Impacts of land use and topography on soil organic carbon in a Mediterranean landscape (north-western Tunisia)

Jendoubi, Donia; Liniger, Hanspeter; Ifejika Speranza, Chinwe

doi:https://doi.org/10.5194/soil-5-239-2019

Articles | Volume 5, issue 2

https://doi.org/10.5194/soil-5-239-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/soil-5-239-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 5, issue 2

Original research article

|

02 Sep 2019

Original research article |

| 02 Sep 2019

Impacts of land use and topography on soil organic carbon in a Mediterranean landscape (north-western Tunisia)

Donia Jendoubi, Hanspeter Liniger, and Chinwe Ifejika Speranza

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Final revised paper (published on 02 Sep 2019)
Preprint (discussion started on 08 Apr 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'The topic is in the scope of the journal', Anonymous Referee #1, 03 May 2019
- SC1: 'Recommended paper', Donia Jendoubi, 11 May 2019
- AC1: 'Feedback', Donia Jendoubi, 03 Jun 2019
- AC4: 'Revised paper', Donia Jendoubi, 03 Jun 2019
RC2: 'soil-2019-15', Anonymous Referee #2, 07 May 2019
- AC2: 'Feedback', Donia Jendoubi, 03 Jun 2019
- AC5: 'Revised paper', Donia Jendoubi, 03 Jun 2019
EC1: 'Editor comment', Estela Nadal Romero, 08 May 2019
- AC3: 'Feedback', Donia Jendoubi, 03 Jun 2019
- AC6: 'Revised paper', Donia Jendoubi, 03 Jun 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Revision (03 Jun 2019) by Estela Nadal Romero

AR by Donia Jendoubi on behalf of the Authors (04 Jun 2019) Manuscript

ED: Referee Nomination & Report Request started (07 Jun 2019) by Estela Nadal Romero

RR by Anonymous Referee #2 (11 Jun 2019)

Suggestions for revision or reasons for rejection

The manuscript SOIL-2019-15 “Impacts of land use and topography on soil organic carbon in a Mediterranean landscape (north-western Tunisia)” has been improved by the authors after having into account most of the comments made by the referees. In this new version, provided information concerning the study area and methodology and sampling design is much clear and understandable. However, still some aspects should be considered before being publishing. Above all discussion should be improved, in the present form is wordy and it is difficult to extract the meaning. Why Authors did not include a brief discussion about the 3.1 soil spectral library as an integrative indicator of soil quality. This is one of the novel aspects of the article.
Please avoid the repetition of the information. Be careful to keep verb tense consistent within sections of a paper. For example, the Results section is usually in the past tense (because the experiments have already been done).

• Please keep the same terminology in the whole manuscript; choose among topographic characteristics or features (instead of topographic units or factors). Similarly SOC levels or contents.
• The acronyms should be defined for the first time. Revise in line 8 soil organic carbon (SOC) and line 51 Soil organic matter (OM); Line 84 SOC instead of soil organic carbon
• Please some concepts should be rewritten to be more accurate Lines 29-30 change people by human activities … exacerbates soil erosion”. Lines 31- 32 Long-term anthropogenic pressure from agricultural use (Kosmas et al., 2015) together with abiotic factors such as climatic and topographical variability.
• A deeper English proofreading can improve the readability of the text. Please remove to avoid the repetition of information Line 35 “Soil degradation is a key component of land degradation in the Mediterranean region” a similar sentence was included in line 28. In addition, revise to avoid the repetition of the same word e.g. “soil quality deterioration contributes to the deterioration”. See also lines 89-90
• It is not clear if Authors refers to north-western Tunisia (lines 67-73, line 101)
• Lines 77, 360 Include a reference
• Line 83 soil organic carbon levels?
• Lines 128-129 ranges of slopes corresponding to high, steep and moderate can be included. These categories are the same as in table 2?
• Line 185 Soil type should be included of the study soils
• Figure 2 The 24 different units can be delineating
• Table 2 include aspect for steep category. “in” can be removed (in %). The exact number of soil samples per unit should be included in Table 2 (see lines 155 – 156) by including land use
• Lines 219 and 251 31%
• Line 203 This sentence from the previous version of the manuscript “Soil samples were air dried (to 30 °C) and sieved to pass through a 2 mm mesh.” Should be included.
• Please avoid the repetition of information by deleting lines 206-207 (info repeated in lines 199-200); lines 207-213 (repeated in lines 200-201 and figure 2); line 245 (info is provided in lines 232-233); line 268 (info is included in line 271); Lines 418 – 423 (info is repeated in lines 394-409)
• Line 253 (vario MICRO tube, Elementar)
• Line 258 This study is focused on SOC then this sentence can be omitted.
Did Authors check that TC measurements and SOC measurements are coherent? TC >> SOC
Authors measured SIC by other method? To control / verify their SOC estimates?
• Line 342 – 350 Please revise the readability for a fluent English style. Similarly in the abstract. See the repetition of decline in two continuous sentences (lines 344-345)
• Lines 366 -372 This is not a discussion of the results. This paragraph presents materials and methods and objectives. Please remove because this information was included previously.
• Line 387 “enhanced the SOC content” instead of improved
• Line 388 appropriate land management instead of good land management
• Line 389 “as it reduced both the area covered only by very old cereal monocultures and the soil degradation.” This sentence is unclear in the present form.
• Line 405 assuming that forest soils are not affected by soil erosion because their higher SOC contents. I do not agree with this statement.
• Line 409 Not only low erosion rates please include other key factors for high SOC content in forest soils: higher carbon input, low litter decomposition …
• Lines 410-417 This general information about Mediterranean soils should be move to the beginning of the discussion
• Lines 420 – 421 Please revise and rewrite, the sentence in the present form is unclear
• “In lands where field crops once were, if they have been interplanted with permanent crops, the SOC content has improved”
• Line 421 “Overgrazing and bad management of grazing lands has led to SOC decreases.” Please move to line 412 and link with inappropriate land management
• Line 422 Remove “Finally, forest land use has the highest SOC content, as it is protected by forest regulation and less disturbed.” This info is included in line 409 “which is highly related to the lower disturbance in the forests”
• Line 428 “Different soil properties encountered among” Which soil properties have been determined by authors apart from SOC. This information should be very useful to include a description in materials and methods about soil characteristics and soil type
• To say “undoubtedly have effects on SOC content” these key soil properties should be included
• Line 436 in soils
• Line 462 I doubt about this statement: “This can be explained by the fact that soils on flat slopes tend to be thicker as a result of deposition”. Have authors any evidence from the results?
• Line 476 nutrients loss instead of nutrition loss
• Lines 478-483 This information is repeated and discussed previously in Discussion section
• Lines 392 and Lines 547 – 552 Since the work is not focused on C sequestration and it is not introduced previously. The main topic was SOC variability as soil quality parameter and its controlling factors (topography and land use). I recommend remove this paragraph.

