Improving Nitrogen Availability and Ananas comosus L. Merr var. Moris Productivity in a Tropical Peat Soil Using Clinoptilolite Zeolite

Round 1

Reviewer 1 Report

The manuscript entitled “Improving Nitrogen Availability and Ananas comosus L. Merr var. Moris 

Productivity on a Tropical Peat Soil Using Clinoptilolite Zeolite” is interesting and fits the scope of Agronomy Journal. However it will need some major revision particularly concerning the discussion section.

The other sections are fairly ok although data presentation should be enhanced. In the 3.3 part of results you should state from the beginning why you use T6 treatment. Otherwise it is not quite understandable.

In the following figures why don’t you put together wet and dry season, instead of making the separation? 

Figure 6. Meaning of different 3 graphs for each a), b) and c) should report the different plant growth stages. Dates can be important but more than that is plant development and, also if it is within the wet and dry season. In this part you have abandoned that separation. Since, ultimately, the focus is pineapple production and quality, you should report all these environment conditions.

 

Discussion should not repeat results section and different divisions. 

You should use your hypothesis and manuscript aims to write the discussion section. This means that you should avoid more explanations about the zelolite characteristics during wet and dry season, rather than explain how this zeolite contribute for the best development and pineapple growth and fruit quality. Quality of pineapple varies due to cultivation technique, growing environment and variety. So, knowing that pineapple goes better with an ammonium nutrition and that fertilizer requirement increases sharply after planting and peak at two to four months before floral initiation you need to pull all your data to pinpoint these previous knowledge. 

 

 

Author Response

Response to Reviewer 1 Comments

 

Point 1: In the 3.3. part of results, you should state from the beginning why you use T6 treatment. Otherwise it is not quite understandable.

Response 1: Treatment T6 (peat soil only) is used as a treatment in this present study because it is necessary to determine the leaching and mobility of nutrients in peat soil throughout the wet and dry seasons without the use of fertilizer or inorganic amendments. The justification on the use of treatment T6 has been explained in the materials and methods section 2.4 (Laboratory Leaching Experiment) (Lines 257 to 260). Amounts of ammonium and nitrate leached and retained in the treatment with peat soils only (T6) were subtracted from those of fertilized treatments (T1 to T5) to account for the effects of the CZ and compound NPK fertilizers. Also, under field conditions, peat oxidation and water table fluctuation might influence nitrogen mineralization and availability of inorganic nitrogen content in the peat soil throughout the wet and dry seasons, thus necessitate the use of treatment T6 in this present study.

Point 2: In the following figures why don’t you put together the wet and dry season, instead of making the separation?

Response 2: Authors acknowledged and agreed with the reviewer to combine the figures for the wet and dry seasons. Revisions have been made to the manuscript to combine ammonium and nitrate losses and retention in the wet and dry seasons for Figure 3, 4, and 5 (Lines 398 to 401, 412 to 415, and 450 to 454).

Point 3: Figure 6. Meaning of different 3 graphs for each (a), (b), and (c) should report the different plant growth stages. Dates can be important but more than that is plant development, and also if it is within the wet and dry season. In this part you have abandoned that separation. Since, ultimately, the focus is pineapple production and quality, you should report all these environmental conditions.

Response 3: Authors acknowledged and agreed with the reviewer. Revisions have been made to Figures 6 (Lines 514 to 519), 9 (Lines 530 to 535), 10 (Lines 594 to 599), and 12 (Lines 628 to 633) to combined the components of (a) mean soil nutrient losses and retention at different pineapple vegetative growth (three, six, and nine months after planting) (b) mean nutrient losses and retention with depth (0 cm to 30 cm, 0 cm to 60 cm, and 0 cm to 90 cm), and (c) mean nutrient losses and retention after fertilization (seven, fifteen, and thirty days) throughout the wet (March and September 2017) and dry (June 2017) seasons. Environmental conditions have also been included in the each figure title.

