The Influence of Cropping Systems and Tillage Intensity on Soil CO₂ Exchange Rate

Round 1

Reviewer 1 Report

General comment：

This paper studied the effects of different tillage methods on the soil CO2 net exchange law, and found that the carbon dioxide exchange amount of no-tillage system was 28% higher than that of the traditional tillage system, and the planting pattern also had an impact on the carbon dioxide flux, and soil surface temperature and humidity were the most important conditions to explain the soil net carbon dioxide exchange law.

Major comment：

1.        This paper has a clear intention and remarkable results, and it is suggested that the significance of the research in carbon emissions should be further emphasized at the beginning and end, for example, the conclusion part is recommended to be expanded to emphasize the research significance of this paper and echo the beginning.

2.        The authors did not establish the relationships between soil moisture and soil temperature and soil respiration, so it is suggested that the authors should do so to better explain the differences in soil respiration between different treatments, such as DOI: 10.1016/j.apsoil.2015.01.015; doi: 10.1186/s40064-016-1761-0; 10.1016/j.scitotenv.2018.08.111. Some temperature sensitivity analysis might even be considered. In addition, since soil respiration is likely to be affected by soil microbial community structure, plant phenology, etc., such as doi: 10.1016/j.scitotenv.2021.152591, doi:10.3390/jof9090885, it is suggested that the authors add some uncertainty analysis in the discussion section.

Minor comment：

1.      Figure 1 is a bit strange, so it is recommended to zoom in on the main image, and the farm overview on the right seems to be discarded

2.      The meteorological environment background of the experimental area should be placed in part 2.2, and the location of the experimental sample plot will be introduced

3.      Moisture content should also be counted as a physical and chemical property of the soil, right? It is suggested to be put together with section 3.1

4.      Figure 7 proposes to adjust the structure to the top and bottom and place the diagram at the bottom

5.      Figure 8 proposes to make the same adjustments as Figure 7

Author Response

Dear reviewer,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “The Influence of Cropping Systems and Tillage Intensity on Soil CO₂ Exchange Rate” for publication in the Sustainability journal. We appreciate the time and effort that you and other reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Comment: This paper has a clear intention and remarkable results, and it is suggested that the significance of the research in carbon emissions should be further emphasized at the beginning and end, for example, the conclusion part is recommended to be expanded to emphasize the research significance of this paper and echo the beginning.

Author response: Thank you for the remark. We added some sentences emphasizing  the research significance of this paper.

         Comment: The authors did not establish the relationships between soil moisture and soil temperature and soil respiration, so it is suggested that the authors should do so to better explain the differences in soil respiration between different treatments, such as DOI: 10.1016/j.apsoil.2015.01.015; doi: 10.1186/s40064-016-1761-0; 10.1016/j.scitotenv.2018.08.111. Some temperature sensitivity analysis might even be considered. In addition, since soil respiration is likely to be affected by soil microbial community structure, plant phenology, etc., such as doi: 10.1016/j.scitotenv.2021.152591, doi:10.3390/jof9090885, it is suggested that the authors add some uncertainty analysis in the discussion section. 

 Author response: Thank you for this suggestion. We found the relationship between soil moisture and soil temperature and soil respiration (please look at the Table 5 and 3.4 part. Also, throughout the article we tried to describe and evaluate all possible factors influencing NCER. However, reviewer is right that additional research is required to fully understand the causes and enhancing aspects of any type of soil conservation strategy, as the influence varies from land to land according to local environmental and climatic circumstances and management scenarios. We will try to do them in further research.

      Comment: Figure 1 is a bit strange, so it is recommended to zoom in on the main image, and  the farm overview on the right seems to be discarded.

Author response: Thank you for pointing this out. The figure was corrected.

Comment: The meteorological environment background of the experimental area should be placed in part 2.2, and the location of the experimental sample plot will be introduced.

Author response: Thank you for the remark. The necessary information was added to the methodological part.

Comment: Moisture content should also be counted as a physical and chemical property of the soil, right? It is suggested to be put together with section 3.1.

Author response: We agree with the reviewer’s assessment, but since soil moisture is one of the important factors influencing the rate of soil CO₂ exchange and emission, we wanted to analyze it in more detail in this experiment, so we presented it separately and did not include it in the table in Section 3.1

Comment: Figure 7 proposes to adjust the structure to the top and bottom and place the diagram at the bottom. Figure 8 proposes to make the same adjustments as Figure 7.

Author response: Thank you for pointing this out. The figures were corrected.

