Effects of Triazole Fungicides on Soil Microbiota and on the Activities of Enzymes Found in Soil: A Review

Round 1

Reviewer 1 Report

Dear authors,

I have no comments for your revised manuscript. Basically, you revised what I suggested.

Author Response

Thank you for your suggestions and reccommendations. 

Reviewer 2 Report

the authors accepted the referees' requests and the text appears to have improved considerably 

Author Response

Thank you for your suggestions and recommendations. 

Reviewer 3 Report

The authors have done a creditable job in revising the manuscript. They have addressed most of the concerns I had from the first review. The introduction is better for a broad audience and defines the soil health terminology. They have also revised the manuscript to be neutral on the effects of fungicides on soil microbial populations. The exception is the added discussion in lines 591-606. What makes a pesticide highly hazardous? Why are certain fungicides banned? Is there a scientific rationale? This discussion is not well integrated with the rest of the paper.

The authors attempted to address my question on why bacterial populations are affected by a fungicide targeting a fungal enzyme. It is surprising that none of the papers reviewed had an explanation or a hypothesis for this widespread phenomenon. The added discussion in lines 622-632 is not very satisfying, which basically says no one knows why bacteria are affected. It appears that no one has investigated this. Perhaps it would be better to simply state that bacterial populations are affected by triazole fungicides but the mechanism is not yet understood.

The English still has many grammatical errors and awkward word usage. I am not sure how much English editing is done by the journal but I feel it is not the place of a reviewer to correct English. Here are some of the most noticeable errors.

265: deep black soils of paddy rice (Oryza sativa L.). (Insert rice before the scientific name).

341-347: Replace contaminated with a more neutral term like treated.

352: Meaning of “revealed to affect the soil state” is not clear. Revise.

416: Meaning of “those composition was not recovered” is not clear. Revise.

428-430, also for 568-570: Replace illustrate, emphasize and correspond with “indicate”.

442: Meaning of “reproduces the changes” is not clear. Revise.

454 forward: In the section on enzymes, each time an enzyme is mentioned it should be followed by “activity” since that is what is being measured, not the amount of enzyme. It should be …and the DHA activity was assessed.

464: The word “conducted” is used frequently when the proper word is “led”.  The highest concentration led to the decrease of UA activity…Also, the words “registered”, “emphasized”, “revealed” and “noticed” should be replaced with “found” or “have”.

530: Revise to: Another study investigated the effect of tebuconazole on the soil enzymes in a greenhouse experiment. Also, the plural of leaf is leaves.

562: “was retrieved” replace with “recovered”.

566: Meaning of “usually is variable in time” is not clear. Revise.

580: Discussion not Discussions.

585-586: Use of “is missing” and “is also missing” suggests that the information was somehow lost. Suggest replacing with “has not been reported” or “has not been investigated.”

607: The phrase “do not produce an unacceptable risk” is a double negative. Please simplify and say …when used at the field rate are not a risk to the environment.

617: Did the papers really show that triazole fungicides can be easily degraded by soil microorganisms? Or is this a conclusion based on recovery of microbial populations?

657 forward: This part of the paragraph does not follow logically from the first sentence. How does reducing effect of the environment reduce the risk of development of resistance by a specific plant pathogen? What are these nebulous negative impacts of fungicides? The final sentence lists methods to reduce the risk of development of resistance; however, the sentence jumps back and forth in word tenses used and needs to be revised.

Author Response

Please see attachment.

Author Response File: Author Response.docx

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

Dear authors,

My comments are as follows.

1. Please select another proper keywords for enzymes found in soil. For example: soil enzyme

2. Please write more in your discussion.

3. Please avoid copies the same words from other articles for the too long sentences.

4. You may pick few fungicides that more wildly usage or/and essential in the world and discuss/address more.

5. The rest comments are

Line 23-28: require references.

Line 30-31: Do you have more recent reference for this statement?

Line 34-36: require references.

Line 41-44: require references.

Figure 1: I suggest to add % in the pie chart.

Figure 2: I suggest to have a line for y axis.

Line 100-101: require citations.

Line 121-124: require citations.

Could you find a more robust Reference to replace or supporting Reference 14?

Line 132-135: require citations.

Line 145-156: require citations.

Line 159-167: require citations.

Line 204-206: require citations.

Line 218-219: add reference 27.

Line 238-243: require citations.

Line 263-268: require citations.

Line 283-286: require citations.

Line 289-291: require citations.

Line 301-305: require citations.

Line 330-336: require citations.

Line 349-357: require citations.

Line 381-390: require citations.

Reviewer 2 Report

As stated by the authors, the paper "Effects of triazole fungicides on soil microbiota and on the activities of enzymes found in soil: a review" intended to present a systematic review of the effects produced on the soil health and quality by triazole fungicides .

