Comparison of soil organic carbon and total nitrogen stocks between farmland treated with three and six years level soil bund and adjacent farmland without conservation measure: In the case of southwestern Ethiopia

Leta Hailu; Mulugeta Betemariyam

doi:10.1371/journal.pone.0252123

. 2021 May 27;16(5):e0252123. doi: 10.1371/journal.pone.0252123

Comparison of soil organic carbon and total nitrogen stocks between farmland treated with three and six years level soil bund and adjacent farmland without conservation measure: In the case of southwestern Ethiopia

Leta Hailu ^1,^*, Mulugeta Betemariyam ²

Editor: Sergio Saia³

PMCID: PMC8158939 PMID: 34043684

Abstract

This study was conducted to examine and compare the status of soil organic carbon (SOC) and total nitrogen (TN) stocks between farmlands treated with level soil bund (LSB) of three and six years and adjacent farmland without conservation measure (control) at Somodo Watershed. Soil samples were collected from farmland treated with LSB-3 years, LSB-6 years and control using randomized complete block design. A total of 108 composite soil samples (3 treatments * 6 replications * 3 bund zones * 2 depths (0–20 and 20–40 cm) were collected for analysis and determination of the Organic Carbon fraction (OC) and Nitrogen fraction (N). OC was determined using Walkley and Black method while N was determined using the Kjeldahl digestion, distillation and titration method. The result indicated that farmland treated with LSB-6 years has insignificantly higher SOC (98.43±11.55 Mg ha^-1) and TN (9.37±1.10 Mg ha^-1) stock than control SOC (93.01±13.51 Mg ha^-1) and TN (9.28±1.60 Mg ha^-1) stock. Likely, farmland treated with LSB-6 years has insignificantly higher SOC and TN stock than farmland treated with LSB-3 years SOC (96.61±11.45 Mg ha^-1) stock. With respect to the age of LSB, farmland treated with LSB-6 years accumulated more SOC stock (5.83%) than control. This study revealed that the age of LSB conservation measures has a critical role in enhancing soil fertility through maintaining and sequestering SOC and TN.

Introduction

Soil erosion is investigated in different disciplines and from different viewpoints. For the purposes of this research, soil erosion is defined as the net long term balance of all factors that detach soil and move it from its original location [1]). Despite different efforts that have been made by different researchers and extensions to mitigate its effects for a century, soil erosion by water, wind and tillage continues to be the greatest threat to soil health and soil ecosystem services in many regions of the world [2]. According to [1] estimation, due to the problem of soil erosion, annually about 0.4 percent of global crop yield is reduced.

Soil erosion is the most detrimental ecological process in Ethiopia and degrading the valuable soil resources which are the reservoir of goods and services essential to ecosystems and human well-being. It brings changes in physicochemical properties such as texture, bulk density, infiltration rate, available water, nutrient holding capacity and depth of favorable root growth. These changes have a negative effect on most of the soil ecological function and services [3]. The Ethiopia highland reclamation study reported that, only at the mid-1980, 27 million hectares or almost half of the highland area was significantly eroded and over 2 million hectares were beyond reclamation [4]. Taking losses from both erosion and nutrient depletion [5] estimated a total of 0.5 million tons’ crop losses in 1985 at the highlands of Ethiopia. Recent studies also revealed the rates of soil erosion as 20 Mg ha⁻¹ year⁻¹ on currently cultivated lands and 33 Mg ha⁻¹ year⁻¹ on formerly cultivated degraded lands in Ethiopia [6]. Lack of an effective watershed management system, low vegetative cover, over grazing and fault crop production and inappropriate soil conservation measures are playing significant role in soil erosion in the Ethiopian highlands [7–9]. In addition, important factors like a slope, aspect and soil types would play a major role in the mechanism of soil erosion [10].

Since the mid-1970s and 80s, different studies conducted in Ethiopia have verified the positive impacts of soil and water conservation practices on soil physicochemical properties and crop yields [11–13]. Among these, mechanical soil water conservation measures (bunds, terraces, check dams, cut off drains and waterways) and biological (homestead and communal tree plantations and enclosures) measures have been implemented in different agroecology of the country [13–15]. For instance, farmland treated by soil bund and stone-faced soil bund structures in the Lole watershed of northwest Ethiopia found significantly improved physicochemical properties of the soils due to the accumulation of fine-textured clay and silt fractions behind the constructed structures [16]. Similarly, conserved farmland exhibited lower bulk density as compared to un-conserved adjacent farmland at Adaa Berga district, western Ethiopia [17]. Moreover, soil and water conservation has also a potential to reduce the loss of runoff and soil by improving water retention capacity on treated farm [18]. The slope gradient treated with soil and water conservation measures for 20 years in Minizr Catchment, Northwest Ethiopia has found a 2.7% slope reduction because of trapped sediment [19].

The Somodo Watershed of southwestern Ethiopia is well known for its inappropriate land use, high population pressure, overgrazing, and erosive tropical rains, which are causing severe soil erosion for the past many years [9,20]. Farmers are practicing farming on a more than the prohibiting range of a slope. This aggravates soil loss and affects the productivity of the agricultural land. Moreover, the eroded sediment also challenging the downstream where, the soil is deposited. To heal the causes of such soil erosion and alleviate the problem, Jimma Agricultural Research Center under the Ethiopian Institute of Agricultural Research have extensively implemented soil and water conservation structures for the past six years. However, no quantitative evidence has been reported on the impacts of LSB on SOC and TN improvement in the watershed. Therefore, the objective of the study was to analyze the status of SOC and TN stocks between farmland treated with LSB of different ages and control. The difference in SOC and TN between the loss zone and accumulation zone within the treated and adjacent untreated plots was also evaluated. The study hypothesized that farmland treated with LSB of different ages has higher SOC and TN than the control due to the availability of retained water for crop growth and return of biomass to the soil as organic matter.

