Investigation of Carbon-Dioxide-Emissions from Underutilized Grassland between 2019 and 2020

Round 1

Reviewer 1 Report

The study investigated the effects of grassland carbon dioxide emissions, soil temperature, and soil moisture under different grassland utilization degrees based on several years of operational experiments. The topic will fit the journal and the results contribute to the understanding of carbon dioxide emissions from underutilized grassland. However, the writing should be further improved to better illustrate the background and the findings.

My concerns are as follows:

1. The content of the introduction should be more comprehensive and logically connected. It is recommended to write 3-4 paragraphs instead of a lot of short paragraphs with only one or two sentences. It would be better to reorganize the introduction to make sure there are logical connections in the context. The necessity of this study should also be pointed out in comparison to related studies in the community.
2. Lines 39-45, it would be better if there would be appropriate summaries for this paragraph.
3. Lines 46-47, this short paragraph does not have a strong connection with the previous and following paragraphs.
4. The discussion seems not sufficient, and it is recommended to discuss your results in the context of more previous studies.
5. The Conclusions section is not informative. It is recommended to expand the content to better summarize this study, especially the important findings.

Author Response

Thank you for your comments. 

The following things have been corrected in the article:

We have reduced the number of paragraphs in the introduction. As a result, we have left 5 paragraphs.

The following literature has been added to the Discussion section:

1. Rustad, L. E.; Campbell, J. L.; Marion, G. M.; Norby, R. J.; Mitchell, M. J .; Hartley, A. E.; Gurevitch, J. A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming. Oecologia 2001, 126, 543–562.
2. Harper, C. W.; Blair, J. M.; Fay, P. A.; Knapp, A. K.; Carlisle, J. D. Increased rainfall variability and reduced rainfall amount decreases soil CO₂ efflux in a grassland ecosystem. Global Change Biol., 2015, 11, 322– 334.
3. Wan, S.; Luo, Y. Substrate regulation of soil respiration in a tallgrass prairie: Results of a clipping and shading experiment. Global Biogeochem. Cycles, 2003, 17, doi:10.1029/2002GB001971.

We have also added the following sentences to the Conclusions section:

The higher amounts of precipitation that are predicted to fall after a longer period of drought due to climate change may be partially retained by a thicker layer of fallow grassland, and thus trend-breaking soil moisture values may be measured.

In the Great Plain, the carbon emissions from fallowing and underutilisation should be addressed in as many semi-natural arid grassland associations as possible.

Reviewer 2 Report

The study attempts to examine CO2 emission in fallow grasslands, which is very important.

However, in its current form, the MS need revision. It is not well written and organized. The language really need improvement. I am also concerned with a series of the presentation of the results and discussion, as well as some scientific background aspects in the introduction.

See below my comments: Introduction

1) The logic is not clear. It cannot provide the certain information for why you do this study and its importance.

2) The information about CO2 emission in fallow grasslands should be provided.

3) A brief of introduction of the methods should be provided at the end of Introduction part. Results All the results in the manuscript should be analyzed with statistical approach. The average cannot provide enough information about the effect of treatments Discussion

The discussion needs more citation to support. More information about your results should be discussed.

Author Response

Thank you for your comments. 

The following things have been corrected in the article:

In the introduction, we clarified the objective of the topic and included the fact that we used instrumental measurements in our study.

In the Central Tisza region, the gradual decline of grazing livestock farming, primar-ily sheep farming - according to the Central Statistical Office, there were 3090 thousand adult sheep in Hungary in 1980, 1129 thousand in 2000 and 1060 thousand in 2019 - and the spread of pasture-based technology due to labour shortages [53], led to the emergence of extreme grassland utilisation methods. This is because pasture-based husbandry can often lead to overgrazing, while the phytomass of the more distant pasture remains unu-tilised (unused/abandonment grassland). If grazing is not possible, the main grass pro-duction can be harvested by mowing (mowing use), while if grazing animals are present, the stubble is also exploited (meadow use). These uses can affect carbon dioxide emis-sions. Therefore, in our study, we investigated the relationships between carbon dioxide emissions, soil temperature and soil moisture in underutilized grassland under different management regimes using different instruments, to which a climate index was assigned. A description of the studies is given in the Materials and methods section.

