The Application of Mixed Organic and Inorganic Fertilizers Drives Soil Nutrient and Bacterial Community Changes in Teak Plantations

Round 1

Reviewer 1 Report

The MS of Zhang et al. entitled “Mixed Organic and Inorganic Fertilizers Application Drives Soil Nutrient and Bacterial Community Changes in Teak Plantations” represents an consistent contribution to the better understanding of the effects of various fertilizers on the bacterial communities in different types of soils cultivated with various plants, including hardwood tree species .

Overall, the paper is written well though in the experimental design they have only one time point and the authors failed to indicate the time interval between fertilization and sampling. Also, the authors should be more careful in some of their conclusions, in a few different parts of the MS, especially when they talk about the bacterial community diversity and abundance, indicating that these parameters were significantly altered. Some changes have been determined, but some crucial parameters such as the alpha diversity, estimated by Shannon index, Simpson index and Chao1 index failed to reveal any differences that were STATISTICALLY SIGNIFICANT (Figure 1). To reflect better the data the authors should change their statements in places like line 23, lines 209-210 and 385-391.

Especially the statements in lines 385-391 are debatable:

“In the study, the effective tags, Shannon, Simpson and Chao1 indices showed a decreasing trend after the combined organic-inorganic fertilization (Figure 1, Table S3). These indices were not significant among the different treatments. The result could be explained by the decrease of certain bacterial groups with the increase of soil nutrients. Overall, combined organic-inorganic fertilization had a negative effect on the diversity and richness of soil bacterial communities in teak plantations.”

Looking at figure 1 one cannot see any decreasing trend as compared to control. Also, in all 4 indices analysed there is no statistical difference between control and treatments! The authors should either add letters to Shannon, Simpson and Chao1 indices or mention, in the legend of Figure 1, that no statistically significant differences have been found between treatments and control.

Going back to the paragraph the authors contradict themselves. If “These indices were not significant among the different treatments.” then, these results do not offer any support for the following 2 sentences: “The result could be explained by the decrease of certain bacterial groups with the increase of soil nutrients. Overall, combined organic-inorganic fertilization had a negative effect on the diversity and richness of soil bacterial communities in teak plantations.”

I strongly recommend authors to review carefully what are they saying!

Also, why the authors refer to the alpha diversity indices as “the effective tags”?

 

Other minor things:

Line 17-18

“None fertilization” should be “no fertilization”.

 

Line 23

“Bacterial community composition and abundance were significantly altered after fertilization.” Actually, globally, as expressed by alpha diversity, this is not true.

 

Line 111. Somewhere in the materials and methods, maybe in section 2.3 the authors should indicate how much time after the fertilization program started, they took the samples for analyses. September 2021 gives the reader no idea about the timing of the experiment.

 

Lines 210-212. Please revise the sentence: “The Shannon and Simpson diversity index in CPF treatment was higher than that of CK, but conversely in OCF, OPF and OCPF treatments. “ Something is missing in this sentence. Conversely, in OCF, OPF and OCPF treatments the alpha diversity was the same as in control or lower? But these differences are not statistically significant!

 

Lines 247-248.

Figure 2. Why only so few phyla and genera were selected as dominant?  We understand that you used a threshold of >1% but later on in the MS other groups are mentioned as important though are not shown in this figure. For example, the phylum WPS-2 (or better Eremiobacteriota).

 

Lines 320-324. These sentences require revisions

“It is widely known that teak prefers best on rich soils with neutral and slightly alkaline pH [47,48]. Teak is regarded as a calcium preferences species and is sensitive to soil acidity in its growth process [37]. In this study, we found that soil pH in teak plantation showed an increasing trend after combined organic and inorganic fertilization and was significantly higher in the OCPF treatment than none fertilization (p < 0.05, Table 1).”

Suggestions:

teak grows better on rich soils with neutral

Teak is a species that shows a strong preference for calcium

“showed an increasing trend after combined organic” What kind of trend?

“None fertilization” should be replaced with “no fertilization”

 

 

Line 333

“release more effective nutrients” should be “release more effectively nutrients”

 

Line 350

“Organic matters” should be “organic matter”

 

Line 449-450

“and enhanced the soil pH of the young teak plantation.”

Please change it to “reduced soil acidity”. By using enhanced one cannot understand if it decreased or increased the pH.

 

 

 

 

Author Response

Dear reviewer：

We are very grateful to your review and valuable advices for this manuscript. we have completed the modification according to your requirements and comments. For the responses to your comments, please see the attachment.

Thank you!

Author Response File: Author Response.pdf

Reviewer 2 Report

1. The relevance, importance and innovative aspects of the paper should be more evident.
2. Introduction - The chapter on the impact of fertilizers on soil microbiome should be expanded. The authors should focus on the impact of both organic and mineral fertilization on soil biodiversity.

A novel information you can find in the following papers:

• Ye, C., Huang, S., Sha, C., Wu, J., Cui, C., Su, J., ... & Xue, J. (2020). Changes of bacterial community in arable soil after short-term application of fresh manures and organic fertilizer. Environmental Technology, 1-11.
• Grzyb, A., Wolna-Maruwka, A., & Niewiadomska, A. (2020). Environmental factors affecting the mineralization of crop residues. Agronomy, 10(12), 1951.
• Wolna-Maruwka, A., Piechota, T., Niewiadomska, A., Kamiński, A., Kayzer, D., Grzyb, A., & Pilarska, A. A. (2021). The effect of biochar-based organic amendments on the structure of soil bacterial community and yield of maize (Zea mays L.). Agronomy, 11(7), 1286.

3. In the ,Materials and methods’ section the authors did not indicate the sources of literature when describing DNA extraction and PCR amplification procedure.
4. Conclusion - Moreover, I think the relevance, importance and innovative aspects of the paper should be more evident.
5. Make sure the references are added correctly according to the journal's instructions.
6. The language correctness should be verified by a native speaker.

Research carried out by the author seems to be important  to the development and enhancement of existing information on this subject. The paper can be accepted for publication after the aforementioned corrections have been made.

Author Response

Dear reviewer：

We are very grateful to your review and valuable advices for this manuscript. we have completed the modification according to your requirements and comments. For the responses to your comments, please see the attachment.

Thank you!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Response from the authors:

For the time interval between fertilization and sampling, we have provided additional information in lines 124-125 of this manuscript: ‘Soil samples of the surface layer (0–10 cm) were collected two years and four months after final fertilization (in September 2021)’.

 

Comment:

Unfortunately, based on the information provided in the revised MS it is now clear that the experimental design is flawed. Looking at soil bacteria community dynamics “two years and four months after final fertilization” is not an acceptable approach. It would be OK to have this time point, but only if having other earlier time points, like after 1 month, 3 months, 6 months, and a year. Bacterial communities are changing very fast, sometimes in days and weeks, not in years. It is unconceivable to assess the initial effects of fertilization (one per year!) looking at bacterial community after such a long time. As such, the whole work is misleading, including conclusions.