Management Zones in Pastures Based on Soil Apparent Electrical Conductivity and Altitude: NDVI, Soil and Biomass Sampling Validation
, Shakib Shahidian 1, LuÃs Paixão 2, José Marques da Silva 1,2 and Francisco Moral 3Round 1
Reviewer 1 Report
This paper presents very interesting and novel research results on the application of precision agriculture technology (soil scanning, proximal plant sensing) and topographic data to determine homogeneous pasture management zones, and propose new "global index". The work is valuable as studies of PA technology in pastures are not frequent. However, the paper needs corrections and additions.
In the literature review, I suggest adding information on: - the use of proximal and remote sensing to determine MZ in pastures, as this method was also used in the study, - methods of MZ map validation.
The description of the methodology needs to be reorganized and additional descriptions are needed. The validation phase needs attention in terms of the statistical methods used to compare the quality of HMZ maps. The proposed "soil global index" is acceptable, but it should be explained why existing and effective methods were not used and referred to.
Results described correctly with minor editing and editorial errors. Discussion conducted correctly.
The conclusions chapter does'nt address the proposed and new "global index".
In addition, the used parameter 'productive potential' was not defined in the review and methodology, and in the description of results changed its form to: “less, intermediate and more potential”. There are also phrases "fertility potential, "potential zones". This confuses the reader and hinders the clarity of reading the paper.
Specific comments and suggestions:
Line 102: I propose to give complete information about EC platforms. ""Veris 2000 XA"? I propose to add, manufacturer and country of origin. Similarly, the other EC scanners.
Line 109 Use GNSS instead of GPS. GNSS is the correct name for the receiver.
Line 117: Figure 1 - This is the scope of the methodology, it should be in the methodology chapter, not before.
Line 121 -122: This paragraph lists 12 field names not 6. The content in parentheses is confusing.
Line 130-132- In these lines you describe the soil, but the reader does not know what methodology was used, according to what classification.
138-142 – Approximate how the annual precipitation value was measured or cite the source.
Line 147: Table 1 - Cite the source of systematic classification of soil material texture as "loam". National?
Line 152: The country name "Canada" is sufficient, the city and state are redundant. Similarly in line 179 and 190.
Line 157: “with a global positioning system (GPS) antenna” Use GNSS. I think it was the integrated GNSS receiver, not the GNSS antenna itself. If it was just the antenna then describe how the GNSS radio messages were processed, what frames were used, etc.?
Line 157: „which simultaneously provided a topographic survey”. A more extensive description of the acquisition of hypsometric data is required. Give the name, type and manufacturer of the antenna and receiver or integrated receiver. At what accuracy did the GNSS work? What type of correction was used? SBAS? GBAS? RTK? DGPS?
Line 173: Setinel-2 data was not used in the study, Remove or explain why Sentinel -2.
Line 179 & 190: ", USA)" If you use the full name "Canada" in line 152 then why does the abbreviation "USA" appear here? Choose and use one standard, if abbreviations then use ISO standard country names.
Line 194: If you did not get a complete result from the "CUB" object due to pandemics then I suggest you skip this object. 5 objects is sufficient. This is a suggestion.
Line 245: In your paper you use the term "topographic data" whereas you used only one topographic data i.e. topographic altitude
Line 257: Missing information about transferring data from GNSS receiver to ArcGiS. As previously mentioned, also need to add information about elevation measurements using GNSS? Additionally, why wasn't the DEM for the site existing in public databases used?
Equatation 1 & 2: What is "n"?
Line 302 – 313: The proposed validation method is a new proposal. It would be advisable to refer to the methods used in the literature, e.g. Kappa coefficient.
Tabela 3. „Altimetry" - Is that height above sea level? I suggest substituting and using " Altitiude"
Tabela 3. If we have given "range" then "amplitude" is no longer needed, It is an obvious data.
Line 327: „The characteristic undulated relief of the Montado ecosystem is evidenced by the amplitude of altimetry recorded in each of the six experimental fields (between 24.2 m in Grous and 40.4 m in Padres; Table 3).
The difference in elevation is not evidence of undulating terrain, it only shows that the terrain is different in elevation. Terrain that is not undulating, with a surface close to the mathematical plane and with a single slope line will also be characterized by elevation differences.
Line 342: What is a " CV?" Please define.
Line 364: What is "CEa?" Please define.
Figure 6. The parameter "Elevation" appears, previously "altimetry" was used, I propose to standardize to altitiude.
