Partitioning of Available P and K in Soils During Post-Agricultural Pine and Spruce Reforestation in Smolensk Lakeland National Park, Russia

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Line 33-40 This first paragraph is not is accordance with the topic of the article: macronutrient mobility in the soil system. It is therefore off-topic

Secondly, references are old. Please quote recent references.

We have reworded the paragraph to make it more relevant.

We have updated the references.

Line 50-51 The state-of-the-art about P is insignificant.

We have updated the references.

Line 53 «the latter is not absorbed...»

The suggested wording has been incorporated.

Line 55-57. This section can be strengthened by considering the biological functioning aspect of the soil. An interesting link will thus be created with the following sentence on Biodiversity...

We have strengthened this section by considering the biological functioning aspect of the soil.

Line 57. Please, specify which reference is link to vegetation or soil aspects. An exemple of transformation of the composition of soil organismes is the reference

https://doi.org/10.1016/j.pedobi.2012.02.001

We have separated these references to aspects of vegetation and soil.  We have added a recommended  reference

Line 97. Country not mentioned

We have mentioned the country

The Materials and Methods section should be reorganized:

- Study site (mentioning the country)

- Experimental design and plot desription

- Soil sampling protocold

- soil analyses

-Statistical analyses

We have reorganized the Materials and Methods section

Table 2. In legend, recall what stages 0,1,2,.....correspond to as done in Lines 146-154

We have added a description of the stages in the note to the table.

Line 329  Wrong numbering...should be 3.3.

We have changed the order of the subsections and corrected the numbering

The English expression lacks fluency and logical coherence, with some passages being difficult to follow. Specific issues are detailed below:

The complete text of the manuscript has undergone English editing.

1.What distinguishes "Mobile P and K" from "Available P and K"? Which term is more appropriate for this study?

The term "Available P and K" is more appropriate for this study. We have corrected this term in the text of the entire manuscript.

2.Lines 37-40: The logical transition between these two sentences is abrupt. How does the second sentence suddenly shift to plant fine roots?

We have changed the structure of this paragraph.

3.Lines 58-60: This sentence is unclear in expression and shows weak logical connection with surrounding context. Please rephrase.

We have rephrased this sentence.

4.The Introduction lacks essential arguments about factors influencing P and K distribution/contents in spruce and pine ecosystems, despite hypotheses proposing two influencing factors.

We have added this sentence: Therefore the vertical distribution of available K and P is determined by the intensity of element removal from soils. This is contingent on soil texture and plant uptake, as well as the return of elements to the topsoil during the process of litter decomposition.

5.Line 84: Replace "aims at" with "aims to". The phrase "content and vertical distribution of available P and K" contains redundancy - delete "content and".

We have made the suggested corrections to the text of the manuscript.

6.Lines 116-117: Add "and" between the two clauses: "In summer, Atlantic cyclones provide cooling and abundant rain, and Asian anticyclones bring sharp warming and dryness."

We have made the suggested corrections to the text of the manuscript.

7.The "Materials and Methods" section requires subheadings to distinguish site description, experimental design, and data analysis.

We have reorganized the Materials and Methods section and added the following  subheadings

8.While soil organic matter measurement is mentioned in Methods, corresponding results are missing in figures/tables.

We have added the results of the organic carbon  measurements to the figures and tables.

9.Tables 1-3 do not comply with three-line table format. Please complete missing lines.

The tables have been formatted in accordance with the three-line format.

10.Line 204: Confirm whether "Kruskall-Wallace" should be corrected to "Kruskal-Wallis".

We have made the suggested corrections to the text of the manuscript.

11.Lines 204-212: The data analysis description lacks clarity. Please provide a more systematic explanation

We have provided a more systematic explanation of data analysis.

12.Lines 276-282: This paragraph lacks clear thematic focus and requires complete restructuring.

This paragraph has been restructured.

13.Lines 330-331: Revise to: "In the 0-5 cm layer, mobile K and P contents decreased significantly from early to late chronosequence stages (Table 3; p<0.05)."