Although the idea is good, its implementation has significant shortcomings. The authors focused attention only on describing whether a fungicide treatment decreased the microbial biomass or not, without taking into account what happens to the different soil quality indicators (e.g. nitrogen, etc.). The results presented in paragraphs 3 and 4 could be summarized in two tables and then commented on.

The description of the results for the various treatments is not uniform.

The discussion of the results is completely missing. Why did the action of each treatment lead to the results described? What are the indications that can be drawn from it?

Finally, the abstract talks about adjuvants and the method of soil management. However, these aspects are practically not considered in the text.

Reviewer 3 Report

This manuscript is a review of the literature on the effects of triazole fungicides on soil microbes and soil enzymes. The authors do an adequate job of reviewing the literature. I have several suggestions for improving the manuscript.

1. The target audience is not clear from the background given in the introduction. The journal has a broad audience of agricultural scientists, and the introduction should reflect this audience. The authors should define what they consider soil health and measurements of soil quality. These terms are used frequently, and fungicides are said to decrease soil health or soil quality without defining what is actually being affected. How does soil health/quality impact plant productivity? Further, for the broad audience, a more thorough discussion of the source, role, and influence of soil enzymes on soil properties would be useful for non-soil scientists reading the article.
2. I felt that the review was slanted towards negative activity of fungicides. The authors should revise the review to make it more balanced. When would fungicides actually be applied to soil in the ways that are described in the experiments reviewed? For the most part, the fungicides would be absorbed by the plants to which they are applied. Fungicides are typically applied when the crop canopy has closed, so that little would be directly applied to soil. How realistic is it to have 2x or 10x the labeled rate applied to large amounts of field soil? The lines 36-39 suggest that fungicides are a major environmental pollutant. What is the evidence for long-term damage to the environment (line 42)? The papers reviewed indicate that some triazoles cause a change in microbial communities. This is hardly surprising as many agricultural activities cause such changes. Microbial communities are dynamic by nature and a change is not by definition detrimental. Again, a definition of soil health/quality would be useful in discussing the impacts of fungicides.
3. The best review articles not only summarize previous research but also provide a prospective on the research gaps and integrate the findings into a larger context. The authors do some of this in the Discussion and Conclusion sections. What is missing is a discussion of why the bacterial communities are affected by a fungicide that targets a fungal enzyme. Perhaps this is obvious to researchers in the field, but left me with wanting to know why this effect seems so pervasive. Is the effect direct on the bacteria and if so, what is that mechanism? Or is the effect indirect through reducing fungal community members? A more thorough discussion of the reasons for microbial community dynamics would be a useful addition to the paper.
4. The authors suggest that a more standard methodology for assessing the impacts of fungicides on soil microbial communities is needed. Can they suggest which factors would be most important in such a standard assay? What kind of metadata in an experiment should be included (soil pH, organic matter, previous cropping history, history of fungicide applications, etc)?
5. Where they feel that certain fungicides are having a negative impact, what measures could be taken to reduce these impacts? Alternative fungicides, application timing/method, soil amendments?
6. Although the English in the paper is adequate, the authors should consider having a native English speaker review the paper for grammar and usage. There is an excessive use of passive voice such as “has been.” Suggest replacing “has been” with “was.”
7. Below are several specific errors that need to be corrected.

Line 176: Actinomycetes are bacteria. The sentence ….soil bacteria  being more affected than actinomycetes… does not make sense.

Lines 200-202: This sentence is not clear. Revise.

Line 245: Besides fungicide, what could have affected microbial populations? Carbon availability, moisture? The effect may not be due to fungicide alone.

Line 302: As an example of a negative slant in the review is the term “soil degraded by fungicides”. However, lines 308-310 indicated that the effect of fungicides as moderate and temporary. This does not appear to be degraded soil.

Line 312: What are the “stressful conditions”? Please define.

Line 344-347: Please revise. The sentences are poorly written. What is soil activity?

Line 413-418: This paper appears to report enzyme activity in bacteria, not soil.

Line 456: What is peanut soil? Soil from a field cropped to peanut?

Line 514: Can you provide prospective of why tebuconazole and propiconazole are the more studied? Are they the widest used? Longest on the market?

Line 519: Why are studies on the other triazoles imperative? Are they becoming more widely used? Are there indications they may have more of an environmental impact? Just because they haven’t been studied before does not mean the research is needed.

Line 520: I could not find any review of the effects of triazoles on soil quality in the paper. Please define soil quality. There are many soil quality indicators. Please be specific. This website defines soil quality and soil health parameters https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/health/assessment/?cid=stelprdb1237387