The Influence of Remediation with Bacillus and Paenibacillus Strains and Biochar on the Biological Activity of Petroleum-Hydrocarbon-Contaminated Haplic Chernozem

Round 1

Reviewer 1 Report

The manuscript entitled “The Influence of Remediation with Bacillus and Paenibacillus Strains and Biochar on the Biological Activity of Petroleum hydrocarbons - Contaminated Haplic Chernozem” reports the results upon the effect of bacterial strains and biochar remediating petroleum hydrocarbons–contaminated soil and the associated ecological state of the soil. Seven groups of experiments with/without the separated or combined involvement of  Strains of Bacillus and Paenibacillus bacteria and biochar were conducted in simulated petroleum-contaminated soils. The study also investigated the ecological state of the remediated soils by determining CO₂ emissions, the number of soil bacteria, the germination indicators, the morphological parameters of barley roots and enzymatic activities. The most valuable findings lie in the instructive contributions of informative biological indicators after remediation. However, its current status may not be suitable for publication in the journal due to the weak experimental design and the overall presentation. It’s strongly suggested that the following comments need to necessarily be addressed before that:

1. The focus of this study was not prominently presented.

In the Abstract, the most valuable findings were not fully expressed. Lines 11-19 are only about the introduction of background and how “the study is done”. Lines 19-21 are information of little significance and can be deleted. When cutting the last sentence in lines 24-25, the reviewer cannot identify enough results and findings/conclusions from the rest three lines. Each word in such a section needs to be used preciously.

The first two sentences are irrelevant to the study and the authors should focus on why this investigation is significant, not the remediation. This research area has been done by numerous researchers. Why this research is necessary and unique? This part needs to be rewritten.

2. In the Conclusions, the reviewer did not see the conclusive summaries, but only the straightforward results presentation. This part needs to be rewritten.

3. In the Introduction, the authors should reorganize the overall structure to avoid scattered narration. A clear and concise logic is highly necessary. The significance/novelty of this study is suggested be the relatively comprehensive evaluation on the ecological state of the remediated soil. Too many studies conducted bacterial strains and biochar-associated soil remediation investigations with sophisticated experimental designs.

4. In the Discussion part, the authors presented a loose discussion but failed to refine the content and express the main views. It’s suggested to divide several parts and each part should provide a clear/conclusive summary. Two or three main points are suggested and all the discussion should be revolved around.

5. line 148: The experimental design is weak. In addition, B, BP, BPx100---B+BP, B+BP x100---Binc.+BP, Binc.+BP x100 are suggested as the names for clear presentation.

6. The determination method is controversial and more details/explanations are needed to be provided.  

7. Table 1 is suggested to be moved to the Supplemental Materials.

8. In the  Results, the authors waste too much ink on describing the figure and data, but failed to show the main trend/discovery. Not every piece of information is needed to be shown in words.

9. A correlation test is needed to determine the overall relationships between these variables (CO₂ emissions, the number of soil bacteria, the germination indicators, the morphological parameters of barley roots and enzymatic activities). The current data presentation is too simple.

10. The authors did not provide an in-depth explanation/discussion on why BP+B group showed superior performance. The decomposition mechanisms are unclear. Thus, the reviewer did not see the valuable findings in the last Conclusions part.

11. The meanings and underlying purpose of testing the indicator need to be clearly presented.

Author Response

I thank the reviewer for the work done. His comments helped to significantly improve the text of the article.
Probably I could improve more if more than 8 days were given to respond to comments.

Author Response File: Author Response.docx

Reviewer 2 Report

Very interesting topic of the article.

The abstract and introduction are written correctly.

Chapter material and methods 2.1. on line 102 the authors cite the literature on properties. The article is available on line, however, I am asking for a broader description of the soil in this chapter.

line 129-130 shows the % biochar that has been added. why 1%? on what basis was it calculated?

line 136-137? same question as above. why 5% concentration added? how was it calculated?

the rest of the methodology was written very extensively and clearly.

chapter results.

above line 207 - please use English, not Russian.

research results presented extensively and discussed in detail, divided into sections. Completed with graphics.

discussion chapter.

line 336, table 2. Please explain whether the data in table 2 are your own results? if so, they should be included in the test results section. If the data comes from other sources, please provide a reference in the literature.

Considering the extensiveness of the research results, the discussion chapter is definitely too short in my opinion. Also, there are too few citations of literature in this chapter and this needs to be corrected.

Please also specify the conclusions in more detail, indicate the novelty in the conducted research. The conclusions presented in the paper are a repetition of the research results.

Author Response

I thank the reviewer for the work done. His comments helped to significantly improve the text of the article.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors addressed most of the comments. However, all the corresponding corrections should be clearly shown with line numbers. It took an unnecessarily long time to identify them.

1. In figure 1, group names in the experimental design are not updated.

2. The reviewer did not identify the correlation test presented in figure form.

Author Response

Author responses to reviewer (1) comments

(agriculture-2218250)

To Reviewer #1

The authors addressed most of the comments. However, all the corresponding corrections should be clearly shown with line numbers. It took an unnecessarily long time to identify them.

1. In figure 1, group names in the experimental design are not updated.

Text have been corrected.

2. The reviewer did not identify the correlation test presented in figure form.

Text have been corrected.

Author Response File: Author Response.docx