Line 574: „Precision Agriculture is one the pillars of the “Agriculture 4.0” concept.” The sentence is correct, but the introduction of the term "Agriculture 4.0" needs to be clarified. The work did not use Agriculture 4.0 technology, only 3.0. The next sentence also needs a reference to be added.
Line 579: „The results of this study show that low-cost data..” Unjustified conclusion. The use of the phrase "low-cost" in relation to EC scaning is very subjective, moreover the paper does not present an economic discussion in this matter.
Line 601: Funding: Give more details about the funding institution. Add country of origin "national funding". The study was conducted in Spain and Portugal.
Line 607: If the research was financed from public funds you should explain the precise access to data repositories and its limitations.
Author Response
REVIEWER#1
Comments and Suggestions for Authors
This paper presents very interesting and novel research results on the application of precision agriculture technology (soil scanning, proximal plant sensing) and topographic data to determine homogeneous pasture management zones, and propose new "global index". The work is valuable as studies of PA technology in pastures are not frequent. However, the paper needs corrections and additions.
R- The authors are grateful for all of the reviewers' suggestions and comments, which contributed decisively to the improvement of the article.
In the literature review, I suggest adding information on: - the use of proximal and remote sensing to determine MZ in pastures, as this method was also used in the study, - methods of MZ map validation.
R- The suggestions were accepted: PS, RS to determine MZ and methods of MZ map validation were included in the literature review.
The description of the methodology needs to be reorganized and additional descriptions are needed. The validation phase needs attention in terms of the statistical methods used to compare the quality of HMZ maps. The proposed "soil global index" is acceptable, but it should be explained why existing and effective methods were not used and referred to.
R- The authors propose this “soil global index”, as an alternative to many other statistical methods used to compare the quality of HMZ maps. This soil fertility index is particularly useful in pasture soils, where factors such as pH, OM, P or CEC are indicators of the limitation of most of these soils in terms of pasture productivity. As suggested, a reference to the other methods of MZ map validation was added in the literature review.
Results described correctly with minor editing and editorial errors. Discussion conducted correctly.
R-Thank you very much.
The conclusions chapter does'nt address the proposed and new "global index".
R- The suggestion was accepted: the “global index” was included in conclusions of the new version of the manuscript.
In addition, the used parameter 'productive potential' was not defined in the review and methodology, and in the description of results changed its form to: “less, intermediate and more potential”. There are also phrases "fertility potential, "potential zones". This confuses the reader and hinders the clarity of reading the paper.
R- The reviewer is right. The suggestions were incorporated with the aim of clarifying the reading of the paper. Thank you very much.
Specific comments and suggestions:
R- The authors are grateful for the reviewer's exhaustive work. Virtually all minor corrections have been accepted and included in the new version of the manuscript (we inserted “Accepted”). In the few cases where we provided some justification, the text was inserted right after the proposed reviewer correction.
Line 102: I propose to give complete information about EC platforms. ""Veris 2000 XA"? I propose to add, manufacturer and country of origin. Similarly, the other EC scanners
R- Accepted.
Line 109 Use GNSS instead of GPS. GNSS is the correct name for the receiver.
R- Accepted.
Line 117: Figure 1 - This is the scope of the methodology; it should be in the methodology chapter, not before.
R- Accepted.
Line 121 -122: This paragraph lists 12 field names not 6. The content in parentheses is confusing.
R- There are only six fields and their abbreviated codes, now separated by a hyphen to clarify.
Line 130-132- In these lines you describe the soil, but the reader does not know what methodology was used, according to what classification.
R- The reference presented [16], right after the soil classification (“Cambisol”), refers to the “World Reference Base for Soil Resources” of the FAO (2006).
138-142 – Approximate how the annual precipitation value was measured or cite the source.
R- Accepted. The source of this data was added to the text.
Line 147: Table 1 - Cite the source of systematic classification of soil material texture as "loam". National?
R- Accepted.
Line 152: The country name "Canada" is sufficient, the city and state are redundant. Similarly in line 179 and 190.
R- Accepted.
Line 157: “with a global positioning system (GPS) antenna” Use GNSS. I think it was the integrated GNSS receiver, not the GNSS antenna itself. If it was just the antenna then describe how the GNSS radio messages were processed, what frames were used, etc.?
Line 157: „which simultaneously provided a topographic survey”. A more extensive description of the acquisition of hypsometric data is required. Give the name, type and manufacturer of the antenna and receiver or integrated receiver. At what accuracy did the GNSS work? What type of correction was used? SBAS? GBAS? RTK? DGPS?
R- The reviewer is right. The text was corrected accordingly.