We have made the suggested corrections to the text of the manuscript.

14.Label subpanels in Figures 5 and 6 using letter notation (a, b, etc.) and indicate accordingly in text.

We have added subpanels in Figures 5 and 6

15.Lines 345-347: Revise to: "Apparently, its content in this layer is governed by other factors, such as clay sorption or pH conditions, which inhibit migration."

We have made the suggested corrections to the text of the manuscript.

16.Most references are outdated. Please supplement with recent literature (last 5-10 years), particularly in Discussion.

The references cited in the discussion and throughout the manuscript have been updated.

17.The Conclusions should not merely reiterate results but rather connect key patterns of P and K dynamics to forest management and ecological restoration practices.

The conclusion of the manuscript has been edited.

Introduction:

While thorough in citing previous work, is overly lengthy, repetitive, and lacks a clear articulation of the specific knowledge gaps the study aims to address. Much of the background information on potassium and phosphorus behavior in soils is textbook-level and could be significantly condensed. Key questions guiding the research are only introduced late in the introduction and are not sharply formulated.

The hypotheses presented are rather general and could be stated in a more testable, falsifiable manner. Additionally, the authors do not sufficiently explain why focusing on mobile forms of P and K is particularly important in the context of forest succession compared to total nutrient pools, nor do they adequately link their hypotheses to specific mechanisms expected during post-agricultural soil evolution.

Consider adding more relevant references to the introduction such as:

Nizamutdinov, T., Yang, S., & Abakumov, E. (2025). Post-Agricultural Shifts in Soils of Subarctic Environment on the Example of Plaggic Podzols Chronosequence. Agronomy, 15(3), 584.

Szerlag, K. D., Siebecker, M. G., Izaditame, F., Northrup, P., Tappero, R., & Sparks, D. L. (2024). Multimodal, microspectroscopic speciation of legacy phosphorus in two US Mid‐Atlantic agricultural soils. Soil Science Society of America Journal, 88(6), 1992–2012.

De Schrijver, A., Vesterdal, L., Hansen, K., De Frenne, P., Augusto, L., Achat, D. L., ... & Verheyen, K. (2012). Four decades of post-agricultural forest development have caused major redistributions of soil phosphorus fractions. Oecologia, 169, 221-234.

He, X., Augusto, L., Goll, D. S., Ringeval, B., Wang, Y., Helfenstein, J., ... & Hou, E. (2021). Global patterns and drivers of soil total phosphorus concentration. Earth System Science Data Discussions, 2021, 1-21.

The introduction of the manuscript has been edited.

We have rewritten the research hypotheses.

P and K are of significance and intrigue due to the fertilization disrupts the background elements content, and succession subsequently results in a return to the original element content in natural soils. The soil restoration process was observed in the present study.

Some suggested references have been added to the to the introduction.

Materials and Methods:

While the study provides valuable insights into the dynamics of mobile P and K in post-agricultural reforestation soils, I have concerns about the use of 0.2 M HCl as the sole extraction method for assessing mobile nutrient forms. This single-step acid extraction is operationally simple but lacks specificity in differentiating between biologically available, adsorbed, and mineral-bound forms, particularly important for phosphorus, which exists in soils in multiple chemically distinct pools with varying mobility and ecological significance. Given the study’s focus on long-term nutrient redistribution and depth-wise variability, especially in relation to past fertilization and biological cycling, a sequential extraction approach such as the Ruttenberg method (for distinguishing Fe/Al-bound, Ca-bound, and residual P forms) or the Hedley fractionation scheme would provide more mechanistic and ecologically meaningful information. Incorporating such methods would strengthen the interpretation of P dynamics and better support the study’s conclusions about nutrient legacy and vertical translocation during forest succession.

A sequential extraction method developed by Ruttenberg and later modified by others has been commonly used to fractionate different forms of P in sediment, dust and suspended particulate matter.

The present study was devoted to the analysis of soils restoration. It was necessary to use a methodology for the study of non-carbonate soils.