Materials and methods

Description of the study area

The study was conducted in the Didessa catchment of Somodo watershed, which is located at about 15 km to West of Jimma Town and 368 km to the South-west of Addis Ababa. Geographically, it is situated between 7°45”00’N-7°47”00’N latitude and 36°48”00’E-36°49”00’E longitude (Fig 1). It covers an area of 400 ha with an altitude ranging from 1900 to 2075 m above sea level.

The area has a bimodal rainfall distribution with maximum rainfall between July and September and moderate rainfall between March and May. The long-time means annual rainfall (16 years) of the watershed is 1948.0 mm. The means monthly temperature of the site is 19.27°C ranging from 13.6°C and 25°C (Fig 2). Nitisols is the most dominant soil type and sandy clay loam is the textural soil class of the watershed [21]. Nitisols are well drained, red or reddish soils with diffuse horizon boundaries and a nitic horizon with more than 30% clay [22]. The major land use system of the watershed was agricultural land, forest land, grazing land and Agroforestry practices [19].

Research design and soil sampling

Soil samples were collected from farmland treated with LSB-3 years, LSB-6 years and adjacent control using randomized complete block design. The samples were collected randomly from the fields by establishing 10*10 m plot for each treatment within a similar range of altitude and location used as a block to reduce soil property variation due to micro-topographic differences.

The composite and undisturbed soil samples were collected from each consecutive inter-bund zones (upper, middle and lower) at two depths (0-20cm and 20-40cm) using an auger and a core sampler respectively, assuming that the deposited sediment depth due to the implemented LSB will not exceed this depth. A total of 108 composite soil samples (3 treatments * 6 replications * 3 bund zones * 2 depths (0–20 and 20–40 cm) were collected for OC and N analysis and for bulk density determination.

Laboratory analyses

The collected soil samples were transported to Jimma Agricultural Research Center laboratory and Jimma, University College of Agriculture and Veterinary medicine for analysis and determination of OC, N and bulk density. Bulk density was determined by the core method, and samples are dried in an oven at 105°C for 48 hours [23]. OC was determined by Walkley and Black method [24]. N was determined using the Kjeldahl digestion, distillation and titration method [25]. Finally, SOC (Mg ha^-1) and TN (Mg ha^-1) stock were calculated based on the fixed depth (FD) approach which is expressed as the product of respective carbon and nitrogen fraction (%), bulk density (g/cm³), and layer thickness (cm).

Statistical analysis

All data were checked for normality prior to doing the analysis of variance using the Kolmogorov-Smirnov test. Statistical differences in the SOC and TN among treatments (with and without LSB), bund zones, and bund ages in the top 40 cm of soil depth were tested following the general linear model (GLM) procedure of SPSS Version 20.0 for Windows. Pearson correlation was also performed to estimate the correlation relationship between SOC and TN within the watershed.

Results and discussion

SOC and TN stock comparison between farmland treated with LSB-3 years and control

The SOC stock of farmland treated with LSB-3 years and control did not showed a significant difference. However, the higher mean value of SOC stock was observed in the farmland treated with LSB-3 years (96.61±11.45 Mg ha^-1) when compared with the SOC stock (93.01±13.51 Mg ha^-1) of control (Table 1). Regarding the inter bund zones, the minimum, medium and maximum SOC stock for the control were recorded in the upper, middle and lower inter bund zones, respectively. While for farmland treated with LSB-3 years, the maximum SOC stock was recorded at the upper bund zone when relatively compared with the lower bund zone. The upper bund zone of farmland treated with LSB-3 years had significantly higher mean value of the SOC stock (101.66±11.96 Mg ha^-1) as compared with the adjacent upper bund zone of control (84.57±9.22 Mg C ha^-1). This result confirms that LSB-3 years can keep the soil at the upper bund zone (loss area) in place and reduce both the on-site and off-site effects of soil erosion. However, the SOC stocks at middle and lower inter bund zones of farmland treated with LSB-3 years and control did not a show significant difference. The non-significant difference in SOC at these bund zones probably due to the young age of LSB and level of past erosion before the structure was built.

Table 1. (Mean ±Std. Deviation) of SOC (Mg ha^-1) and TN (Mg ha^-1) stock of farmland treated with LSB-3 years, LSB-6 years and control.

Bund Zone	Depth	SOC stock			TN stock
Bund Zone	Depth	Control	LSB-3 years	LSB-6 years	Control	LSB-3 years	LSB-6 years
Upper	0–20	45.38±5.84	54.72±6.55	51.34±6.30	5.23±0.77	4.50±0.88	4.96±0.72
	20–40	39.19±5.34	46.94±6.50	46.34±9.52	4.75±1.45	4.33±0.49	4.57±0.28
	0–40	84.57±9.22^a	101.66±11.96^b	97.67±15.43^b	9.98±1.93^a	8.83±1.36^a	9.53±0.63^a
Middle	0–20	50.35±7.67	47.74±7.42	51.89±5.76	4.59±1.40	4.36±1.21	4.79±1.42
	20–40	43.29±7.69	46.06±8.435	47.93±5.37	4.71±1.13	5.12±1.27	4.69±0.69
	0–40	93.64±10.27^a	93.80±14.08^a	99.82±10.11^a	9.30±1.35^a	9.48±2.06^a	9.48±1.86^a
Lower	0–20	53.66±9.29	51.55±4.99	52.30±4.91	4.26±0.53	5.25±0.62	4.89±0.28
	20–40	47.16±8.24	42.82±3.00	45.51±6.25	4.30±1.25	4.75±1.00	4.20±0.31
	0–40	100.82±16.46^a	94.37±7.65^a	97.81±10.49^a	8.56±1.37^a	10.00±1.22^a	9.10±0.37^a
Total	0–20	49.80±8.06	51.33±6.67	51.84±5.35	4.69±1.00	4.70±0.97	4.88±0.88
	20–40	43.21±7.55	45.28±6.27	46.59±6.91	4.59±1.22	4.73±0.97	4.49±0.49
	0–40	93.01±13.51^a	96.61±11.45^a	98.43±11.55^a	9.28±1.60^a	9.44±1.57^a	9.37±1.10^a

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Means followed by the same letter(s) horizontally for the same parameter are not significantly different at (p ≤ 0.05) with respect to treatments and bund zones.

