The Effects of Nitrogen Reduction and Sheep Manure Incorporation on the Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchards

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study examines the impact of reducing nitrogen fertilizer and adding sheep manure on soil health, microbial communities, and yield in Korla fragrant pear orchards. Over two years, five fertilization treatments were tested: no nitrogen (N0PK), conventional nitrogen (NPK), 20% reduced nitrogen (N2PK), and reduced nitrogen combined with low or high sheep manure doses (N2F1, N2F2). Results show nitrogen application boosts soil fertility but lowers pH and microbial diversity. Adding sheep manure with reduced nitrogen improves soil organic matter, microbial biomass, and bacterial diversity while maintaining yield. The N2F2 treatment (33,750 kg/ha manure with 20% nitrogen reduction) provided the best outcomes for soil stability and microbial health without affecting pear yield. This integrated strategy supports sustainable soil management and orchard productivity.While the results are promising, further clarification is needed on the long-term applicability, economic feasibility, and broader environmental impacts of these practices.

 

Questions to the Authors

1.Given the short duration of the experiment (two years), how do you justify the long-term applicability of the findings, especially regarding microbial community dynamics and soil fertility?

2.While microbial diversity metrics were analyzed, why were functional roles (e.g., nitrogen fixation, enzymatic activity) of microbial communities not included? These could provide deeper insights into ecosystem functioning.

3.The study focuses on chemical and microbial indicators but lacks physical metrics such as aggregate stability or water retention.

4.What is the cost comparison between conventional nitrogen fertilization and the proposed treatments involving reduced nitrogen and sheep manure? Are these approaches economically feasible for farmers?

5. The study is conducted in a specific region with unique climatic and soil conditions. How do you anticipate these findings to translate to other crops, regions, or soil types?

6. Can you elaborate on why the yield did not show significant changes with nitrogen reduction and sheep manure? Could this be due to existing nutrient reserves or the short duration of the study?

7. Why was sheep manure selected over other common organic fertilizers, such as compost or cow manure? Would you expect similar results with alternative organic inputs?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper describes an interesting study based on the evaluation of the effect of nitrogen reduction combined with sheep manure on the soil physico-chemical and microbiological characteristics of Korla Fragrant Pear Orchard crops. The authors have made a great effort to analyse from different points of view both the physico-chemical properties and the diversity, abundance and composition of the bacterial and fungal communities in the soils where those prized pears are grown. However, the manuscript is not well written and needs significant improvement. Format, writing and presentation of data are neglected: treatment codes are not standardised throughout the manuscript, figure numbering is incorrect, explanations of lowercase letters used to indicate significant statistical differences in tables are not well described, standard deviations of means are not presented in Tables 1, 2 and 3, and throughout the manuscript the authors confuse the term species with taxon. Moreover, the discussion is too long and somewhat vague. For this reason, the format needs to be standardised throughout the manuscript, certain questions need to be answered and some parts of the manuscript need to be corrected to fully reflect the content of the article.

Line 20:  20 % reduction of nitrogen? Does this correspond to the combined treatment with organic fertiliser application? If so, the authors should rephrase the sentence to make it clear. As the sentence is now worded, it seems that the authors are presenting a total of 6 treatments.

 

Line 23: What type of nitrogen application, as the authors have used a variety of nitrogen-based treatments. Authors should give the acronym for the type of treatment so that the reader does not get lost in the article.

 

Line 30: Soil should be included in Soil Organic Matter (SOM).

 

Lines 77-87: The reviewer recommends that the authors include the reduction percentages of inorganic fertilisers used in the scientific literature.

 

Lines 106: Where it has been written Further write further.

 

Lines 119-128: Authors should include the size of the study area in this section.

 

Lines 125-128: These data should correspond to averages obtained for the study area and these averages should be accompanied by their standard deviations.