Point 4: Discussion should not repeat results section and different sections

Response 4: Revisions have been made to the manuscript to ensure no repetitions of the results sections in the discussions (Lines 784, 813 to 814, 818, 834, 845, 888, 955, 973, 1028 to 1029, and 1054). However, explanations and justifications provided in different discussion sections are used to validate the differing results obtained in the laboratory leaching studies and field trials for pineapple cultivation on drained tropical peat soils. 

Point 5: You should use your hypothesis and manuscript aims to write the discussion section. This means that you should avoid more explanations about the zeolite characteristics during wet and dry season, rather than explain how this zeolite contribute for the best development and pineapple growth and fruit quality. Quality of pineapple varies due to cultivation technique, growing environment and variety. So, knowing that pineapple goes better with an ammonium nutrition and that fertilizer requirement increases sharply after planting and peat at two to four months before floral initiation you need to pull all your data to pinpoint these previous knowledge.

Response 5: Authors acknowledged the view of the reviewer for the discussion section. The objective of the present study was to determine the effects of clinoptilolite zeolite on retaining and reducing leaching of ammonium and nitrate in a tropical peat soil which is cultivated with Moris pineapple. In line with this, the discussion of the manuscript provided explanations on the adsorption mechanisms of clinoptilolite zeolite in improving nitrogen availability in drained tropical peat soils throughout the wet and dry seasons, particularly ammonium and nitrate based on the pineapple fertilization regime at three, six, and nine months after planting in combination with clinoptilolite zeolite application. Conversely, laboratory leaching experiments were carried out under high and low rainfall conditions to validate the potential of clinoptilolite zeolite in reducing leaching and retaining ammonium and nitrate in tropical peat soils. This is because results between laboratory experiments and field trials (pineapple cultivation on peat soils) might differ as ammonium and nitrate availability in peat soils with clinoptilolite zeolite is highly influenced by the peat preferential flow and peat oxidation throughout the dry and wet monsoon seasons. Thus, the need to elaborate in-depth on the use of clinoptilolite zeolite to improve nitrogen availability in drained tropical peat soils. However, the second objective of the study was to determine the effects of clinoptilolite zeolite on nitrogen uptake and use efficiency, growth performance, fresh fruit yield, and quality of pineapple fruits. For this second objective, revisions have been made to the manuscript in Section 4.7 (Growth, nutrients uptake and use efficiency, fruit quality, and yield of Ananas comosus L. Merr var. Moris) to provide further explanations on how clinoptilolite zeolite improved pineapple productivity on peat soils (Lines 1111 to 1130). Based on the foregoing discussion, the findings of this present study demonstrated that application of clinoptilolite zeolite in conjunction with compound NPK 30:1:32 fertilizer at three, six, and nine months after planting positively influenced pineapple growth attributes, yield, and fruit quality. This could be attributed to the accumulation of clinoptilolite zeolite in the peat soils, which did not break down rapidly over time but instead remained in the soil to improve nutrient retention, particularly ammonium. The gradual build-up of inorganic nitrogen with clinoptilolite zeolite in the peat soil play an important role in promoting plant cell division, multiplication, and photosynthesis that resulted in increased plant height and leaf area, and improved plant N contents. Also, the positive response of pineapple yield and fruit quality to adequate supply of nitrogen stimulated by clinoptilolite zeolite application could be attributed to the increased physiological activities resulting in assimilate production and their translocation and utilization for fruit development. In this present study, the use of compound NPK 30:1:32 fertilizer could not significantly improve the growth, uptake and use efficiency of N, fruit yield, and fruit quality of the pineapple plants, not only because of the acidity of the peat soil, but also because of the leaching of ammonium and nitrate from the peat soils, particularly during the wet monsoon season. Thus, split application of compound NPK 30:1:32 fertilizer and CZ during the wet season could be considered as a nutrient management strategy to provide time for nitrogen (particularly ammonium) to be absorbed and taken up by pineapple plants to ensure production of good pineapple fruit yields. 

Reviewer 2 Report

This is a complex, high quality article, that describes the soil-plant system. Although the excessive length of article makes it difficult to maintain attention when reading.

