Effects of mild alternate wetting and  drying irrigation  and rice straw application  on N<sub>2</sub>O emissions in rice cultivation

Wu, Kaikuo; Li, Wentao; Wei, Zhanbo; Dong, Zhi; Meng, Yue; Lv, Na; Zhang, Lili

doi:https://doi.org/10.5194/soil-8-645-2022

Articles | Volume 8, issue 2

https://doi.org/10.5194/soil-8-645-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/soil-8-645-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 8, issue 2

Original research article

|

06 Oct 2022

Original research article |

| 06 Oct 2022

Effects of mild alternate wetting and drying irrigation and rice straw application on N₂O emissions in rice cultivation

Kaikuo Wu, Wentao Li, Zhanbo Wei, Zhi Dong, Yue Meng, Na Lv, and Lili Zhang

Download

Final revised paper (published on 06 Oct 2022)
Supplement to the final revised paper
Preprint (discussion started on 13 Jun 2022)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2022-429', Anonymous Referee #1, 29 Jun 2022

The authors conducted a laboratory pot experiment to investigate the effects of mild alternate wetting and drying (AWD) irrigation and rice straw application on N2O emissions in rice cultivation through 15N tracer technique. Their results showed that mild AWD irrigation increased cumulative N2O emissions by 28.8%. Adding rice straw to mild AWD irrigation further stimulated N2O emissions. These evidences have significance for monitoring N₂O emissions in paddy fields. However, I still have some comments here for the authors to address before it’s ready for publication.

For several places, there are something important missing for the authors to have their conclusions.

For example, in abstract L33-36 “mild AWD reduced GWP by 62.9%”, but there is neither GWP calculation nor CH4 data reported, which also lacks CO2 data.

L39-L42 Since either mild AWD or straw return increased N2O, it is difficult to directly conclude they are promising agronomic measures to reduce greenhouse effect.

L36-39 “mild AWD irrigation reduced N uptake by rice in the soil and rice aboveground biomass” This is also difficult to directly see the difference from either Fig. 4 or others. We can see adding either urea or straw increased N from N inputs instead of soil, but the difference between CF and AWD should be better presented.

In addition, the description of results was hard to follow. The authors compared their treatments of CK, S, U, U+S in all their figures and tables, but the main conclusion of this experiment was the effects of mild AWD irrigation, so the comparison between CF and mild AWD was often missing for statistics either in the figures or tables.

Finally, language needs improvement throughout the manuscript. For example, nitrogen can be replaced by N after first-time mentioning.

Minor points:

In Abstract, the description of treatments was missing.

L33 Numbers of percentage increase are needed here

L57 reduce water waste and environmental pollution

L65-67 Possible reasons to explain can be introduced here.

L70-72 It seems the balance between CH4 and N2O should emphasized.

L78-81 Way too long containing two which

L95-98 Combine or rephrase the purpose of this study.

L98-101 The hypotheses lack connection between each other

L103-107 2.1 can be combined with 2.2

L184 It is not one-way ANOVA in Table 2, which is three factors instead.

Fig. 1 legend font is too large

L198-202 The difference is dependent on treatments which needs to be specific.

L252-253 No direct evidence is from this experiment in the perspective of microorganisms.

L401-402 Correct “mild AWD irrigation…under mild AWD irrigation”

Citation: https://doi.org/10.5194/egusphere-2022-429-RC1
- AC1: 'Reply on RC1', Kaikuo Wu, 09 Jul 2022
  
  Dear editors and reviewer #1,
  Thank you very much for your comments concerning our manuscript entitled “Effects of mild alternate wetting and drying irrigation and rice straw application on N₂O emissions in rice cultivation” (egusphere-2022-429). We have endeavored to fully address them. These comments are of great significance to the optimization of our work. Here, we describe our answers to these questions in detail; the line numbers refer to the Revised Manuscript.
  
