Multiple Cropping System Expansion: Increasing Agricultural Greenhouse Gas Emissions in the North China Plain and Neighboring Regions
Round 1
Reviewer 1 Report
MANUSCRIPT DESCRIPTION
The manuscript “Multiple cropping system expansion increasing agricultural greenhouse gas emissions in the North China Plain and neighboring regions” presents a study based on the Life Cycle Assessment (LCA) to quantify the greenhouse gasses emission from agricultural activities in the North China Plain. The authors compared two 5-year periods (1982-1986 and 2008-2012) considering the expansion of the area where multiple cropping systems (MCSs) is adopted and the different cultivation techniques used in the two periods. Analysis of the greenhouse gasses emissions from different sources in the two periods is provided.
GENERAL COMMENTS
The manuscript is quite well written, but it can benefit from the reading of a native English speaker. Some sentences are difficult to understand while in some of them something is missing, or the construct is wrong. For example: Line 36-38 "The growth rate of agricultural GHG emissions of 4.08% in China during 1993-2008, including fertilizer, pesticide, plastic sheeting, diesel, electricity, and soil carbon emission". Line 54 "The assessment methods of agriculture GHG emission accounting are differ greatly". Lines 75-77 "The NCP and neighboring regions are one of the most obvious area for development of MCS in China. It is dominated by the winter wheat and summer maize double cropping system, including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Henan, and Shandong Provinces".
I think that it would be useful if the author could provide some simple examples of Multiple Cropping Systems (MCSs).
At line 107, the authors stated that returning the straw to the soil is the main source of N2O emission. Can the author provide a reference? I am asking this because it seems that the impact on N2O emission of incorporating straw into the soil is still debated.
Please, check the quality of the equations printed in the PDF. Some of them are difficult to read because letters and symbols are overlapping.
SPECIFIC COMMENTS
Line 5: the name of the second author is missing!
Lines 33-35: the authors said that the GHG emissions from agriculture have increased from 1994 to 2012, and it will continue to increase until 2030. This is a repetition of the concept written at lines 29-30 (China will reach peak emissions by 2030).
Line 37: I suggest to change “plastic sheeting” with “plastic mulch”.
Line 50: Do the authors actually mean crop yields (production for unit area) or do they mean the total crop production?
Line 81: Soil type are mainly Cinnamon and black. Can the authors provide information on the classification of these soils?
Line 100: I know that the authors have included this information later in the text but, I think that in table 1 it can be useful to have a legend with the meaning of some variables like EF, Ym, etc.
Line 110: Check the sentence "emission released by combusting agricultural waste…".
Line 133: I don’t understand the meaning of “nitrogen returned to upper ground” or upper ground straw returning used in equation 5 (line 139). Is it referred to the above-ground crop residues or are the authors referring to the residues incorporated into the topsoil?
Lines 180-182: Please, check the sentence that begins with “Furthermore, in order to eliminate the change…”.
Lines 180-191: I am trying to understand what is reported here. The authors stated that “we assumed that the MCI was still 1.00 (as same as the value during 1982-1986) during 2008-2012, rather than 1.13. In my understanding, according to this, the result of equation 10 should be zero and, as a consequence also equation 9 should be equal to zero. Can the authors provide some information on this?
Lines 215-216: Please, check the sentence “There are 35 counties with reduced GHG emissions are located in counties…”.
Line 243 and 245: The authors report R2 values between MCI and GHG emissions of 0.413 for the 1982-1986, and 0101 for the 2008-2012 period and refer to figure 6a and 6b respectively, but the R2 values included in the figures don’t match the value reported in the text. Am I wrong and perhaps not understanding what the authors are reporting?
Line 262: Can the author define NDRC?
Lines 275-276: How this sentence is related to the previous and following sentences?
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Multiple cropping system (MCS) is gaining popularity nowadays more than before due to its various positive impacts on the livelihood of the farmer. However, the negative impacts of MCS were largely neglected. This manuscript explored the viability of sustainable multiple cropping system and determined its environmental impact. The author has raised the important issue of GHG emissions through this research. However, there are some minor issues in the manuscripts which is below:
Line 5: Check on the author name
Line 29-32: Confusing. why China want to reach peak? I think they want to reduce it, right?
Line 52-53: “Unfortunately, the assessment of GHG emissions attributed from MCSs is lack.” Is lack or lacking? Unfortunately, the information of GHG emissions attributed from MCSs is lacking
Line 81: What is “Cinnamon and black”? Is this the name of the soil series? what is the characteristic feature of this series?
Line 174: how did you calculate the activity level? Please write or cite the method.
Line 179-180: To determine the contribution of MCSs to GHG emissions, we assumed that the MCI was still 1.00 (as same as the value during 1982-1986) during 2008-2012, rather than 1.13. What is the reason for not assuming 1.13?
Line 284-291: This should be under “Conclusion” section.
Author Response
Please see the attachment
Author Response File: Author Response.docx
