Fertilizer Potential of Organic-Based Soil Amendments on cv. Sangiovese (V. vinifera L.) Vines: Preliminary Results

Round 1

Reviewer 1 Report

 from these preliminary results  this paper can be observed a higher N availability as a consequence of SS supply that resulted in higher plant biomass, but reduced yield and berry quality supporting the theory that for vineyard N should be carefully managed to reach an equilibrium between vegetative and reproductive activity. this research is meaningful, but please polish abstract again and discussion is needed discuss and add related research, give your view. Such as

1 Vegetative growth determination . how to do ?  please describe it detail.

2 Soil sampling and analysis, how to choose soil samples ?  please describe it detail

Author Response

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Reviewer 2 Report

The development of resource-saving fertilizer systems that meet modern requirements of adaptive agriculture is an actual agrochemical measure to increase soil fertility. For this purpose, the results of many years of research conducted on the basis of stationary experience are most acceptable, allowing to develop scientifically-based recommendations for rational, environmentally safe use of fertilizers with a high level of payback. The work submitted for review in this aspect is of certain scientific interest.

However, the authors did not quite methodically correctly present and develop a scheme of the experiment: there is no control; in this regard, I have certain doubts about the correctness of the presentation of statistical processing of the obtained data. The influence of cultivar on agrochemical techniques is not taken into account in this experiment, and therefore it is not entirely correct to make recommendations based on one cultivar (variety specificity for the use of agrochemical measures is completely absent). Secondly: if the authors investigate the effect of organic fertilizers on the biochemical composition, fruit yield, then why do they not take into account the accumulation effect, which can be achieved only in the second or third year after application (in this case, it is 2021-2022, but not 2020). Thirdly, for fruit crops after grafting, you will be able to get the first harvest and full-fledged biochemical records only for the second year (2021). The data obtained in 2020 are questionable (i.e., the next year after grafting).

The authors have not shown in detail how weather conditions (temperature and humidity) in the years of the studies affect the content and movement of nitrogen forms in the soil and microbial biomass.

In the "Introduction" section, also, the authors should clearly formulate and justify the scientific novelty of their research.

As suggestions (recommendations), I recommend that the authors do not rush to submit the initial data, methodically lay the experiment correctly, add control and at least 2 more cultivars to the experiment scheme, and then re-submit the manuscript for consideration.

Author Response

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Reviewer 3 Report

This manuscript describes the results of and experiment assessing the effects of municipal waste compost and sewage sludge compost relative to mineral fertilizers on soil mineral N, microbial biomass C, grape yield, and grape quality in the two years following the vineyard establishment year. The authors report differential effects of the two organic amendments on measured parameters. The effect on crop performance and quality was found to be similar to mineral fertilizer following municipal waste compost application. In contrast, sewage sludge compost resulted in excess available soil N concentrations, undesirable excess vegetative vine growth, and reduced grape quality. Application of both composts resulted in temporarily increased microbial biomass, but sewage sludge compost appeared to have a larger effect resulting in greater N mineralization. The results of this study are of interest; however, the manuscript requires extensive revision to improve its clarity, provide necessary missing information and better discuss the results in the context of the stated study objectives as well as tie those results to the existing literature.

General note: The authors need to check all figure and table references to ensure that capitalization is used throughout. Also, spelling varies between British and American English (e.g., behaviour vs. behavior) in several instances within the text.

Introduction

This section should be revised to include information currently included in the Discussion as indicated on the marked manuscript. I have made specific comments within the marked manuscript.

Materials and Methods

The description of the experimental methods in this section requires more information to allow the reader to adequately assess the study and its results. In particular, the characterization of the composts, the compost application methods, and soil sampling and analysis descriptions all require additional information. The Vegetative growth determination section is extremely confusing and needs to be rewritten for clarity. Finally, additional information is needed describing the statistical methods. Were separate ANOVAs  used to determine treatment effects at each time point? A repeated measures ANOVA seems a more appropriate and possibly more informative approach. A more thorough description of the CDA procedures and output would be helpful to readers who are less familiar with this method. Specific comments can be found in the marked manuscript.

