Evaluation of Almond Hull and Shell Amendments across Organic Matter Management of Orchard Soils

Round 1

Reviewer 1 Report

Dear Authors

I would like to thank you very much for the invitation as a reviewer for the manuscript soilsystems-2902308 “Evaluation of almond hull and shell amendments across organic matter management of orchard soils” The article is interesting and dedicated to the vital problem of soil improvement with organic amandments. The authors did a big job during this study, which should be highly appreciated. The problem of the application of organic amandments  into the soil and their impact on some soil characteristics (like C and N cycling, microbial activity) requires clarification.

I hope that my remarks will help to improve some points of this article.

Introduction

Line 27-29 It is not clear from this citation how was the amount of amandmet with hulls, shells and kernels to provide a specific number of trees in a certain area with this amount of nutrients.

Lines 67-77. It is better to formulate the study goals more clearly and briefly.

Material and Methods

Lines 91-95, 112. It would be better to present the experiment design also as Tables. 

Lines 130, 141, 159. It looks that authors should explain this timing of sampling – periods with different duration.  

Results

Lines 203, 261, 265, 270. In the Materials and Method Section is mentioned a significance level 0.05 (Line 196). Please, add more information required information to the subsection Statistical analysis.

Line 206. In the Materials and Method section, two sampling periods are indicated:  September 2020 and October 2021. It schould be better to add to Table 1 caption the sampling date. It is also not seen the mentioned upward tending in Fall 2021.

Line 238. The authors have to clarify the abbreviation UA.

Lines 317, 383. It would be better (if possible) to give some information, at least as a supplementary material.

Line 346. If this is a reference on a source, it should be formatted under the Instructions for Authors, and a source description must be added to the list of References.

References

The "References" header is missing, which should be there. See the Instructions for the Authors

Line 423. According to the Template, the abbreviated name of the journal should be written in italics and the year of publication should be highlighted in bold. Here and further in Reference list.

Line 425. Please format this reference under the Instruction for Authors. Here and further in Reference list.

Lines 448, 536, 540, 545. Please, add DOI.

Author Response

Dear Reviewer,

Thank you for you thoughtful and detailed comments. These helped bring more clarity to the article. The attached file appended with track changes shows these and other changes. The file with changes made represents our final submission. I address each of your comments below:

1) The Introduction was confusing and we rewrote these sentences and brought in new references specifically showing the link between hull and shell application and almond crop demand with a highlight on potassium (K).

2) We also removed a sentences from the final paragraph of the Introduction to make it more streamlined.

3) Thank you for the comment on the experimental design presentation. We feel our diagram shows the unique set up of the incubation while the description of both experiments in the section is complete. We do not think an additional table adds value.

4) The durations of the experiments in the lab and the field did differ and the days for each are clearly articulated in the section. We do not think additional changes are needed here per the comment. 

5) We added the significance level of p<0.05 in Table 1.

6) Since the table aims to combine the initial and final dates of both studies in one table, then the seasonal dates mentioned are only relevant to the field study. Since the duration of both experiments are clearly articulated in the text, we will the presentation is sufficient.

7) Thank you for this oversight, we added (UA) to the figure caption.

8) These data are under review in another publication, so we are not at liberty to supply them here.

9) We added the References section and updated all references with the proper style of italics and bolding along with DOI values for each.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presents scientific justifications for the use of hulls and shells as a surface-applied layer to improve soil properties. Such research is very important. The soils were studied by several analytical methods. But the microbiological analysis seemed to me to be incomplete. The authors discuss the role of microbial biomass, but do not characterize it in any way, even at the level of large taxa. In my opinion, the contribution of microbial biomass to the present study could have been better 

Author Response

Dear Reviewer,

Thank you for your time reviewing our manuscript. We appreciate your feedback. The student responsible for this study and the lead author focused on microbial biomass and its interactions with nitrogen availability. We had another student work on characterizing the microbiome of these soils. That paper is now published here and cited in the text of this paper:

Andrews, E.M.; Tabassum, M.; Galatis, E.G.; Yao, E.H.; Gaudin, A.C.M.; Lazcano, C.; Brown, P.H.; Khalsa, S.D.S. Almond Hull and Shell Organic Matter Amendments Increase Microbial Biomass and Multifunctionality in Orchard Soil and the Undisturbed Organic Layer. App. Soil. Eco. 2024, 197, 105321. doi:10.1016/j.apsoil.2024.105321

We hope this work with satisfy your interests in this subject to a greater extent. For this particular study it was out-of-scope to do additional analysis and we feel the questions around microbiome were addressed in Andrews et al. 2024

Reviewer 3 Report

The scope of this manuscript aligns with the aims and scope of the journal, focusing on nutrient cycling, particularly for Carbon (C) and Nitrogen (N). The study investigates the effects of almond hull and shell amendments on the C and N status of soil, utilizing both lab-scale experiments and a field test. Given the limited existing research on the application of almond hull and shell amendments particularly in orchard soil, this study offers new insights into this area.

However, I have two small questions. Could you provide the information or any comment about it?

-          According to the result, the degree of N mineralization and immobilization was highly dependent on the C/N ratio. But, how about the effect of other trace elements (Mn, F, Cl, Zn, …) in soil?

-          How did the effect of atmospheric condition (temperature, rain, UV) interpret in the result?

-          Do you have any practical suggestions regarding the application of hulls and shells of almond as an amendment to orchard soil such as the pre-measurement of C/N ratio of soil, the ratio of it to other OMAs, etc.

Author Response

Dear Reviewer,

Thank you for your review and feedback on our manuscript.

N mineralization is directly linked to C:N of residues and this was the focus of our study. We did conduct another study examining the K release from the residues and K uptake by almond trees. We also observed K competition for Mg and lower Mg uptake by the trees. This same study also linked the decompostion of hulls and shells to the amount of applied water.

This work is published here:

Andrews, E.M.; Rivers, D.J.; Gaudin, A.C.M.; Geisseler, D.; Brown, P.H.; Khalsa, S.D.S. In a Nutshell: Almond Hull and Shell Organic Matter Amendments Increase Soil and Tree Potassium Status. Plant Soil 2023, doi:10.1007/s11104-023-06361-4.

This work was funded by a research and education grant. We completed a number of field days with farmers to explain our results. We also published article online discussing the practices at a practical level. Here is an example:

https://www.sacvalleyorchards.com/blog/almonds-blog/applying-amendments/