Effects of Straw Maize on the Bacterial Community and Carbon Stability at Different Soil Depths

Round 1

Reviewer 1 Report

In the article, the authors studied the effect of straw application on the bacterial community and carbon stability at different soil depths. This topic is relevant because organic carbon plays an important role in regulating global climate change and affects the structure of terrestrial ecosystems and crop yields. It is important to use organic additives to improve soil quality.

The work is relevant, but there are a number of comments:

1. What database was used to determine the structure of the bacterial community? What next steps were taken after sequencing? Section 2.4 should be supplemented.

2. There are no tables 1 and 3 in the text of the article.

3. The figures in the article are hard to read (Figures 1, 3, 4).

4. What is indicated by the letters ‘a, b, c, d’ in the figures? For example, pictures 2, 3, 4.

5. Why did the authors limit themselves to phyla when studying the structure of the community? It may be worth looking at changes in the structure of dominant genera.

6. What is the novelty and essence of the work?

Sincerely, reviewer.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In the article, the authors study the impact of straw return on soil carbon and soil bacterial community. Straw return is a good practice to improve the quality of agricultural soils. However, there are a number of questions and comments to this article.

General comments and questions:

1) What is the general relevance of this work? In general, the increase in carbon content when straw is applied is not a big surprise.

2) Is there any practical significance of the results of this study, expressed, for example, in increasing the yield of corn?

Specific remarks

1) Keywords: It is better to replace «Physical protection» with «protected C», because the paper deals not only with physically protected carbon, but also with other types of protection

2) Section «2.1. Site description», Table 1 is missing

3) Section «2.2. Experimental design and soil sampling». From the description of the sites (0-20, 0-40, 0-60 cm), it is not very clear to what depth the straw was brought in - only 20, 40, 60 cm or throughout the entire thickness of the soil (from the surface of 0 cm to 20, 40, 60 cm respectively)

4) Section 2.3. Fractionation scheme of SOC. It is better to decipher what the abbreviations MA, MA(c)POC, Free(f)POC and M(f)POC, etc. mean.

5) Figure 1. The figure is poorly readable

6) Section «2.4. Bacterial community analysis». Add more information about the sequencing procedure

7) Section «2.5. Statistical analysis». Add links to programs for statistical analysis

8) Section «3.2. Changes in SOC fractions». Table 3 is missing.

9) Section «3.5. Relationships between various protected carbon pools and soul bacterial community», first sentence. Does the bacterial community affect soil carbon pools or vice versa?

10) 5. Conclusion. Conclusions should not briefly retell the results, you need to reformulate a little.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear editor:

 

I have carefully read the manuscript entitled “Effects of straw amendment on the bacterial community and carbon stability in different soil depths”. I believe that the manuscript should be significantly improved.

 

Title

I suggest modifying the title as only maize straw was incorporated into the soil. Change the title to: “Effects of straw maize on the bacterial community and carbon stability in different soil depths”.

 

Abstract

Include soil sampling method, the number of soil samples collected, as well as the experimental design used.

 

Introduction

Explain the mechanisms for the physical, chemical, and biological protection of soil organic carbon. This is crucial for a better understanding of the study by the reader.

 

What does agglomeration process mean? Please explain.

 

How do organic amendments and physical protection mechanisms affect soil microorganisms and carbon sequestration according to Wang (20)?

 

Material and Methods

I was unable to locate Table 1.

 

Specify soil management practices clearly. It is essential to know the tillage type in order to provide a better explanation of the obtained results.

 

Indicate how many soil samples were collected at each soil depth, as well as the sampling method used

Explain clearly what you mean by 'phy-biochemically protected'.

 

Specify the methodology used to analyze soil organic carbon

 

Data normality tests and variance homogeneity tests were conducted?

 

Discussion

 

How can the authors indicate this? Was root biomass determined?

 

What type of clay is present in the studied soils? Low-activity clays like kaolinite can have variable charges and are less reactive

 

What does MA mean?

 

Consider that previous studies mention that maize residues have a high content of potentially mineralizable labile C (e.g. Bautista-Cruz et al., 2018).

 

It is crucial to know the type of soil tillage to better understand this result

 

What is the chemical composition of maize straw? Is it rich in labile carbon? Is it rich in recalcitrant carbon?

 

Why do the authors claim this? Were tests conducted for organic carbon mineralization?

 

How can you be certain that the changes in abundance and composition of the microbial community are a result of the addition of maize straw and not due to seasonality? Soil sampling was not conducted throughout the year

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I have reviewed the corrected version of the manuscript titled "Effects of straw amendment on the bacterial community and carbon stability in different soil depths". I consider that it can be publishable in Agriculture journal.