Effects of Straw and Biochar Amendments on Grassland Productivity and Root Morphology

Round 1

Reviewer 1 Report

In general, I found that this manuscript is well written and the experimental is reasonable. I have some specific comments as follows:

Abstract: lack of information on botanical composition. Please add a conclusion sentence after the last sentence.

Line 30 add a “.” after the last word.

Line 46-50 I would like to summarize this content into one sentence, as the present study did not test the effect of straw amendment on invasion.

Line 154 add “to” between years

Line 158-159: dash was lost between numbers. Please check throughout this paper.

Line 186: please highlight the significant responses using bold or italic. And explain abbreviations under the table as note.

Line 190 revise “during 2014 2018”?

Line 192 please explain abbreviations under the table as note. In addition, it is interesting to see how treatments affect these responses along years. For instance, whether the effect of treatments become stronger or smaller with years?

Line 193 please report SE or SD of each value in this table and the following figures and tables.

Line 195-196 please show us the data. It seems weird that the whole paragraph presented the results of total productivity while this sentence focused on ryegrass yields. Delete?

Line 196 please make this term “productivity” consistent throughout this paper. You can use either productivity or yield.

Line 196-198 nice summary!

Line 277 please explain abbreviations under figures or tables throughout this paper. Otherwise, audiences have to find the meaning of each abbreviation in the text. Please number and explain each sub-figures. If there is enough space, please avoid to use some abbreviations. For instance, RLD in this first figure.

Line 347 variance in root responses may be attributed to the direct effect of treatment and the indirect effect of changes in plant composition. This should be discussed somewhere.

Line 368-370 remove these sentences to discussion.

Line 373 “The soil amendments resulted in red clover percentage” a decrease or increase in red clover percentage?

Line 378 “The soil amendments resulted in forb content.”?

Line 398 please provide more details in fig 5. Now there is only sentence related to fig 5. It interesting to see how treatment affected grasses, herbs and legumes.

Lien 402-403 citation?

Line 449 “This effect may be ascribed to the N availability in soil.” How?

Line 487-495 yield and plant community composition may also be interesting. Please make a conclusion for this.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript outlines a 5-year project investigating the effects of straw and biochar amendments on grassland above and below ground growth.  In general, the organic additions increased above ground yields and root growth over that of the control, regardless of type of amendment.

The strength of the work is in the results pertaining to root growth and morphology as affected by the organic amendments, as much previous work has been done on above ground yields after straw and biochar additions.  I especially appreciated the way the authors led me through the article.  Several times throughout, questions arose as I was reading.  As I was preparing to make a comment about the question, the authors answered that question.

Specific comments are as follows:

Abstract      Specify in the abstract that the experiment was conducted on grassland/rangeland, not agricultural production land.

L90             Should the word herbs be forbs?

L114           Table 1 is the soil properties table, but in the text, it refers to the feedstocks table.

L129           Switch Tables 1 and 2 to match text.

L132-147     Explain more about how the plots were arranged.  How was mixing of amendments between plots prevented when such small plots were used and the amendments were incorporated with a rotary harrow?  Was the harrow a tractor attached implement? It would seem that significant amendments would drag between plots.

L153           Also related to table 4, explain why three cuttings were done.  Why not just one final end of season yield?  Also, if the plants were harvested from the whole plot area, how was there anything left after the first cutting?  It seems that the reason there was no significant difference in the third cutting is simply because vegetative growth was generally less at that later point of the growing season.

L167           The word rot should be root.

L205           I cannot figure out where the value of 2.25 t ha-1 comes from.  That sentence doesn’t make sense.

L206           The sentence “The above ground biomass was 1.56 t DM ha-1.” Seems out of place.  What is this referring to?

L241           Part of the upper two panes of Figure 4 is cut off so that the legend is not fully visible.

L344           The heading in Table 6 (MDR) should be MRD.

L377           What is meant by “The soil amendments resulted in forb content”?  Does this mean that there was an increase in forbs on the plots with amendments, or that somehow forbs were introduced with the amendments?

Responses to questions about aspects of the manuscript:

• Originality/Novelty: Is the question original and well defined? Do the results provide an advance in current knowledge?

The question of whether straw and biochar affect yield and root morphology of grassland is original in that root biomass and morphology after straw and biochar has not been investigated in this manner.

• Significance: Are the results interpreted appropriately? Are they significant? Are all conclusions justified and supported by the results? Are hypotheses and speculations carefully identified as such?

The results were significant and were interpreted appropriately.  The conclusions were well supported by the results and were discussed sufficiently.

• Quality of Presentation: Is the article written in an appropriate way? Are the data and analyses presented appropriately? Are the highest standards for presentation of the results used? 

The article was written in an articulate manner that was easy to read and the method of presentation of the data was appropriate.

• Scientific Soundness: is the study correctly designed and technically sound? Are the analyses performed with the highest technical standards? Are the data robust enough to draw the conclusions? Are the methods, tools, software, and reagents described with sufficient details to allow another researcher to reproduce the results?

The design of the experiment was sound and enough detail was provided to recreate the experiment. The conclusions were appropriate based on the detail of the data provided.

• Interest to the Readers: Are the conclusions interesting for the readership of the Journal? Will the paper attract a wide readership, or be of interest only to a limited number of people? (please see the Aims and Scope of the journal)

The results of the study would be of interest to a wide range of readers, from rangeland scientist who wish to improve grazing quality to those concerned with carbon sequestration.

• Overall Merit: Is there an overall benefit to publishing this work? Does the work provide an advance towards the current knowledge? Do the authors have addressed an important long-standing question with smart experiments? 

The work provides additional knowledge about the effects of straw and biochar on grassland roots and yield that was different than some of the literature cited.

• English Level: Is the English language appropriate and understandable?

The flow of the article with regards to the English language was very good. Grammar and spelling were excellent.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf