Impact of Polymer-Coated Controlled-Release Fertilizer on Maize Growth, Production, and Soil Nitrate in Sandy Soils

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

It is of great significance to study the effect of temperature and rainfall on the release of available nitrogen from coated fertilizer in specific environment for scientific fertilization of maize. However, the writing logic needs to be further modified and adjusted before publication. Soil available nitrogen was affected directly by Polymer-coated controlled-release fertilizers（CRF）, which further affects the yield and quality of maize. Therefore, the writing process should follow this logical sequence, especially the topics and results and discussion sections.

Author Response

We thank Reviewer 1 for his/her excellent comments and suggestions to improve the quality of the manuscript. All the comments and suggestions have resulted in significant improvement of our manuscript, and we are truly appreciative of the time and effort of the Reviewer 1.

Reviewer 1: It is of great significance to study the effect of temperature and rainfall on the release of available nitrogen from coated fertilizer in specific environment for scientific fertilization of maize. However, the writing logic needs to be further modified and adjusted before publication. Soil available nitrogen was affected directly by Polymer-coated controlled-release fertilizers (CRF, which further affects the yield and quality of maize. Therefore, the writing process should follow this logical sequence, especially the topics and results and discussion sections.

Authors: We thank reviewer 1 for recognizing the value and application of our work. As per the suggestion, we have adjusted the writing logic of the result and discussion section. We have moved the “Yield Analysis” section after the “Soil Nitrate” section. Please see Page 15-16, Line 405-452, Page 21-22, Line 559-606. We have revised the figure numbers, as well as the reference sequence.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The subject addressed in the manuscript entitled “Impact of polymer-coated controlled-release fertilizer on 2 maize growth, production, and soil nitrate in sandy soils” is extremely current and necessary for contemporary society. In this manuscript, the authors aimed to evaluate the capacity of a polymer-coated CRF to maintain maize (Zea mays L.) crop growth/health indicators and production goals while reducing NO₃-N leach-ing risks compared to conventional (CONV) fertilizers in North Florida. Four CRF rates (168, 224, 280, 336 kg N ha⁻¹) were assessed against a no nitrogen (N) application and the current University of Florida Institute for Food and Agricultural Sciences (UF/IFAS) recommended CONV (269 kg N ha⁻¹) fertilizer rate. All CRF treatments, even the lowest CRF rate (168 kg N ha⁻¹), produced yields, leaf tissue N concentrations, plant heights, aboveground biomasses (AGB), and leaf area index (LAI) significantly (p < 0.05) greater than or similar to the CONV fertilizer treatment. Additionally, in 2022 the CONV fertilizer treatment resulted in increases in late-season movement of soil NO₃- N into highly leachable areas of the soil profile (60-120 cm), while none of the CRF treatments did. However, back-to-back leaching rainfall (> 76.2 mm over three days) events in the 2023 growing season masked any trends as NO₃-N  was likely completely flushed from the system. The results of this two-year study suggest that polymer-coated CRF can achieve desirable crop growth, crop health, and production goals while also having the potential to reduce late-season leaching potential of NO₃-N; however, more research is needed to fully capture and quantify the movement of NO₃-N through the soil profile. Correlation and Principal Component Analysis (PCA) revealed that CRF  performance was significantly influenced by environmental factors such as rainfall and temperature. In 2022, temperature-driven nitrogen release aligned with crop uptake, supporting higher yields and minimizing NO_3-N movement. In 2023, however, rainfall-driven variability led to increase NO₃-N leaching and masked the benefits of CRF treatments. These analyses provided critical insights into the relationships between environmental factors and CRF performance, emphasizing the importance of adaptive fertilizer management under varying climatic conditions. One of the advantages of this publication is the relatively large amount of experimental data and results. Below are some considerations: 

 

·         Manuscript needs minor English proofreading. 

 

·         What polymer was used to coat the fertilizer?

 ·         The coefficients (K₂O et. al.) should be written properly.

·         The legend of the second table needs to be edited.

 ·         The precipitation and temperature scales in Figure 1 are difficult to understand, I would suggest that both precipitation and temperature scales be on both figures.

 ·         In the materials and methods part, the literature source is not indicated (experimental design, statistical analysis processing methods et al.).

 ·         The authors should more precisely, consistently and rigorously give the specifications of all devices used by them.

 ·         In Figure 3 it is not clear which figure is about the results obtained in 2022 and which is about 2023?

 ·         Figure 6 must be clearer, it lost of quality.