In line with this case study, different studies [17,26] have also reported that fields treated with above three years’ soil and water conservation measures had higher organic matter accumulation as compared to the non-conserved fields. But the research report on level soil bund without any agronomic or biological techniques by [27] showed no improvement in soil fertility during the first 3–5 years that did not agree with the result of this study. Concerning to soil depth, within each farmland and bund zone, SOC stock was higher (p>0.05) in the top layer (0–20 cm) than in the lower layer (20–40 cm) but the mean difference was not significant (p>0.05) (Fig 3). This find is in line with the finding of [28] that showed the decrement of SOC concentration with the increment of soil depth.

The overall mean TN stock (0–40 cm depth) was not significantly different between farmland treated with LSB-3 years and control (Table 1). But, higher TN stock (9.44±1.57 Mg ha^-1) was observed in the farmland treated with LSB-3 years than TN stock (9.28±1.60 Mg ha^-1) of control. This low TN in control might be due to the unrestricted downward movement of organic matter with runoff water from the upper landscape. According to [2], organic matter accumulation is often favored at the bottom of hills due to its transport through erosion from the upper and mid position to the lowest point in the landscape. With respect to soil depth, except the middle bund zone, the TN stocks was higher in the upper layer (0–20 cm) than in the lower layer (20–40 cm) for both farmlands treated with LSB-3 years and control (Table 1).

SOC and TN comparison between farmland treated with LSB-6 years and control

Overall, the mean of SOC stock did not exhibit a significant (P>0.05) variation between farmland treated with LSB-6 years and control (Table 1). Concerning zones, the upper bund zone (97.67±15.43 Mg ha^-1) of farmland treated with LSB-6 years was significantly higher than the respective adjacent upper bund zone of control (84.57±9.22 Mg ha^-1) (Table 1). However, variations in SOC stocks among the middle and lower bund zones of farmland treated with LSB-6 years and adjacent control were not statistically significant (P>0.05).

This finding indicates that long term age of the LSB (greater than six years) has a key role for significant change of SOC in the middle and lower bund zones of treated farmland than the corresponding untreated bund zones. Many research results also confirmed that soil erosion resulted in nutrient depletion through reducing and changing the physicochemical conditions of the soil like soil organic matter content, soil structure, water holding capacity, soil bulk density, soil porosity, soil pH and its workability [9,29,30]. The estimated overall mean (0–40 cm depth) SOC stocks for middle and lower bund zone of farmland treated with LSB-6 years was 99.82±10.11 Mg ha^-1 and 97.81±10.49 Mg ha^-1, respectively.

TN stock showed no significant variation between farmlands treated with LSB-6 years and adjacent control. However, the overall mean value of TN in farmlands treated with LSB- 6 years (9.37±1.10 Mg ha^-1) was relatively higher than the TN stock (9.28±1.60 Mg ha^-1) of control (Table 1). Except for the middle one, within each bund zone, TN stock was higher in the top layer (0–20 cm) than in the lower layer (20–40 cm). The lower mean value of TN observed in the control might be allied with the removal of fertile topsoil by erosion process and the use of crop residues for fuel and animal feed rather than leaving in the farm to decompose and enrich the soil organic matter content. Different case studies showed that TN content of the soil is directly associated with the amount of organic matter constituted in the soil [17,31]. So, if organic matter input from crop residues, manure and any other sources were not balanced the rate of decomposition, there is a faster TN depletion.

SOC and TN comparison between farmland treated with LSB-3 years and LSB-6 years

The SOC stock did not show a significant difference (P>0.05) between farmland treated with LSB-3 years and LSB-6 years. However, LSB-6 year exhibited more SOC stock at the upper, middle and lower bund zone (Table 1). Similar study on LSB in Bokole watershed, Dawuro zone, Southern Ethiopia also showed that SOC in treated land with LSB-6 years was insignificantly higher than the treated land with LSB-4 years [31].

TN socks of LSB-3 and LSB-6 treated farmlands did not show significant difference (p>0.05). However, LSB-3 years showed higher overall mean value of TN stock (9.44±1.57 Mg ha^-1) than LSB-6 years (9.37±1.10 Mg ha^-1) (Table 1). This might be due to the variation in application of nitrogen containing inputs such as commercial fertilizer, plant residues and animal manure on the farmland before LSB intervention. [32] also reported as the increment of TN stock of treated farmland is determined by the past deposition of soil materials and physical, chemical, biological and anthropogenic factors with complex interactions.

As it was reported in most of the studies [17,33,34], in this study there was a positive and significant correlation between SOC and TN (R² = 0.86). This confirms the contribution of enhanced organic matter resulted from the implementation of LSB structure stabilized with Vetiver grass as a significant role to increase TN.

Conclusions

This study confirmed that the proper construction of LSB structure has been influenced the accumulation of the SOC and TN of treated fields as compared to adjacent land without conservation measures. However, the effective outcome is basically based on the age of the structure. That means; old aged treated farmland has enhanced higher SOC and TN than young aged treated farmlands. With respect to inter bund zones, higher SOC and TN were accumulated in the lower bund zone than the upper and middle inter bund zones. This is due to the downward movement of organic matter with runoff water from the upper zone and accumulation of it at the lower area. Since this study is solely focused on the analysis and comparison of SOC and TN effects of LSB without incorporating some other physicochemical properties, socio-economic, institutional and physical aspects of conservation approach due to various limitations, further researches are required to get a comprehensive conclusion. Finally, it could be concluded that; LSB-3 years and LSB-6 years accumulates more amounts of SOC and TN than adjacent non-treated farmlands and hence this contributes to mitigating climate change by preventing erosion-induced greenhouse gas emission into the atmosphere.

Supporting information

S1 Appendix. Processed data of SOC stocks.

(XLSX)

Click here for additional data file.^{(26.9KB, xlsx)}

S2 Appendix. Processed data of TN stocks.