Therefore we used the certified method accepted in Russia for evaluating of the available P and K content in soils. According to the GOST 54650-2011 (Soils. Determination of mobile phosphorus and potassium compounds by Kirsanov method modified by ClNAO).

In our further researches, we will consider the possibility of using the Hedley fractionation, which is employed in instances where an index of plant-available phosphorus is required, in conjunction with a separation of organic and inorganic forms.

Results and Discussion:

The results and discussion sections present a large amount of data but suffer from being excessively descriptive and fragmented. Rather than synthesizing the findings around core mechanisms or hypotheses, the authors largely describe trends site-by-site and depth-by-depth without adequately integrating them into broader ecological processes. Important concepts such as nutrient leaching, biological recycling, and changes in soil sorption capacity during succession are mentioned but not deeply analyzed or tied back to the initial questions. In several cases, explanations for observed trends are speculative without supporting evidence. For example, the discussion of pH effects on mobile P and K is interesting but would benefit from more rigorous interpretation in the context of known chemical processes (e.g., P sorption dynamics as pH declines during podzolization).

Moreover, the statistical treatment, although based on appropriate nonparametric tests and correlations, would benefit from a more coherent narrative. The regression models are presented with minimal biological interpretation, and it remains unclear to what extent the reported variances explained are meaningful ecologically. A critical weakness is the lack of consideration for variability within stages and the possibility that other unmeasured factors (e.g., microtopography, historical management differences) could confound chronosequence interpretations.

One serious shortcoming is the graphical presentation of the data. The figures are of poor quality, appear to have been generated using basic Excel templates, and lack the professionalism expected for a scientific journal. Axis labels are small, font choices are inconsistent, and legends are often unclear. Boxplots, for instance, are difficult to interpret without explicit n-values, and color choices or marker shapes could be better optimized to distinguish between the two chronosequences. I strongly recommend that all figures be regenerated using professional scientific graphing software (e.g., Origin, R, Python Matplotlib/Seaborn, or equivalent) to improve clarity, visual appeal, and the ability to convey complex patterns more effectively. In addition, figure captions should be expanded to stand alone, allowing readers to understand the key messages without needing to cross-reference the main text extensively. Furthermore, although the authors emphasize vertical nutrient distribution, the description of "types" of differentiation (e.g., "regressive-accumulative," "progressive-eluvial") is introduced with minimal explanation, and non-specialists may find these classifications confusing without visual schematics or clearer definitions. It would strengthen the manuscript to include a conceptual diagram illustrating expected nutrient redistribution processes during reforestation.

The description of the results was revised, with particular attention paid to the aspects of nutrient leaching, biological recycling, and changes in soil sorption capacity during succession. The interpretation was revised and made more rigorous.

We have added statistical analyses, including PCA and the Wilcoxon significance test, have been incorporated and subsequently illustrated.

In the present study, an attempt was made to take into account such factors as microtopography and historical differences in management. We have selected study sites in similar conditions of an autonomous flat position, with a similar history of use.

All figures were regenerated using R graphing software to improve clarity, visual appeal, and the ability to convey complex patterns more effectively.

All Figure captions were expanded to stand alone.

The "types" of vertical differentiation were removed  from the article.

Conclusion:

This section restates the main findings but are overly general and do not effectively highlight the broader implications of the work. There is little discussion of how these findings could inform forest management, soil conservation strategies, or predictions under changing climate conditions, which limits the impact of the study.

Finally, the manuscript would benefit from substantial English language editing. While the writing is generally understandable, awkward phrasing, grammatical errors, and inconsistent terminology (e.g., postagrogenic vs. post-agrogenic) detract from the clarity and professionalism of the presentation.

In summary, this study contains valuable primary data and addresses an important topic, but in its current form requires major revision. Improvements are needed in framing the research questions, condensing and sharpening the Introduction, synthesizing the Discussion around ecological processes rather than descriptive trends, enhancing the quality of figures, and improving the overall clarity and fluency of the writing. Addressing these issues would significantly strengthen the manuscript and its contribution to the field of soil science and forest ecosystem recovery.

We have rewritten the text of the conclusion and considered the suggestions.

