PONE-D-22-07890Use of soil spectral reflectance to estimate texture and fertility affected by land management practices in Ethiopian tropical highlandPLOS ONE

Dear Dr. Tiruneh,

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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: No

Reviewer #2: Partly

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

Reviewer #1: No

Reviewer #2: No

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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: Yes

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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: No

Reviewer #2: No

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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: This paper presents the use of Vis-NIR spectrometer to measure soil fertility parameters for some experimental sites in Ethiopia. While interesting, unfortunately the study was conducted on a small number of samples, even if the prediction is meaningful it does not have any meaning or scientific contribution. The relationship between spectra index and soil properties are dubious and there is no independent validation of the data. As such, this paper has serious flaws in the analysis and provided no real value.

Reviewer #2: The authors are presenting an interesting research topic addressing current needs for understanding soil fertility status which play important role in addressing food security and climate change challenges. The choice of technique to analyze soil is laudable especially when large areas are targeted.

However, the authors fell to explain the end-to-end scientific workflow for the procedure. All spectroscopic datasets are known to contain some level of redundant information in form of noise which should be filtered prior to modeling. This step was not explained.

Another important lacking is how the simple linear regression models were created. Which spectral bands were used? How were they selected?

The choice of Nash- Sutcliffe Efficiency is mostly used in simulation models. The authors should justify why it was used. Other metrics commonly used and acceptable in spectroscopy studies like bias, RPD should be considered.

Closely related to this aspect of metric is about selection of calibration (training set) and validation (testing sets) from the 48 spectra acquired.

I recommend further work to be done on this paper to improve on it is general quality.

I highlight below specific areas which requires amendment.

L127 .. well mixed…should be … mixed well…

L129 correct repeated word ‘at’.

Determination of Sand content from the difference as authors suggests on line 137 should be written clearly.

L173, mean spectra should not be obtained before checking for quality of spectra to screen bad spectra. Authors should outline what measures were taken to avoid including a bad spectrum (‘noisy’ replicate among the five into the averaged).

L180 to 183 – The requirement for assumption of normality is not clear. Why was this necessary? Was this done on the spectral dataset or on the physicochemical data?

L302 to 303 is not clear; it should be rewritten.

L310 to L315 gives model summary statistics for R-squared as a range instead of a single value for the calibration data set. Why is this?

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Reviewer #1: No

Reviewer #2: Yes: ok

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Use of soil spectral reflectance to estimate texture and fertility affected by land management practices in Ethiopian tropical highland

PONE-D-22-07890R1

Dear Dr. Tiruneh,

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,

Chun Liu

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

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 #2: All comments have been addressed

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2. 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 #2: Yes

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

Reviewer #2: Yes

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4. 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 #2: Yes

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5. 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 #2: Yes

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6. 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 #2: The authors have addressed review comments adequately.

For future work an approach that does not use linear models should be tested to ensure multicollinearities from highly correlated variables is addressed.

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If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: Yes: Dr. Andrew M. Sila

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