Review Reports - Effects of Rice Straw Mulching on Nematode Communities in Upland-Paddy Rice Systems in Salt-Affected Soils

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Effects of Rice Straw Mulching On Nematode Community in Upland-Paddy Rice Systems in 3 Salt-Affected Soils

This manuscript addresses an important topic, soil ecological responses to rice straw mulching in salt-affected systems. However, the manuscript in its current form has serious deficiencies in writing quality, structure, clarity of results, which significantly limit its scientific value and interpretability.

While the experimental design and dataset appear potentially valuable, the presentation and analysis are not sufficiently robust or clear to support publication without substantial revision.

The manuscript is poorly written and difficult to follow. There are frequent grammatical errors, incorrect sentence structure, awkward and unclear phrasing.

The Introduction, lacks logical flow, as it moves between salinity, cropping systems, mulching

Nematodes. The manuscript does not clearly state: What is unknown, What previous studies failed to address, Why this study is necessary.

The results primarily list observations: “increased”, “decreased”, “significant differences”, but do not explain: patterns, trends, meaning.

The Discussion section contains relevant information but is poorly structured and lacks clarity, making it difficult to follow the main arguments. Although the authors attempt to explain changes in nematode community composition and trophic structure, the discussion is largely descriptive and often shifts between topics without clear logical progression. Key findings, such as the effects of mulching on functional guilds and plant-parasitic nematodes, are mentioned but not critically analysed in relation to the study objectives. In addition, there is excessive reliance on general statements and literature citations without adequately synthesizing them with the present results.

The manuscript relies primarily on ANOVA, which may not be appropriate for all data types, consider using Generalized Linear Models (GLMs): Poisson or negative binomial (counts).

Comments on the Quality of English Language

The manuscript is poorly written and difficult to follow. There are frequent grammatical errors, incorrect sentence structure, awkward and unclear phrasing.

Author Response

Dear Professor/Doctor,

Thank you very much for your valuable comments and detailed guidance on the manuscript preparation. We have carefully revised the manuscript in accordance with the reviewers’ suggestions.

We sincerely appreciate your time and constructive feedback, and we hope that the revised manuscript adequately addresses all comments, suggestions, and required corrections.

Best regards,
Nguyen Van Sinh
On behalf of all co-authors

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

his manuscript addresses a scientifically relevant and timely topic, examining nematode community dynamics in salt-affected soils of the Mekong Delta under rice straw mulching. The comparative design across two sites, the use of comprehensive nematode indicators (including trophic groups, cp-values, metabolic footprints, biomass, and diversity indices), and the attempt to relate these parameters to cowpea yield represent important strengths of the study. However, the manuscript requires major revision before it can be considered for publication. Key issues that must be addressed include: 1- Thorough professional English editing to improve clarity and readability; b-Clear validation and methodological ; and c- Clarification of the potential confounding effect associated with the fallow control treatment. In addition, Supplementary Tables S1- S4 are missing and must be provided to allow proper evaluation during re-review.

Abstract

The abstract is well organized and provides a general overview of the study and its main findings. However, the statement referring to “increased cowpea yield” remains too vague. It is recommended to include specific quantitative values (e.g., 5.1 to 13.9 t/ha at Lieu Tu) to better inform the reader of the magnitude of the effect. Additionally, the term “importantly” is used excessively and should be removed to maintain a more formal scientific tone.

Introduction

The introduction provides a relevant context by linking the Mekong Delta salinity issues with the use of nematodes as bioindicators of soil health. The narrative from intensified rice monoculture to the potential effects of mulching is generally well-structured. However, there are some points that need attention:

Root-knot nematodes (Meloidogyne spp.) can reduce rice productivity by up to 80% [14]. Please specify, if possible, the species of root-knot nematodes involved. (Lines 65-66)
The research gap addressed by this study is not clearly articulated until lines 111-122. Presenting it earlier would help frame the study more effectively.
The rationale for choosing cowpea as the upland crop is not explained. It is unclear whether the selection was based on agronomic suitability, economic importance, or experimental considerations.

M&M

The randomized block design with four mulching rates (M0–M3) across two sites is generally appropriate. However, several points need clarification:

Plot size is not reported. This information is essential for evaluating edge effects and the representativeness of soil sampling.
It is unclear whether the three replicates were spatially randomized within each field or if they are pseudo-replicates from adjacent plots. The field layout should be explicitly described.
The rationale for selecting mulching rates of 3.5, 7.0, and 10.5 t/ha is not provided. It should be clarified whether these values were based on previous studies, local farming practices, or preliminary trials.
Using only 20 g of homogenized soil for nematode extraction from plots of unspecified size raises concerns. Many studies recommend 100 g or pooled subsamples to adequately capture soil heterogeneity. The authors should justify this choice, ideally by referencing local soil variability or citing relevant precedent.
The manuscript does not specify the number of nematodes counted per sample for identification. It is unclear whether all individuals were identified or only a subsample. If a subsample was used, the authors should indicate the minimum count threshold to ensure representative identification.
The use of the NINJA online tool (Sieriebriennikov et al. 2014) for calculating metabolic footprints is appropriate; however, the manuscript should specify the version employed, as the tool undergoes periodic updates that may affect results.
PCA was performed on normalized nematode abundance using PRIMER v6, which is appropriate. However, the percentage variance explained by PC1 and PC2 must be stated in Figure 9.
Tables S1- S4 and Figures S1A-D are frequently referenced in the Results section, yet they were not provided for review. These supplementary materials are crucial for assessing the genus-level abundance data and must be included in the revised submission
Figure 9 (PCA): Axis titles must include the percentage of variance explained (e.g., 'PC1 (XX%)').

Discussion

Lines 418- 437 propose potential mechanisms for plant-parasitic nematode (PPN) suppression by mulching; however, no direct evidence from the current dataset is provided to support these claims. Data on soil moisture, temperature, or microbial biomass are not presented. If such measurements were taken, they should be included or properly referenced. Otherwise, the discussion of mechanisms should be explicitly framed as speculative.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Dear Professor/ Doctor,

Thank you very much for your valuable comments and detailed guidance on the manuscript preparation. We have carefully revised the manuscript in accordance with your comments, suggestions, and corrections. We sincerely appreciate your time and support, and we hope that the revised version now adequately addresses all of your concerns.

Best regards,
Nguyen Van Sinh
On behalf of all co-authors

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents some concerns regarding the clarity of the experimental design and the robustness of the statistical analysis. The description of treatments is ambiguous, as the text refers to five treatments but lists M0, M1, M2, M3, and a fallow control without clearly explaining their structure or distinction. Additionally, the level of replication (n = 3) is relatively low for field experiments, which may limit the reliability of the results given natural variability. There is also an inconsistency in the reported sampling timeline, with references to both May 2023 and May 2024, which needs clarification.

Furthermore, the statistical analysis is limited to one-way ANOVA despite the experimental design including multiple factors such as site and sampling time (beginning vs. end of the season). The absence of more appropriate analyses, such as two-way ANOVA or mixed-effects models, represents a methodological limitation and may affect the interpretation of the results.

It is recommended that the authors clearly define the treatment structure, experimental layout, and correct the timeline inconsistencies. In addition, the statistical approach should be strengthened by incorporating analyses that account for multiple factors (e.g., site × treatment interactions and temporal effects), and the assumptions and structure of the statistical models should be explicitly described.

Author Response

Dear Professor/Dr.,

Best regards,
Nguyen Van Sinh

On behalf of all co-authors

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript describes the results of field experiments to assess the impact, if any, of straw mulching on soil nematode communities in a rice paddy production system

Missing from the Methods section is an indication of the level of replication of the study. On line 150 it is clear that five subsoil samples were collected but as described they were then "mixed evenly". Do the authors mean a single composite sample was created from the five subsoil samples or whether, each sample was mixed evenly and consequently there were 5 replicate samples per treatment. Please revise the text for clarity.

Nematode abundance data rarely, if ever, conforms to normality and consequently the vast majority of published papers use nematode abundance data that has been log transformed using the notation log (x+1). Firstly, from the methods it is unclear whether the nematode abundance data was checked for normality and secondly whether the data required to be transformed - Figure 3 would suggest the data was not transformed.

There are several formatting errors including differing font sizes of the manuscript text.

Line 46: should the text not read "the dominant cultivated crop"?

Line 66: previous MD was used not VMD, please select one acronym and use throughout the manuscript

Table 1: data presented are not to the same decimal place, please be consistent. Also, unclear if these are singular data points or averages but the error surrounding the means omitted. Please be clear in what is being presented

Line 149: why is subsoil important? Would it not have been better to sample rhizosphere soil that was in close contact with the plant roots?

Figure 2: what do "He Thu", "Thu Dong" and "Dong Xuan" represent? Please revise the Figure legend to inform the reader

Lines 159-160: please note that 20 g of soil is insufficient for robust nematode community analysis and will likely result in stochastic data, please see Wiesel et al. (2015, Soil Biology & Biochemistry)

Lines 234-237: it is also true to say that at Long Phu, the M2 treatment had more genera than the M0 treatment

Lines 282-283: should state the omnivore abundance was greater at M2 vs M0

Lines 302-303: this is not easily seen from the cited Figure 6A

Lines 306-308: the text does not agree with the data presented in Figure 6B

Lines 315-324: the authors have not provided a convincing scientific argument as to the importance of nematode biomass

Line 344: this statement is incorrect, fallow and M1 is correct

Lines 357-358: this statement is incorrect, M1 and M2 is correct

Lines 381-382: this is results not discussion

Lines 385-386: this is speculation as not climate data has been presented for either field site

References: please carefully check each reference as there are several formatting errors

Comments on the Quality of English Language

It is genuinely appreciated that the majority of the authors are non-native English speakers. However, it is assumed that at least two of the authors are native English speakers and the manuscript would greatly benefit from their input regarding the English language of the manuscript such as sentence construction, tense and where appropriate use of singular or plural forms.

Particular attention should be made to the Introduction to ensure that a clear rationale for the study is communicated to the reader.

Author Response

Dear Professor/Doctor,

Thank you very much for your valuable comments and detailed instructions regarding the manuscript preparation. We have carefully revised the manuscript based on your comments, suggestions, and corrections. We sincerely appreciate your time and guidance, and we hope that the revised manuscript now meets your expectations.

Best regards,
Nguyen Van Sinh

On behalf of all co-authors

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors replied to the comments.

Author Response

Dear Prof./Dr.,

Thank you very much for handling and reviewing our manuscript submitted to Crops. We sincerely appreciate your valuable comments and suggestions on the revised version. Your constructive feedback has greatly helped us improve the quality of the manuscript and has also enhanced our knowledge and experience in scientific research and publication.

Best regards,

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have addressed the comments that I raised in my original review, except the citing of van den Hoogen et al (2019), see comment above.

As a consequence of the revised text, I note the following:

Lines 332-335: a supporting reference for this new text should be provided as otherwise it is merely opinion.

Table 3: I missed this in my original review but many of the listed variables are presented to 2 decimal places. It is unlikely that the resolution of the equipment is sufficiently good enough for data to be presented at anything better than the resolution of 1 decimal place. Thus, please amend the data accordingly to 1 decimal place.

Lines 417-423: the new text on soil pH has not citations to previous studies on nematodes supporting this perspective. Please provide a supporting reference or references. For example did Griffiths et al. (2002, 2003) find pH a driving factor? Alternatively, if there has been no work published on soil pH and nematodes, then draw learnings from published microbial community studies where pH has frequently been reported to drive microbial community composition.

Line 503: "bacterivors" should read "bacterivores"

Author Response

Dear Prof./Dr.,

Best regards,

Author Response File: Author Response.pdf