Green Manure Amendment Increases Soil Phosphorus Bioavailability and Peanut Absorption of Phosphorus in Red Soil of South China

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Review Manuscript ID: agronomy-2145622

The manuscript “Green manure amendment increases soil phosphorus bioavailability and peanut absorption of phosphorus in red soil of South China” was resubmitted in a new version. Profound improvements made by the authors were observed, but there are still corrections to be made, mainly in Results:

- Authors should reformulate the Results in a general way, mainly removing the passages that refer to the Discussion and relocating them in the appropriate section. Examples: End of L.190 to L.194; L.203 to L.205.

- L.202: insert “while” before “the yield of MV was....

- Authors should improve the wording of the statistical interpretation of the results in general. For example, L.213 through L.221 there is no difference between MR, BR, and R for total amount of nutrients, but the authors say that the highest value was in R, followed by BR and MR, but as there is no difference significant, the three values are equivalent. Another example, N accumulation is said to be significantly higher in MV, but there is no significant difference between the values for the four green manure crops. In addition, the authors should better describe the P and K results, as there were significant differences.

Author Response

Response to reviewer 2

Point 1: In the descriptive section of the material, I recommend that the authors read and supplement the manuscript with a discussion with research about more chemical, physical or energetic aspects of biomass. I recommend reading the article: https://doi.org/10.3390/en14113270

In these articles, you can also find information about correlation using ANOVA with the Duncan test. Similar studies, in particular the division into homogeneous groups, were also missing in the article. You can find information about a fractional breakdown or CHONS analysis as well as correlation using ANOVA with the Duncan test. It will certainly enrich the manuscript.

 Response：Thank you for your kind suggestion. We downloaded the article entitled “Evaluation of Mechanical and Energetic Properties of the Forest Residues Shredded Chips during Briquetting Process”. We think the subject of this article is totally different from the subject of our manuscript. However, we do find information about fractional breakdown or CHONS analysis, as well as correlation using ANOVA with the Duncan test from your suggested article, valuable. We agree with you that this information will certainly enrich our further research.

Author Response File: Author Response.docx

Reviewer 2 Report (New Reviewer)

In the descriptive section of the material, I recommend that the authors read and supplement the manuscript with a discussion with research about more chemical, physical or energetic aspects of biomass. I recommend reading the article: https://doi.org/10.3390/en14113270

In these articles, you can also find information about correlation using ANOVA with the Duncan test. Similar studies, in particular the division into homogeneous groups, were also missing in the article. You can find information about a fractional breakdown or CHONS analysis as well as correlation using ANOVA with the Duncan test. It will certainly enrich the manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report (New Reviewer)

Dear Authors,

You have answered the comments of the former reviewers.

However, some new questions have arisen.

Lines 124-125

The aboveground biomass was cut into 20 cm at the stage of flowering of oilseed rape in the second week of March and returned into the 15 – 30 cm soil layer.

For what purpose did you cut aboveground biomass at a 20 cm height? Which way did you use this biomass? How did you return the biomass? Was there a reason to use underground biomass?  

Lines 127-133

…chemical fertilizer used in the experiment…

Why did you decide to use a chemical fertilizer? A green manure is a substitute for mineral fertilizer.

The full standard quantities of … fertilizers…

What is a full standard fertilizer quantity?

Lines 148-150

… soil samples were taken from the soil surface layer (0-20 cm) using a soil borer...

As a rule, the 0-20 cm soil samples can be taken with shovel.

In the study area, a precipitation overcomes an evaporation. This means a leaching mode of the soil formation. Thus, a huge part of nutrients can be leached to the deeper soil layers and vadose zone. The relevant data on nutrients content should be useful.

Line 207

While a green manure yield was circa 30-80 t/ha, a soil nutrient accumulation was 1000 and more times less. This question of a green manure use remains the same for decades. Now, there is a possibility to use oilseeds for a livestock feed, then gasify an animal manure and use the gas for energy production. A gasification byproduct can be applied to the soil. In this case, an amount of byproduct is 10-100 fold less compared to the initial amount. This reduces transportation costs.

