Drip Fertigation with Relatively Low Water and N Input Achieved Higher Grain Yield of Maize by Improving Pre- and Post-Silking Dry Matter Accumulation

Round 1

Reviewer 1 Report

The work is well described, but in the methodology should be a table with terms and plant protection products (there is only short information in the text). It is worth supplementing this. I have no more comments.

Author Response

Reviewer’s Comments:

The work is well described, but in the methodology should be a table with terms and plant protection products (there is only short information in the text). It is worth supplementing this. I have no more comments.

1. but in the methodology should be a table with terms and plant protection products (there is only short information in the text).

Response: Thanks for your suggestion. I have added a table (Table 3) with terms and plant protection products in the methodology of the new manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript investigated “Manipulating Irrigation Method and Nitrogen Rate to Improve Grain Yield and Nitrogen Use Efficiency of Maize”. The major concern is that the article is not sufficiently novel and interesting to warrant its publication since the obtained results are absolute as one could expect. The major data have no novelty. Overall, the manuscript is too diffusive to understand what the authors want to suggest. Also, it was found that the article has problems regarding the quality of writing, being relatively difficult to follow because it is quite repetitive in certain parts of the text, and the text has a lot of misconnections between the topics and flows. That being said, I do not recommend this manuscript for publication in Sustainability.

Author Response

Reviewer’s Comments:

1. The manuscript investigated “Manipulating Irrigation Method and Nitrogen Rate to Improve Grain Yield and Nitrogen Use Efficiency of Maize”. The major concern is that the article is not sufficiently novel and interesting to warrant its publication since the obtained results are absolute as one could expect. The major data have no novelty. Overall, the manuscript is too diffusive to understand what the authors want to suggest. Also, it was found that the article has problems regarding the quality of writing, being relatively difficult to follow because it is quite repetitive in certain parts of the text, and the text has a lot of misconnections between the topics and flows. That being said, I do not recommend this manuscript for publication in Sustainability.

Response: Thanks for your suggestion. I have clarified the sufficiently novel and interesting of the full text. We found that, compared with flood fertigation (FF), drip fertigation (DF) improved the soil water content (SWC) from 0 to 40 cm soil layer to maintain a greater soil mineral N content (N_min) of that soil layer, which resulted in increased soil N_min from 0 to 40 cm soil layer for N3 under DF compared with N4 under FF during both pre- and post-silking of maize. Thus, maize for N3 under DF accumulated greater N at both pre- and post-silking compared with N4 under FF. Greater pre-silking N accumulation increase both leaf area and plant growth rate to accumulate more dry matter (DM) and develop more kernels, while sufficient post-silking N accumulation maintained high leaf area to produce more DM post-silking and promote maize ability to support grain filling. As a result, maximum maize yield (10.4 Mg ha^-1) was achieved due to increased kernel number and kernel weight for N3 (375 kg N ha⁻¹) under DF with 20% reduced N fertilizer input compared with N4 (450 kg N ha⁻¹) under FF. Due to greater grain yield and N uptake and less water consumption, the agronomic N efficiency (AE_N), N partial factor productivity (PFP_N), water use efficiency (WUE), and net income for N3 under DF increased compared to N4 under FF.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments for author File: Comments.pdf

Author Response

Reviewer’s Comments:

Abstract

1. Comment 1: A solid conclusion regarding the obtained results should be given.

Response: Thanks for your suggestion. I have made further revisions in the manuscript and come in the corresponding conclusions.

Introduction

2. Comment 2: Should be add one paragraph about flood fertigation.

Response: Thanks for your suggestion. I have added one paragraph about flood in the new manuscript.

3. Comment 3: The study has no mechanistic hypothesis. The significance of the study and a solid hypothesis of the present study at the end of the introduction should be provided.

Response: Thanks for your suggestion. I have added one paragraph about mechanistic hypothesis in the new manuscript. as “It is not clear whether drip irrigation can achieve higher yield and economic benefits by reducing the amount of water and nitrogen while improving the efficiency of water and nitrogen use. We hypothesized that drip irrigation can improve the growth and development of maize by improving the distribution of water and nitrogen in soil, so as to further increase yield and economic benefits”.

Methods

4. Comment 4: Why five N application rate: N0 (0), N1 (225 kg N ha⁻¹), N2 (300 kg N ha⁻¹), N3 (375 kg N ha⁻¹), and N4 (450 kg N ha⁻¹) were used in the experiment?

Response: Thanks for your suggestion. N4 (450 kg N ha⁻¹) is a fertilizer application rate often used by local farmers, a reduction of 75kg N ha-1 per gradient is achieved based on local fertilizer application rates

5. Comment 5: Why drip fertigation and flood fertigation were used in the experiment?

Response: Thanks for your suggestion. Flood fertigation is a conventional irrigation method in the production of local farmers, while drip fertigation is a new type of irrigation, which has been widely used in production and achieved good results in water saving and nitrogen reduction.

