Sorghum–Grass Intercropping Systems under Varying Planting Densities in a Semi-Arid Region: Focusing on Soil Carbon and Grain Yield in the Conservation Systems

Round 1

Reviewer 1 Report

The manuscript "agriculture-1939545" by Ferraz-Almeida et al., suggested that Sorghum-grass intercropping systems under varying planting densities in semi-arid region: focusing on C stocks and grain yield in the conservation systems. Manuscript has significant novelty. But it has few writing mistakes. In addition, the calculation of the LER index, which is necessary for the evaluation of intercropping systems, hasn't been done.  Some minor suggestions are given as under which need to be discussed during the revision.

Title, line 3: Change the "regions" to the "regions".

Table 1: Add the amount of "soil EC" to the table.

Table 1: The amount of "organic matter" is very low. Check again.

Line 122, 127, 131, and ....: Modify the "m2", "P2O5", "K2O" and .. via superscript and subscript.

154: Land equivalent ratio (LER) should be calculated and presented in the results and discussion section.

 Line 178: What was the result of Bartlett's test for variances homogeneity?

Line 292: In the figure caption, write power of units as superscript.

Line 243: Soil organic matter and carbon stocks have the same trend. Carbon stocks is the repetition of organic matter and the only difference is its unit. Remove the carbon stocks or organic matter in the text.

Conclusion, line 481: Improve the conclusions baced on LER results. 

Author Response

REVIEWER1

Reviewer1: The manuscript "agriculture-1939545" by Ferraz-Almeida et al., suggested that Sorghum-grass intercropping systems under varying planting densities in semi-arid region: focusing on C stocks and grain yield in the conservation systems. Manuscript has significant novelty. But it has few writing mistakes. In addition, the calculation of the LER index, which is necessary for the evaluation of intercropping systems, hasn't been done.  Some minor suggestions are given as under which need to be discussed during the revision. 154: Land equivalent ratio (LER) should be calculated and presented in the results and discussion section. Conclusion, line 481: Improve the conclusions baced on LER results. 

Authors: Dear reviewer, thank you for your suggestions. We are presenting the sorghum yield per hectare (1 unit per 1 hectare), and there is no possibility to present the land equivalent ratio (LER) because there is other crop production.

Reviewer1: Title, line 3: Change the "regions" to the "regions".; Line 122, 127, 131, and ....: Modify the "m2", "P2O5", "K2O" and .. via superscript and subscript. Line 292: In the figure caption, write power of units as superscript.

Authors: We edited all these comments.

Reviewer1: Table 1: The amount of "organic matter" is very low. Check again.; Table 1: Add the amount of "soil EC" to the table. Line 243: Soil organic matter and carbon stocks have the same trend. Carbon stocks is the repetition of organic matter and the only difference is its unit. Remove the carbon stocks or organic matter in the text.

Authors: Dear reviewer, the low carbon stocks were expected due to the conditions of semi-arid in study. We checked the units in Table 1 and Figure 2. In semi-arid regions, the intercropping system is a challenge due to the seasonal water restrictions that impact crop production and crop residue accumulation on the soil. In addition, the semi-arid region presents a long dry period during March and November, and a rainy period during December and February; both periods present high temperatures. The production systems were cultivated during the rainy period, presenting climate conditions that promote a high residue accumulation and decomposition in the soil that promotes a lower carbon accumulation in soil.  Based on your suggestions, we maintain the organic matter in the manuscript without information of carbon stocks and soil EC because have the same trend. Carbon stocks is the repetition of organic matter and soil EC, and the only difference is its unit.

Reviewer1: Line 178: What was the result of Bartlett's test for variances homogeneity?

Authors: The result of Bartlett's test was added in the mansucript.

Reviewer 2 Report

Table1 soil organic matter was 5 g/kg averagely, but Figure 2 soil organic matter was around 0.6g/kg, why?

Table1 soil chemical including Al, Cu, Fe, these ion could affect the growth and development of sorghum or grass?

Generally, the bigger total porosity, and the lower bulk density, so why there was different significant of total porosity among the treatment. More, better soil aeration with high total porosity was not benefit with C-stock, but the result of the manuscript found the C-stock was increase, why.

Line127 P2O5, Line131 K2O, using subscript, and the same as Line 136-137, elsewhere.

Poor logic in the measurement section

Data in the manuscript don’t need R and Python.

The results of this manuscript was not concluded that the success of the intercropping system with sorghum and grasses depends on the cultivar of grasses and planting densities, because the sole sorghum was the best option to increase the C-sequestration under the 0.8 m row spacing.

Author Response

Reviewer1: Table1 soil organic matter was 5 g/kg averagely, but Figure 2 soil organic matter was around 0.6g/kg, why?

Authors: Dear reviewer, thank you for the observation. We checked the units in Table 1 and Figure 2. The low carbon stocks were expected due to the conditions of semi-arid in study. In semi-arid regions, the intercropping system is a challenge due to the seasonal water restrictions that impact crop production and crop residue accumulation on the soil. In addition, the semi-arid region presents a long dry period during March and November, and a rainy period during December and February; both periods present high temperatures. The production systems were cultivated during the rainy period, presenting climate conditions that promote a high residue accumulation and decomposition in the soil that promotes a lower carbon accumulation in soil.  

Reviewer1: Table1 soil chemical including Al, Cu, Fe, these ions could affect the growth and development of sorghum or grass?

Authors: Yes, but in our study the contents of Al, Cu, Fe did not impact the plant development according to literature.

Reviewer1: Line127 P2O5, Line131 K2O, using subscript, and the same as Line 136-137, elsewhere. Poor logic in the measurement section. Data in the manuscript don’t need R and Python.

Authors: We edited all these comments and part of data analysis were

Reviewer1: The results of this manuscript was not concluded that the success of the intercropping system with sorghum and grasses depends on the cultivar of grasses and planting densities, because the sole sorghum was the best option to increase the C-sequestration under the 0.8 m row spacing.

Authors: We edited the conclusion based on your suggestions.

Round 2

Reviewer 1 Report

no comment.

Author Response

Dear reviwer, thank you for the suggestion.

A double check was made in the Manuscript.

Author Response File: Author Response.docx