Responses of Cereal Yields and Soil Carbon Sequestration to Four Long-Term Tillage Practices in the North China Plain
, Yuming Zhang 1, Wenxu Dong 1,*, Chunsheng Hu 1 and Oene Oenema 2,3
Round 1
Reviewer 1 Report
Dear Authors,
the presented paper, which evaluated changes in yields and soil carbon and nutrient reserves in a double cropping system of winter wheat and summer maize with 4 different tillage systems for 17 years, is very valuable. You have presented the results of impressive and numerous analyses, which can be successfully used in agricultural practice.
Please consider the following comments, the completion of which will improve the presented manuscript.
Introduction
Please give a brief comment on the importance of SOC in soils.
Material and methods
Please paste the map with the experimental location.
Please give a diagram of the crop rotation in the described cropping system (wheat, maize, rice) including the set of crop treatments.
Please correct superscript throughout the text (for example ha-1).
How soil samples were collected.
Please add DOi references in the References section (where possible).
Author Response
Comments and Suggestions for Authors
Dear Authors,
the presented paper, which evaluated changes in yields and soil carbon and nutrient reserves in a double cropping system of winter wheat and summer maize with 4 different tillage systems for 17 years, is very valuable. You have presented the results of impressive and numerous analyses, which can be successfully used in agricultural practice.
Response:
Thank you for the review and the appreciation of our research.
Please consider the following comments, the completion of which will improve the presented manuscript.
Introduction
Please give a brief comment on the importance of SOC in soils.
Response:
We have added now more details on the importance of the SOC in soils in the Introduction section of the main text.
Material and methods
Please paste the map with the experimental location.
Response:
We have added the map of the experimental location in the SI file (because we don’t think it should be the most important information in this study).
Please give a diagram of the crop rotation in the described cropping system (wheat, maize, rice) including the set of crop treatments.
Response:
Done. we added more information about the planting and harvesting time, as well as the fallow period. See section 2.1.
Please correct superscript throughout the text (for example ha-1).
Response:
Superscripts has been corrected; see the text.
How soil samples were collected.
Response:
We have added now more details on the soil sampling process in section 2.3.2.
Please add DOi references in the References section (where possible).
Response:
Doi have been added now in the Reference section.
Reviewer 2 Report
Dear authors. This is an important study and its long-time implementation make this even higher important! The current structure is good, but you must change words, shrink text. and other textual operations, as noted in the attached file, to clarify it and make it more readable. In the discussion you must focus on SOC changes along with the soil profile. This issue is poorly studied!
Good Luck!
Comments for author File: 
Comments.pdf
Author Response
Comments and Suggestions for Authors
Dear authors. This is an important study and its long-time implementation make this even higher important! The current structure is good, but you must change words, shrink text. and other textual operations, as noted in the attached file, to clarify it and make it more readable. In the discussion you must focus on SOC changes along with the soil profile. This issue is poorly studied!
Good Luck!
Response:
Thank you for the review and the appreciation of our research.
Line 11: Does it the loess plain? If so, note it in the text and the manuscript title
Response:
No, it’s not the loess plain.
Line 12: Delete ‘possibly’, change from ‘explore to determine”.
Response:
Done; see the text.
Line 13: To increase the text ‘flowing’ t add: ‘Four treatments were defined’
Response:
Done; see the text.
Line 20: Change ‘then’ to compare.
Response:
Done; see the text.
Line 20 Not? ‘Surface soil’, but ‘surface layer’.
Use most of the time for description singular terms: not the ‘SOC contents’ but SOC content.
Instead ‘but the opposite was true for the’ use “but lower”…
Response:
Done; see the text.
Line 24: Use: ‘the finding indicates ‘ instead of ‘we conclude…’
You use many times ‘significantly higher’ write only ‘higher’ in the abstract.
Response:
Done; see the text.
Line 25-26 too many ‘and’s, split the sentences, and use equivalent words to make it more readable.
Response:
Done; see the text.
Summary: The text structure of the abstract is good, but think about ways to clarify more the text theme only by changing words and all upper notes.
Key words: Maybe to change: Long-term experiment to a more specific one.
Response:
Done; we have deleted long-term experiment, and added more keywords.
Introduction:
Line 31. Add ‘for several proposes’. You use different tillers for each propose you noted
Response:
I guess you mean “purposes”. Then I added “for several purpose” in the text.
Line 35. What is ‘soil life’ use an accurate and scientific term.
Response:
Done; see the text.
- 35: Delete the word ‘traditional’
Response:
Done; see the text.
Line 34-35. Mineralization is good for soil but the following process- oxidization is problematic, please check it with your colleagues and correct it.
Response:
Done; see L40.
Line 35 Use singular SOC decline not declines.
Response:
Done; see the text.
Line 38. Define please what is ‘conservation tillage’
Response:
Done; see L43.
Line 43-45. What is the difference between minimal tillage to a reduced tillage? Even summarize all the types in Table.
Response:
Here we use “no-tillage (NT) and reduced tillage (RT) or minimum tillage (MT)”, which means “reduced tillage (RT)” can be equivalent to “minimum tillage (MT)”. Actually, there is very little difference between the two. Literally, reduced tillage means it’s unknown whether the tillage can be even reduced; but minimum tillage means it’s already the optimum condition. Therefore we consider reduced tillage as another way of putting the same thing of minimum tillage.
