Effect of Clay Mineralogy and Soil Organic Carbon in Aggregates under Straw Incorporation
, Li Huang 1,*, Xiaokun Li 1, Jianwei Lu 1, Ruili Gao 3, Muhammad Kamran 1 and Shah Fahad 4Round 1
Reviewer 1 Report
There needs to be a better introduction into the problematics.
What are the novelties of this paper?
More details of the studied area, slope, precipitation, and temperatures, how much straw per ha was applied?
In Figure 2, it is not described what do the small and capital letters define in the graphs.
In Figure 3, also the same as in Figure 2
Row 449- do You have the data about the growth and activity of the microorganisms?
Inconsistencies in Figures, with colors, they need to be more appealing to the reader.
Author Response
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We have carefully considered all comments from the reviewers and revised our manuscript accordingly. In the following section, we summarize our responses to each comment from the reviewers. We believe that our responses have well addressed all concerns from the reviewer 1. I hope that the revised manuscript would meet your requirements for publication in Agronomy.
Comments and Suggestions for Authors
1 There needs to be a better introduction into the problematics.
Response: Thanks for your comments and suggestions. We have revised the introduction based on your suggestions, including paragraph structure (stabilization of soil organic carbon, role of soil phyllosilicate minerals and iron (oxyhydr)oxides in SOC stabilization, research purposes and formulate hypothesis. This study mainly explores the molecular structure of SOC, species of clay minerals, and interactions between these components in clay fractions within aggregates under long-term straw incorporation. Please see introduction section of the revised manuscript.
2 What are the novelties of this paper?
Response: Previous studies have investigated the stability and organic carbon of aggregates, but the SOC composition and minerals speciation in clay fractions (<2 μm) within soil aggregates are no detailed studies. The molecular structure of SOC, species of clay minerals, and interactions between these components was examined in clay fractions within aggregates under long-term straw incorporation. We have revised the introduction, please see lines 86-89 of the revised manuscript.
3 More details of the studied area, slope, precipitation, and temperatures, how much straw per ha was applied
Response: Thanks for your comments and suggestions. We have revised the materials and methods based on your suggestions. Please see lines 101-113 and 118-127 of the revised manuscript.
The mean annual precipitation, temperature, and evaporation are 1489 mm (mainly from July to September), 16.9 °C, and 1361 mm, respectively. The frost-free period is about 262 days and the sunshine radiation averages 12.2 MJ m−2 d−1, with an average annual sunshine duration of 1913 h. The predominant clay minerals are kaolinite, illite, and 1.4 nm hydroxy interlayer hydroxyl minerals. It has long been cultivated with winter rape (Brassica napus L.) and summer rice (Oryza sativa L.), which represents one of the main cropping systems in China. The main soil properties of the upper sur-face horizon (0–20 cm) of the experimental site were as follows: soil pH (water: soil = 2.5:1), 5.23; organic carbon concentration, 19.8 g C kg−1; total nitrogen (N) concentration, 1.92 g N kg−1; total potassium (K) concentration, 6.68 g K kg−1; alkaline hydrolysable N concentration, 129.2 mg N kg−1; Olsen phosphorus (P) concentration, 21.7 mg P kg−1; and ammonium acetate-extractable K concentration, 86.1 mg K kg−1.
The conventional tillage treatments consisted of moldboard plowing (20–22 cm) in May and October followed by secondary seedbed preparation by disking (7.5–10 cm) using a disk harrow. After harvesting, residues were chopped into 2–3 cm pieces for rape and 6–7 cm pieces for rice. For the treatments without straw removing, all crop residues were removed from the experiments. In the straw incorporation fields, after the rice and rape harvests, 5250 kg ha−1 rice straw and 4500 kg ha−1 rape straw were applied. All other field management practices were the same for all plots during the experiment. The application of N fertilizer, phosphate fertilizer, and potash in rice and rape was 150 and 210 kg ha−2 as urea (N 46%), 45 and 75 kg ha−2 as superphosphate (P2O5 12%), and 150 and 150 kg ha−2 as potassium chloride (K2O 60%), respectively.
