Long-Term Chemical and Organic Fertilization Differently Affect Soil Aggregates and Associated Carbon and Nitrogen in the Loess Plateau of China

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Dear,

Accept in present form.

Best regards

Author Response

Dear,

Accept in present form.

Best regards

R: Thank you very much for reviewing our manuscript.

Reviewer 2 Report

OBSERVATIONS TO MANUSCRIPT 2394478: Long-term chemical and organic fertilization differently affect soil aggregates and associated carbon and nitrogen in the Loess Plateau of China.

The document is interesting, it presents the results of the development of aggregates, carbon and nitrogen content in a soil subjected to organic amendments in combination with fertilizers for more than thirty years; for example, the C/N ratio in bulk soil and aggregates decreased with fertilization, especially in fertilizer with manure and in macro- aggregates. The improved soil structure was related to the increased SOC and STN, which was proved by the positive correlation among SOC and STN with macro-aggregates and MWD. Correlation analysis also showed that the contribution rate of SOC and STN in macro- aggregates was positively with the macro- aggregate and stability. Therefore, the sequestration of C and N in soil was related to aggregate size and mainly affected by larger aggregates. Results demonstrated that fertilizer with manure improved soil structure and fertility better than fertilizer alone, thus increasing crop yield.

The writing can improve if the observations are considered.

Introduction

This part is correct as written by the authors

Materials and Methods

Line 100. Please, you must correct any of the amounts of sand, silt or clay, since the sum results in 1010 g kg^-1. When the sum of the relative amounts of the particles must be 1000 g kg^-1

Line 110. It's written: … was applied at 120 kg N ha^-1, 90 kg P ha^-1, and 75 t ha^-1, respectively. The organic manure had an average C, N, and P concentrations of 800 kg C ha^-1, 87 kg N ha^-1, and 44 kg P ha^-1, respectively.. … . Please, the sentence must be written: … and doses of N and P were applied at a rate of 120 and 90 kg ha^-1, respectively, in 75 t ha^-1 of organic nutrients. The organic manure had an average C, N, and P concentrations of 800, 87 and 44 kg P ha^-1, respectively. … .

Line 122. . It's written: … 70°C for 7 d. … . Please, can you define the d. Do you indicate days?

Results

Line 180, 183, 185, 186, 187. Please, if the same unit appears in several digits, the unit appears in the last digit; for example: 3.6%-6.6%, you should write: 3.6-6.6%.

Table 1, 2, 3 and 4. What is the value of the least significant difference in each column?

Line 195 – 252. Similar situation to line 180.

Comments for author File: Comments.pdf

Author Response

The document is interesting, it presents the results of the development of aggregates, carbon and nitrogen content in a soil subjected to organic amendments in combination with fertilizers for more than thirty years; for example, the C/N ratio in bulk soil and aggregates decreased with fertilization, especially in fertilizer with manure and in macro- aggregates. The improved soil structure was related to the increased SOC and STN, which was proved by the positive correlation among SOC and STN with macro-aggregates and MWD. Correlation analysis also showed that the contribution rate of SOC and STN in macro- aggregates was positively with the macro- aggregate and stability. Therefore, the sequestration of C and N in soil was related to aggregate size and mainly affected by larger aggregates. Results demonstrated that fertilizer with manure improved soil structure and fertility better than fertilizer alone, thus increasing crop yield.

The writing can improve if the observations are considered.

R: Thank you very much for your valuable comments and suggestions. We have carefully revised the manuscript accordingly, and all comments have incorporated in this revised version (highlighted in red color). Responses to the comments are listed below point by point.

 

Introduction

This part is correct as written by the authors.

R: Thank you very much for reviewing our manuscript.

 

Materials and Methods

Line 100. Please, you must correct any of the amounts of sand, silt or clay, since the sum results in 1010 g kg^-1. When the sum of the relative amounts of the particles must be 1000 g kg^-1

R: This has been corrected in the revised manuscript (line 100). “…with sand, silt, and clay concentrations of 35, 656, and 309 g kg^-1, respectively…”

 

Line 110. It's written: … was applied at 120 kg N ha^-1, 90 kg P ha^-1, and 75 t ha^-1, respectively. The organic manure had an average C, N, and P concentrations of 800 kg C ha^-1, 87 kg N ha^-1, and 44 kg P ha^-1, respectively.. … . Please, the sentence must be written: … and doses of N and P were applied at a rate of 120 and 90 kg ha^-1, respectively, in 75 t ha^-1 of organic nutrients. The organic manure had an average C, N, and P concentrations of 800, 87 and 44 kg P ha^-1, respectively. … .