Additional comments and suggestions are as follows:

line 75: better sentence would be; However, N supply should be increased for four mounth...

line 77: Instead of recommended fertilzation rates "The recommended fertilizer rates" would be better. 

 

line 78: What is the composition of Bordeaux mixture? It is advisable to describe

line 97: However, the concentration of nitrate ions would be better!

line 98: the nitrification would be better

line 100: to build nitrate ions would be better

line 140: increase the amount of exchangeable...

line 181: The better title is " Characterization of Physical and Chemical Properties of Peat Soil

lines 220-221. It would be better to write the exact amount of NPK fertilizers!

line 227: In Table 1. The order of treatments (T1-T6) does not the same as it is written Figures 3,4,5...! This is a big mistake, it should definitely be corrected!

line 227: What does 100% CZ mean? Is it pure zeolite? It would be advisable to describe in the material and method chapter.

line 249: Soil samples at 24 and 90 days of the leaching expreiment were analyzed. In what depth?

line 292: What was the amount of NPK fertilizer?

line 319: A=N uptake of plant with fertilizer would be better!

lines 320-322: What are the units of N uptake and the unit of the total amount of fertilizer?

lines 324-325: What is the exact methods of determinations of fruit quality parameters? Literature or exact mehod should be written!

line 355: Available phosphorus is expressed in P2O5 or P? Available potassium is expressed in K2O or K? It is not clear!

line 414: at the deeper soil layer would be better

line 499: Figure 6. Larger columns with larger numbers would have been more readable!

line 616: „compared to” instead of „compared with”. All other places should be corrected!

line 619: Table 5. The pineapple plant age and Soil pH would be better written in two lines, as it is confusing. As it is written in in Table 6.

line 647: Instead of "N content", "Nitrogen concentration" should be better!

line 748: Instead of „Availability”, „Leachability” wuold be better

lines 759, 760: If it is an ion, positive charge must be written: K+

lines 774, 776: instead of P, phosphate is necessary!

line 805: What are these soil pH values? In the Table 5, all values are lower!

lines 822, 832: Instead of P, phosphate is necessary!

line 849: Instead of high soil pH, higher soil pH would be better!

line 853: What kind of materials is written?

lines 874, 879, 936: Instead of P, phosphate is necessary!

line 946: Instead of phophorus, phosphate is necessary!

line 1001: "which cause increase" is better!

line 1001: "This explains the higher soil pH" is better!

Author Response

Response to Reviewer 2 Comments

 

Point 1: Line 75 – Better sentence would be; However, N supply should be increased for four month…

Response 1: Authors acknowledged and agreed with the reviewer on the specific term for ‘N supply’ instead of ‘N level’. Revisions have been made to the manuscript to replace the word ‘level’ with ‘supply’ in the introduction section (Line 75).

 

Point 2: Line 77 – Instead of recommended fertilization rates “The recommended fertilizer rates” would be better.

Response 2: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 77. Revisions have been made to the manuscript to replace the word ‘fertilization’ with ‘fertilizer’ in the introduction section (Line 77).

 

Point 3: Line 78 – What is the composition of Bordeaux mixture? It is advisable to describe.

Response 3: Revisions have been made to the manuscript in the introduction section to include a description of the foliar fertilizer, which is commonly known as Bordeaux mixture and its application to pineapple plants (Lines 79 to 84). The Bordeaux mixture is a foliar fertilizer containing 42 g of copper sulphate, 21 g of iron sulphate, 42 g of zinc sulphate, and 640 g of lime. This foliar fertilizer is applied to pineapple plants at 1.5 and 4.5 months after planting to reduce micronutrient deficiency that is a common problem in peat soils, whereas compound NPK fertilizer is applied thrice at three, six, and nine months after pineapple planting.  

 

Point 4: Line 97 – However, the concentration of nitrate ions would be better!

Response 4: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 97. Revisions have been made to the manuscript to replace the sentence ‘However, nitrate ions are…’ to ‘However, the concentration of nitrate ions are…’ in the introduction section (Line 101).