Results

Figures 1, 2 and 3: The authors should reanalyze this data as a repeated measures ANOVA and perhaps split the years into separate panels. As presented, it is difficult to observe the treatment differences, particularly in 2020, where some of the letters appear to be disconnected from the mean with which they are associated.

The results of the CDA analysis would be more effective if the positioning of the canonical variables were described in relation to the clustering of the treatments, rather than their positioning within the plot. Specific comments are in the marked manuscript.

Mean biomass data should be presented.

The authors should present weather data which may help to explain the yield differences between years.

Discussion

General Comment: This section requires extensive revision to remove statements that are more appropriately included in the Introduction and to more thoroughly, explicitly, and completely discuss the data presented in the Results and how they relate to the authors' stated objectives and the literature. The soil N and plant uptake data require much more discussion. Why did the elevated nitrate concentrations not lead to increased yield? Presenting and discussing the biomass data would be an interesting addition to the manuscript. Why was there only minimal soil response to applied mineral fertilizer? The authors report increased and persistent soil NO3-N from SS compost relative to MOW compost despite a much higher C/N – an observation that warrants much more explanation that it is given in the text. Much of the data presented in the Results requires expanded Discussion more explicitly tying the results of this study with the literature. The discriminant analysis of treatment effects on fruit quality is some of the most interesting data presented and deserves more discussion of why such effects were observed in this study and their implications for fruit quality (presumably as wine?). Specific comments are in the marked manuscript in addition to the comments below.

L319-321: This statement is questionable as you do not present data on soil organic carbon. The increases in microbial C appear to be short-term responses to increased substrate availability following compost incorporation.

L321-323: This sentence reads like a description of the Results. More discussion of the differing treatment responses is needed.

L334-337: This is simply describing the Results. Discussion of the relevance of these observations relative to vine growth, grape yield and grape quality are needed.

L338-340: Was NH4-N measured in the composts? Was it similar in each year? If it was measured it should be reported in Table 2 for each year. The authors should note the corresponding greater increase in microbial C following compost incorporation in 2021 to support this statement.

L340-343: Is there support a difference in organic matter composition that would affect degradability? How does this modify the effect of the C/N ratio? The authors need to provide more information to support this statement or delete it.

L348-353: This sentence should be the start of the next paragraph.

L353-365: Is N limited in this study? It doesn't appear to be and so the discussion of N limitation effects on fruit doesn't seem relevant here. The experimental results should be more explicitly tied to the remaining discussion in this paragraph.

L357-360: This sentence is awkward and should be reworded in response to the previous comment. Perhaps, "This is supported by experimental evidence from fruit trees where synthesis of ascorbic acid increases in response to low N availability and the decrease in the concentration of phenolic antioxidants and contemporary increase of proteins in response to increased N availability."

L360-363: More specific discussion of the CDA results in relation to the literature is needed here.

L368: The authors should present leaf nutrient concentrations in spring and fall in the Results to support this discussion.

L367-388: How is this information relevant to vine performance, grape yield, and grape quality? More discussion is needed.

Conclusions

The conclusions need to be strengthened and put into the context of vineyard management. Why do the results of this study matter? How will they improve vineyard soil fertility and organic matter and what impact will that have on vineyard management?

L399-401: Strategies were not discussed above. This statement would be better incorporated into the Discussion.

References

Check all references for consistent style. For example, some journal abbreviations are not italicized.

Comments for author File: Comments.pdf

Author Response

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Round 2

Reviewer 1 Report

please confirm reference is cited in right place, 

Author Response

Dear reviewer,

I double checked the literature and everything is correct.

Kind regards

Elena Baldi

Reviewer 2 Report

The manuscript can be published in the journal subject to editorial corrections (take into account the reviewer's comments)

Author Response

Dear reviewer,

thanks for taking time to read again the manuscript.  