The following literature has been added to the Discussion section:

1. Rustad, L. E.; Campbell, J. L.; Marion, G. M.; Norby, R. J.; Mitchell, M. J .; Hartley, A. E.; Gurevitch, J. A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming. Oecologia 2001, 126, 543–562.
2. Harper, C. W.; Blair, J. M.; Fay, P. A.; Knapp, A. K.; Carlisle, J. D. Increased rainfall variability and reduced rainfall amount decreases soil CO₂ efflux in a grassland ecosystem. Global Change Biol., 2015, 11, 322– 334.
3. Wan, S.; Luo, Y. Substrate regulation of soil respiration in a tallgrass prairie: Results of a clipping and shading experiment. Global Biogeochem. Cycles, 2003, 17, doi:10.1029/2002GB001971.

Reviewer 3 Report

Comments to the paper manuscript, entitled „Investigation of carbon-dioxide-emissions from underutilized grassland between 2019 and 2020”

Climate change, carbon-dioxide-emissions have attracting attention by scientists for a long period. In general, grasslands are considered as an important carbon sink. However, there are different management strategies with different impact on biodiversity, forage value, soil properties and carbon sequestration and emission as well.

The study has two objectives:

- How are carbon dioxide emissions, soil temperature and soil moisture measured at specific time intervals in the studied organic grassland site related for different land use types?

- How does atmospheric natural precipitation affect carbon dioxide emissions in grassland under different treatments?

The authors made a good experiment at Karcag Research Institute in Hungary.

The experiment was established on underutilized grassland belonging to the NATURA 2000 network in Pannonian flora region.

My comments to the paper are as follows:

Introduction

• The 1^st question of the paper is: “How are carbon dioxide emissions, soil temperature and soil moisture measured at specific time intervals in the studied organic grassland site related for different land use types?”

The authors should reconsider if this question is really the objective of the study. The way of measurement of carbon dioxide emissions is describe in the part “Material and methods”.

• The 2^nd question of the paper is: “How does atmospheric natural precipitation affect carbon dioxide emissions in grassland under different treatments?”

The authors evaluated the effect of grassland management/or land use on carbon emissions during 2019 – 2020. But the discussion does not content specific evaluation of impact of precipitation on carbon emission. I would recommend to reconsider objectives of the study. Or to divide “Results” in several parts to show clearly an impact of precipitation on carbon dioxide emissions from grassland.

Material and methods

I am critical to use the term “Zero tillage”. Tillage is the mechanical manipulation of the soil for seedbed preparation (Arriaga et al. 2017, Conventional Agricultural Production Systems and Soil Functions, doi: 10.1016/B978-0-12-805317-1.00005-1). In general, tillage refer to the soil treatment on arable land. In the case of grassland, it is a practice to establish grass-legume mixtures on arable land in crop rotation for app. 3-4 years, or to establish permanent grassland. Tillage is not “common annual” management practice.

I would recommend changing the term “Zero tillage treatment” to “Unused/abandonment grassland”.

Results

Statistical values are mentioned in the paper and text. However, it is needed to provide statistical data in the table.

Discussion

This part is too short. There are only 3 references mentioned in discussion. I would recommend improving discussion and to also mention several world or minimally European references.

Author Response

Thank you for your comments. 

The following things have been corrected in the article:

Clarified the objective of the topic in the introduction.

In the Central Tisza region, the gradual decline of grazing livestock farming, primar-ily sheep farming - according to the Central Statistical Office, there were 3090 thousand adult sheep in Hungary in 1980, 1129 thousand in 2000 and 1060 thousand in 2019 - and the spread of pasture-based technology due to labour shortages [53], led to the emergence of extreme grassland utilisation methods. This is because pasture-based husbandry can often lead to overgrazing, while the phytomass of the more distant pasture remains unu-tilised (unused/abandonment grassland). If grazing is not possible, the main grass pro-duction can be harvested by mowing (mowing use), while if grazing animals are present, the stubble is also exploited (meadow use). These uses can affect carbon dioxide emis-sions. Therefore, in our study, we investigated the relationships between carbon dioxide emissions, soil temperature and soil moisture in underutilized grassland under different management regimes using different instruments, to which a climate index was assigned.

The term "zero tillage" has been changed to "unused/abandonment grassland".

The following literature has been added to the Discussion section:

1. Rustad, L. E.; Campbell, J. L.; Marion, G. M.; Norby, R. J.; Mitchell, M. J .; Hartley, A. E.; Gurevitch, J. A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming. Oecologia 2001, 126, 543–562.
2. Harper, C. W.; Blair, J. M.; Fay, P. A.; Knapp, A. K.; Carlisle, J. D. Increased rainfall variability and reduced rainfall amount decreases soil CO₂ efflux in a grassland ecosystem. Global Change Biol., 2015, 11, 322– 334.
3. Wan, S.; Luo, Y. Substrate regulation of soil respiration in a tallgrass prairie: Results of a clipping and shading experiment. Global Biogeochem. Cycles, 2003, 17, doi:10.1029/2002GB001971.

Round 2

Reviewer 2 Report

The author did much effects on improving the quality of the manuscript. But the language still need to be improved.

Reviewer 3 Report

The authors accepted my comments.

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

The manuscript investigates soil carbon dioxide emissions from underutilized grasslands between 2019 and 2020.  While the authors have chosen to study a topic of interest to various scientific communities (soil, ecology, environmental, etc.), there are many concerns associated with the manuscript.  Listed below are some of my major concerns related to the manuscript.

Introduction:  The authors did not clearly define what constitutes an underutilized grassland.  The concept of an underutilized grassland was not discussed in the introduction.  The authors have neglected to include any published literature related to soil carbon dioxide emissions under grasslands.  Although the authors state the objective of the manuscript is to assess seasonal CO2 emissions, soil temperature, and soil moisture in underutilized grasslands, they neglect to include any literature regarding the influences of soil moisture and soil temperature on soil CO2 emissions. Overall, the introduction is inadequate. The flow of this section can be improved by varying word usage and sentence structure (e.g. Page 1, lines 29 – 38). 

Materials & Methods:  The “Materials & Methods” section of the manuscript does not adequately describe the methods used to perform the study.  The authors did not state the reasoning for using the optimum climate index.  A simpler diagram should be used to illustrate the study layout.  A more thorough description of the CO2 emission measurements is needed.   The authors do not indicate if the soil CO2 emission measurements were made at regular intervals (days, weeks, etc.).  In addition, the authors need to define the term “incubation time” (Page 4, Line 132).  The authors should state if and how covering the soil surface for 30 min influenced the soil CO2 emissions and the soil microclimate.  Further, the authors should note whether the soil moisture/temperature utilized a soil-specific calibration.

Results:  The “Results” section of the manuscript needs a major revision.  A major concern with this section of the manuscript is the presentation of the results. Perhaps, a line or scatter plot should be utilized to better illustrate how soil CO2 emissions, soil temperature, and soil moisture varied by date (Figs. 3 & 4).  This will allow viewers to get a better idea of the relationships between the three measured variables.  Another major concern with this section is the simultaneous presentation of results and interpretations/explanations for the results that are presented (Page 6, Lines 169 – 176; Page 7, Lines 200 – 204; Lines 210 – 214).  The authors have chosen to have a section labeled “Results” and another labeled “Discussion”.  Therefore, only results should be presented in the “Results” section of the manuscript.  Explanations and interpretations of the results should be presented in the “Discussion” section of the manuscript.  Figures 5, 6, 9, and 10 are not clear.  All axes are not clearly labeled and the authors have not indicated the meaning of the category letters on the x-axis for these graphs.  The authors noted their hypothesis was confirmed by analysis of variance (ANOVA).  However, no hypothesis was presented in the “Introduction” of the manuscript and no details regarding the statistical treatment of the measured data were provided in the “Materials & Method” section of the manuscript.

Discussion:  The “Discussion” section of the manuscript is inadequate.  The results of the study were interpreted, explained, or placed in the proper context as it relates to previous studies.

Conclusion:  The “Conclusion” section of the manuscript is inadequate and should be rewritten. 

Reviewer 2 Report

This is a two-year last research focus on carbon-dioxide emissions from underutilized grassland. The research provides some information to better understand the grassland CO2 emissions.

However, the manuscript exists a lot of flaws.

First, the introduction no scientific question and hypothesis. And, many texts are general knowledge.

Second, Figure 2 of the method section, no need presents there. Meanwhile, you use inverted plastic basin? to sample to CO2, and no any information to show how the author to control the inner temperature.

Third, the format of figures is not matched the journal requirement.

Fourth, the discussion is too short, and no deep explains why you get these results.

Specific comments

1. Table 2. What means of desert in 2019? Is it the drought?

2. Figure 3. X-axis no need to use measurement 1, 2... And, the unit of axis-y title needs to revise.

3. Figure 4. A/M, A/K.., what’ this? Footnotes should be given. Checking throughout the paper.