Line 229

The pH of MR, BR, R, and MV soils decreased significantly…

However, if the pH value is low, this means an increased mobility of nutrients.  Are you sure, that additional green manure nutrients were not leached out from the soil?

Lines 337-339

…a series of physicochemical and biological reactions take place in the micro-zone of its residues during the process of decomposition, which will affect the bioavailability of soil phosphorus…

Please present these processes in details basing on your own data.

Line 393

After 4 years of returning 15 ~ 22.5t/ha of green manure each year,…

The phrase is perceived as if you return the green manure every year. Maybe you mean once every four years?

Lines 396-398

The phosphorus accumulation of peanut plants in the green manure returning treatments was significantly higher than that in the winter fallow treatment,…

According to your data, an increment was not too high.

Previous reviewers have called your attention to a certain lightness in your manuscript. Unfortunately, a refinement that you have performed does not allow us to conclude that you have overcome a disadvantage indicated before.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report (New Reviewer)

The entire article is about a few pages of content, but nothing innovative is written in it. The manuscript has a big lack of topic knowledge.

No research on it has helped to enrich science. The article is very little research and is not suitable for publication in this state, it would be necessary to thoroughly rebuild all parts of the manuscript.

The discussion was not conducted by the guidelines of the journal. An expansion of literature, conclusions, and discussions is required.

In this form, I advise against publishing the article in this journal.

English needs a lot of improvement.

There is no in-depth statistical analysis. Statistical analysis was not sufficiently discussed. The entire manuscript looks like an excerpt from a report from some major work. Without statistics and research, the article does not contribute to any knowledge development. An expansion of literature, conclusions, and discussions is required.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

1.      The "Figure 1. ..." is suitable for a popular science article, but not a scientific one.

2.      The article contains layout errors.

3.      The determination methods of crop water use and water use efficiency is not described in the section “Materials and methods“.

4. Crop water use and water use efficiency data not provided in the article.

5.      All Figures and Tables should be inserted into the main text close to their first citation.

6.      Significant differences (p < 0.05) is not marked in the Table 1 and Table 4 (root nodule number plant^-1; root nodule weight g plant^-1), though although the text states that “green manure treatment significantly increased the number of nodules per peanut plant and the weight of nodules per plant”…

7.      References are not correct. You need replace the references according to the methodological requirements. Example: 1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.

8.      DOI are not included in the bibliography.

9.      The other comments are in the article.

Comments for author File: Comments.pdf

Reviewer 2 Report

The manuscript described above does not have the conditions to be accepted by the journal Agronomy, a journal with an impact factor of 3.949.

In addition to being poorly structured, with deficiencies in scientific writing, such as Abstract and long paragraphs, keywords with repeated terms in the title, acronyms without a denomination (p.3, L.104), and figure and table placed before the citation in the text, the manuscript suffers from poorly formulated hypotheses, mainly (i) which should be a statement based on what is presented in the Introduction. Still, the authors try unsuccessfully to show that the experiment is long-term, but they do not provide subsidies for this, and only present results for one year. The Material and Methods section has errors (six treatments x three replicates = 24 plots?) and is missing several pieces of information, such as: how were green manure yield and nutrient accumulation obtained, and the effect of different green manure treatments on peanut growth and phosphorus nutrient absorption? The analysis of the meteorological data is wrong, it cannot say that the data are significantly different, and it is still confusing, as seedling success rate and yield of green manure were affected by higher temperature if it was said to be lower. Finally, there is not enough information throughout the manuscript to draw Conclusions related to four years.

Reviewer 3 Report

Dear authors.

The main goal of the topic was previously studied extensively, as this research lacks objectively, and although the topic of green manure is an important topic, the manuscript did not deal with it in a proper scientific way. In addition to the lack of results obtained. My full apologize that this manuscript in its current form does not fit the requirements of the Agronomy

Kind Regards

Reviewer