Discussion

6. Comment 6: Discussion should be improved. Why drip fertigation has these positive effects, in which particular part or mechanism is affecting?

Response: Thanks for your suggestion. I have added one paragraph about drip fertigation has these positive effects in the new manuscript. as “The results showed that drip irrigation could affect the distribution of soil water and nitrogen, increase the content of soil water and nitrogen, and benefit the root system to absorb water and nitrogen.”.

7. Comment 7: Should be add one paragraph about effect of drip fertigation and flood fertigation on growth parameters in crops under field conditions.

Response: Thanks for your suggestion. I have added one paragraph drip fertigation and flood fertigation on growth parameters in the new manuscript.

8. Comment 8: The conclusion needs to be rewritten

Response: Thanks for your suggestion. I have rewritten the conclusion in the manuscript

Author Response File: Author Response.pdf

Reviewer 4 Report

dear Author, thanks for your manuscript. it is well written and reports the results of the use of fertigation compared to flood fertigation. the thematic is actual. I report suggestions to improve your research work.

1. title: why did you choose "Manipulating Irrigation Method"? consider to rephrase it.
2. rephase line 14 it is unclear
3. line 34 and reference and change reference number 1
4. line 41. expand the concept of n20o release in terms of biotic production
5. concerning the field area, can you describe better the how you choose the sampling area? I think that a figure of the field could improve this section. Moreover, did you measure if the relase of the water form hose was the same for holes?
6. line 135: check pH, it is unclear
7. tables. please rewrite all the tables, they are unclear (add lines..)

Author Response

Reviewer’s Comments4:

1. title: why did you choose "Manipulating Irrigation Method"? consider to rephrase it.

Response: Thanks for your suggestion. I have revised the title as “Drip Fertigation with a Relatively Lower Water and N Input Achieved Higher Grian Yield of Maize by Improving Pre- and post-silking Dry Matter Accumulation”.

2. rephase line 14 it is unclear

Response: Thanks for your suggestion. I have revised the sentence as “Appropriate irrigation and nitrogen (N) management strategies are necessary to achieve sustainable yield of maize with a relatively lower water and N input”.

3. line 34 and reference and change reference number 1

Response: Thanks for your suggestion. I have modified it according to your requirements.

4. line 41. expand the concept of N₂O release in terms of biotic production

Response: Thanks for your suggestion. The main greenhouse gas emitted from agricultural production, N₂O, is released from soils following the application of N fertilizer; it represents 38% of the total direct greenhouse gas emissions from global agriculture. The relationship between N₂O and N fertilizers is usually demonstrated to be exponential. Optimal N management improves crop yields, but it also contributes to higher NUE, thus reducing environmental costs. 

5. concerning the field area, can you describe better the how you choose the sampling area? I think that a figure of the field could improve this section.

Response: Thanks for your suggestion. I have added one paragraph sampling area in the new manuscript. “At harvest, about 24 m² (central four rows (2.4 m) of each plot, 10 m long) area of each plot were harvested to measure grain yield”

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Reviewer’s Comments were given in the last round.

 

Regarding reviewing that manuscript for sustainability, I found in the first and second review rounds that the article is not sufficiently novel, and the major data have no novelty. Overall, the manuscript has problems regarding the quality of writing, and it has a lot of misconnections between the topics and flows. Therefore, I did not recommend this manuscript for publication. With kind regards!     Throughout "abstract" only, the following issues ,but not limited, can be seen; Flood fertigation (FF), Do we flood maize! Do you mean "surface irrigation"?  How irrigation was performed? On what base ET? FC? SWC? Please note that "fertigation is a method of fertilizer application in which fertilizer is incorporated within the irrigation water by the drip system". Please check title and content.  "Soil mineral N content"!. Which form of N is referred here? NH4, NO3, TN? Water use efficiency (WUE, kg/m3) is randomly reported in the text. It should be either removed or detailed based on water use (m3) and yield (kg/ha). Based on this study, how much water (m3) do farmers need to produce 1 kg of maize? The manuscript reports on "Nitrogen Use Efficiency" of Maize. However, the values of agronomic N efficiency, N partial factor productivity neither present nor briefly detailed in the abstract! In general, the key results are improperly presented, and very few values can be seen. "Therefore, drip fertigation of maize at 375 kg N ha-1 would improve maize yield and NUE, and reduced negative impact of N fertilizer use in maize production compared with flood fertigation". The conclusion on drip fertigation brings nothing new. Also, could the application of N fertilizer at the rate 375 kg N/ha reduce the negative impact of N fertilizer on the environment? For cereal production, the application of N fertilizer at the rate of 300 kg N/ ha is considered as over-fertilization practice.

 

Reviewer 3 Report

The authors have sufficiently improved their paper, in reaction to my comments made.