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ED: Revision (12 Jun 2019) by Estela Nadal Romero

AR by Donia Jendoubi on behalf of the Authors (20 Jun 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jun 2019) by Estela Nadal Romero

RR by Anonymous Referee #2 (10 Jul 2019)

Suggestions for revision or reasons for rejection

Manuscript has been improved considerably and a great effort was made by Authors. Please see below some comments:
• A deeper English proofreading can improve the readability of the text.
• Lines 42-44 Agricultural practices is not the only factor for soil degradation processes (biological, physical, chemical). A more generic statement could be included: Soil degradation processes comprises or include biological degradation … chemical degradation (References).
Also revise brackets “(e.g. acidification nutrient and depletion (Diodato and Ceccarelli, 2004; Post and Kwon, 2000)” I suggest move the reference at the end of the sentence.
• Lines 112-113 Information repeated in lines 113—116 please delete (this suggestion was included in the previous report) “In this study, we explore SOC distribution according to land use across topography (slopes and aspects) in north-western Tunisia”.

See lines 113-116: The aim of this study is to quantify SOC content and evaluate the factors that affect SOC variation, specifically the mechanisms affecting differences in SOC distribution patterns along different land use systems and topographic features (slope and aspect) in a Mediterranean ecosystem dominated by agricultural activities in north-wester Tunisia.

• Lines 169-170 Please include the ranges of slopes corresponding to steep (>16%), moderate (8% – 16%) and flat (0% – 8%) should be included. (this suggestion was included in the previous report)
Line 170 Correct high to steep? Only three categories are included in Table 2: steep, moderate and flat. High?
• Table 2 include aspect for steep category.
• Line 415 north-facing areas whereas 1.14% of SOC ….
• Line 564 lower disturbance in forest soils by erosion?
• Line 569 The accumulation of SOC variation? Authors mean: High SOC variation on hillslopes?
• Line 600 “the highest”
• Line 639 Minimal erosion in flatter areas and higher deposition of sediments therefore SOC accumulation?

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ED: Publish subject to minor revisions (review by editor) (12 Jul 2019) by Estela Nadal Romero

AR by Donia Jendoubi on behalf of the Authors (15 Jul 2019) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (17 Jul 2019) by Estela Nadal Romero

AR by Donia Jendoubi on behalf of the Authors (30 Jul 2019) Author's response Manuscript

ED: Publish as is (12 Aug 2019) by Estela Nadal Romero

ED: Publish as is (13 Aug 2019) by Jorge Mataix-Solera (Executive editor)

AR by Donia Jendoubi on behalf of the Authors (14 Aug 2019) Manuscript

Short summary

This paper is original research done in north-western Tunisia; it presents the impacts of the topography (slope and aspect) and the land use systems in the SOC storage in a Mediterranean area. It provides a soil spectral library, describes the variation of SOC under different conditions, and highlights the positive impact of agroforestry as good management in improving the SOC. Therefore this finding is very important to support decision making and inform sustainable land management in Tunisia.