Zeolite as a Tool to Recycle Nitrogen and Phosphorus in Paddy Fields under Straw Returning Conditions
Round 1
Reviewer 1 Report
Comments on: “Zeolite as a tool to recycle the nitrogen and phosphorus in paddy fields under straw returning condition”.
Straws are an interesting topic and are one of the most absorbent materials available. It has been used for thousands of year’s in house construction, as stuffing for mattresses and upholstery, in baskets, as fuel, and as bedding and feed for horses, cows, and pigs. Although straw does not readily release moisture, the addition of zeolite can aid in the reduction of ammonia. Zeolite absorbs moisture like a sponge and neutralises odours by attracting harmful ammonia gas molecules. It benefits the environment and captures carbon, just like any organic material.
Abstract:
The abstract is really a summary, include key findings and has an appropriate length and can be understood without reading the manuscript.
Introduction:
Lines 37-38: avoid repeating the word "utilization" three times in the same sentence.
The introduction is well written and summarizes recent research related to the topic, but at the same time other new information could be added.
Even if the manuscript is not entirely unique due to previously published works on similar topic in agriculture, there are few materials concerning the excess of N and P from wastewater from paddy fields under straw incorporation by zeolite; therefore a new model that can effectively reduce excess N and P, resulting in cleaner production and sustainable agricultural development, is welcomed.
I think the reason for performing the study are clearly defined and gives a clear idea of the target readership, and the novelty and topicality of the manuscript.
Material and methods:
The authors provide enough information about the soil type and main properties from Hohai university Test Field, Jiangsu province in China.
Figures and tables, as well as experimental design and sampling from the material and methods section, make the entire experiment simple for other researchers to replicate and obtain similar results. The description of new model is accurate.
The statistical analyses used to process the data resulted in the experiment is not explained!!
Results:
The data are reliable, and they are supported by nine graphs that are some are clear and clean with appropriate labelling and easy to understand regarding nitrogen kinetics adsorption and dynamic changes in NH4+-N, TN and TP concentrations under different treatments, but there are also poorly executed analysis of data like in figure 4.
Line 228: Table 6 doesn’t exist. Maybe Figure 6?
Line 231: Table 4 doesn’t exist. Maybe Figure 4?
Line 234: The title of the figures is correct?
Line 237: where is the graph for “pseudo-first-order model”?
The figures illustrate the important features of the methods and results. Figure legends adequately explain their meaning and allow the reader to understand the figure without having to refer back to the text of the manuscript.
Discussions:
The section is long enough for the discussion of findings of possibility of using zeolite to alleviate the nitrogen 460 excess caused by straw returning to the field and reuse of N and P against the background of previous work and explain discrepancies with previously published reports.
The authors don’t reiterate the results in the Discussion section.
Conclusions:
The authors' conclusions are justified by the obtained results which highlighted that a quantity of about 20 t/ha zeolite is a better scheme to recycle use N and P in paddy fields.
References:
References were carefully selected and appropriate to the topic.
Lines 508, 516, 547: bold the year.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The study is scientifically sound and provides novel data on the potential of using zeolite amendments to drainage ditches and paddy rice fields to reduce nutrient losses and associated negative environmental impacts and nutrient use efficiency in intensive Chinese rice/wheat double crossing rotations.
However, in its current form the English language use is poor/clumsy, the article is very wordy and the description and discussion of results is not appropriately separate.
I therefore strongly recommend the authors use either (ii) an scientific English proof reading service with experience in revising soil science or chemistry articles to improve the English language use throughout the article.
There are also several deficiencies in the Method descriptions, discussion and conclusion sections
I have made some specific recommendations below
Material and Methods
Line 92. Add information on the cation exchange capacity (CEC) of the zeolite used in experiments
Table 2. Explain acronyms used for Treatments in the Table legend or provide replace acronyms in the 2nd column of Table 2 with the treatment description. Tables should be self-explanatory!
Line 130-140. Explain why you compared air-dried with oven dried zeolite. Was it to test whether over drying reduces its CEC?
Line 177-181. Provide references for each method used or detailed method descriptions as supplementary material.
Line 183-189. In section 2.3.2 Application analysis it is difficult to understand what was done and why! Especially the sentence “The second phase was in the paddy field, in which the zeolite was recycled from the ditch and reused to the N and P excess caused by straw incorporation.” Is confusing Do you mean to say “The second phase was in the paddy field; the zeolite was recovered from the ditch (describe how!) and applied in the field next to the drainage ditch (describe how!) to absorb/remove excess N and P from the soil solution (or surface water layer in the paddy rice field?) resulting from straw incorporation into soil.”
Results and discussion
The description of the results needs to be clearly separated from the discussion of the results.
At is stands, the manuscript includes discussion and conclusions in the results section (e.g. lines 208-217, lines 238-239, lines 297-300, lines 318, lines 381-382).
I strongly recommend the authors go through the results section, and move all sections that are discussing or draw conclusions from the results into the discussion or conclusion section.
Discussion or conclusions
The authors only touch on the potential for reducing mineral N and K fertilizer inputs without reducing crop yields that the use of zeolite to increase cation exchange capacity may provide to farmers.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Purpose of this work was to detect whether zeolite can be used as a tool for the sorption of N and P from wastewater and subsequently as fertilizer releaser in the paddy fields. The work mainly concerns issues in the field of Agronomy. Study confirms that the findings could have certain practical significance for lighten the N and P excess and sustainable development of Agriculture.
1. I agree, that there are many forms of straw utilization (Line 37), but it would be very useful to name what other methods of processing of straw utilization exist, for example using it for the production of fuel, etc. Straw incorporation in to soil is very popular form of straw utilization, but there are existing others.
2. In my opinion, g/kg should be g kg-1 (Line 89). It is the same, but is more acceptable. The same with unit marking throughout the all text.
3. There is some lack of information about relevance of the research methods. It would be informative to present the methods as they were obtained chemical composition (Table 1). Table ends without text. Also, there is a lack of information on how the all research data were statistically processed, for example repetition number quantity and so on.
4. Not clear meaning of “The experiment” (Line 94).
5. There are many abbreviations in the text. It would be helpful to explain them. In example what is TN and TP (Line 104).
6. It would be useful to specify what is Basic Fertilizer, Reviving Fertilizer, Tillering Fertilizer and Panicle Fertilizer were used in Table 3. It can be main fertilizers properties, like mineral or organic, liquid or solid (granular form), what kind of urea and so on.
7. Meteorological conditions is quite important for agronomical research. I think that at least minimal information about meteorological conditions should be provided or justify that these conditions could not affect the results. I mean that part of experiments which was performed in paddy field.
8. At last, the level of text formatting according requirements throughout this manuscript should be strictly improved.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