(XLSX)

Click here for additional data file.^{(28.1KB, xlsx)}

Acknowledgments

We acknowledge the logistic and technical support we got from Jimma Agricultural Research Center and Jimma University college of Agriculture and Veterinary Medicine. We are also thankful to the farmers of Somodo Watershed, who kindly allowed us to take measurements on their farmlands. Our gratitude goes to Mr. Frew Kapito, Tamirat Kebede and Murad Abaraya, for their ample support on field-work that makes our stay very fruitful.

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

Ethiopian Institute of Agricultural Research is the institution that supported this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.The corresponding author received a salary from the funders.

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PLoS One. doi: 10.1371/journal.pone.0252123.r001

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20 Jan 2021

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Comparison of soil organic carbon and total nitrogen stocks between farmland treated with level soil bund of different age and adjacent farmland without conservation measure: in the case of southwestern Ethiopia

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9.We noticed you have some minor occurrence of overlapping text with the following previous publication(s), which needs to be addressed:

http://article.sciencepublishinggroup.com/html/10.11648.j.ijnrem.20160102.15.html

https://file.scirp.org/Html/6776.html

https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/6167

In your revision ensure you cite all your sources (including your own works), and quote or rephrase any duplicated text outside the methods section. Further consideration is dependent on these concerns being addressed.

Additional Editor Comments:

Specifically, it seems that your manuscript reports similar results of those reported by the work indicated from 2 out of 3 reviewers: Leta Hailu, Fantaw Yimer, Teklu Erkossa, 2020. Evaluation of the effectiveness of level soil bund and soil bund age on selected soil physicochemical properties in Somodo Watershed, Jimma Zone, SouthWestern Ethiopia J. Degrade. Min. Land Manage., pp. 2491-2502 DOI https://doi.org/10.15243/jdmlm.2020.081.2491

In the article in "Journal of Degraded and Mining Lands Management" wide parts of the abstract are identical to the present ms. In the cover letter, you specified <<I confirm that this work is original and has not been published elsewhere, nor is it currently under consideration for publication elsewhere>>. I wish to pinpoint that Plos1 consider the acceptance of a ms as a research article without taking into account its novelty and potential impact, upon that the methods are correct. However, Plos1 does not allow to publish data already published in other journals and the present data seems to derive from another articles, with a computation of stock.

In the Hailu et al. J. Degrade. Min. Land Manage article, you seem to show the data on SOC and STN concentrations (and other soil traits) at varying the age of soil bund (0, 3, 6 years), whereas in the present ms in Plos1 you show the SOC and STN stocks at varying the time of soil bund (3 or 6 year, in tab 1 and 2, respectively) while varying the presence of not of conservative management practices in apparently similar zones and layers than the previous. Data on the farms without the conservation measure in tab 1 and 2 are the same and may be derived from the data at 0 years of soil bunds. Lastly, data of tab. 3 are the same of those shown in tab 1 and 2 relative to the conservation measures.

Also, it sounds quite strange to me that here in this ms you don’t cite the former article, that was published before the submission of the present ms, whom results would help you discussing these ones.

It seems thus that the data on a stock basis in the present manuscript may derive from the ones of the former article, thus invite you to revise the present ms and clearly indicate the differences between the article in the J. Degrade. Min. Land Manage and the present one. Also, please carefully take into account the reviewer’s suggestions.

Lastly, I invite you to clearly diversify the previous article from the present ms. Wide parts of the materials and methods may be shared, but not of the other sections. In addition, data should not be replicated within the ms, so that just 1 table is enough.

In addition, tab. 4 is useless. You can just report the one number (R=0.86) in the main text.

Finally, if the data on the Stocks you are reporting derive from the previous work, this should be spelled out and cited in the abstract of the present work, given that stock directly derive from a computation from the concentration, bulk density and depth, all of which can be found in your previous ms. Finally, please indicate if the computation of the stock take into account of the coarse fraction, if any.

Please mind that decision to allow you to opt for a revision is not a pre-requisite for the acceptance of the ms as a research article.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Review report

Manuscript Number: PONE-D-20-35754 “Comparison of soil organic carbon and total nitrogen stocks between farmland treated with level soil bund of different age and adjacent farmland without conservation measure: in the case of southwestern Ethiopia”

The manuscript addresses a subject of current interest related to the effect of level soil bund (aged 3 and 6 years) an) on Soil organic carbon and total nitrogen Stocks compared to a control farmland. Overall, I do like this paper, but the novelty and potential for impact are somewhat limited. I here encourage the authors to revise the paper.

Some suggestions for further improvement are given below:

1. The paper is written in poor English. There are many grammar mistakes and some sentences that are not easily understood. A very careful and intensive revision by a native speaker is necessary.

2. The title corresponds to the text. However, it has to be redone and reformulated.

3. The authors must pay attention to the abbreviation. Try to use the same abbreviation. Please specify if the values are for SOC or TN amount or for the stocks .

Abstract section

4. Line 22 : “The result indicated that farmland treated with LSB of 6 years has insignificantly higher SOC (102.57±9.00 Mg ha-1) and TN (9.74±0.9 Mg ha-1) than farmland treated with LSB of 3 years (98.42±10.24 Mg ha-1).” It is preferable that the authors add the value of TN for LSB of 3 years for a better comprehension.

5. Line 26 :“Similarly, farmland treated with LSB of 6 years was sequestered more 5.20% % of SOC ..” Please delete the double symbol %.

Introduction section

6. The introduction should be developed. , there are many researches related to this problematic have been done. It would benefit of more detail and supported with the related references.

7. Line 48 :“In addition, important terrain like a slope, aspect and soil types...” Slope, aspect and soil types are considered like factors or parameters not terrain.

8. Line 58 “ Similarly, fields treated with soil and water conservation practices were founded the lower mean bulk density than the untreated fields in Adaa Berga district, western Ethiopia [15].” Please rephrase appropriately

Materials and methods section

9. Description of the study area, line 86 :“ 7°46’’00’N-7°47’’00’N latitude and 36°44’’10’E-36°46’’50’E longitude (Fig 1).” These coordinates system does not correspond to the Fig 1.