 

Line 138: Authors are requested to standardise the treatment codes. In this line the treatments are described as and the combination of the N2 treatment with two levels of organic fertiliser (OF1 and OF2), but in the adjacent lines 139-140 and 22-23 of the abstract the same treatments are referred to as: N0, 22 NPK, N2, N2F1 and N2F2. Furthermore, in Table 1, the codes of the last treatments are again named differently.

 

Line 141: Where it says Single write single.

 

Reference Table 1 in the text.

 

Lines 153-155: In this paragraph the timing of sampling is detailed, but on the one hand the authors give the sampling days, which correspond to 4 samplings, but not when the inorganic and organic fertilisers were inoculated. On the other hand, in the abstract, lines 14-15, it says: "This study involved a two-year field experiment ...", which is in contrast to the sampling dates given in lines 153-155, which are less than 6 months. The authors should clarify this point.

 

Lines 184-185: The reviewer suggests that the authors should at least describe which molecular regions were used for the analysis of the bacterial and fungal community by metabarcoding carried out in this study.

 

Line 199: Delete one "to".

 

Lines 206-207: The reviewer suggests rephrasing the last part of the sentence. As it stands, the sentence is not understood.

 

Table 2: Authors should include the standard error data and detailed ± sign in the legend (line 223) and standardise the treatment codes with the text and figures, N0 or N also appearing in the article as N0PK or NPK.

 

Line 221: Include Soil in SOC: Soil Organic Carbon.

 

Lines 223-224: The authors do not describe in sufficient detail what each of the lowercase letters means, which makes it difficult to interpret the statistical data. The same applies to Table 3.

 

Line 226: Correct figure numbering. This figure corresponds to Figure 2-A.

 

Line 242: Authors should correct the numbering of figures from now on. For example, this figure should be Figure 2. Authors should pay attention to this and also correct the references in the text of the figures.

 

Line 250: Delete “compared with N0 treatment,”.

 

Line 256: Authors should indicate which treatment “from those of the treatment…”.

 

Line 263:  Write Observed species in italics.

 

Line 274: “the” is not italicised.

 

Line 281: Include richness, not just diversity.

 

Lines 295-296: Authors should rewrite the figure caption. The sentence is poorly written and is not understood. What is shown is: a Venn diagram with the number of bacterial OTUs (A) and the number of amplified fungal OTUs (B) for each treatment and those shared between treatments. 

 

Line 307: Only genera and species should be written in italics. Authors should be aware of this error and correct it throughout the manuscript.

 

Lines 320-321: Authors do not specify what figure A and figure B represent. The reviewer suggests that the authors detail the content of both figures. The same applies to Figure 5.

 

Lines 322-323: Increased of what? The authors should clarify this point.

 

Lines 334-341: Why the authors do not mention in the results section the data obtained for the phylum Chytridiomycota in the NPK treatment, taking into account its possible ecological implication.

 

Line 351: Write Figure 6.B.

 

Line: 374: Authors mention species, which is not the case, because they correspond to taxa. The same applies to line 343. Authors should take note of this and correct this error throughout the manuscript.

 

Lines 353-363: The authors compare the results by confronting different taxonomic levels. This is not scientifically correct as it is not comparable. All taxa should be at the same taxonomic level, e.g. order or family, in order to be able to interpret and discuss the results correctly.

 

Lines 367-376: The same happens with fungi. The authors talk about species when they are taxa and comparisons are made between different taxonomic levels.

 

Line 429: To which type of fertilisation the author Ding et al. refers to, [28]. The authors should clarify this point.

 

Line 484: Goat or sheep?

 

Lines 531-547: The authors do not discusse the result for the phylum Chytridiomycota in the NPK treatment, taking into account its possible ecological implications, as it is a phylum consisting of saprophytic, animal and plant parasites species.

 

The discussion is too long and somewhat vague. The reviewer recommends that the authors try to reduce superfluous or repetitive content.

