Soil Greenhouse Gas Emissions in Different Pastures Implemented as a Management Strategy for Climate Change

Round 1

Reviewer 1 Report

The current manuscript entitled “Soil greenhouse gas emissions in different pastures implemented as an adaptation strategy for climate change”, is fully reviewed just now. This research work can provide the management strategy/policy for the cultivate of suitable mixed pasture species in response to future climate changes, and suggestions can be offered to the nomads about how to provide adequate food for livestock, hence for human kind. However, the major concern is that there were lots of concerns/detailed information that the author did not offer in the manuscript and the corresponding supplementary files, see the major concerns and specific comments as I denoted below. Furthermore, the significance of the current study is not well revealed right now.

Major concerns:

1. After carefully reading this manuscript, I do not think that this manuscript provides any significance regarding the adaptation of the pasture species to the current climate changes, however, to replace the “adaptation” with management, for example, is much more suitable. Please consider these changes throughout the whole text, including the title.

 

2. The introduction and discussion needed to improve to clearly point out the significance of the current study, especially regarding the management strategy/policy for the cultivate of suitable mixed pasture species in response to the future climate changes, and suggestions needed to raise and inform the nomads about how to provide adequate food for livestock, hence for human kind.

 

3. Lines 84-86. The author mentioned that before the establishment of this experiment, the soil had a natural permanent pasture used for beef grazing (Lolium perenne, Holcus lanatus L. and Dactylis glomerata L.) for a period of 25 years. When the author conducted the experiment, and analyzed and discussed the related results, did the author consider how this period of 25 years would result in the influences (i.e., after this the characteristics of the soil remain almost the same?) of the experiment conducted in 2015 to 2017? If the author did, then please provide the original soil characteristics, if not please strictly discuss it in the manuscript.

 

4. Lines 95-96. The author introduced that only the first 20-cm-depth soil was performed using conventional tillage before the seeding. The major concern is that do these chosen pasture species have a shallow root system? In addition, the subsequent fertilization also applied to the shallow 20-cm soil profile.

 

5. Lines 107-108. Did the Lotus fix all the soil N? If the background of the soil is severely lacking of soil N (considered that this plot had been grazed for 25 years), how can the Lotus perform the fixation of soil N? Again, before the conventional tillage and the subsequent fertilization, detailed soil characteristics information is needed to provide.

 

6. Lines 152-153. How long will it take to start the samplings/measurements after the static chambers were installed? Obviously, lots of the disturbances will come from if the installment disturb the soil structure and other characteristics, therefore, resulting in the large variation of GHGs at the beginning of the experiments. In addition, why just measure the NO₂ and CH₄? How about CO₂? Why not measure it directly? Furthermore, when did the author sample the gases every time? Did the author increase the sampling frequency to measure the daily patterns during the different seasons? If not, how can the measurements represent the mean value of one day in a specific season? If yes, please the author provides all the detailed information in the methods or supplementary files.

 

7. Lines 187-188. The best way to deal with such kind of data is to draw the data points according to the date you sampled/measured, then use polylines to connect data points, rather than fill the data with linear interpolation to make the data look However, data with linear interpolation are not the real/true ones, so please remove all the data which “Days without measures were filled by linear interpolation”, including the data displayed in any related figures.

 

Specific comments:

1. Line 25. What do “ME” and “CP” mean in the abstract?
2. Lines 26-27. “at dry critical periods during the year” had better change to “at critical dry periods during the year”. A similar situation needs to be revised throughout the manuscript, i.e., Line 487.
3. Line 28. “N-N2O” needs to be changed as “N-N2O”.
4. Lines 37 and 136. According to the requirement of this journal, all references or citations need to use the number index to refer to them, so that please change references (Brown & Funk, 2008; Tabatabai, 1982) to the correct format. Similar situation needs to be revised throughout the manuscript, i.e., Lines 49-50, 51-52, 54-55, 61, and so on.
5. Line 82. “43 masl” please change to “43 m a.s.l.”.
6. Line 90. “Lotus corniculatus cv Quimey (Lotus)”. I think there is a dot needed to append to “cv” according to your description of other pasture species.
7. Lines 133-141. Please carefully deal with the chemical formula, especially the superscript of positive and negative ions, i.e., NO3-. I do not think that the author uses the superscript to correctly present the positive and negative ions.
8. Lines 180-181. Please rephrase this sentence since it lacks conjunction or punctuation.
9. Lines 208-227. In the “Statistical analysis” part, the author please reduce duplication and rephrase the paragraph, for example, please delete “using the MIXED procedure of SAS” since it repeated at least 3 times.
10. Line 230. Please clearly indicate which 7 years refer to.
11. Line 238, Figure (a). It’s hard to distinguish the data points of the four treatments (Control, Bromus, Lotus, and Br/L). One of the choices is to draw the WFPS data of Control treatment only, if the other three treatments are not significantly higher or lower than that of control one, and indicated it in the caption of the figure. In addition, it is better to put the labels, i.e., (a) and (b) should be onto the top and bottom panels of the figure at the proper location (usually left-top).
12. Lines 251-252. Please put the word “only” in the proper position in this sentence.
13. Line 265, Figure 2. On the top panel of this figure, large variation comes from the data of the treatments of Control and Bromus, and obviously lots of data was very close to zero. Therefore, my suggestion is redrawing this figure, and using the other kind of scale to display the range of the value of the y scale, i.e., you can use the scale like 0, 1, 10, 100, 1000 and so on to better display your valuable data set. As well, for Figure 2b on the bottom panel of the same figure, the advice is reducing the range of the y values, for example, adjusting the range to 0 to 150 is perfect. Similar problems also adapted to Figure 3a and 3b, on Line 194.
14. Lines 307-308. Please check the grammar of the sentence “During the second year, emissions were greater than in year one”.
15. Lines 355-357. Please rephrase this sentence because the expression here is similar to discussion, while this is the results, so that remove such kind of expression.
16. Lines 482 and 486, as well as the title. I do not think that this manuscript provides any significance regarding the adaptation of the pasture species to the current climate changes. However, it offers a valuable management strategy of the yield of pasture species to meet the required food for graziery (furthermore, for human kind) in future climate warming. Please consider this change throughout the whole text, including the title, to replace the “adaptation” with management, for example.
17. About the supplementary file. I checked all the figures and tables in the supplementary file, and found that these figures and tables are the same as displayed in the manuscript, so why not remove them?

