion, please highlight in a separate paragraph the strengths and the weakness (if there is one)  of the present study.

Thank you for comment.

The final of the discussion has been modified to make it more appropriate. The main findings, the limitation of the present study, and suggestions for future study are presented in the section “5. Conclusions and Suggestions for future study”.