This paper studied soil nitrogen and organic carbon stock in impervious surface areas in China. In general, this is an interesting study, which could improve our understanding of the special pattern of soil N under impervious surfaces. However, the methods used in this study and the results are not convincing at the current stage. I would suggest the authors carefully revise the manuscript based on the following comments.

• Abstract, line (L) 20, urbanization indeed change the permeable surface areas to impervious surface areas. Why did the urbanization not cause soil N loss?
• Figure 1, the land use type of each site can be added in the figure.
• L85, what kinds of roads, elevated piers, and floor buildings? It would be great if the authors can support some pictures! I am also curious how did you take soil samples from roads, elevated piers, and floor buildings? You directly dug a soil pit under different impervious surface areas? Is it possible for the floor buildings?
• The unit of parameters in ALL equations should be clarified.
• L132-133, the citation should be formatted, and other citations in similar format should also be revised.
• The equation 3 is hard to understand. What’s the meaning of 130? Why not use your own data to create the equation?
• L139-140, why did you select these parameters? Please explain and describe the detailed process of model construction.
• Random forest is not an explainable model and might not be convincing. More methods are encouraged to be included in this manuscript, such as biogeochemistry model.
• Figure 4, the error bars of the intra-city column should also added.
• Figure 5, the origin coordinates should also be indicated to distinguish different directions.
• In equation 4, N_ISA% was 2.31 when d=0, which should not be the case. Please revise the equation.
• Figure 6, which data did you use in this figure? Why not include all of the sampling points?
• From the data of figure 7, the predicted N_ISA density will be overestimated when the value is lower than ~ 0.6 kg m⁻², while the opposite when the value is higher than ~ 0.6 kg m⁻². The worth thing is the deviation will be much higher when the value is far away from ~ 0.6 kg m⁻². Thus, I strongly suggest the authors optimize their model and the predicted value.

Ding and coauthors have conducted a national scale soil samplings and reports the patterns of soil nitrogen (N) stocks and C:N stoichiometry under impervious surfaces in China. They found that soil N density in the 0-100 cm profile under impervious surface areas was significantly lower than that under the permeable surface areas, and pointed out that the impervious surfaces could result in the convergence of soil C:N stoichiometry. Overall, this is an interesting study and provide the knowledge of biogeochemical cycles under impervious surfaces. However, I have several concerns on the present manuscript.

Introduction: All previous studies have already demonstrated that impervious surface areas had lower soil N density than permeable surface areas, what is the novelty of comparing soil N density under impervious surface areas with that under permeable surface areas (In the present study, the authors also found that soil N density under impervious surface areas was significantly lower than that under the permeable surface areas)? Moreover, even though there is a lack of information of vertical variations in soil N densities under impervious surface areas, the authors should introduce the necessity of studying vertical distributions of soil N and should be better to propose the hypothesis (is it different from that in natural soils or the soils under permeable surface areas)? I would suggest the authors further improve the novelty and significance of their study. In addition, the data in the sentence “ISA covers …… during 2000-2030” is pretty old, please use the updated information. I am also confused with the expression in the sentence “We chose to use …… from construction materials”, to the best of my knowledge, soil C:N stoichiometry represents the SOC:total N ratio rather than the total C:total N ratio, why did the authors state an information different from the common sense?

Materials and methods: A big concern is the calculation of soil N density, why the authors did not consider the rock fragments in calculating the soil N density? For calculating the soil C and N density, using the fine earth bulk density and soil N concentration can provide more accurate N density estimation. In addition, there are some mistakes for the citation formats, for example, Yang et al. (2017) (Yang et al., 2007), Zhang et al. (2021) (Zhang et al., 2021), the authors should treat their manuscript more carefully throughout the whole manuscript.

Results: I am a little bit confused about the Figure 4 and its description, please make it clearer.

Discussion: A big concern in the discussion is that can the authors differentiate the impacts of impervious surfaces and natural soil background on soil N density? For example, “The northern region accounted for the largest share (33%) of the N_ISA stock in China (Figure 8d), mainly due to its large area of impervious surfaces”, is this true after considering the natural soil background?