 

Point 5: Line 98 – the nitrification would be better

Response 5: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 98. Revisions have been made to the manuscript to include the word ‘the’ before the sentence ‘nitrification of ammonium’ (Line 102).

 

Point 6: Line 100 – to build nitrate ions would be better

Response 6: Authors acknowledged and agreed with the reviewer on the use of the specific term for building nitrogen in peat soils via fertilizer applications by including both ammonium and nitrate ions. Revisions have been made to the manuscript to include the ‘ammonium and nitrate ions’ in the sentence ‘…it is not advisable to apply high levels of N fertilizers to build ammonium and nitrate ions in drained peat soils…’ (Line 104).

 

Point 7: Line 140 – increase the amount of exchangeable…

Response 7: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 140. Revisions have been made to the manuscript to include the sentence ‘…will increase the amount of exchangeable…” (Line 144).

 

Point 8: Line 181 – The better title is “Characterization of Physical and Chemical Properties of Peat Soil”

Response 8: Authors acknowledged and agreed with the reviewer on the title for section 2.2. (Line 181). Revisions have been made to the manuscript and the sub-title for the materials and methods section in 2.2 was revised to ‘Characterization of Physical and Chemical Properties of Peat Soil” (Lines 185).

 

Point 9: Lines 220-221 – It would be better to write the exact amount of NPK fertilizers!

Response 9: Revisions have been made to revise the manuscript to include the exact amount of clinoptilolite zeolite (CZ) used as treatments in this present study. The treatments comprised of different amounts of CZ (25%, 50%, 70%, and 100% of the existing recommended rate of CZ). Amounts of CZ (5 g, 10 g, 14 g, and 20 g) utilized were computed based on the compound NPK fertilizer requirement of Moris pineapple at the vegetative and fruiting stages cultivated on tropical peat soils (Lines 224 to 225). 

 

Point 10: Line 227 – In Table 1. The order of treatments (T1-T6) does not the same as it is written Figures 3, 4, 5…! This is a big mistake; it should definitely be corrected.

Response 10: Authors acknowledged and agreed with the reviewer on the typo error in Table 1. Revisions have been made to Table 1 in Section 2.4 (Laboratory Experiment). The order of the treatments in Table 1 was revised accordingly (Lines 232 to 234) to that of all treatments in the figures and tables in the manuscript as follows:

 

Table 1. Clinoptilolite zeolite and compound nitrogen, phosphorus, and potassium fertilizer application rates used in the laboratory leaching experiments

Fertilization Treatments		Application Rate
T1	25% CZ + compound NPK fertilizer	5.0 g of CZ + 20 g of NPK fertilizer 30:1:32
T2	50% CZ + compound NPK fertilizer	10.0 g of CZ + 20 g of NPK fertilizer 30:1:32
T3	70% CZ + compound NPK fertilizer	14.0 g of CZ + 20 g of NPK fertilizer 30:1:32
T4	100% CZ + compound NPK fertilizer	20.0 g of CZ + 20 g of NPK fertilizer 30:1:32
T5	Control: Compound NPK fertilizer only	20 g of NPK fertilizer 30:1:32
T6	Control: Peat soil alone (without fertilizer)	Nil

Note: CZ—clinoptilolite zeolite; compound N:P₂O₅:K₂O fertilizer ratio—30:1:32.

 

Point 11: Line 227 – What does 100% zeolite mean? Is it pure zeolite? It would be advisable to describe in the material and method chapter.

Response 11: Revisions have been made to the manuscript where the percentages of the clinoptilolite zeolite refers to the existing recommended rate of zeolite for use in tropical peat soils (25%, 50%, 70%, and 100%). Amounts of clinoptilolite zeolite of clinoptilolite zeolite (5 g, 10 g, 14 g, and 20 g) utilized were computed based on the compound NPK fertilizer (30:1:32) requirement of Moris pineapple at the vegetative and fruiting stages cultivated on tropical peat soils. Revisions have been made to include information on the recommended rates of clinoptilolite zeolite used in this present study (Lines 224 to 225) and Table 1 (232 to 234).

