Aerated Buffalo Slurry Improves Spinach Plant Growth and Mitigates CO2 and N2O Emissions from Soil
, Gaetano De Tommaso 2, Mauro Iuliano 2, Giulia Costanzo 3, Ermenegilda Vitale 3, Carmen Arena 3,4 and Luca Vitale 5,*Round 1
Reviewer 1 Report
Introduction
Provide literature on what type of heavy metals are influenced by the aeration treatment?
Provide literature on what types of heavy metals are concerned by the contamination of the food chain when using manure?
Make hypotheses of the study?
Methodology
Table 2: What process explains the reduction of heavy metals by the aeration treatment?
Table 1 and 2 should be moved to the section “Results and discussions”
In the methodology part, only show the characteristic of the untreated slurry
Results-Discussion
Present results and discussions separately or correct “results and discussions” instead of “results”. Refer to the journal guidelines
The explanation given at L214-L215 is not convincing as alkalinity cannot affect the total heavy metals contents.
The lower heavy metals in plant material with the AS slurry compared to the US Slurry might be related to differences of heavy metals contents in those two fertilizing materials. This is the more likely explanation and not the one given at L274-287.
It would have been interesting to discuss the large-scale application of this AS technology.
Author Response
Reviewer 1
Introduction
Reviewer (R): Provide literature on what type of heavy metals are influenced by the aeration treatment?
Authors’ replay (AR): No literature is available on the effect of aeration treatment on heavy metal. This issue has been better clarified in “Introduction” section.
R: Provide literature on what types of heavy metals are concerned by the contamination of the food chain when using manure?
AR: This information has been added in the “Introduction” section.
R: Make hypotheses of the study?
AR: A hypothesis of study has been added at the end of the “Introduction” section.
Methodology
R: Table 2: What process explains the reduction of heavy metals by the aeration treatment?
AR: We hypothesise that the aeration of slurry determined an increase of pH with formation of insoluble oxides and hydroxides. The rise of alkalinity might have contributed to reduce the solubility of Pb, Cu, and Cd and enhance the solubility of Zn. In addition, it might also have increased the surface adsorption of metal cations on silicates and aluminosilicates, contributing to reduce their availability. See for reference Król et al., 2020, J. Hazard Mater. 384, 121502.
This information has been added in “Results and Discussion” section.
R: Table 1 and 2 should be moved to the section “Results and discussions”
AR: Done
R: In the methodology part, only show the characteristic of the untreated slurry
AR: We moved Table 1 and 2 in “Results and Discussion” section.
Results-Discussion
R: Present results and discussions separately or correct “results and discussions” instead of “results”. Refer to the journal guidelines
AR: We have properly corrected the section heading renamed it “Results and Discussion”.
R: The explanation given at L214-L215 is not convincing as alkalinity cannot affect the total heavy metals contents.
AR: As previously specified, in our hypothesis the treatment of slurry by air insufflation may have determined an increase of pH. The alkalinity led to the formation of insoluble oxides and hydroxides, contributing to reduce the solubility of some heavy metals such as Pb, Cu, and Cd and enhance the solubility of Zn. In addition, the alkaline environment might also have increased the surface adsorption of metal cations on silicates and aluminosilicates, contributing to reduce their availability.
This information has been added in “Results and Discussion” section.
R: The lower heavy metals in plant material with the AS slurry compared to the US Slurry might be related to differences of heavy metals contents in those two fertilizing materials. This is the more likely explanation and not the one given at L274-287.
AR: We thanks the Reviewer for his/her comment and modified the sentence accordingly.
R: It would have been interesting to discuss the large-scale application of this AS technology.
AR: We added this information in the “Conclusion” section.
Reviewer 2 Report
I have only some small remarks concerning some term names and the absence of a Discussion section.
I would expect a more detailed analysis of both FTIR and NMR spectra, evidencing the differences between untreated and aerated slurry.
More details could be found in the attached annotated pdf. file
Comments for author File: 
Comments.pdf
Author Response
Reviewer 2
Reviewer (R): I would suggest the authors to add (if they have) the ORCID numbers. This provides a better visibility.
Authors’ replay (AR): Done
R: According to IUPAC Green Book, the correct term is "mass fraction" and not "content". The authors should correct for this term.
AR: We thanks the Reviewer’s suggestion and corrected the text accordingly.
R: A supplementary section devoted to the Quality Assurance could increase the paper quality.
AR: We agree with the Reviewer that the addition of the section “Quality Assurance” could elevate the quality of the manuscript, improving the value of overall research. However, unfortunately, no author has the specific skills to perform this kind of analysis. The Reviewer will excuse us if we cannot accomplish this request this time. In a further progression of this research topic, we will consider the added value of this specific analysis.
R: Beside Kolmogorov-Smirnov test for normality, the authors could use attentively Shapiro-Wilk, Anderson-Darling, Jarque-Bera, etc. NB: This is only a suggestion for future works.
AR: We thanks Reviewer for his/her fruitful comment; we will take care to his/her suggestion in the next works.
R: I have only some small remarks concerning some term names and the absence of a Discussion section.
AR: We made the changes suggested by the Reviewer and introduced the section “Results and Discussion” in the revised version of manuscript.
R: I would expect a more detailed analysis of both FTIR and NMR spectra, evidencing the differences between untreated and aerated slurry.
AR: NMR and FT-IR measurements were carried out on the insoluble solid phase which aeration does not cause significant variations. In fact, similar absorption bands are observed: band centered at 1100 cm-1 (ether and alcoholic re-sidues (C-O), large signal at 1500 cm-1 (aliphatic compounds with C=C, C-N bonds) and peak around 1700 cm-1 is due to the presence of C = O groups (lipids, etc.). Aeration influences the soluble fraction of the organic substance (polyphenols, fulvic acid, etc.), with an increase in hydroxyl groups (as in polyphenols).
R: These two FTIR and NMR spectra should be explained evidencing the dynamics of different moieties as a result of pre-treated process.
AR: Since the aeration treatment has little influence on the solid fraction, the FT-IR and NMR spectra of the two samples do not show significant differences. The aliphatic organic fraction is predominant respect aromatic (signals at 1-2 ppm respect signal at 7 ppm) and the non-polar compounds with CO and CN bonds (lipids, triglycerides, etc.) do not undergo changes with aeration.
R: Please a reference for "translocation factor" or better a completely explained equation.
AR: We have added the reference to equations.
R: More details could be found in the attached annotated pdf. file
AR: We improved the manuscript following the Reviewer’s suggestions.
