A Critical Review of Biochar Application for the Remediation of Greenhouse Gas Emissions and Nutrient Loss in Rice Paddies: Characteristics, Mechanisms, and Future Recommendations
Round 1
Reviewer 1 Report
REVIEW COMMENTS
The present article focusses on the application of bio chars in crop improvement and the authors are appreciated for reviewing upon a topic which is of societal importance and much needed at present. However the following points can be discussed in detail.
1. The effect of pH on the performance characteristics of BC’s can be discussed in detail because there is a wide variation in pH for the used feedstock. So this factor also may have a notable effect on the application of BC’s in yield of the plants or increase in nutrients.
2. The points relevant to the effect of feed stock on a particular soil type (Table 2) can be discussed in detail.
3. It was stated that the microbial load is increased upon the usage of bio chars. The role of microbes in nutrient increase can be tabulated so that it may a source of information for various other researches in soil microbiology.
4. Production of various enzymes plays a vital role in promoting soil bioremediation and plant growth and yield. So the authors can address about the particular enzymes produced due to the use of bio chars.
5. The negative effects of using BC’s are discussed in detail. A possible solution for overcoming those can also be addressed.
Author Response
Replies to Reviewer 1：
The present article focusses on the application of bio chars in crop improvement and the authors are appreciated for reviewing upon a topic which is of societal importance and much needed at present. However, the following points can be discussed in detail.
- The effect of pH on the performance characteristics of BC’s can be discussed in detail because there is a wide variation in pH for the used feedstock. So this factor also may have a notable effect on the application of BC’s in yield of the plants or increase in nutrients.
Answer: Thank you for your valuable advice and recommendation. We more deeply discussed the effect of feedstocks on the pH of biochar to provide support for further application of biochar to the environment (L220-224).
- The points relevant to the effect of feed stock on a particular soil type (Table 2) can be discussed in detail.
Answer: Thank you for your valuable advice and recommendation. We have added this section (L293-306) and recommended biochar as a raw material for four different soil textures in order to alleviate environmental problems and increase rice yields as much as possible.
- It was stated that the microbial load is increased upon the usage of bio chars. The role of microbes in nutrient increase can be tabulated so that it may a source of information for various other researches in soil microbiology.
Answer: Thank you for your valuable advice and recommendation. We have added this section in Table 2
- Production of various enzymes plays a vital role in promoting soil bioremediation and plant growth and yield. So the authors can address about the particular enzymes produced due to the use of bio chars.
Answer: Thank you for your valuable advice and recommendation. We further discussed the role of enzymes in promoting rice growth and yield after the application of biochar (L313-317 and L335-338). In addition, the literature on specific enzymes produced by using biochar is very limited. We also stressed in the revised manuscript that this might be the direction of future research.
- The negative effects of using BC’s are discussed in detail. A possible solution for overcoming those can also be addressed.
Answer: Thank you for your valuable advice and recommendation. We have added possible solutions to overcome the negative effects of biochar in our conclusions and prospects.
Reviewer 2 Report
The authors wrote a very interesting review on biochar application in rice paddies. The authors reported very interesting findings about factors affecting biochar characteristics, biochar effects on rice growth and yield, and GHG emissions mitigation from rice fields, as well as potential negative effects and ecological risks of biochar application.
I recommend acceptand after a few minor revisions.
1. Please revise the title. I believe 'remediation' is not the most appropriate term.
2. Line 59 – „thus for“ please rephrase
3. The authors reported that 535 paper were included into the review, but there are only 202 references. Please explain – is it due to journal's limitations or some other reason?
4. Lines 223-226 „For a long time, …“ Part of the sentence is missing.
5. Please check all the manuscript for missing spaces and general formatting.
Author Response
- Please revise the title. I believe 'remediation' is not the most appropriate term.
Answer: Thank you for your valuable advice and recommendation. We have revised the title. ‘A critical review of biochar application for the improvements of greenhouse gas emissions and nutrient loss in rice paddies: Characteristics, mechanisms, and future recommendations’
- Line 59 – „thus for“ please rephrase
Answer: Thank you for your valuable advice and recommendation. We have revised it.
- The authors reported that 535 paper were included into the review, but there are only 202 references. Please explain – is it due to journal's limitations or some other reason?
Answer: Thank you for your valuable advice and recommendation. We revised the presentation here, and in fact we filtered 535 papers by keywords and topics of the publications, after which we determined their relevance to the topic of this work, based on titles and abstracts, and obtained more than 200 papers that were closely related to the topic.
- Lines 223-226 „For a long time, …“ Part of the sentence is missing.
Answer: Thank you for your valuable advice and recommendation. We have revised the sentence.
- Please check all the manuscript for missing spaces and general formatting.
Answer: Done.
Reviewer 3 Report
In the proposed study, the authors gave an overview of the current knowledge about the influence of the most important parameters on the characteristics of the obtained biochars, and considered their application from the aspect of the remediation of greenhouse gas emissions and nutrient loss in rice paddies. The manuscript is very well organized and has collected knowledge from numerous studies. Certain deficiencies have been noted and need to be corrected before publication.
1. Minor English and typographical errors need to be corrected.
2. Authors are encouraged to add a graphical abstract.
3. Although the authors point out that there are no review papers on this matter, in the introduction part it is necessary to give a brief review of the application of biochars application so far in addition to the applications for improving the soil quality.
4. At the end of the paragraphs in part 2., draw a comprehensive conclusion that provides insight into the influence of the process parameters and the selected biomass, for example, which factors ensure better carbon stability and why it is important.
5. In section 5.1. can the authors, based on the collected knowledge, propose how to reduce the presence of toxic substances in BCs?
Author Response
- Minor English and typographical errors need to be corrected.
Answer: Thank you for your valuable advice and recommendation. We have revised the manuscript carefully.
- Authors are encouraged to add a graphical abstract.
Answer: Thank you for your valuable advice and recommendation. We have added this section.
- Although the authors point out that there are no review papers on this matter, in the introduction part it is necessary to give a brief review of the application of biochars application so far in addition to the applications for improving the soil quality.
Answer: Thank you for your valuable advice and recommendation. We briefly reviewed the application of biochars in various environments (L313-317).
- At the end of the paragraphs in part 2., draw a comprehensive conclusion that provides insight into the influence of the process parameters and the selected biomass, for example, which factors ensure better carbon stability and why it is important.
Answer: Thank you for your valuable advice and recommendation. We have added this section (L240-245) and discussed the effects of process parameters, modification methods and selected biomass feedstocks on biochar characteristics to provide support for the further application.
- In section 5.1. can the authors, based on the collected knowledge, propose how to reduce the presence of toxic substances in BCs?
Answer: Thank you for your valuable advice and recommendation. We have added possible solutions to reduce the presence of toxic substances in BCs in our conclusions and prospects (L556-559).
Round 2
Reviewer 3 Report
Manuscript can be considered for publication.