  Best regards,
  Lili Zhang
  
  Reviewer #1:
  The authors conducted a laboratory pot experiment to investigate the effects of mild alternate wetting and drying (AWD) irrigation and rice straw application on N2O emissions in rice cultivation through 15N tracer technique. Their results showed that mild AWD irrigation increased cumulative N2O emissions by 28.8%. Adding rice straw to mild AWD irrigation further stimulated N2O emissions. These evidences have significance for monitoring N2O emissions in paddy fields. However, I still have some comments here for the authors to address before it’s ready for publication.
  Answer: We thank you for your recognition and praise of our manuscript, and hope that our research can provide valuable reference for other colleagues.
  For several places, there are something important missing for the authors to have their conclusions.
  For example, in abstract L33-36 “mild AWD reduced GWP by 62.9%”, but there is neither GWP calculation nor CH4 data reported, which also lacks CO2 data.
  Answer: We further refined our conclusions and supplemented the CH4 data in the "Supplements". Please see lines 31-36.
  L39-L42 Since either mild AWD or straw return increased N2O, it is difficult to directly conclude they are promising agronomic measures to reduce greenhouse effect.
  Answer: We further described our conclusions and the limitations of this study in the Abstract and Discussion. Please see lines 45-48, 419, 436-438.
  L36-39 “mild AWD irrigation reduced N uptake by rice in the soil and rice aboveground biomass” This is also difficult to directly see the difference from either Fig. 4 or others. We can see adding either urea or straw increased N from N inputs instead of soil, but the difference between CF and AWD should be better presented.
  Answer: We further described the conclusion that under nitrogen fertilization conditions, rice under AWD irrigation absorbed less soil-derived nitrogen than under CF irrigation. Please see lines 42-45.
  In addition, the description of results was hard to follow. The authors compared their treatments of CK, S, U, U+S in all their figures and tables, but the main conclusion of this experiment was the effects of mild AWD irrigation, so the comparison between CF and mild AWD was often missing for statistics either in the figures or tables.
  Answer: We added the comparative statistics of CF irrigation and mild AWD irrigation in the manuscript. Please see lines 34-42, 202-205, 282-284, 305-309.
  Finally, language needs improvement throughout the manuscript. For example, nitrogen can be replaced by N after first-time mentioning.
  Answer: We replaced nitrogen with N.
  Minor points:
  In Abstract, the description of treatments was missing.
  Answer: We supplement the description of treatments in Abstract. Please see lines 27-31.
  L33 Numbers of percentage increase are needed here
  Answer: We increased the corresponding percentage. Please see lines 37-42.
  L57 reduce water waste and environmental pollution
  Answer: We perfected this sentence in the manuscript. Please see lines 62-63.
  L65-67 Possible reasons to explain can be introduced here.
  Answer: We added the reasons for rice yield reduction under severe AWD irrigation. Please see lines 69-72.
  L70-72 It seems the balance between CH4 and N2O should emphasized.
  Answer: This manuscript mainly focuses on the impact of AWD irrigation and rice straw returning on N₂O emissions, but in order to make the results more referential, relevant data of CH₄ are also introduced (Supplements).
  L78-81 Way too long containing two which
  Answer: This sentence has been revised. Please see lines 81-84.
  L95-98 Combine or rephrase the purpose of this study.
  Answer: We redefined the purpose of the study. Please see lines 102-104.
  L98-101 The hypotheses lack connection between each other
  Answer: We've refined the hypothesis. Please see lines 102-104.
  L103-107 2.1 can be combined with 2.2
  Answer: We combined 2.1 with 2.2 and added the description of soil properties. Please see lines 106-139.
  L184 It is not one-way ANOVA in Table 2, which is three factors instead.
  Answer: Table 2 was analyzed using univariate analysis of variance. Please see lines 188-190.
  Fig. 1 legend font is too large
  Answer: We have scaled down the legend of Figure 1. Please see lines 646-648.
  L198-202 The difference is dependent on treatments which needs to be specific.
  Answer: We further detail the differences in N₂O emission peaks between different treatments. Please see lines 200-205.
  L252-253 No direct evidence is from this experiment in the perspective of microorganisms.
  Answer: We have redefined the sentence. Please see lines 255-256.
  L401-402 Correct “mild AWD irrigation…under mild AWD irrigation”
  Answer: We confirmed the sentence in the manuscript. Please see lines 407-408.
  
  Citation: https://doi.org/10.5194/egusphere-2022-429-AC1
RC2:
'Comment on egusphere-2022-429', Anonymous Referee #2, 30 Jul 2022

please refer to the attachment.

Citation: https://doi.org/10.5194/egusphere-2022-429-RC2
- AC2:
  'Reply on RC2', Kaikuo Wu, 10 Aug 2022
  Dear editors and reviewer #2,
  Thank you very much for your comments concerning our manuscript entitled “Effects of mild alternate wetting and drying irrigation and rice straw application on N₂O emissions in rice cultivation” (egusphere-2022-429). We have endeavored to fully address them. These comments are of great significance to the optimization of our work. Here, we describe our answers to these questions in detail; the line numbers refer to the Revised Manuscript. However, the revised manuscript cannot be uploaded at this stage, and we await further notice from the editor.
  
  Best regards,
  Lili Zhang
  
  Reviewer #2:
  This present work aims to investigate the effects of mild alternate wetting and drying irrigation and rice straw application on N₂O emissions in rice cultivation. Your research work is interesting and somewhat innovative with ¹⁵N tracer technique, but it is suggested to repair major revision. The followings are the points need to be addressed and considered:
  Answer: Thank you for your recognition and praise of our manuscript, and hereby reply to your comments as follows.
  Paper explored the effects of mild AWD irrigation combined with rice straw return on N₂O emissions and rice yield through rice pot experiments. The authors should supplement the experimental treatment concisely.
  
