Modified Biochars and Their Effects on Soil Quality: A Review

Reviewer # 1

We are highly thankful to reviewer for reviewing our manuscript, appreciations and valuable suggestions to improve the quality of paper for publication in Environment.  Our responses to the specific comments are as following:

Reviewer’s Comment

Response

I have a main question about the title of the manuscript. Is about soil health?

Soil health is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans but the manuscript lacks any relevant information about the effect of modified biochars for  filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic contaminants in soil; an important aspect of soil health. For more details see https://doi.org/10.1016/j.scitotenv.2022.153054,  https://doi.org/10.3390/toxics9080184

We have revised soil health as soil quality.

Soil filtration is deeply mentioned in soil hydraulics properties, while the buffering capacity of the soil is well defended in soil pH attributes linked with modified biochar. Besides, there are no studies related to the detoxification of organic and inorganic matter by using modified biochar. The linked research articles are only related to biochar not related to modified biochar. 

·         Abstract - please emphasize the main message. Current version is a bit off topic with long introduction and lack of main message.

Added

·         Introduction. Authors should end this section with a clear statement what we know and what we need to know. Please add a few sentences at the end. Moreover, the statement ‘’….and a comprehensive review is still missing to address the effect of various modified  BCs on soil health’’ is not true.

Suggestions are incorporated

·         Section 6 :This section is too short and needs additional serious work (see https://doi.org/10.1016/j.scitotenv.2021.148756

Suggestions are incorporated, we have combined this section into conclusion

·         Summary and future considerations –. What we know and what else we need to study? What are the main differences between pristine and modified biochars that we have keep in mind?

·         Further research is urgently required to determine how modified BCs influences the environmental fate and to verify the proposed mechanisms involved in modifying BC properties for soil health improvement. For instance, BC modification by Cd risked the Cd desorption due to aging. The major disadvantage of ball milling modified BC is their finer size, which poses potential risk of ground water pollution. In addition, the stability of BC after pollutant absorption is also a main concern. Recently, little efforts have been done to explore the effect of modified BCs on soil born microbes and plants, so further studies are deliberately required to expose their environmental risk before their more intensive exploitations. Moreover, new development in analysis of BCs properties and surface functional groups will no doubt be pivotal to uncovering the hidden dimensions of microbe’s interactions and soil nutrients, and pave the way for sustainable agriculture development. However, some are risks of modified BCs that must be consider for developing BCs.

·         Pristine biochar is its original condition or unspoilt biochar, however, is chemical modification of biochar with the use of acids, bases or polymers usually enhances its adsorption efficiency is called modified biochar.

Reviewer # 2

Thank you for reviewing our manuscript, appreciations and making correction to improve the quality of paper for publication in Environment. The suggested changes have been added.  A brief of these changes are as follows:

Reviewer’s Comment

Response

The abstract reports long sentences, which should be shortened. The long sentences should be broken into 2 small.

Suggestions are incorporated

line 16, poor word selection, chemical and mineral? use only one word

Suggestions are incorporated

Introduction line 31, rephrase biochar and its application as biochar application

Rephrased

Please very precisely mention the objectives of this review. the introduction needs to be improved. A proper background of the studies is required. What are you going to report? A good introduction leaves open questions which should be answered in the next sections. 

Suggestions are incorporated

Please summarize, what you have reviewed here and what you are reporting in this review. Add this info in abstract.

Suggestions are incorporated

Heading 4.4 rephrase as biochar modification with microbes

Rephrased

Line 461, the name of biological entities should be italicized. Please check other places too. 

Italicized.

I suggest combining heading 6 together with conclusion. 

Combined

Please be specific with the conclusion. To me the authors have described the ways of biochar modification and its application effects of on soil health and quality, what they report in conclusion is something else. The lack of specificity is crucial and hence must be revised to match the contents of the review.

Suggestions are incorporated

Reviewer # 3

We are highly thankful to reviewer for reviewing our manuscript, appreciations and valuable suggestions to improve the quality of paper for publication in Environment.  Our responses to the specific comments are as following:

The review summarizes some interesting information about the effect of modified biochar on soil fertility, but in my opinion a lot of improvements are need before to reach a level sufficient for publication in an international audience.

Suggestions are incorporated

have you only positive notice about biochar? any concerns? i.e. organic contaminates such as PHA?

Most Positive effects, but still have some potential negative effects and  risks, we  have added these issues in Conclusions and future  prospects section

Frist of all provide the definition of biochar?

Provided

This sentence is nonsense

Deleted

This sentence is unclear, revise it.

Revised

Is it important to report all these effects in this point

Yes, firstly cited in introduction

Please report some information about the review process how you have selected the references? please report the keywords used and the databases consulted

Its based on the recent literature based on the single theme i.e. the effect of modified biochar on soil quality, so, there is no need to add key findings here. It represents the importance of this review based study.

I suggest you to introduce an index of chapters and evidence, in the introduction, the structure of the review, because it is not clear how you have organized the review

Added

In my opinion the chapters 2 and 3 are out of focus of review: the modified biochars. My opinion must be deleted or summarized in the introduction.

These sections highlights why the BC use is important for plant and soil health.

Physiochemical

Physio-chemical

Technique

Techniques

No reference

Cited

popular chips? how do you mean? Popular chips I suppose.

Changed

Please use only one approach: sodium hydroxide (NaOH) or NaOH (sodium hydroxide) not either.

Suggestions are incorporated

Auricular is a fungus, please report the scientific name correctly.

Added

The soil health is a controversial term, I suggest you to report an exact definition as you intend as soil health. In my opinion your use of this term in the review is more similar to soil quality concept as reported by Doran & Parkin 1994

Changed, we have revised soil health as soil quality

Gas exchange? Please introduce this argument in chapter, because it is not reported anywhere

Highlighted

In my opinion the increase of enzymatic activities of soil it is not directly related to the soil health or the enzymatic activities would be a measure of soil health. I suggest you to rewrite this sentence

Rewritten