Reviewer 2 Report

Manuscript title: The Influence of Cropping Systems and Tillage Intensity on Soil CO2 Exchange Rate

Manuscript number: sustainability-2923916

Journal: Sustainability

General comments

The effect of different tillage treatments and different crop rotation was investigated during a three-year long period and the results are shown in the Manuscript. The topic is a very important one, since both the way the soil is cultivated and the use of crop rotation and catch crops are important agrotechnical measures to protect soil carbon stocks and maintain soil health, which is the basis for safe crop production. However, there are parts of the manuscript that need to be clarified or improved.

Specific comments

Abstract

Lines 10-11. This sentence is not true in that way: there are many agricultural practices that have an impact on agricultural greenhouse gas emissions. The available results are not always clear and can obviously be improved, but this is why research is needed to provide results on the effects of measures on as many soil types/climate characteristics as possible.

Line 14: pH is not a nutrient, please correct the sentence.

Introduction 

Line 50: “the” is not needed before the word positive.           

Line 55: Please rephrase the sentence: global carbon cycle doesn’t need to be improved. The word “improved” should be changed.

Line 58: Microbial contact with the substrate and substrate distribution are not soil physical properties.

Lines 67-68: The effect of NT and CT on soil NCER are not so clear, results from different studies can differ.

Line 74: The word “but” is not needed in the sentence.

Line 78: Protect soils from erosion would sound better.

Materials and Methods

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “The Influence of Cropping Systems and Tillage Intensity on Soil CO₂ Exchange Rate” for publication in the Sustainability journal. We appreciate the time and effort that you and other reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Comment: Abstract: Lines 10-11. This sentence is not true in that way: there are many agricultural practices that have an impact on agricultural greenhouse gas emissions. The available results are not always clear and can obviously be improved, but this is why research is needed to provide results on the effects of measures on as many soil types/climate characteristics as possible.

Line 14: pH is not a nutrient, please correct the sentence.

Author response: Thank you for pointing this out. We corrected the sentences according reviewers’ remarks.

Comment: Introduction: Line 50: “the” is not needed before the word positive.

Line 55: Please rephrase the sentence: global carbon cycle doesn’t need to be improved. The word

“improved” should be changed.

Line 58: Microbial contact with the substrate and substrate distribution are not soil physical. properties.

Lines 67-68: The effect of NT and CT on soil NCER are not so clear, results from different studies can differ.

Line 74: The word “but” is not needed in the sentence.

Line 78: Protect soils from erosion would sound better.

Author response: Thank you for the remarks. We corrected it.

Comment: Materials and Methods: Line 115: I don’t understand the 40 treatments… What are these 40 treatments?

Author response: Thank you for the remarks. The total number of treatments is correct. It is 40. The experiment consists of 5 crop rotations in two different tillage systems. Every treatment was done in four replications ( 5 x 2 x 4 = 40).

Comment: Lines 138-159: The description of weather characteristics is too detailed for me. The graph clearly shows the differences between years, I think it is unnecessary to go into so much detail about how many degrees it was in which month of the year. A few sentences about how the year in question compared to the multi-year average would be sufficient.

Author response: Thank you for the suggestion. Since precipitation and temperature are considered to be one of the main ecological factors that influence the processes of decomposition of organic matter, as well as the intensity of CO₂formation and emissions from the soil, we think it is better to examine weather conditions in more detail. a more detailed analysis of weather conditions allows to better explain the obtained results and to link the obtained trends not only with the applied agricultural measures, but also with the influence of climatic conditions.

Comment: Lines 185: Please specify where the soil samples were taken from? From all treatments? (from all crop rotations of both soil tillage treatments?)

Author response: Thank you for pointing this out. We added more information about soil sampling: In the year 2021 – 2023 soil samples from 0 – 10 cm and 10 -20 cm layer was taken to determine the basic chemical characteristics. Soil samples was taken using steel auger with three replicates from all study treatments (including different crop rotations and tillage systems).

Comment: Line 194-197: Please write a sentence or two about how the NCER measurement is done. How long does each measurement take? How long does it take to complete all the treatments? Are the measurements taken continuously between 10 am and 5 pm or is this only the interval within which the measurements are taken. There are huge temperature variations between 10 am and 5 pm which have a significant impact on the results. How was this error avoided?

Author response: Thank you for the remarks. We added the necessary information about NCER measurement.

Comment: Line 197: Figure 5 shows that 4 measurements were done per year, not six, please clarify.

Author response: Thank you for pointing this out. There was a mistake, only 4 measurements per month were done. We corrected the description in methodological part.

Comment: Results: Lines 215-216: Tillage and cropping system have no immediate effect on the productivity. Both have long term effect by changing soil physical, chemical and biological properties of the soil. These changes have effect on productivity…

Author response: Thank you for pointing this out. We corrected the sentence.