10. Figure 2 : On the axis of temperature please add the unit and delete “Max. And Min.” because it is defined on the legend.

11. Research design and soil sampling, line 103-106 and line 107-112 : Please rephrase appropriately to avoid redundancy.

12. Research design and soil sampling, line 115 “Finally, SOC (Mg ha-1) and TN (Mg ha-1) were calculated….” Please specify that it is SOC and TN stocks.

13. Research design and soil sampling, line 112-117 “The collected soil samples were transported to Jimma Agricultural Research Centre laboratory … bulk density (g/cm3), and layer thickness (cm).” The authors should move this paragraph in the laboratory analysis section.

14. The authors must improve the table 1, 2 and 3 : Specify that the values are for SOC and TN stocks as l mentioned before. Also, please try to be brief when writing the name of x-axis, it could be SOC stock LSB-3 years / LSB-6years/ Control.

Results and discussion section

15. The authors showed that total nitrogen, organic carbon and bulk density were used in this paper, but in the results and discussion section, why it was not included? The authors should add these data to this section using a table.

16. Line 149 : TOC and TN data can not completely represent soil organic matter content. As fields treated with above three years’ soil and water conservation measures had higher organic matter accumulation as compared to the non-conserved fields. The data of OM would be more accurate.

17. Figure 3: Please specify that the values are for SOC stocks, on the y-axis and for the legend. Same as I mentioned below, try to write briefly, instead of writing “farmland with three years LSB” The authors can just write LSB-3years and Control.

18. Line 202-204 :“The top layer accounted for 52% of the TN in the upper bund zone of farmland treated with six years aged LSB and 51% of the TN in adjacent upper zone of farmland without conservation measures.” Please provide explanation how the authors get these values?

19. Line 228 “The upper, middle and lower bund zones of SOC stocks in farmland treated with six years LSB was approximately 10.5%, 10.3% and 10.3% higher than the upper, middle and lower bund zones of farmland treated with three years LSB, respectively.” Please explain how the authors get these values?

20. For table 4: The Pearson`s correlation matrix for soil organic carbon and total Nitrogen, is it for the stocks values ?

21. References: Please be sure that all the references cited in the manuscript are also included in the reference list and vice versa with matching spellings and dates and according to the journal format, "Instructions for Authors".

Looking forward for your positive consideration of these comments.

Regards,

Reviewer of the manuscript

Reviewer #2: The Hailu & Betemariyam manuscript compares organic carbon and total nitrogen stocks as critically important soil quality parameters in farmland treated with 3 and 6 years aged level soil bund and adjacent farmland without conservation measures. The results section is divided into three subsections, but due to a data repetition in each subsection please consider a possibility to construct the results section comparing all 3 treatments in one table, if it`s possible to present data of statistical analysis this way.

Data Availability Statement in the manuscript PDF file is Yes, but there is no information where the data may be found.

Add information to Research design section about the soil you were studied: Was it Nitisol or Acrisol?, What is the clay content in it?, etc. Is a sampling site on adjacent farmland without conservation measures representative? Was it the same soil type? Which type of crops were grown on adjacent farmland?

Consider adding initial data (bulk density and content of organic carbon and total nitrogen in the soil) to the results section. This will give additional information to understand the reasons for your findings.

Other than that there were the following minor observations:

Laboratory analyses. Line 120: Walkley and black (use Upper case)

P. 7 Line 172: Text is about TN stocks but the reference is to a figure about SOC stocks (Fig. 3). Delete this reference and insert Figure 3 after Line 154.

Conclusions. Line 261: Finally, it could be concluded that… Avoid “enormous amounts of SOC and TN” because as you`ve found the mean difference in SOC and TN stocks is not significant between 3-years aged LSB and non-treated farmland. To conclude “considerable role in mitigating climate change by sequestering corresponding greenhouse gases” research findings do not seem to be completely enough.

Fig. 3: Delete “a” and “b” symbols in the figure?

Fig. 3 and tables: Round off numbers to 2 decimal places

Consider language editing to make some sentences more easily understandable

Reviewer #3: Dear Authors, unfortunately, the manuscript seems very similar to a previous research published form the same or almost the same Authors. I cannot discuss about the quality if a similar experiment is already published "" ext-link-type="uri" xlink:type="simple">https://jdmlm.ub.ac.id/index.php/jdmlm/article/view/751".

I would be pleased to be invited to revise other research of yours, the topic is sound and actual.

Please try to provide a systematic literature search before to do any experiment, it might be useful perform a more comprehensive search with a structured query in a citation and abstract database such as Scopus or Web of Knowledge, as it was carried out in Modelling of Soil Organic Carbon in the Mediterranean area: a systematic map November 2018Rendiconti Online Societa Geologica Italiana 46/2018 DOI: 10.3301/ROL.2018.68

I suggest to read also other systematic map applications to improve the state of the art writing style.

Kind regards

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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PLoS One. 2021 May 27;16(5):e0252123. doi: 10.1371/journal.pone.0252123.r002

Author response to Decision Letter 0

3 Mar 2021

Dear Editor-in Chief

We are very grateful to the anonymous reviewers for their valuable and constructive comments to our manuscript entitled “Comparison of soil organic carbon and total nitrogen stocks between farmland treated with level soil bund and adjacent farmland without conservation measure: in the case of southwestern Ethiopia, ms number “PONE-D-20-35754”. We have endeavored to address all comments in this revised manuscript and believe the manuscript is now greatly improved, including the language. We highlighted yellow colour on the “revised Manuscript with Track Change” for highlights additional inputs and changes made to the original version. The page where specific responses given for comments are highlighted red colour in Authors’ responses page. Below are our responses to the specific comments raised by the reviewers.

Queries related to manuscript format and funding source

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

We ensured that the style of our manuscript meet the PLOS ONE style requirements.

2a. please clarify the sources of funding (financial or material support) for your study. List the grants or organizations that supported your study, including funding received from your institution.

Ethiopian Institute of Agricultural Research” is the institution that supported this study

2b. State what role the funders took in the study. If the funders had no role in your study, please state: “The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.”

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

2c. if any authors received a salary from any of your funders, please state which authors and which funders?

The corresponding author received a salary from the funders.

2d. if you did not receive any funding for this study, please state: “The authors received no specific funding for this work.”

Please see the response under query 2c

3. Thank you for stating the following in your Competing Interests section: "No"

4. Please complete your Competing Interests on the online submission form to state any Competing Interests. If you have no competing interests, please state "The authors have declared that no competing interests exist.", as detailed online in our guide for authors at http://journals.plos.org/plosone/s/submit-now

Competing Interests on the online submission form is completed as stated (The authors have declared that no competing interests exist).

5. In your Data Availability statement, you have not specified where the minimal data set underlying the results described in your manuscript can be found……………..

Now our underlining data set is uploaded as Supporting Information files

5. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016…………………….

Thank you for the information. Now the ORCID ID of the corresponding author is updated

6. Please amend either the abstract on the online submission form (via Edit Submission) or the abstract in the manuscript so that they are identical.

We edited and made as the abstract at both site (online submission form and revised manuscript) are identical

7. We note that [Figure(s) 1] in your submission contain map images which may be copyrighted.

Thank you for your note, but the source of this map is the authors. We now sketched the map by including necessary map information (Fig 1)

Now we included Supporting Information files at the end of manuscript by following PLOS ONE format and style guideline

Additional Editor Comments:

9. We noticed you have some minor occurrence of overlapping text with the following previous publication(s), which needs to be addressed…………………………. It seems thus that the data on a stock basis in the present manuscript may derive from the ones of the former article, thus invite you to revise the present ms and clearly indicate the differences between the article in the J. Degrade. Min. Land Manage and the present one. Also, please carefully take into account the reviewer’s suggestions.

Thank you for your suggestion. In this research, the gap which was not addressed in the previous research which is SOC and TN stocks were determined and compared. Therefore, this research can add a value for the scientific knowledge. Even if the sample data is collected from the same sampling unit, the objective of the first work (previously published) is different from this work. In this research, we estimate and compare the soil organic carbon and nitrogen stocks which are not addressed in the first activities. Due to this we confirmed in our previous cover letter as this work is original and has not been published elsewhere, nor is it currently under consideration for publication elsewhere.

We excuse for not clarifying it. We now made great efforts for clarification all parts of the manuscript

In addition, tab. 4 is useless. You can just report the one number (R=0.86) in the main text.

Now, we removed table 4 and only report the value in the text

Reviewer #1:

1. The paper is written in poor English. There are many grammar mistakes and some sentences that are not easily understood. A very careful and intensive revision by a native speaker is necessary.

We have endeavored to address all comments in this revised manuscript and believe the manuscript is now greatly improved, including the language.

2. The title corresponds to the text. However, it has to be redone and reformulated.

Now we modified our title for differentiation and easily understandable

3. The authors must pay attention to the abbreviation. Try to use the same abbreviation. Please specify if the values are for SOC or TN amount or for the stocks .

4. Thank you for your comment. Now, we have made great efforts to use abbreviations consistently throughout the revised manuscript. The value is for SOC and TN stocks

Abstract Section

5. Line 22 : “The result indicated that farmland treated with LSB of 6 years has insignificantly higher SOC (102.57±9.00 Mg ha-1) and TN (9.74±0.9 Mg ha-1) than farmland treated with LSB of 3 years (98.42±10.24 Mg ha-1).” It is preferable that the authors add the value of TN for LSB of 3 years for a better comprehension

We accepted the comment and now we add the value of TN for LSB of 3 years as suggested in the revised manuscript (Page 2, line 55-56).

5. Line 26 :“Similarly, farmland treated with LSB of 6 years was sequestered more 5.20% % of SOC ..” Please delete the double symbol %

It is deleted from the abstract part of the revised manuscript as commented

Introduction section

6. The introduction should be developed. , there are many researches related to this problematic have been done. It would benefit of more detail and supported with the related references.

We have now considerably improved the introduction section as suggested in the revised manuscript

7. Line 48 :“In addition, important terrain like a slope, aspect and soil types...” Slope, aspect and soil types are considered like factors or parameters not terrain

We accepted the comment and replaced “, terrain” by “factors’ in the revised manuscript (page 3, line 85-86)

We accepted the comment, and now clarified the sentence in the revised manuscript (page 4, line 95-96)

Materials and methods section

Description of the study area, line 86 :“ 7°46’’00’N-7°47’’00’N latitude and 36°44’’10’E-36°46’’50’E longitude (Fig 1).” These coordinates system does not correspond to the Fig 1.

We now sketched the coordinate system explicitly for the study area as our description match with the text (Fig 1)

10. Figure 2 : On the axis of temperature please add the unit and delete “Max. And Min.” because it is defined on the legend.

We deleted and added the unit as commented ( Fig 2)

11. Research design and soil sampling, line 103-106 and line 107-112 : Please rephrase appropriately to avoid redundancy

We have now considerably improved the sentences (Page 5, Line 139-142)

12. Research design and soil sampling, line 115 “Finally, SOC (Mg ha-1) and TN (Mg ha-1) were calculated….” Please specify that it is SOC and TN stocks.

We clarified it as commented in the revised manuscript (page 6, line 152-154)

We now moved the mentioned paragraph as commented in the revised manuscript (page 6, line 147-149)

Now, we improved the x-axis of merged table as commented in the revised manuscript (Table 1)

Results and discussion section

Thanks for your suggestion, but since the main objective of this paper is to determine and compare the SOC and TN of farmland treated with 3-years and 6-years and adjacent farmland without conservation measures we didn’t include organic carbon fraction, nitrogen and bulk density in the result part to avoid the redundancy. A reviewer of this paper can find that information from the supportive file folder.