  Answer: We supplement the experimental treatments. Please see lines 27-32, 113-117.
  In this study, compared with continuous flooding (CF) irrigation, mild AWD irrigation increased cumulative N₂O emissions, with an average increase of 28.8%. In addition, adding rice straw to mild AWD irrigation further stimulated N₂O emissions. Compared with CF irrigation, mild AWD irrigation increased the yieldscaled N₂O emissions, and the addition of rice straw further promoted the yieldscaled N₂O emissions under mild AWD irrigation but reduced the global warming potential (GWP) by 62.9%. Under the condition of urea application, compared with CF irrigation, mild AWD irrigation reduced nitrogen uptake by rice in the soil and rice aboveground biomass without reducing rice yield. This is mainly due to a weak problem statement and no clear enough of the extraction of the results. It is recommended to continue in-depth research on this issue.
  
  Answer: We've refined the hypothesis and further refined the Results and Discussion. Please see lines 36-42, 45-48, 102-104, 201-206, 269-272, 283-285, 287-290, 308-312, 351, 376, 427-438.
  In paper, it gives the illusion that introduction and conclusion was related to the effects of mild AWD irrigation, but a detailed comparison and account of mild AWD irrigation is lacking in the results.
  
  Answer: We have added a comparison of CF irrigation and mild AWD irrigation to the results. Please see lines 200-206，282-285，304-310.
  English language should be checked and revised throughout the entire manuscript. For example, the use of abbreviations in article. -L33-36 “mild AWD reduced GWP by 62.9%”, I don't see any description to greenhouse gas excepting the data of supplementary document.
  
  Answer: We improved the language and used abbreviations such as: Nitrogen is replaced by N after first-time mentioning. This manuscript mainly focuses on the impact of AWD irrigation and rice straw returning on N₂O emissions, but in order to make the results more referential, relevant data of CH₄ are also introduced (Supplements). In addition, we have also included additional clarifications in the manuscript. Please see lines 42, 414, 419-420, 432-433.
  -Line62-65: Please add reference.
  Answer: We have added the reference. Please see line 69.
  -Line117-119: Depth of soil?
  Answer: Described here is the thickness of the water layer above the soil.
  -Line119-127: Please the description of the test treatment corresponds to Line 110-114.
  Answer: We further describe the experimental treatments. This experiment included two irrigation methods, two N application levels, and two rice straw return levels, with three replicates of each combination, for a total of 30 rice pots (urea and straw were labeled with ¹⁵N, respectively). Please see lines 113-117.
  -L184: It involves three factors.
  Answer: Table 2 was analyzed using univariate analysis of variance, and we made annotations. Please see lines 190-192.
  -Line312-314: What is the purpose of description that N₂O emission is significantly affected by soil temperature?
  Answer: This experiment did not explore the influence of temperature on N₂O, so this part was deleted. Please see lines 319-320.
  -Line396-398: Compared with U, under CF irrigation and mild AWD irrigation, US reduced the uptake of soil-derived nitrogen by rice (the difference was not significant), please reorganize the meaning of the sentence.
  Answer: Combined application of urea and rice straw may be more beneficial to the maintenance of soil fertility than single application of urea. We have rephrased this sentence so that the reader can understand it better. Please see lines 402-406.
  -The abbreviation in the figures should indicate the full name.
  Answer: We explain the abbreviation in each figures and tables.
  -Fig. 4: It is suggested to put CF and AWD in the same picture for clearer comparison.
  Answer: We put CF and AWD on the same picture. Please see Fig. 4.
  
  Citation: https://doi.org/10.5194/egusphere-2022-429-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Publish subject to minor revisions (review by editor) (23 Aug 2022) by Ping He

AR by Kaikuo Wu on behalf of the Authors (25 Aug 2022) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (06 Sep 2022) by Ping He

ED: Publish subject to technical corrections (19 Sep 2022) by Jeanette Whitaker (Executive editor)

AR by Kaikuo Wu on behalf of the Authors (20 Sep 2022) Author's response Manuscript

Short summary

We explored the effects of mild alternate wetting and drying (AWD) irrigation combined with rice straw return on N₂O emissions and rice yield through rice pot experiments. Mild AWD irrigation significantly increased both N₂O and yield-scaled N₂O emissions. The addition of rice straw under mild AWD irrigation could promote N₂O emissions. Mild AWD irrigation could reduce soil-nitrogen uptake by rice when urea was applied. Mild AWD irrigation reduced rice aboveground biomass but not rice yield.

Effects of mild alternate wetting and drying irrigation and rice straw application on N2O emissions in rice cultivation

Download

Interactive discussion

Peer review completion

Effects of mild alternate wetting and drying irrigation and rice straw application on N₂O emissions in rice cultivation