Comment: Table 2: Which year are these results? In line 185 it says that soil samples were taken between 2021 and 2023. If each year, what is in this table? If not every year, then the 185 rows need to be corrected. The experiment was set up in 2021, we would definitely need the results of the soil sample analyses from that year to show that the area was homogeneous when the experiment was set up and that the differences were indeed due to the treatments.

Author response: Thank you for the remarks. Table 2 presents the average data for the years 2021 – 2023, we have provided a clarification in the footnote of the table. The initial data before the start of experiment is written in 2.1 part “The main average topsoil (0-20 cm) chemical characteristics were as follows: pH_KCl – 6.6, humus content was 31 g kg^-1, plant available phosphorus (P₂O₅) and potassium (K₂O) - 200 and 150 mg kg^-1, respectively.”

Comment: Figure 5: Only 4 measurement days are per year, not 6.

Author response: Thank you for pointing this out. We corrected a mistake in methodological part.

Comment: Lines 283-317: Temperature and rainfall were the same in both tillage treatments, which cannot explain the results. Please reconsider and rephrase this part.

Author response: Thank you for the suggestion. We corrected the sentences.

Comment: Figure 7: Please do not connect the discrete measurement points.

Author response: Thank you for the suggestion. As we measured the soil surface moisture content dynamics during active crop growth season in the soils, it is allowed to connect individual measuring points. In addition, in such way the results are displayed more clearly, which is more understandable for the reader.

Reviewer 3 Report

Research is relevant and interesting.

1. Spring or winter rape was included in the experiment (line 130)?;

2. The cultivation technology of catch crop white mustard should be described in more detail;

3. In the Figures No. 5 and 6 significant differences between the treatments are not marked;

4. I recommend presenting the discussion in a separate chapter.

Author Response

Dear reviewer,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “The Influence of Cropping Systems and Tillage Intensity on Soil CO₂ Exchange Rate” for publication in the Sustainability journal. We appreciate the time and effort that you and other reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Comment: Spring or winter rape was included in the experiment (line 130)?

Author response: Thank you for pointing this out. Winter rape was included into rotation. In Line 141 was a mistake, we corrected it.

Comment: The cultivation technology of catch crop white mustard should be described in more detail.

Author response: Thank you for the remark. We added the necessary information.

Comment: In the Figures No. 5 and 6 significant differences between the treatments are not marked.

Author response: Thank you for the remark. The standard error ensures the reliability of the results. As far as we know, significance testing of NCER cannot be considered separate as independent parameters according to the statistics rules. Therefore, we decide to leave the statistical analysis in this format. Actions and interactions related to soil net carbon dioxide exchange rate (NCER) are given in the Table 3.

Comment: I recommend presenting the discussion in a separate chapter.

Author response: Thank you for the suggestion. But we decided to combine these sections with the aim to discuss the data in more detail.

Round 2

Reviewer 2 Report

I cannot accept two answers.
One: the 40 treatments. Repetition and treatment are not to be confused. If there are 5 crop rotations and 2 tillages, that is 10 treatments. If each has 4 repetitions, it is still only 10 treatments.

The second: The fact that the soil moisture measurements are taken during the active growing season makes them discrete measurement points and cannot be combined. A large amount of precipitation may fall between the measurement days and if the data are linearly connected it is not shown on the graph. In such a case, connecting the two measurement points does not show a relevant result, since the soil moisture content increases during a high precipitation event.

Author Response

Dear reviewer,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “The Influence of Cropping Systems and Tillage Intensity on Soil CO₂ Exchange Rate” for publication in the Sustainability journal. We appreciate the time and effort that you and other reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Comment: the 40 treatments. Repetition and treatment are not to be confused. If there are 5 crop rotations and 2 tillage’s, that is 10 treatments. If each has 4 repetitions, it is still only 10 treatments.

Author response: Thank you for the remark. We agree with your suggestion that the previous description is a little bit confused. we corrected the description of treatments as follows: Five different crop rotations and two tillage systems were analyzed in this research. The field experiment with 10 treatments was laid out in a split – plot design with four replications. In the two-factor field experiment, different tillage systems (Factor A: conventional tillage (CT) and no-tillage (NT)) and different crop rotations (Factor B) were investigated (Table 1).

         Comment: The fact that the soil moisture measurements are taken during the active growing season makes them discrete measurement points and cannot be combined. A large amount of precipitation may fall between the measurement days and if the data are linearly connected it is not shown on the graph. In such a case, connecting the two measurement points does not show a relevant result, since the soil moisture content increases during a high precipitation event.

 Author response: Thank you for this suggestion and explanation. We changed the type og graphics, now the measurement points are not connected.