 

Author Response

Reviewer 2:

We thank Reviewer 2 for his/her excellent comments and suggestions to improve the quality of the manuscript. All the comments and suggestions have resulted in significant improvement of our manuscript, and we are truly appreciative of the time and effort of the Reviewer 2.

 

Reviewer 2: The subject addressed in the manuscript entitled “Impact of polymer-coated controlled-release fertilizer on 2 maize growth, production, and soil nitrate in sandy soils” is extremely current and necessary for contemporary society. In this manuscript, the authors aimed to evaluate the capacity of a polymer-coated CRF to maintain maize (Zea mays L.) crop growth/health indicators and production goals while reducing NO₃-N leaching risks compared to conventional (CONV) fertilizers in North Florida. Four CRF rates (168, 224, 280, 336 kg N ha⁻¹) were assessed against a no nitrogen (N) application and the current University of Florida Institute for Food and Agricultural Sciences (UF/IFAS) recommended CONV (269 kg N ha⁻¹) fertilizer rate. All CRF treatments, even the lowest CRF rate (168 kg N ha⁻¹), produced yields, leaf tissue N concentrations, plant heights, aboveground biomasses (AGB), and leaf area index (LAI) significantly (p < 0.05) greater than or similar to the CONV fertilizer treatment. Additionally, in 2022 the CONV fertilizer treatment resulted in increases in late-season movement of soil NO₃- N into highly leachable areas of the soil profile (60-120 cm), while none of the CRF treatments did. However, back-to-back leaching rainfall (> 76.2 mm over three days) events in the 2023 growing season masked any trends as NO₃-N was likely completely flushed from the system. The results of this two-year study suggest that polymer-coated CRF can achieve desirable crop growth, crop health, and production goals while also having the potential to reduce late-season leaching potential of NO₃-N; however, more research is needed to fully capture and quantify the movement of NO₃-N through the soil profile. Correlation and Principal Component Analysis (PCA) revealed that CRF performance was significantly influenced by environmental factors such as rainfall and temperature. In 2022, temperature-driven nitrogen release aligned with crop uptake, supporting higher yields and minimizing NO3-N movement. In 2023, however, rainfall-driven variability led to increase NO₃-N leaching and masked the benefits of CRF treatments. These analyses provided critical insights into the relationships between environmental factors and CRF performance, emphasizing the importance of adaptive fertilizer management under varying climatic conditions. One of the advantages of this publication is the relatively large amount of experimental data and results. Below are some considerations: 

Authors: We thank the reviewer for recognizing the value and application of our work. We agree with the reviewers’ observation that more research is required to fully capture and quantify the movement of NO₃-N and potential leaching below the soil profile. Therefore, as an extension to this study, research efforts are underway that incorporate water quality sampling and predictive modeling to comprehensively quantify NO₃-N leaching events. These approaches would provide greater clarity on the environmental benefits of polymer-coated CRFs, particularly in terms of their role in mitigating NO₃-N leaching. In addition, apart from studying the impact of different rates of CRF on maize productivity and leaching potential, we are also investigating the impact of CRF placement (broadcasting vs side-dressing vs incorporated) on maize productivity and leaching potential. We have listed our future research plan in the manuscript. Please see Page 30, Lines 782-788.

 

Reviewer 2: Manuscript needs minor English proofreading. 

Authors: Changes have been made throughout the manuscript to improve the English and sentence structure.

Reviewer 2: What polymer was used to coat the fertilizer?

Authors: The CRF product used in this research is POLYON® CRF (43-0-0) (Harrell’s LLC, Lakeland, FL) which is coated with polyurethane polymer. The information has been added to the manuscript. Please see Page 5, Lines 183-184.

Reviewer 2: The coefficients (K2O et. al.) should be written properly.

Authors: Thank you for the comments. We have revised it as suggested. Please see Page 6, Lines 208-210.

Reviewer 2: The legend of the second table needs to be edited.

Authors: We have edited the legend of Table 2. We also edited the legend and table content of Table 3 for more clarity. Please see Page 6, Line 213, and Page 7, Line 215.

Reviewer 2: The precipitation and temperature scales in Figure 1 are difficult to understand, I would suggest that both precipitation and temperature scales be on both figures.

Authors: We have revised the figure 1, as suggested. Please see Page 11, Line 324, Figure 1.

Reviewer 2: In the materials and methods part, the literature source is not indicated (experimental design, statistical analysis processing methods et al.).