Line 58. Be specific. Which type of ‘Conservation tillage’?
Response:
Done; see L43. “Conservation tillage is defined as a field management approach that minimizes the intensity and frequency of tillage operations, so as to achieve agronomic and environ-mental benefits”
Line 60-61 Give please two-three sentences on SOC infiltration in soil. Maybe this is the reason for the lack of difference.
Response:
Done; see L 63-66.
Line 67. Does it the loess plain? If so, gives several sentences on it and its soil.
Minimal the use of abbreviations. Why use NCP?
Response:
NCP is not a loess plain.
We have deleted the abbreviation of NCP in the main text.
- 70 Use : “moldboard plowing’ don’t add ‘tillage’. Are the farmers don’t use discus plowing? In Israel the moldboard plowing became rare.
Response:
Done; see the text.
*Explain which plowing the farmers commonly use (depth/ disk or moldboard…).
Response:
Done; see the notes of Table 1.
Moldboard ploughing is traditionally applied by local famer, at the depth of ~20cm, but in recent years rotary (~10 cm depth) becomes popular.
- 73- 74. I do not understand the concept: “mechanization has facilitated combine harvesting and straw chopping and return to the soil”.
Response:
Changed into “the increasingly used mechanization has facilitated combine harvesting and straw chopping and return to the soil”; see the text.
The “combine harvesting” is pointed to the harvesting machine here.
- 79 Why use arrogant description: “the field experiment reported here was to increase the under-79 standing”. Use the objective of the current study is to determine”.
Response:
Done, see the text.
- 80 What is rotary? Does it discus?
Response:
See the notes of Table 1.
- 82 Hypothesizes: Wrongly worded: “replacing moldboard ploughing after the maize harvest by no-till or rotary tillage will increase but may affect soil C sequestration, improve soil fertility and thereby increase the crop yield in the long term, and that”. Check and correct the other ones! You do not describe the results in the hypothesizes!!!
Response:
Done, see the text.
Materials and Methods
Give the scientific names of wheat and maize and if you have the types it is also blessed to add in brackets.
Response:
Done, see the text.
Line 103- Please describe what is the rotary tillage, I taught a course for soil management and we did not use this term, but discussing, plowing…
Response:
Done. See the note in Table 1.
- 110 Add mechanically chopped
Response:
Done, see the text.
L.115 How the urea and diammonium hydrogen phosphate (DAP) were applied? By sprinkler or dropper? Delete the word: ‘fertilizers.
Response:
Done, see the text.
- 123 change it to Litter/Cube per hectare not: “40–50 mm water was applied in each irrigation”
Response:
Done, see the text.
- 126-131. Does it describe the grain collection of wheat or maize? Give reference to this methodology!
Response:
In the text we mentioned “the ears from the plants were manually harvested and threshed”. The work was all manually finished. For more detailed description see the section 2.3.1.
2.3.3 Carbon input via straw return. Very important section! Do the values relate to one year? Can the differences be correlated to rainfall values? How do you use this data?
Response:
The straw returned to the field was calculated each growing season (wheat and maize independently). The amount of straw was significantly related to the biomass yield, and of course related to the rainfall values; however, we didn’t make correlations between straw amount and rainfall values, because the main role of the returned straw amount was a reference to the SOC change in the following growing season.
Section 2.3.4 Indicate the type of the standard weather station, which company built it or it a governmental one. In addition, How the rainfall was determined in this station (electronically or manual gauge)?
Response:
See the more detailed information of Luancheng experimental station in section 2.1.
The rainfall there was manual gauge.
Line 174 Why you use ‘T’ , reduce the abbreviations along the text for the only ones that are really needed.
Response:
the abbreviations have been deleted.
Fig. 1 and other graphs, use letters for the significance grades on the graph results it will reduce the text and clarify the results in the graph
Response:
There are no comparisons between treatments (significant or not) in the figures. Significantly statistical comparisons were only shown in the tables.
Fig. 2 Carbon input from where? Put it in brackets
Response:
Done. Changed into “C input (from aboveground residues)”
Fig. 6 I think that per each treatment is better to demonstrate the change between the soil layers along with the study. In such a way, trends can be defined. See an example. Each line in your graph will be a year, then it’ll be visible the changes of carbon stocks during the study.
Response:
I’m so sorry. The purpose of this figure is to show the differences between treatments and years of each soil layer. We tried to take your suggestion, and found the yearly differences within each treatment would be not so clear.
- 218 Check the journal policy regarding noting 0.99 kg/ha/year or 0.99 kg ha-1 year-1. Also this result should be 1.0 kg ha-1 year-1. It will simplify the reading. Line 277 as an additional example, use 0.7
Response:
Done. See the text.
Discussion
Many data, think how to shrink it, omitting part of the numeric data and focusing the trends in soil.
Response:
Done. See the text.
Line 31. Do not state: “Hence, there are two main reasons”, but: “there are two possible reasons for this state”.
Response:
Done. See the text.
The conclusion should be ‘strict’ and has to relate to other soil and regions worldwide.
Response:
Done. We re-arranged the conclusion section.
*Explain in the caption the abbreviations, the reader doesn’t have to run backward in the text to found…
Response:
Done.
