Cropland Zoning Based on District and County Scales in the Black Soil Region of Northeastern China

Round 1

Reviewer 1 Report

The manuscript provides interesting analytical case study based on commonly used data sources and statistical methods. Also, the selection of parameters meets the most common standards. So, the paper is well done, final conclusions are clearly derived from the data used and methods applied.

However, I made my private, very simple experiment. I checked the soil types (in fact the Soil Reference Groups=RSG) distinguished according to international classification FAO-WRB, available on global soil maps here: https://soilgrids.org/     (select the Soil Classes, and then tick the WRB)

 I draw, just manually, the soil zones (considering the dominant RSG) within the area under your study based on the RSGs distribution only. And then I checked your cropland zoning in your Figure 9 (and also last 3 pictures in Figure 6). I was surprised with the spatial similarity of my zoning and your results!

It means, you shouldn't omit this aspect in your manuscript, at least in the Introduction, description of the Study area (2.1) and Discussion. The term "black soils" is very broad and may be misleading if we remember how different soils may be included in this general group. Both Chinese (but my knowledge is limited in this topic) and international (FAO-WRB) soil classifications distinguish at least 5-6 types of "black soils" developed specifically and differently in relation to parent materials, climate and vegetation. Thus, soil type may be used as a very synthetic indicator of environmental conditions, which influence the soil productivity and crop yields! This is missing in your paper; whereas, the area under your study may be suggested as the model area for presenting the relationships between soil types and crop zones. Of course, when talking about "soil type" I mean "genetic soil types" such as Chernozems, Phaeozems, Kastanozems, Luvisols, Calcisols, etc., because using this term in relation to soil texture only does not reflect the relations to climate and vegetation.

So my suggestion is to refer to the "genetic" soil variability reflected in RSGs of FAO-WRB in the area under study and its potential relation to crop zones at the beginning (Introduction and Area description) as potentially influencing/related factors, and confront the soil map with crop zones in the Discussion. 

Two additional remarks:

1. In line 27 replace the word 'powder' with 'silt'.

2. Consider, please, that many researchers in the world do not like political statements in the scientific papers. Your study are is located in NE China, so you must not refer to politically disputable borders on the sea south of China (figure 1). I suggest another, politically neutral, indication of the location of the area under study. A lot of physiographical views without political borders are used by Chinese authors to avoid any unnecessary confrontations. Thank you.             

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This is a thoroughly carried-out research study on cropland zoning at a county scale. I have minor comments for the authors to address. The comments are marked in the attached PDF file. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The research is interesting and relevant.

1. Research hypothesis is not presented in the introduction.

2. Conclusions should be more concrete with a suggestion for future research.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has been improved in line with reviewers' suggestions and can be accepted in its present form.