Authors: Thank you for pointing this. We have added the reference to support the statement associated with experimental design, and statistical analysis processing methods. Please see Page 5, Line 175; Section 2.7, Page 14, Line 277, 279, 284, 286, 288, 290, 296, and 300.

Reviewer 2: The authors should more precisely, consistently and rigorously give the specifications of all devices used by them.

Authors: We have added the details of each device and provided references for detailed information on the different devices used in this research, e.g., fertilizer applicator, soil moisture sensor, etc.

For example, we used the First Product (First Product Inc., Tifton, Georgia) double disc opener to apply the starter fertilizer (23-9-0) at 2-in deep and 2-in to the side of the row. Information added, please see Page 5, Lines 188-190.

Similarly, Conventional fertilizer was applied in multiple splits using the Miller High Boy (CNH Industrial America LL) rig. The information is added to the manuscript. Please see Page 5, Lines 197-198.

The soil moisture was measured using the Meter group TEROS 12 soil moisture sensor. We have provided the web link for the product for more information. Please see Page 8, Line 220.

LAI was measured using the LICOR LAI-2000 Plant Canopy Analyzer. We have provided the web link for the product for more information. Please see Page 8, Line 242.

For NO₃-N data, we sent the samples to the Water Ag Laboratory where the samples were analyzed for NO³-N using the KCl extraction and colorimetry with the Cadmium Reduction method with Flow Injection. The reference “Knepel, K. 2003. Determination of Nitrate in 2M KCl soil extracts by Flow Injection Analysis. QuikChem Method 12-107-04-1-B. Lachat Instruments, Loveland, CO” is provided for the detailed description of this method. Please see Page 9, Lines 270-274.

Reviewer 2: In Figure 3 it is not clear which figure is about the results obtained in 2022 and which is about 2023?

Authors: We have revised the figure as suggested and added the years. The new figures is listed as Figure 4 in the revised manuscript. Please see Page 23, Line 603, Figure 4.

Reviewer 2: Figure 6 must be clearer; it lost of quality.

Authors: We have revised the figure to make it clearer. Please see Page 26, Line 706, Figure 6.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors, I greatly appreciate your contribution to the preparation of the manuscript and the performance of the research. The subject of your research is very interesting and fits into the current global trend of increasing the efficiency of nitrogen use and reducing its losses. As a reviewer, I have a duty to critically look at the work before publication and point out weak points that need to be improved.

I present my comments in the points below

1. Keywords overlap with words in the title. This should not be the case. Keywords should be related to the research topic, but they should be such that they can be searched for as a second selection criterion after the title. Change the keywords to other ones to have a wider search range by other authors, which will increase the reach and citation of your work in the future after publication.

2. In lines 50-53. Maize (Zea mays L.) is one of the highest yielding crops globally with a production of about 1.2 billion tons in 2021 that contributes significantly to human and animal consumption, bioenergy, and a multitude of industrial products [1]. - I recommend rewording this sentence because it is too broad and does not provide the appropriate content. Corn is one of the most important plants in the world due to its arable area. However, it is also worth adding that its area has expanded due to its adaptability to various environments "Nowadays, due to its adaptation to various environmental conditions, the crop is widely cultivated." This sentence is from the work: Święcick, W. K.; Surma, M. The big five in the world of plants–the species that have changed the course of history. Polish Journal of Agronomy 2021, (47), 68-77. which I recommend quoting.

3. After line 63 it is also worth adding that they are looking for ways to reduce nitrogen losses from both mineral and organic fertilizers. Currently, they want to use all possible ways to retain nitrogen in the soil supplied with fertilizers. these are, for example, urease inhibitors, information from a work worth citing Matczuk D, Siczek A. Effectiveness of the use of urease inhibitors in agriculture: a review. Int. Agrophys. 2021;35(2):197-208. doi:10.31545/intagr/139714.

4 In line 319-322 you use literature no. 47 which was published in 1988. It is recommended to use newer literature. You can replace it with e.g. the work: Różewicz, M., Grabiński, J., Wyzińska, M. (2024). Effect of strip-till and cultivar on photosynthetic parameters and grain yield of winter wheat. Int. Agrophysics, 38, 279-291.

5. In the manuscript of the work that I am attaching to the review, I have several suggestions for improving the sentences - suggested corrections in the comments.

