The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry

Round 1

Reviewer 1 Report

I reviewed the article titled: "The exudation of surplus products links plant functional traits and plant-microbial stoichiometry" and I found it interesting and well-prepared. The methods selected by the authors are reasonable according to the actual state of knowledge. The results provided by this research group widens knowledge of soil-plant nutrient trails, which I find very significant. Based on my experience and according to the actual state of knowledge I accept this article after minor revision.

It should be stated that the study methods were selected appropriately to the given research goal. The methodology itself would allow to recreate the conditions of the conducted experiment, provided that the authors complete the missing information. The descriptive part of the results section exhaustively describes the obtained research results. To a large extent, the text in an informative way connects data presented in the figures. Altogether novelty and significance of content as well as scientific soundness of the manuscript are on top level and after accomplishing improvements it is worth for publication.

Authors should check and verify the following points:

 [47-48] - Please do correct referencing. Adding citation after comma makes it difficult to understand if it's connected to the part about bulk soil or perhaps the part about regulating rhizosphere microbiological activity.

[65-66] - Referencing format should be corrected. If authors have chosen to use numerical citation format they shouldn't change it in the middle of manuscript.

 [113-114] "The We used..." - linguistic mistake. Please do change it into: "We used a set.." or "The 8 grass species(..) were used"

[133-134] "irrigated by tap water according to requirements" - What does it mean? Please do mind that it is crucial to provide all the information enabling your research to be repeatable. It should be clearly presented how often the plant were irrigated and how soil moisture were measured and maintained through experiment.

[142-143] There's no need to put information about rinsing roots in the brackets as it's as important as the rest part of roots cleaning procedure. The word "few" should be changed into precise value.

[152-155] Given information about determining C and N values are insufficient to repeat given experiments. Please do add specific description of used methodology. Knowledge of used equipment is not enough to understand what authors did to measure given parameters. As far as I know it is not possible to measure N content in soluble matrix using TOC analyzer.  

[163-165] Same as above. Please provide more specific information on the methods used for the analysis.

 [280- 282] Table 1. should be placed on whole page, without dividing it on two pages, especially when second page has so much free space on it. Please move it few lines below to ensure better visuality. Also please do add multiplication signs in each unit column.

[285] Please move " 3.2. Variable Clustering and correlation" to section opening page. It will look much better than as it is now, where after the title is half a page, which is completely blank.

[367-374][377-405] - Please perform some editorial amendments. Wasting so much blank space is at least undesirable. Changing size of the figures would be advisable.

The discussion section is very well prepared. I do not make any comments. No correction needed. The conclusions results directly from the authors results and are in a way supported by the discussion section.

Author Response

 [47-48] - Please do correct referencing. Adding citation after comma makes it difficult to understand if it's connected to the part about bulk soil or perhaps the part about regulating rhizosphere microbiological activity. Corrected

[65-66] - Referencing format should be corrected. If authors have chosen to use numerical citation format they shouldn't change it in the middle of manuscript. Corrected

 [113-114] "The We used..." - linguistic mistake. Please do change it into: "We used a set.." or "The 8 grass species(..) were used" Changed

[133-134] "irrigated by tap water according to requirements" - What does it mean? Please do mind that it is crucial to provide all the information enabling your research to be repeatable. It should be clearly presented how often the plant were irrigated and how soil moisture were measured and maintained through experiment. We irrigated the pots 2 times a week with 10-20 ml of water to keep the water content at the field water capacity. The amount of water in pot at the level of field water capacity was set before the experiment and checked by regular pot weighting. Lines137-140.

[142-143] There's no need to put information about rinsing roots in the brackets as it's as important as the rest part of roots cleaning procedure. The word "few" should be changed into precise value. We described the procedure of root cleaning in more detail because we understand that it is the critical step in gaining reasonable results about exudation amount and composition. The soil, which was used, had 55% of sand, which made the cleaning of roots possible without causing a large damage using described approach.  We used similar approach in several other experiments, so we are skilled in it. Lines 144-160

[152-155] Given information about determining C and N values are insufficient to repeat given experiments. Please do add specific description of used methodology. Knowledge of used equipment is not enough to understand what authors did to measure given parameters. As far as I know it is not possible to measure N content in soluble matrix using TOC analyzer.  