R: This has been corrected in the revised manuscript (lines 111-113). “…and the doses of N and P were at a rate of 120 and 90 kg ha^-1, respectively, in 75 t ha^-1 of organic nutrients. The organic manure had an average C, N, and P concentrations of 800, 87, and 44 kg ha^-1, respectively.”

 

Line 122. It's written: … 70°C for 7 d. Please, can you define the d. Do you indicate days?

R: This has been corrected in the revised manuscript (line 122). “…for 7 days.”

 

Results

Line 180, 183, 185, 186, 187. Please, if the same unit appears in several digits, the unit appears in the last digit; for example: 3.6%-6.6%, you should write: 3.6-6.6%.

R: These have been modified in the revised manuscript (lines 180, 183, 184, 186, 187, 195-196, 198, 200, 201, 203, 204, 222-223, 224, 225, 228, 232, 235, 240, 245, 247, 248, 306, 307).

 

Table 1, 2, 3 and 4. What is the value of the least significant difference in each column?

R: The value of the least significant difference has been introduced in the section 2.6 (Statistical analysis), which also has been added in each column (lines 193, 219-220, 266, 271-272). “Different letters indicate significant difference between treatments (p < 0.05, LSD test).”

 

Line 195 – 252. Similar situation to line 180.

R: These have been modified in the revised manuscript (lines 195-196, 198, 200, 201, 203, 204, 222-223, 224, 225, 228, 232, 235, 240, 245, 247, 248).

Author Response File: Author Response.docx

Reviewer 3 Report

The paper "Long-term chemical and organic fertilization differently affect  soil aggregates and associated carbon and nitrogen in the Loess Plateau of China" presents relevant material from 34 years of long-term experimental studies to assess the effects of different fertilisers on soil, plants, and the environment.

Observations:

1. The paper also focuses on soil structure when using different fertilisers. Still, the question arises about why a rotary tiller was used, which often breaks up the soil into small particles too much.

2. The data in the results is often described as 'decreased', 'increased', or 'influenced', but no explanation is given as to why the data values changed. Explanations would be helpful and make the article more interesting to read.

3. The analysis of the literature is very extensive. I would advise against using very old literature sources (e.g., 38 is from 1982, 53 - 1964).

Author Response

The paper "Long-term chemical and organic fertilization differently affect  soil aggregates and associated carbon and nitrogen in the Loess Plateau of China" presents relevant material from 34 years of long-term experimental studies to assess the effects of different fertilisers on soil, plants, and the environment.

Observations:

1. The paper also focuses on soil structure when using different fertilisers. Still, the question arises about why a rotary tiller was used, which often breaks up the soil into small particles too much.

R: According to the local farmland practice, on the one hand, the use of rotary tiller to sow chemical fertilizers and organic fertilizers can prevent the loss of nutrients caused by shallow spread, on the other hand, the use of rotary tiller can loosen and smooth the soil, which is conducive to the germination and growth of seeds.

 

2. The data in the results is often described as 'decreased', 'increased', or 'influenced', but no explanation is given as to why the data values changed. Explanations would be helpful and make the article more interesting to read.

R: Explanations for why the data values changed are discussed in detail in Section 4, including the effects of long-term fertilization on SOC and STN in bulk soil (line 325-338), aggregate proportion and stability (line 340-359), aggregate associated carbon and nitrogen (line 361-406), and winter wheat yield (line 408-443).

 

3. The analysis of the literature is very extensive. I would advise against using very old literature sources (e.g., 38 is from 1982, 53 - 1964).

R: The old literatures (3, 5, 10, 53) have been modified in the revised manuscript (3-lines 484-486, 5-lines 490-492, 10-lines 501-503, 53-lines 611-613). Literatures 37 and 38 were the experimental methods and therefore are not modified.

Author Response File: Author Response.docx