 

Point 12: Line 249 – Soil samples at 24 and 90 days of the leaching experiment were analyzed. In what depth?

Response 12: At the end of the leaching experiment (wet season – 90 days and dry season – 24 days), soil samples were analyzed at the aerobic zone (0 cm to 10 cm and 10 cm to 30 cm) and saturated depth (30 cm to 60 cm and 60 cm to 90 cm). Revisions have been made to the manuscript to include information on soil depth for the analysis of pH, exchangeable ammonium, and available nitrate in Section 2.4 (Laboratory Leaching Experiment). Soil samples at 24 and 30 days of the leaching experiment were analyzed for pH, exchangeable ammonium, and available nitrate at depths of 0 cm to 10 cm, 10 cm to 30 cm, 30 cm to 60 cm, and 60 cm to 90 cm using the standard procedures as outlined previously (Line 256).

 

Point 13: Line 292 – What was the amount of NPK fertilizer?

Response 13: The amount of NPK 30:1:32 fertilizer applied to pineapple plants at three, six, and nine months after planting was 20 g/plant. The information on the amount of compound NPK fertilizer were outlined in Table 1 (Lines 232 to 234). However, revisions have been made to the manuscript to include the amount of NPK fertilizer (20 g) in the text (Section 2.5: Field Experimental Design and Nutrient Measurements in a Peat Soil Grown with Pineapples) (Line 298).

 

Point 14: Line 319 – A – N uptake of plant with fertilizer would be better!

Response 14: Authors acknowledged and agreed with the reviewer on the typo error for the description in equation 1. Revisions have been made to the manuscript to include the word ‘of plant’ in description A and B (equation 1) in section 2.6 (Lines 325 to 327) as follows:

A = Total N uptake of plant with fertilizer at harvest (kg ha^-1)

B =  Total N uptake of plant without fertilizer at harvest (kg ha^-1)

 

Point 15: Lines 320-322 – What are the units of N uptake and the unit of the total amount of fertilizer?

Response 15: The units of N uptake and the unit of the total amount of fertilizer are kg ha^-1. Revisions have been made to the description in equation 1 to include the units used (Lines 325 to 327) as follows:

A = Total N uptake of plant with fertilizer at harvest (kg ha^-1)

B =  Total N uptake of plant without fertilizer at harvest (kg ha^-1)

C = Total amount of N fertilizer applied (kg ha^-1)

 

Point 16: Lines 324-325 – What is the exact methods of determination of fruit quality parameters? Literature or exact method should be written!

Response 16: Details of method for fruit quality characteristics, particularly fresh fruit weight, total soluble solids (TTS), titratable acidity (TA), and juice pH of the fresh pineapple fruit were described in section 2.6 (Growth performance, nutrients uptake and use efficiency, pineapple fresh yield, and fruit quality) (Lines 332 to 340). However, revisions have been made to the manuscript by incorporating references [61,80,81] for fruit quality determination methods in the text (Lines 332 to 340). Fruit quality characteristics namely fresh fruit weight, total soluble solids (TTS), titratable acidity (TA), and juice pH of the fresh pineapple fruits were also determined. Pineapple fruit yield was calculated based on the mean fruit weight and plant density [80], whereas pineapple fresh fruit weight was determined using a digital weighing balance (EK-15KL, A&D Company, Toshima-ku, Tokyo, Japan) [80]. Pineapple fruits with similar attributes (maturity Index 5: 50% ripe) were selected, hand-peeled, cored, sliced, and blended using a food processor [61,80]. Total soluble solids were determined using a handheld refractometer (Atago PAL-1, Spectrum Technologies Inc, Aurora, IL, USA) [61]. Titratable acidity contents were measured using the method of Hajar et al. [81], whereas pineapple fresh fruit juice pH was measured using a pH meter (Laqua PH1200, Horiba Scientific, Kyoto, Tokyo, Japan). All references [61, 80, 81] cited are listed in the reference section.