6. When improving the manuscript, you should also improve the references according to the requirements of MDPI journals, according to this, the references in the list should look like this: Yasin, S.; Zavala-García, F.; Niño-Medina, G.; Rodríguez-Salinas, P.A.; Gutiérrez-Diez, A.; Sinagawa-García, S.R.; Lugo-Cruz, E. Morphological and Physiological Response of Maize (Zea mays L.) to Drought Stress during Reproductive Stage. Agronomy 2024, 14, 1718. https://doi.org/10.3390/agronomy14081718

Comments for author File: Comments.pdf

Author Response

Reviewer 3:

We thank Reviewer 3 for his/her excellent comments and suggestions to improve the quality of the manuscript. All the comments and suggestions have resulted in significant improvement of our manuscript, and we are truly appreciative of the time and effort of Reviewer 3.

Dear Authors, I greatly appreciate your contribution to the preparation of the manuscript and the performance of the research. The subject of your research is very interesting and fits into the current global trend of increasing the efficiency of nitrogen use and reducing its losses. As a reviewer, I have a duty to critically look at the work before publication and point out weak points that need to be improved.

Authors: We thank the reviewer for recognizing the value and application of our work. We also thank the reviewer for providing constructive comments and suggestions to improve the overall quality of the manuscript. Significant changes have been made throughout the manuscript to improve the overall quality.

I present my comments in the points below

Reviewer 3: Keywords overlap with words in the title. This should not be the case. Keywords should be related to the research topic, but they should be such that they can be searched for as a second selection criterion after the title. Change the keywords to other ones to have a wider search range by other authors, which will increase the reach and citation of your work in the future after publication.

Authors: Thank you for your comment. We have revised the keywords as suggested. Please see Page 2, Line 47-48.

Reviewer 3: In lines 50-53. Maize (Zea mays L.) is one of the highest yielding crops globally with a production of about 1.2 billion tons in 2021 that contributes significantly to human and animal consumption, bioenergy, and a multitude of industrial products [1]. - I recommend rewording this sentence because it is too broad and does not provide the appropriate content. Corn is one of the most important plants in the world due to its arable area. However, it is also worth adding that its area has expanded due to its adaptability to various environments "Nowadays, due to its adaptation to various environmental conditions, the crop is widely cultivated." This sentence is from the work: Święcick, W. K.; Surma, M. The big five in the world of plants–the species that have changed the course of history. Polish Journal of Agronomy 2021, (47), 68-77. which I recommend quoting.

Authors: We agree with the reviewers and added the reference as suggested. Please see Page 2, Line 51-53.

Reviewer 3: After line 63 it is also worth adding that they are looking for ways to reduce nitrogen losses from both mineral and organic fertilizers. Currently, they want to use all possible ways to retain nitrogen in the soil supplied with fertilizers. these are, for example, urease inhibitors, information from a work worth citing Matczuk D, Siczek A. Effectiveness of the use of urease inhibitors in agriculture: a review. Int. Agrophys. 2021;35(2):197-208. doi:10.31545/intagr/139714.

Authors: We thank the reviewer for the valuable input. We have revised the section and added the appropriate references. Please see Page 2, Lines 66-72.

Reviewer: In line 319-322 you use literature no. 47 which was published in 1988. It is recommended to use newer literature. You can replace it with e.g. the work: Różewicz, M., Grabiński, J., Wyzińska, M. (2024). Effect of strip-till and cultivar on photosynthetic parameters and grain yield of winter wheat. Int. Agrophysics, 38, 279-291.

Authors: Thank you for your suggestion. We have added the reference as suggested. We have retained the other reference as well, as it is more especially related to maize. Please Page 12, Line 332.

Reviewer 3: In the manuscript of the work that I am attaching to the review, I have several suggestions for improving the sentences - suggested corrections in the comments.

Authors: We would like to thank the reviewer for the detailed comments. We have addressed all the comments and suggestions listed in the attached file.

Reviewer 3: When improving the manuscript, you should also improve the references according to the requirements of MDPI journals, according to this, the references in the list should look like this: Yasin, S.; Zavala-García, F.; Niño-Medina, G.; Rodríguez-Salinas, P.A.; Gutiérrez-Diez, A.; Sinagawa-García, S.R.; Lugo-Cruz, E. Morphological and Physiological Response of Maize (Zea mays L.) to Drought Stress during Reproductive Stage. Agronomy 2024, 14, 1718. https://doi.org/10.3390/agronomy14081718

Authors: We have revised all the references according to the requirements of MDPI journals. Please see the reference section. Page 31-36 and Line 842-1083.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I have read the entire manuscript of the paper carefully. I can see that you have put a lot of work into improving the manuscript and I appreciate it very much. I believe that the current form after the corrections is suitable for publication.