4 In Figure 2, it is not described what do the small and capital letters define in the graphs. In Figure 3, also the same as in Figure 2
Response: It’s done. Please see Figure 2 and 3 captions of the revised manuscript.
5 Row 449- do You have the data about the growth and activity of the microorganisms
Response: I'm very sorry, we didn't measure the data about the growth and activity of the microorganisms, The accumulation of Fe(III) ions in the clay fraction within microaggregates may also have changed the soil surface properties and thus influenced SOC stabilization processes. Fe(III) polymerization could trap large amounts of organic matter, thus stabilizing the organic matter (especially dissolved organic C) against microbial mineralization according to the results of previous studies (Chen et al., 2014; Riedel et al., 2013; Sodano et al., 2017).
6 Inconsistencies in Figures, with colors, they need to be more appealing to the reader.
Response: Thanks for your comments and suggestions. We have revised the all of the figure based on your suggestions. Please see revised manuscript.
Chen, C., Dynes, J.J., Wang, J., Sparks, D.L., 2014. Properties of Fe-organic matter associations via coprecipitation versus adsorption. Environ Sci Technol, 48, 13751-9.
Riedel, T., Zak, D., Biester, H., Dittmar, T., 2013. Iron traps terrestrially derived dissolved organic matter at redox interfaces. Proc Natl Acad Sci U S A, 110, 10101-5.
Sodano, M., Lerda, C., Nisticò, R., Martin, M., Magnacca, G., Celi, L., Said-Pullicino, D., 2017. Dissolved organic carbon retention by coprecipitation during the oxidation of ferrous iron. Geoderma, 307, 19-29.
Reviewer 2 Report
Overall, I find the article well written and helpful. Despite this, I have a few remarks.
1) Be more specific in the Abstract (give particular results, for example, numerically).
2) In the Introduction section, focus more on the importance of soil aggregates. For example:
Li, N., Long, J., Han, X., Yuan, Y., & Sheng, M. (2020). Molecular characterization of soil organic carbon in water-stable aggregate fractions during the early pedogenesis from parent material of Mollisols. Journal of Soils and Sediments, 20(4), 1869-1880.
Mustafa, A., Minggang, X., Shah, S. A. A., Abrar, M. M., Nan, S., Baoren, W., ... & Núñez-Delgado, A. (2020). Soil aggregation and soil aggregate stability regulate organic carbon and nitrogen storage in a red soil of southern China. Journal of Environmental Management, 270, 110894.
3) The Materials and Methods section should describe the basic agrotechnical operations in rice cultivation (including procedure dates).
4) All figures and tables must be self-explanatory. Therefore, check them and ensure that each reader can understand them (including statistical evaluation).
5) There are two decimal places somewhere in Table 1. I understand it's because of the better graphics. However, it should be uniform (use only one decimal place in this table).
6) I would insert Figure 10 into the Results section (not Discussion).
7) In the Discussion and Conclusion sections, better describe and highlight the benefits of your work.
Author Response
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We have carefully considered all comments from the reviewers and revised our manuscript accordingly. In the following section, we summarize our responses to each comment from the reviewers. We believe that our responses have well addressed all concerns from the reviewer 2. I hope that the revised manuscript would meet your requirements for publication in Agronomy.
Comments and Suggestions for Authors
Overall, I find the article well written and helpful. Despite this, I have a few remarks.
1) Be more specific in the Abstract (give particular results, for example, numerically).
Response: Thanks for your comments and suggestions. We have revised the abstract based on your suggestions. Please see abstract of the revised manuscript.