Kind regards

Elena Baldi

Reviewer 3 Report

The authors have made many of the requested revisions and the manuscript is improved. However, additional revisions are required. In particular, the Discussion section requires greater and more detailed comparison of the experimental results with the existing literature. The authors’ points within the Discussion are also difficult to follow. It appears to me that the authors are trying to state that N release from MOW compost is better timed with vine uptake -similar to mineral fertilizer - with fewer negative effects of excessive vegetative growth and reduced grape quality compared to SS compost. Subheadings breaking the discussion into these elements (as a suggestion: the effect on soil N, the effect on vine growth, the effect on grape quality) would make this section clearer. As it is written, the authors fail to make a convincing case as to why their results are important, how they contribute new information to the existing literature, or the implications of their results for vineyard establishment and sustainability.
L78-79: “available N fraction in the medium- and long-term”
This would be better restated as, “medium- to long-term N availability”
L93: Thank you for the reference. A sentence briefly describing the guidelines pertaining to mineral fertilizer and organic amendment use would be helpful to the reader.
L94: ‘through’ instead of ‘thought’
L96: “….first two years of cultivation of a long-term ….”
L97: The use of the word ‘ameliorate’ suggests that wine quality in the region is currently unsatisfactory.
L122-125: This description is still not very clear. As written, it isn’t clear whether it was 40 kg N/ha applied in May and 60 kg N/ha applied in June in both 2020 and 2021, or if it was a total of 40 kg N/ha applied in a split application in 2020 and 60 kg N/ha applied in a split application in 2021. The authors should include the reasoning for the increased application rate that they described in their response to reviewers within the manuscript.
Furthermore, the authors did not answer my question regarding the different N rates from mineral fertilizers vs. organic amendments. I asked why the fertilizer treatment applied 100 kg/ha of available N, while the compost treatments applied 120 kg/ha. If the guidelines call for a greater available N application rate when using composts to account for variability in N availability relative to mineral fertilizers then the authors should state that in the text.
L167: “limpid” Plain language would be better. If limpid means clear, then it would be better to use the latter word.
L225-226: “One of the main purposes of CDA is to separate classes in a lower dimensional discriminant space” is not a very clear description for a reader not steeped in multivariate techniques. What is required is a plain language description.
L219: The authors state in their reply that a repeated measures ANOVA. The authors need to include the results of that analysis. Furthermore, the authors need to include the results of the F tests. There is insufficient information provided to allow the reader to assess the statistical results.
Discussion:
The discussion still requires more specific comparisons of the experimental results presented in this manuscript and the existing literature. Simply providing citations and stating that the literature supports the results is insufficient.
References to the specific table or figure within the manuscript containing the results being discussed would be helpful to the reader. It is difficult to navigate this section and figure/table references and subheaders would make this section easier to follow and connect the discussion to the data presented in the result.
L358: How much N per ha is recommended? This information should be included in the description of the called for at L93.
L364-367: Please expand and explicitly compare the results of this experiment with the values found in the literature. Please provide more discussion of how trends in temperature and moisture influenced soil microbial activity during the experimental period.
L370-372: This statement seems questionable and requires more discussion. The C:N given for SS in Table 2 suggests that it should be decomposed more slowly and release less available N over the same time period relative to MOW, and yet the opposite was observed.
L389-394: Please provide a more detailed comparison with the cited literature. It is unfortunate that the authors did not measure NH4-N. Given the greater SS C:N it seems more likely that this material had greater initial NH4-N concentrations relative to MOW which led to greater soil NH4-N concentrations and nitrification.
L396: replace “soil holding capacity” with “soil adsorption capacity”
L400-403: This is more appropriate in the Introduction.
L406-420: Please add more explicit comparisons of the results observed here with the literature. A discussion of the implications of the observed shifts in secondary metabolite synthesis due to treatment would be helpful.
L420-447: I think that a table containing the measured leaf nutrient concentrations should be included in the manuscript or as supplementary material.

Author Response

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