Thank you for your suggestion. In this research, the SOC and TN stocks of LSB treated and untreated farmland were determined and compared. Investigation on Soil organic carbon and total Nitrogen stocks is a fundamental to know:

The fertility, Chemical, physical and biological properties of soil

Soil structure: The water holding capacity and rainfall infiltration properties of organic carbon soils creates better landscape moisture availability. Root development and rainfall variation tolerance is also significantly enhanced in soils with improved aggregation from carbon. Therefore, Investigation of SOC is the strong indicator of the soils biological health.

Ecological soil function: The type and function of soil microbes is impacted by the availability of soil organic carbon and Nitrogen stocks. A healthy soil system supports pasture nutrient uptake, assisting root growth and crop disease suppression has also been associated. So, determination of soil organic carbon and nitrogen stock is a crucial way of identifying the ecological function of one soil.

Basis of sustainable agriculture: In addition to the atmospheric benefits of carbon and nitrogen stocked in soils, the ecology and function of agricultural systems are improved. Resulting physically cohesive soil resists soil losses by wind or water erosion. So, determination of soil organic carbon and nitrogen is the bases for characterizing of farmland and implementation of further intervention.

We accepted the comment, and replaced “farmland with three years LSB” by “LSB-3years” and control in the revised manuscript (Figure 3)

Thank you for explanation question. Now, the authors removed these confused values in the revised manuscript.

20. For table 4: The Pearson`s correlation matrix for soil organic carbon and total Nitrogen, is it for the stocks values?

Yes. It is for stock values

Thank you for comment, we assured that our manuscript reference list and citation are followed the journal format, "Instructions for Authors".

Reviewer #2:

1. The results section is divided into three subsections, but due to a data repetition in each subsection please consider a possibility to construct the results section comparing all 3 treatments in one table, if it`s possible to present data of statistical analysis this way.

Thank you for your comment, now we are merged all three tables at one in the revised manuscript

6. Data Availability Statement in the manuscript PDF file is Yes, but there is no information where the data may be found.

Now our underlining data set is uploaded as Supporting Information files

7. Add information to Research design section about the soil you were studied: Was it Nitisol or Acrisol?, What is the clay content in it?, etc. Is a sampling site on adjacent farmland without conservation measures representative? Was it the same soil type? Which type of crops was grown on adjacent farmland?

We accepted the comments and now the dominant soil type of the area which is Nitisolis described in the revised manuscript. Similarly crop which is grown on the control is also described (page 4, line 128-129)

8. Consider adding initial data (bulk density and content of organic carbon and total nitrogen in the soil) to the results section. This will give additional information to understand the reasons for your findings.

9. Laboratory analyses. Line 120: Walkley and black (use Upper case)

Now, we rewrote as commented in the revised manuscript (Page 5, Line 150-151)

10. P. 7 Line 172: Text is about TN stocks but the reference is to a figure about SOC stocks (Fig. 3). Delete this reference and insert Figure 3 after Line 154.

Thank you for the comment, now we put the table at its appropriate place in the revised manuscript as commented

11. Conclusions. Line 261: Finally, it could be concluded that… Avoid “enormous amounts of SOC and TN” because as you`ve found the mean difference in SOC and TN stocks is not significant between 3-years aged LSB and non-treated farmland. To conclude “considerable role in mitigating climate change by sequestering corresponding greenhouse gases” research findings do not seem to be completely enough.

Now, we have made great efforts to conclude our result in the revised manuscript ((Page 10, Line 157-260)

12. Fig. 3: Delete “a” and “b” symbols in the figure?

We deleted symbols as commented ( Fig 3)

13. Fig. 3 and tables: Round off numbers to 2 decimal places

We made it as commented in the revised manuscript (Fig. 3, Table 1)

14. Consider language editing to make some sentences more easily understandable

We have made an effort to address all comments in this revised manuscript and believe the manuscript is now greatly improved, including the language.

Reviewer #3

Dear Authors, unfortunately, the manuscript seems very similar to a previous research published form the same or almost the same Authors. I cannot discuss about the quality if a similar experiment is already published "https://jdmlm.ub.ac.id/index.php/jdmlm/article/view/751".

I would be pleased to be invited to revise other research of yours, the topic is sound and actual.

I suggest to read also other systematic map applications to improve the state of the art writing style.

Thank you for your suggestion. In this research, the gap which was not addressed in the previous research which is SOC and TN stocks were determined and compared. Therefore, this research can add a value for the scientific knowledge. Investigation on Soil organic carbon and total Nitrogen stocks is a fundamental to know:

The fertility, Chemical, physical and biological properties of soil

Attachment

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PLoS One. doi: 10.1371/journal.pone.0252123.r003

Decision Letter 1

Sergio Saia

11 Apr 2021

PONE-D-20-35754R1

Comparison of soil organic carbon and total nitrogen stocks between farmland treated with three and six years level soil bund and adjacent farmland without conservation measure: in the case of southwestern Ethiopia

PLOS ONE

Dear Dr. Gemechu,

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: I Don't Know

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #1: Review report

The manuscript addresses a subject of current interest related to the effect of level soil bund (aged 3 and 6 years) on Soil organic carbon and total nitrogen Stocks compared to a control farmland. Overall, I do like this paper, but the novelty and potential for impact are somewhat limited. I here encourage the authors to revise the paper.

In overall I fell the study can be suitable for publication in PLOS ONE after minor revision. Some suggestions for further improvement are given below and other are reported in attached word file:

Abstract

Line24-25: the authors said ‘’With respect to the age of LSB, farmland treated with LSB-6 years accumulated more 2.83% SOC stock than control.”

If they are comparing the overall mean of LSB-6 year to control, normally the corrected value will be 5.83% not 2.83%. Please check it

Results and discussion section

Line 203-205 : the authors said that ‘’ The overall mean value of LSB-6 years has exhibited higher mean value of SOC at the lower bund zone (97.81±10.49 Mg ha-1) as compared to LSB-3 years (94.37±7.65 Mg ha-1) (Table 1).’’

Or LSB-6 year exhibited more SOC stock at the lower and middle bund zone.