 

 

 

 

 

 

 

 

 

 

 

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors

The research you conducted strongly supports sustainable agriculture in terms of soil health. The manuscript has been compiled in a coherent manner with reference evidence and field observations/measurements. However, there are several things that need to be improved, including:

ü Experimental design. This study uses an existing orchard and you apply several treatments (N0PK, NPK, N2, etc). Lines 140-141 state “Five fragrant pear trees were selected for each fertilization treatment, and a Single plant pear tree as a repeat”. What is the basis for selecting these five plants? Is it age, variety, location in the orchard? The next focus is how you control for other factors such as differences in soil type, microclimate, and landscaping morphology, which may affect soil microbiology and plant productivity. In lines 147-149, you have explained that the treatment plants were applied at an early stage of germination and explained that other feld management practices are consistent with those used

ü Soil sample collection. Why did you take samples at a depth of 0-20 cm? Does this depth represent plant roots?

ü Figure 2: What is the function of this image, because the numbers listed are no different from the shape/graphics.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

The manuscript addresses a highly relevant and timely topic in sustainable agriculture: integrating organic and inorganic fertilization strategies to improve soil health and optimize agricultural practices. The authors have made commendable efforts in designing and executing a field experiment to evaluate the combined effects of reduction in nitrogen applications and sheep manure application on soil physicochemical properties, microbial diversity, and pear yield. While the study has potential, several aspects of the manuscript require substantial revision to strengthen its scientific rigor, clarity, and overall impact.

1. Abstract:

Suggestions:

Clearly indicate how this work differs from or extends the previous work.

Also include a short statement on how this could impact practical uses in either fruit orchard management or in the policy of more sustainable fertilization practices.

2. Material and Methods

Experimental Design: It is not evident why nitrogen and sheep manure have been used at a particular rate. Is this from pilot work, from local practices, or from previous research? Please, Justify the values adopted.

The sample size used is very small, 25 trees. Discuss the effect of sample size on the power and representativeness of the results.

Soil Microbial Analysis: The manuscript does not describe the sequencing pipeline. What software and version was used for bioinformatics? For instance, OTU clustering and alpha diversity metric estimations? At what threshold was quality control performed?

Please, include per-sample sequencing depth and any potential implications for microbial diversity analyses.

Further Controls: Add to the experiment a long-term control treatment to test the residual effect of sheep manure for longer than studied here inward (two years).

Consider including treatments with higher or lower rates of sheep manure than tested to examine dose-response relationships.

Statistical Analysis: The manuscript does not indicate how treatment effects were tested for significance. Was ANOVA or some other statistical method used? Were assumptions such as normality and homoscedasticity checked?

3. Inconsistent Statements:
The conclusion states that a 20% reduction in nitrogen combined with sheep manure improves soil microbiota health, but the evidence also shows that bacterial richness decreased significantly under these treatments. The manuscript does not adequately address why reduced richness might still indicate an improvement in soil health.

Yield Discussion:
The manuscript concludes that the yield remains unaffected, yet it fails to discuss the potential implications of this finding. Does this suggest a trade-off between soil health and productivity? Or might the yield effects emerge only after longer-term applications?

Author Response

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Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The manuscript The Effects of Nitrogen Reduction and Sheep Manure Incorporation on Soil Characteristics and Microbial Community of Korla Fragrant Pear Orchard, is interesting and useful for farmers, researchers and anyone interested in improving soil health and reducing the use of mineral nitrogen fertilizers. The manuscript contains all relevant sections, is within the scope of Agronomy, and meets the general requirements for publication in this journal. It is a pity that the experiment seems to have been carried out for one year. It is difficult to draw the right conclusions from one year's data.

Overall, it is a well-written manuscript, and the authors provide useful research data. The experimental design should be clarified. I have only a few comments:

Line 157 - Were all the soil samples taken at different growth stages mixed into one sample? There is no data for the different growth stages in the manuscript.

Line 223 - You haven't specified the standard error in the table. What statistical analysis method have you used to calculate the standard error?

Best wishes to the authors.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have responded to the reviewer's questions and have modified the manuscript according to the reviewer's suggestions. Therefore, in the opinion of this reviewer, the article can be published in its present form.

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

Thank you.

Author Response

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