2) In the Introduction section, focus more on the importance of soil aggregates. For example:
Li, N., Long, J., Han, X., Yuan, Y., & Sheng, M. (2020). Molecular characterization of soil organic carbon in water-stable aggregate fractions during the early pedogenesis from parent material of Mollisols. Journal of Soils and Sediments, 20(4), 1869-1880.
Mustafa, A., Minggang, X., Shah, S. A. A., Abrar, M. M., Nan, S., Baoren, W., ... & Núñez-Delgado, A. (2020). Soil aggregation and soil aggregate stability regulate organic carbon and nitrogen storage in a red soil of southern China. Journal of Environmental Management, 270, 110894.
Response: Thanks for your comments and suggestions. We have revised the introduction section based on your suggestions. The importance of soil aggregates is described, please see lines 37-39 of the revised manuscript.
3) The Materials and Methods section should describe the basic agrotechnical operations in rice cultivation (including procedure dates).
Response: Thanks for your comments and suggestions. We have revised the materials and methods based on your suggestions. Please see lines 101-113 and 118-127 of the revised manuscript.
The mean annual precipitation, temperature, and evaporation are 1489 mm (mainly from July to September), 16.9 °C, and 1361 mm, respectively. The frost-free period is about 262 days and the sunshine radiation averages 12.2 MJ m−2 d−1, with an average annual sunshine duration of 1913 h. The predominant clay minerals are kaolinite, illite, and 1.4 nm hydroxy interlayer hydroxyl minerals. It has long been cultivated with winter rape (Brassica napus L.) and summer rice (Oryza sativa L.), which represents one of the main cropping systems in China. The main soil properties of the upper sur-face horizon (0–20 cm) of the experimental site were as follows: soil pH (water: soil = 2.5:1), 5.23; organic carbon concentration, 19.8 g C kg−1; total nitrogen (N) concentration, 1.92 g N kg−1; total potassium (K) concentration, 6.68 g K kg−1; alkaline hydrolysable N concentration, 129.2 mg N kg−1; Olsen phosphorus (P) concentration, 21.7 mg P kg−1; and ammonium acetate-extractable K concentration, 86.1 mg K kg−1.
The conventional tillage treatments consisted of moldboard plowing (20–22 cm) in May and October followed by secondary seedbed preparation by disking (7.5–10 cm) using a disk harrow. After harvesting, residues were chopped into 2–3 cm pieces for rape and 6–7 cm pieces for rice. For the treatments without straw removing, all crop residues were removed from the experiments. In the straw incorporation fields, after the rice and rape harvests, 5250 kg ha−1 rice straw and 4500 kg ha−1 rape straw were applied. All other field management practices were the same for all plots during the experiment. The application of N fertilizer, phosphate fertilizer, and potash in rice and rape was 150 and 210 kg ha−2 as urea (N 46%), 45 and 75 kg ha−2 as superphosphate (P2O5 12%), and 150 and 150 kg ha−2 as potassium chloride (K2O 60%), respectively.
4) All figures and tables must be self-explanatory. Therefore, check them and ensure that each reader can understand them (including statistical evaluation).
Response: Thanks for your comments and suggestions. It’s done. Please see Figure 2 and 3 captions of the revised manuscript.
5) There are two decimal places somewhere in Table 1. I understand it's because of the better graphics. However, it should be uniform (use only one decimal place in this table).
Response: Thanks for your comments and suggestions. It’s done. Please see Table 1 of the revised manuscript.
6) I would insert Figure 10 into the Results section (not Discussion).
Response: Thanks for your comments and suggestions. It’s done. Please see results section 3.7 of the revised manuscript.
7) In the Discussion and Conclusion sections, better describe and highlight the benefits of your work.
Response: Thanks for your comments and suggestions. We have revised the Discussion and Conclusion based on your suggestions. Please see lines 455-456, 497-498 and 529-531 of the revised manuscript.
The results of this study indicate that clay mineral governed the distribution of the organic component in organic-mineral complexes.