Line 208-211: the authors said “TN socks did not show significant difference (p0.05) between all inter bund zones. However, under all bund zones, the TN stock showed higher overall mean value under LSB-6 years (9.44±1.57 Mg ha-1) than LSB-3 years (9.28±1.60 Mg ha-1) (Table 1). Similar results were reported by [26] in Zikre watershed, Adaa Berga district. “

But for LSB-6 year, the TN stock is 9.37±1.10 Mg ha-1 and for the LSB-3 year is 9.44±1.57 Mg ha-1. In this case TN stock showed higher mean under LSB-3 year as compared to LSB-6 year.

Looking forward for your positive consideration of these comments.

Regards,

Reviewer of the manuscript

Reviewer #2: Here some suggestion to improve the manuscript:

1) Lines 139-140 “inter-bund zone …” use the same terminology that you use in the Results section: (upper, middle and lower) instead of (loss, middle and deposition)

2) In line 144 “and the same size undisturbed soil samples were collected for bulk density determination” do not repeat 141-142 lines “Similar sample sizes of undisturbed soil were also collected for bulk density determination using core sampler”, just use “bulk density determination”

3) Line 154: bulk density (g/cm3) (use superscript)

4) In table 1 do not repeat “SOC stock of/ TN stock of”. Write it only once at the top line of the table and indicate below: “control, LSB-3 years, LSB-6 years”

5) Lines 259-260: “this contribute in mitigating climate change…” According to obtained results it’s better to conclude the deposition of carbon and nitrogen than their sequestering (from the atmosphere). So, I suggest to write “by preventing erosion-induced greenhouse gases emission into the atmosphere” instead of “by sequestering corresponding greenhouse gases”

Reviewer #3: Dear Authors

I read the revised version of the manuscript “Comparison of soil organic carbon and total nitrogen stocks between farmland treated with level soil bund of different age and adjacent farmland without conservation measure: in the case of southwestern Ethiopia” I have seen some improvement and I think the paper can be revised again and go ahead in the publishing process, but please amend all the things listed below and the other review request. Reviewers suggested many things to improved your manuscript much than I have done due to the similarity with your previous unacknowledged research about SOC % with the same experimental settings. The experimental setting is decent, the authors can bring more evidences about the study area and they can translate the effect found in the trial in order to give a practical benefit addressed to the local policy makers.

The manuscript is proposed as a research article, due to the length (3200 words) the similarity with the previous study (shared experimental settings) of the same work of the authors about SOC %, and the limited novelty, I think it can be proposed as a short communication, a normal research article is made by approximately 6000 works, although I found normal manuscript of 8000 words.

Line24-25: Please check it ‘’With respect to the age of LSB, farmland treated with LSB-6 years accumulated more 2.83% SOC stock than control.” It should be around 5.83%?

Terminology must be consistent throughout the manuscript (e.g. lines 139-140 inter-bund zone), please check the consistency

I would rephrase the sentence “by sequestering corresponding greenhouse gases” in something more neutral.

Please define better the conclusion of the experiment. Do not oversell the findings.

Why not include the authors who revised the manuscript? They must be capable to understand the problem to check the language. I do not know in what extend they were involved in the research activities but in case they were, they must be rewarded.

Kind regards

**********

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes: Calogero Schillaci

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PLoS One. 2021 May 27;16(5):e0252123. doi: 10.1371/journal.pone.0252123.r004

Author response to Decision Letter 1

27 Apr 2021

Attached as supportive materials

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PLoS One. doi: 10.1371/journal.pone.0252123.r005

Decision Letter 2

Sergio Saia

11 May 2021

PONE-D-20-35754R2

Dear Dr. Gemechu,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Sergio Saia, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0252123.r006

Acceptance letter

Sergio Saia

17 May 2021

PONE-D-20-35754R2

Dear Dr. Hailu:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

prof Sergio Saia

Academic Editor

PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 Appendix. Processed data of SOC stocks.

(XLSX)

Click here for additional data file.^{(26.9KB, xlsx)}

S2 Appendix. Processed data of TN stocks.

(XLSX)

Click here for additional data file.^{(28.1KB, xlsx)}

Attachment

Submitted filename: Response to Reviewers.docx

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Attachment

Submitted filename: Manuscript_Rev_A.doc

Click here for additional data file.^{(215KB, doc)}

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Data Availability Statement

All relevant data are within the manuscript and its Supporting Information files.

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PERMALINK

Comparison of soil organic carbon and total nitrogen stocks between farmland treated with three and six years level soil bund and adjacent farmland without conservation measure: In the case of southwestern Ethiopia

Leta Hailu

Mulugeta Betemariyam

Roles

Abstract

Introduction

Materials and methods

Description of the study area

Fig 1. Map of Somodo watershed, Jimma Zone, South-western of Ethiopia.

Fig 2. Mean of annual rain fall (mm) and temperature (°C) of Sodomo watershed.

Research design and soil sampling

Laboratory analyses

Statistical analysis

Results and discussion

SOC and TN stock comparison between farmland treated with LSB-3 years and control

Table 1. (Mean ±Std. Deviation) of SOC (Mg ha-1) and TN (Mg ha-1) stock of farmland treated with LSB-3 years, LSB-6 years and control.

Fig 3. Status of SOC in LSB 3-years LSB 6 years treated and untreated farmland with respect with soil depth.

SOC and TN comparison between farmland treated with LSB-6 years and control

SOC and TN comparison between farmland treated with LSB-3 years and LSB-6 years

Conclusions

Supporting information

Acknowledgments

Data Availability

Funding Statement

References

Decision Letter 0

Sergio Saia

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Author response to Decision Letter 0

Decision Letter 1

Sergio Saia

Roles

Author response to Decision Letter 1

Decision Letter 2

Sergio Saia

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Acceptance letter

Sergio Saia

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Associated Data

Supplementary Materials

Data Availability Statement

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Table 1. (Mean ±Std. Deviation) of SOC (Mg ha^-1) and TN (Mg ha^-1) stock of farmland treated with LSB-3 years, LSB-6 years and control.