 

Point 17: Line 355 – Available phosphorus is expressed in P2O5 or P? Available potassium is expressed in K2O or K? It is not clear!

Response 17: Throughout the manuscript, soil analysis results are given as mg/kg. The term available phosphorus refers to the amount of soil P in solution which can be extracted by plant roots and expressed as phosphate (PO₄^3-), whereas exchangeable potassium refers to K⁺ ions in the soil which is readily available. Revisions have been made to the Table 2. to express available phosphorus as ‘available P’ and exchangeable potassium as ‘exchangeable K’ (Lines 361 to 362).

 

Point 18: Line 414 – at the deeper soil layer would be better

Response 18: Authors acknowledged and agreed with the reviewer on the more suitable term for the anaerobic soil depth. Revisions have been made to the manuscript to replace the sentence ‘…available nitrate retention at the lower soil depths…” as ‘…available nitrate retention as the deeper soil layer…” (Line 426).

 

Point 19: Line 499 – Figure 6. Larger columns with larger numbers would have been more readable

Response 19: Revisions have been made to the manuscript and improvements have been made to Figures 3 (Lines 398 to 401), 4 (Lines 412 to 415), 5 (Lines 450 to 454), 6 (Lines 514 to 519), 9 (Lines 530 to 535), 10 (Lines 594 to 599), and 12 (Lines 628 to 633) to give a better representation of data to readers.

 

 Point 20: Line 616 – “compared to” instead of “compared with”. All other places should be corrected.

Response 20: Throughout the manuscript, the term ‘compared with’ is used to refer two objects of similar classification (soils to soils) and to point out differences between the two object comparisons. Conversely, the use of ‘compared to’ is usually referring to two items in different classifications and to point out similarities between the two seemingly unrelated objects.

 

Point 21: Line 619 – Table 5. The pineapple plant age and soil pH would be better written in two lines, as it is confusing. As it is written in Table 6.

Response 21: Authors acknowledged and agreed with the reviewer on the soil pH parameter. Revisions have been made to Table 6 to separate the parameters between pineapple plant age and soil pH to give a better representation of data (Line 651).

 

Point 22: Line 647 – Instead of “N content”, “N concentration” should be better

Response 22: Authors acknowledged and agreed with the reviewer on the use of the term ‘concentration’. Revisions have been made to Table 6 and the ‘Nitrogen content (%)” have been replaced with ‘Nitrogen concentration (%)’ (Lines 681 to 682).

 

Point 23: Line 748 – Instead of “Availability”, “Leachability” would be better

Response 23: Authors acknowledged the viewpoint of the reviewer and considered a better term for the effect of clinoptilolite zeolite on the soil leachates during the wet and dry seasons under laboratory leaching experiments. Revisions have been made to the title in section 4.3 where the word ‘Availability’ was replaced with ‘Leachability’ (Line 780).

 

Point 24: Lines 759, 760 – If it is an ion, positive charge must be written: K+

Response 24: Authors acknowledged and agreed with the reviewer on the chemical formula for potassium. In this section (4.3), authors are referring to potassium ions. Revisions have been made to include the chemical formula for potassium ions as “K⁺” throughout the manuscript (Lines 791 to 792, 806, 809, 849, 860, 906, 950, and 1075).

 

Point 25: Lines 774, 776 – Instead of P, phosphate is necessary

Response 25: Authors acknowledged and agreed with the reviewer on the use of phosphate for the competitive sorption of nutrients comprising ammonium, nitrate, and K⁺ ions on the charged surfaces of the clinoptilolite zeolite. Revision have been made to replace P with ‘phosphate’ in Section 4.3 (Lines 806 and 809).

 

Point 26: Line 805 – what are these soil pH values? In the Table 5, all values are lower

Response 26: The soil pH values (range pH 8.04 to 8.07) refers to the mean pH values at depth of 0 cm to 10 cm for treatment T4 (100% clinoptilolite zeolite) in the wet and dry seasons throughout the wet and dry seasons (laboratory leaching experiments). These values (pH 8.04 to 8.07) are presented in Table 4, whereas the lower soil pH values in Table 5 represents mean pH of peat soils cultivated with pineapples at different vegetative stage (three, six, and nine months after planting).

