Manure Application Is the Key to Improving Soil Quality of New Terraces
Round 1
Reviewer 1 Report
The authors highlighted the importance of applying manure to improve soil quality in newly built terraces. Based on the 18-year long-term field experiment they reported the dynamic evolution of soil quality in the terrace under different fertilization treatments. The soil indicators used to calculate the soil quality index captured the key factors affecting crop yield and soil quality. The results are very useful to guide mountain agricultural practice and the topic is important.
Overall, the study is very informative and worthy of publication.
After reading the current version of the manuscript, however, I think there are a few questions that need to be resolved. The detailed comments are listed as follows:
1. For lines 45-46, 47, I suggest updating the references.
2. Study site: In lines 86-87, references should be cited.
3. The average annual precipitation was 331 mm. Where does this meteorological data come from? The authors need to clarify the sources of meteorological data.
4. In line 101, the unit "m2" is incorrectly written. I think "m2" referred to "m2".
5. I noticed a change in the amount of manure applied during the 18 years of the experiment (20 or 10 t/ha), why was the amount of manure applied reduced at the later stage in the experiment?
6. Please check the writing carefully, there should be a space after the parentheses. See line 107: "organic carbon (C)150 g kg-1".
7. Species names should be in italics, see lines 108-109. And writing needs to be corrected (harvest).
8. "From 2004 onwards, field pea (P. sativum L.), spring wheat (T. aestivuml.) and potato (S. tuberosum L.) were planted in a rotation sequence, and the crops were harvest in sequence annually." Does crop ripe once a year in this study area? It should be made clear in the manuscript.
9. "Yield was determined after drying at 70 °C to constant weight." Is potato tuber yield also measured after drying? please confirm.
10. soil samples (0-20 cm) were taken annually after the crop was harvested. Are soil samples taken at the same time of year?
11. "Soil samples were taken at 20 cm intervals, and dried at 105 °C to determine soil water content at 0 to 2 m depth. " In table 1, SWS refers to soil water storage at 0-2 m depth. So, the calculation formula of SWS should be presented.
12. In line 161, Xi should be written as Xi, so the others in lines 162, 168, 173, 174.
13. "The increase of TN may be partially related to the biological N2 fixation of the legume crops (pea). " Writing (N2) needs correction.
14. Use abbreviations throughout the manuscript after you clarify it at its first appearance. See lines 248, 375-378.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript is well prepared and presented. The data collected showed good planning and execution. However, few things need clarification like why only the sixth cycle of treatment was evaluated. Furthermore, why the biological indicators were not at all evaluated in the study.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
Why not use sheep manure after a treatment? Such as composting or anaerobic digestion.
Soil microbial community structure may change after sheep manure land utilization, which should be discussed in revised manuscript.
Microbial community structure of sheep manure should be provided in revised manuscript.
Abstract and Conclusions are lengthy and unsupported by data.
-Line 100-103：The more basic characteristics of sheep manure should be provided. Such as pH, TS, VS, heavy metal, and so on.
-L101：29.25 m2→m2
-L103：Why does the dosage of sheep manure increase first and then decrease from 2004 to 2021? And why was only 5 t ha- sheep manure used in 2010?
-L133:Don't use the abbreviation when TDS、MDS appear in the text at the first time -L193:What does ‘a b c d’ mean after the values in Table 2?
-L234: Error bar of figure 1 should be provided.
Author Response
Revision Notes
Comment 1. Why not use sheep manure after a treatment? Such as composting or anaerobic digestion.
Reply: Thanks. This is a local regular practice of using sheep manure. The farm area is very dry and cool. Usually, local farmers transfer the sheep manure from sheepfolds to the crop fields without composting or anaerobic digestion.
Comment 2. Soil microbial community structure may change after sheep manure land utilization, which should be discussed in revised manuscript.
Reply: Thanks very much. We highly appreciate and agree with your comments. Microbial biomass carbon could reflect microbial activity. We measured microbial biomass carbon and combined it with other soil indicators to evaluate soil quality. We added a discussion about it based on the literature, please see lines 289-293 in the revised version.
Comment 3. Microbial community structure of sheep manure should be provided in revised manuscript.
Reply: Thanks very much. We are sorry that we did not determine the microbial community structure in sheep manure. Therefore, we provided the message of microbial community structure in sheep manure based on literature, please see the revised version: lines 112-114.
Comment 4. Abstract and Conclusions are lengthy and unsupported by data.
Reply: Thanks very much. Sorry for the lengthy Abstract and Conclusions. Now, we controlled the word count of the Abstract to make it fit the requirements of the journal. Also, we made modifications to the Conclusions to make it shorter. Please see lines 23-24 & 401-402 in the revised version. We carefully examined the Abstract and the Conclusions, and we are sure that both sections were supported by the data.
Comment 5. The more basic characteristics of sheep manure should be provided. Such as pH, TS, VS, heavy metal, and so on.
Reply: Thanks very much. We are sorry that we mainly measured the content of organic carbon, total nitrogen, and total phosphorus in sheep manure. But we did not measure other parameters. We provided some properties of sheep manure based on the literature (see the revised version: lines109-111). pH and EC data were obtained from a study (Dingxi, Gansu Province, China) near our study area (Lanzhou, Gansu Province, China). The TS (total solids) and VS (volatile solids) values referred to a study from Qinghai province, close to the research site, in China. For the heavy metal content in sheep manure, we provided an approximate range because the corresponding data in the literature are collected from many studies, and on the other hand, the heavy metal content in sheep manure may different vary with the breeds and forage species.
Comment 6. L101: 29.25 m2→m2
Reply: Thanks very much. We corrected it, please see line 102 in the revised version.
Comment 7. L103: Why does the dosage of sheep manure increase first and then decrease from 2004 to 2021? And why was only 5 t ha- sheep manure used in 2010?
Reply: Thanks. As we know, applying manure is very important to improve soil organic matter in barren soil. However, when the application of manure exceeds a certain number of years, the content of soil organic matter will reach a ceiling level. In contrast, continuing to apply a large amount of organic fertilizer will not necessarily increase the content of soil organic matter content. Obviously, overuse of manure would be a waste to dryland. Therefore, for years 1 to 3, 20 t ha-1 manure was applied in M and MNP, but then we reduced the amount of manure applied. The amount of manure applied in M and MNP treatment in 2010 was 5 t ha-1, this is because we want to study the effect of further reduction of manure application on soil properties. Moreover, we added a clarification, please see line 105 in the revised version.
Comment 8. L133:Don't use the abbreviation when TDS, MDS appear in the text at the first time.
Reply: Thanks very much. We revised it, please see line 141 in the revised version.
Comment 9. L193:What does ‘a b c d’ mean after the values in Table 2?
Reply: Thanks very much. We have clarified it in the text, please see lines 203-204 in the revised version. And we also find the same problem in the captions of Figure 2 and clarified it, please see the revised version: lines 257-259.
Comment 10. L234: Error bar of figure 1 should be provided.
Reply: Thanks very much. We added the error bar in figure 1 and clarified it, please see the revised version: Figure 1, lines 251-252. The error bar represents the mean ± standard deviation. In Figure 2, we found a writing error and corrected it, please see the revised version: line 256.
Round 2
Reviewer 3 Report
The manuscript has been well revised.