Straw incorporation induced transformation of Fe-bearing minerals in clay fractions.
These findings should facilitate better understanding of the effects of clay mineral on SOC stabilization in clay fractions within macroaggregates and microaggregates under long-term straw incorporation.
Reviewer 3 Report
The paper addresses an important topic for conservation agriculture. The paper contributes to the development of knowledge and facilitates a better understanding of the effects of clay mineral on SOC stabilization in clay fractions within macroaggregates and microaggregates under long-term straw incorporation.
The paper is well documented and describes the experiment relatively well.
There are some aspects that need to be improved for a better understanding of the paper:
- line 97: when describing the soil, I consider it necessary to present the essential properties of humus and pH.
- line 101-102: I consider necessary the synthetic description of the experimental variants (I understand that it was presented in another paper, but a short synthesis can be edifying).
- in the tables and figures must be mentioned, in footnotes, all abbreviations.
Author Response
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We have carefully considered all comments from the reviewers and revised our manuscript accordingly. In the following section, we summarize our responses to each comment from the reviewers. We believe that our responses have well addressed all concerns from the reviewer 3. I hope that the revised manuscript would meet your requirements for publication in Agronomy.
Comments and Suggestions for Authors
The paper addresses an important topic for conservation agriculture. The paper contributes to the development of knowledge and facilitates a better understanding of the effects of clay mineral on SOC stabilization in clay fractions within macroaggregates and microaggregates under long-term straw incorporation.
The paper is well documented and describes the experiment relatively well. There are some aspects that need to be improved for a better understanding of the paper:
1 - line 97: when describing the soil, I consider it necessary to present the essential properties of humus and pH.
Response: Thanks for your comments and suggestions. We have added detailed basic properties of the soil in the materials and methods based on your suggestions. Please see lines 108-113 of the revised manuscript.
The main soil properties of the upper surface horizon (0–20 cm) of the experimental site were as follows: soil pH (water: soil = 2.5:1), 5.23; organic carbon concentration, 19.8 g C kg−1; total nitrogen (N) concentration, 1.92 g N kg−1; total potassium (K) concentration, 6.68 g K kg−1; alkaline hydrolysable N concentration, 129.2 mg N kg−1; Olsen phosphorus (P) concentration, 21.7 mg P kg−1; and ammonium acetate-extractable K con-centration, 86.1 mg K kg−1.
2 - line 101-102: I consider necessary the synthetic description of the experimental variants (I understand that it was presented in another paper, but a short synthesis can be edifying).
Response: Thanks for your comments and suggestions. We have revised the materials and methods based on your suggestions. Please see lines 564-566 of the revised manuscript.
The mean annual precipitation, temperature, and evaporation are 1489 mm (mainly from July to September), 16.9 °C, and 1361 mm, respectively. The frost-free period is about 262 days and the sunshine radiation averages 12.2 MJ m−2 d−1, with an average annual sunshine duration of 1913 h. The predominant clay minerals are kaolinite, illite, and 1.4 nm hydroxy interlayer hydroxyl minerals. It has long been cultivated with winter rape (Brassica napus L.) and summer rice (Oryza sativa L.), which represents one of the main cropping systems in China. The main soil properties of the upper sur-face horizon (0–20 cm) of the experimental site were as follows: soil pH (water: soil = 2.5:1), 5.23; organic carbon concentration, 19.8 g C kg−1; total nitrogen (N) concentration, 1.92 g N kg−1; total potassium (K) concentration, 6.68 g K kg−1; alkaline hydrolysable N concentration, 129.2 mg N kg−1; Olsen phosphorus (P) concentration, 21.7 mg P kg−1; and ammonium acetate-extractable K concentration, 86.1 mg K kg−1.
3- in the tables and figures must be mentioned, in footnotes, all abbreviations.
Response: Thanks for your comments and suggestions. We have revised the all of the figures and tables based on your suggestions. Please see revised manuscript.