Author Response

Thank you for your comments, please find attached a file with the respective responses.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors:

The manuscript evaluated different forage species providing animal feed during dry periods as an adaptation strategy for livestock grazing systems, and its implications for greenhouse gas (GHG) emissions. The result is interesting and meet production demand. I think that the following suggestions, comments and questions may help to further improve the paper.

Line 25 ME? The abbreviation of PCDD/Fs and DL-PCBs should be unified in the whole manuscript. Please recheck and revise (if any) all acronyms and/or abbreviations in terms of consistency of style and/or conformity with journal's standard. Each acronym and/or abbreviation used in this paper should be explained/in full at its first mention only. After that, the abbreviation(s) and/or acronym(s) should be referred to by the acronym/ abbreviation throughout the article.

Line 28 should be changed to “N₂O”

Line 61 Luo et al., 2018 should be deleted.

Line 208 Description of statistical analysis is a little confusing and unclear. Therefore, this part should reorganize the language.

Line 239 Not found the data of 7-year average.

Figure 1a should You need to specify which part of the data the left and right ordinates represent. In addition, the figure1 not clear, especially the column.

All figure should change the ordinate value range making the data with different treatments can be distinguished.

Line 273 List the formula for calculating Metabolizable Energy (ME)

Line 348 List the formula for calculating emission intensity (EI)

Line 314 Why the values of fluxes of C-CH₄ are negative.

In discussion elaborate on key variables driving the N-N₂O and C-CH4 fluxes, however, there is a lack of discussion on the relationship between different treatments and soil WFPS and temperature.

Author Response

Thank you for your comments, please find attached a file with the respective responses.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Major concerns:

Results and Discussion.

The effects/influences of the farming soil (which had been used for grazing for a period of 25 years) and the depth soil (which may affect the productivity of the pastures planted/conducted in this study, i.e., through the changes in nutrition of deep soil), should be deeply discussed. If the author cannot prove that there were no legacy effects of the prior 25-year grazing (Did the initial data (showed in Table 1) of the plots of control, Bromus, Lotus, and Br/L differ significantly? We don’t know.), and the deep soil did not affect the later conducted experiments for GHGs emission, pastures’ productivity, and so on, so how can the readers conclude that all the results and conclusions come out from your tested experiments based on serval treatments and levels? I require the author to address these concerns directly, and do not evade them. Whether there were no legacy effects or the influences from the background nutrients of the deep soil, or was there no such investigated data on this aspect at all?

Specific comments:

1. The author did not provide a clean version of the revised manuscript, which made the current submission hard to read. So that a clean version needs to be provided for reviewing again.
2. Throughout the whole manuscript, I noticed that the author tries to untied all units following the suggestion raised by Reviewer 2. That’s good, but don’t forget to check the transformation procedures perform correctly, accurately and properly.
3. Lines 124-128, in Table 1. I notice that the values have some changes, especially for the Organic Matter, g kg^-1, of which is more than ten times the old version. Please do check all the data again seriously to make sure whether they are correct or not. Please also carefully check the other tables.
4. Line 176. Please correct any expression about “year 1”, i.e., changing it to “the first year” would be much better. Similar situations also occurred on lines 26, 176, 309-314, 397 509, and 567.
5. Lines 179-180. The author mentioned that all gas samplings were conducted at 11 o’clock. Does the author properly cite the work conducted by the previous one? If yes, please cite properly, if not, please provide the daily dynamic pattern of the variation in GHG emission.

Author Response

Thank you for your R2 comments, please find attached a file with our responses.

 

Kind regards, 

Author Response File: Author Response.pdf

Reviewer 2 Report

This article is basically revised in accordance with the opinions and the quality of the article has been improved .

Author Response

Thank you for your comments.