 

Point 27: Lines 822, 832: Instead of P, phosphate is necessary!

Response 27: Authors acknowledged and agreed with the reviewer on the use of phosphate for the sorption of nutrients comprising ammonium, nitrate, and K⁺ ions on the charged surfaces of the clinoptilolite zeolite. Revision have been made to replace P with ‘phosphate’ in Section 4.3 (Lines 850 and 860).

 

Point 28: Line 849 – Instead of high soil pH, higher soil pH would be better!

Response 28: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 849. Revisions have been made to the manuscript to replace the word ‘high’ with ‘higher’ in the Section 4.4 (Line 877).

 

Point 29: Line 853 – What kind of materials is written?

Response 29: The materials in Line 853 refers to clinoptilolite zeolite. Revisions have been made to the manuscript to replace ‘material’ with ‘clinoptilolite zeolite’ in Line 881.

 

Point 30: Lines 874, 879, 936 – Instead of P, phosphate is necessary!

Response 30: Authors acknowledged and agreed with the reviewer on the use of phosphate for the sorption of nutrients comprising ammonium, nitrate, and K⁺ ions on the charged surfaces of the clinoptilolite zeolite. Revision have been made to replace P with ‘phosphate’ (Lines 901, 906, and 938).

 

Point 31: Line 946 – Instead of P, phosphate is necessary!

Response 31: Authors acknowledged and agreed with the reviewer on the use of phosphate for the sorption of nutrients comprising ammonium, nitrate, and K⁺ ions on the charged surfaces of the clinoptilolite zeolite. Revision have been made to replace P with ‘phosphate’ throughout the manuscript (Lines 950, 964 to 965, 992, and 1075).

 

Point 32: Line 1001 – “which cause increase” is better!

Response 32: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 1001. Revisions have been made to the manuscript to replace the word ‘causes increases’ with ‘cause increase’ in the Section 4.6 (Line 1025).

 

Point 33: Line 1001 – “This explains the higher soil pH” is better!

Response 323: Authors acknowledged and agreed with the reviewer on the grammatical error in Line 1001. Revisions have been made to the manuscript to replace the word ‘high’ with ‘higher’ in the Section 4.6 (Line 1026).

Round 2

Reviewer 1 Report

Your manuscript has been improved. However, when I mentioned that  discussion should not repeat results section, apparently you didn't understand. Why use sections in discussion section? where are your answers to the hypothesis of the introduction? You need to be much more concise otherwise the reader will be lost before your conclusions.

Author Response

Response to Reviewer 1 Comments

 

Point 1: Your manuscript has been improved. However, when I mentioned that discussion should not repeat results section, apparently you didn’t understand. Why use sections in discussion section? Where are your answers to the hypothesis of the introduction? You need to be much more concise otherwise the reader will be lost before your conclusions.

Response 1: Revisions have been made to the manuscript, particularly for the discussion section. Various sections in the discussion were deleted and combined. Discussions have been revised accordingly based on Section 4.3 (Laboratory Soil Leaching Experiment) and Section 4.4 (Improving Soil Nitrogen Availability and Pineapple Productivity on a Drained Tropical Peat Soil Using Clinoptilolite Zeolite) by presenting key findings with clear and concise outcomes and recommendations (Lines 780 to 883, 885 to 945, 973 to 977, 1025 to 1031, 1031 to 1038, 1055 to 1068, 1088 to 1099, 1099 to 1104, and 1108 to 1112). Answers to the hypothesis of the introduction were clearly discussed and stated in Section 4.3 (Lines 879 to 883) and Section 4.4 (Lines 1031 to 1036, 1055 to 1056, 1065 to 1068). The conclusion section has also been improved with recommendations for the community (Lines 1135 to 1137).