The complete text of the manuscript has undergone English editing.

Line 34: "[5].." - Delete one redundant dot.

We had edited this.

Line 267: A space is required between the numerical value and its unit; please check and correct other instances throughout the manuscript.

We had deleted space between the numerical value and its unit.

Line 416: "table 3" should be written as "Table 3" (capitalize the "T" in table).

We had corrected the table links.

Several of my key comments were not addressed in the revised manuscript, and important concerns remain unresolved. I had recommended incorporating a more robust extraction method) such as the Hedley or Ruttenberg sequential fractionation schemes (instead of relying solely on 0.2 M HCl to better capture biologically relevant forms of phosphorus. This suggestion was not implemented, and the authors provided no justification for continuing with the single-step extraction. If more advanced methods are not feasible, they should at least explain the rationale behind their methodological choice and clarify the limitations it introduces in interpreting the mobility and bioavailability of P and K.

As the sequential procedures used worldwide to fractionate P compounds (e.g., a sequential extraction (Ruttenberg, 1992) of P from sediments, dusts and suspended particulate matter, methods developed by Mehlich (Mehlich, 1953), Bray (Bray and Kurtz, 1945) and Olsen (Watanabe and Olsen, 1965) and others (Pansu and Gautheyrou, 2006)) do not fit our objects, we used the method that is most popular in Russia for such cases (GOST 54650-2011 (SS 54650-2011, 2011)). The available phosphorus (AP) and potassium (AK) were extracted by Kirsanov method modified by ClNAO. Their concentration was determined by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). - We had added this phrase to the manuscript.

I also pointed out that the figures were of poor quality and lacked clarity in terms of labels, legends, and overall presentation. Unfortunately, the figures remain unchanged and appear to have been produced using basic plotting tools, with minimal improvements to readability or professional appearance.

All figures have been revised using the R software.

In the discussion section, I had asked the authors to move beyond descriptive summaries and connect their findings to broader ecological mechanisms such as nutrient leaching, biological recycling, or sorption dynamics.

While some statistical analysis was added, the interpretation remains surface-level, and there is little effort to integrate the results into a conceptual framework.

The findings had been strengthened in terms of their correlation with broader ecological mechanisms, including nutrient leaching, biological recycling, and sorption dynamics.

Likewise, my suggestion to include conceptual diagrams or schematics to help illustrate vertical nutrient redistribution and clarify terms such as “regressive-accumulative” or “progressive-eluvial” was not acted upon, leaving the text difficult to follow for non-specialists. In addition, these terms remain poorly defined, despite my request for clearer explanations or supporting visuals.

These terms characterize the "types" of vertical differentiation were removed from the article.

Moreover, I had emphasized the need for thorough English language editing to address awkward phrasing, grammar issues, and inconsistent terminology (e.g., “postagrogenic” vs. “post-agrogenic”), but many of these problems persist, detracting from the overall clarity and professionalism of the manuscript. I also encouraged the authors to expand their conclusion to include broader implications for forest management, soil restoration, or climate resilience; however, this section remains vague and underdeveloped.

Before the second review of the manuscript, a revision of the terminology was conducted. In the presented version of the manuscript, the terms "postagrogenic" and "post-agrocultural" were not used. However, the term "post-agricultural" was used instead of both.

English language editing was made.

I also encouraged the authors to expand their conclusion to include broader implications for forest management, soil restoration, or climate resilience; however, this section remains vague and underdeveloped.

We have thoroughly revised the manuscript's conclusion, addressing the previous feedback. We have also written about the climatic aspects.

Importantly, some of the references I suggested—such as Szerlag et al. (2024), De Schrijver et al. (2012), and He et al. (2021)—are still missing. Including these sources would help situate the study within the broader literature on phosphorus dynamics and post-agricultural soil development and strengthen both the Introduction and Discussion by providing context, comparative insights, and mechanistic understanding.

We did not cite ' Szerlag et al. (2024) ' as studies of XANEX is too far away of the topic of our manuscript. Other recommended publications were added in the revised version of the manuscript.