[163-165] Same as above. Please provide more specific information on the methods used for the analysis.

We added more information about measuring our liquid samples. Please, see lines 165-166. The measurement of soluble organic C and soluble N using the machine TOC-L from Shimadzu is very simple and automated. It has an autosampler, it does its own mixing and acidification of the liquid sample. User only calibrates the machine with the standards recommended by the manufacturer and dilutes particular samples to fit in the calibration range if necessary. The machine is equipped with the unit enabling the measurement of total soluble N. So, the measurement of dissolved organic C and dissolved N is done from the sample within one injection.

Detailed protocols of colorimetric reactions used in FIA were provided by the machine manufacturer. We added more detailed information in text, in lines 182-187.

We also provided information about the weight of the samples, material of capsules and combustion temperature used in automated elemental analyzer (from Elementar, Germany). All other steps in procedure were done according to the operating manual provided by the manufacturer. In the case of measuring total P content in plant material, we added the reference to the method which was used. See lines 180-181.

 [280- 282] Table 1. should be placed on whole page, without dividing it on two pages, especially when second page has so much free space on it. Please move it few lines below to ensure better visuality. Also please do add multiplication signs in each unit column. DONE. The dot was put in the units

[285] Please move " 3.2. Variable Clustering and correlation" to section opening page. It will look much better than as it is now, where after the title is half a page, which is completely blank. Changed

[367-374][377-405] - Please perform some editorial amendments. Wasting so much blank space is at least undesirable. Changing size of the figures would be advisable. We reduced the spaces and size of the graphs

The discussion section is very well prepared. I do not make any comments. No correction needed. The conclusions results directly from the authors results and are in a way supported by the discussion section.

Reviewer 2 Report

The work entitled “The exudation of surplus products links plant functional 2 traits and plant-microbial stoichiometry” is within scope of journal. The manuscript is well written. Below are few suggestions.

Comments: Minor revision

1. At some places, sentences are too long along with grammatically mistake. Try to break up these long sentences.
2. Mention the sand and clay content.
3. Why agar powder was used and please also specifies its quantity.
4. Have you seen nutrients added through irrigation water?
5. How much plant sample was taken for C and N contents? Give some reference of vario MICRO cube Elementar, Germany
6. Decrease the font size of legends in Fig. 1 for more clarity to audience.
7. Give few lines on futuristic research at the end of conclusion section.

Author Response

1. At some places, sentences are too long along with grammatically mistake. Try to break up these long sentences.

The text was corrected before submitting by native English speaker (the company offering the proof-reading) and we paid for the service. We sent the manuscript again for corrections with your note. We hope that the English will be good enough to publish.

1. Mention the sand and clay content. Added

3. Why agar powder was used and please also specifies its quantity.

We added necessary information and the purpose and amount of agar, which was used. Lines 129-132

1. Have you seen nutrients added through irrigation water?

We used a drinking tap water. Its quality is daily monitored by state institutions. We did not analyze its nutrient content ourselves. The water has pH of 8, contents of Ca of 30 mg/l, Mg of 2,7 mg/l and NO3- of 5,4 mg/l. It contains no ammonium N and soluble reactive P is in ng/l. Each pot was irrigated 2 times a week by 10-20 ml of water to keep the soil content at field water capacity (ca 50% of soil porosity), which was set before the experiment and checked by regular weighting of pots. The water that was added by irrigation contained only very limited amount of nutrients due to their content in soil and requirements of plants.

1. How much plant sample was taken for C and N contents? Give some reference of vario MICRO cube Elementar, Germany

We weighted cca 3-4 mg of the milled sample into tin capsules and combusted them in the commercial CN analyzer (from Elementar, Germany) at temperate 980°C. We added the information in the text. See lines 180-181.

1. Decrease the font size of legends in Fig. 1 for more clarity to audience. The colors and font size of text was changed in order to make visually clearer.

1. Give few lines on futuristic research at the end of conclusion section. Added

Author Response File: Author Response.docx