Line 173: Setinel-2 data was not used in the study, Remove or explain why Sentinel -2.
R- Accepted.
Line 179 & 190: ", USA)" If you use the full name "Canada" in line 152 then why does the abbreviation "USA" appear here? Choose and use one standard, if abbreviations then use ISO standard country names. :
R- Accepted.
Line 194: If you did not get a complete result from the "CUB" object due to pandemics then I suggest you skip this object. 5 objects is sufficient. This is a suggestion.
R- The authors are grateful for the suggestion, however, they consider it important to keep this field (“CUB”), since it represents a soil with a texture that is different from the others (see Figure 3), increasing the variability and representativeness of the results obtained.
Line 245: In your paper you use the term "topographic data" whereas you used only one topographic data i.e. topographic altitude.
R- Accepted.
Line 257: Missing information about transferring data from GNSS receiver to ArcGiS. As previously mentioned, also need to add information about elevation measurements using GNSS? Additionally, why wasn't the DEM for the site existing in public databases used?
R- Accepted.
Equation 1 & 2: What is "n"?
R- The meaning of the letter "n" was added.
Line 302 – 313: The proposed validation method is a new proposal. It would be advisable to refer to the methods used in the literature, e.g. Kappa coefficient.
R- As suggested, a reference to other methods of MZ map validation was added in the literature review.
Table 3. „Altimetry" - Is that height above sea level? I suggest substituting and using " Altitude"
R- Accepted.
Tabela 3. If we have given "range" then "amplitude" is no longer needed, It is an obvious data.
R- The reviewer is right. The table has been corrected accordingly.
Line 327: „The characteristic undulated relief of the Montado ecosystem is evidenced by the amplitude of altimetry recorded in each of the six experimental fields (between 24.2 m in Grous and 40.4 m in Padres; Table 3). The difference in elevation is not evidence of undulating terrain, it only shows that the terrain is different in elevation. Terrain that is not undulating, with a surface close to the mathematical plane and with a single slope line will also be characterized by elevation differences.
R- The reviewer is right. The sentence was deleted.
Line 342: What is a " CV?" Please define.
R- Accepted.
Line 364: What is "CEa?" Please define.
R- Accepted.
Figure 6. The parameter "Elevation" appears, previously "altimetry" was used, I propose to standardize to altitude.
R- Accepted.
Line 574: „Precision Agriculture is one the pillars of the “Agriculture 4.0” concept.” The sentence is correct, but the introduction of the term "Agriculture 4.0" needs to be clarified. The work did not use Agriculture 4.0 technology, only 3.0. The next sentence also needs a reference to be added
R- The reviewer is right: Precision Agriculture is common to both concepts (Agriculture 3.0 and Agriculture 4.0), but this work uses the concept of smart farming based on techniques to monitor and optimise agricultural processes (“Agriculture 3.0 Technology”), but not the internet of things and big data (“Agriculture 4.0 Technology”). Therefore, the sentence was rewritten accordingly.
Line 579: „The results of this study show that low-cost data.” Unjustified conclusion. The use of the phrase "low-cost" in relation to EC scanning is very subjective, moreover the paper does not present an economic discussion in this matter.
R- The reviewer is right. The term “low-cost” was deleted.
Line 601: Funding: Give more details about the funding institution. Add country of origin "national funding". The study was conducted in Spain and Portugal.
R- Accepted. The study was financed by Portuguese Funds.
Line 607: If the research was financed from public funds you should explain the precise access to data repositories and its limitations.
R- We are not aware of any limitation of access to scientific data repositories published in international open access journals, such as “Agronomy”.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article is quite okay and impressive. The article is detailed enough.
Author Response
REVIEWER#2
Comments and Suggestions for Authors
The article is quite okay and impressive. The article is detailed enough.
R-Thank you very much.
Author Response File: Author Response.pdf
Reviewer 3 Report
I find some merit in the paper. However, has many shortcomings.
- I would like the introduction to document the need to measure the apparent electrical conductivity
- The electrical conductivity had to be measured in the soil samples. The electrical conductivity of the saturation paste extract should be measured or at least the 1: 5 conductivity.
- In the captions of Figures 6-11 the units of apparent electrical conductivity had to be given. Only then can one assess the level of salinity
Author Response
REVIEWER#3
Comments and Suggestions for Authors
I find some merit in the paper. However, has many shortcomings.
- I would like the introduction to document the need to measure the apparent electrical conductivity.
R- The following two paragraphs are already part of the “Introduction” section and seem sufficient to show the interest in measuring apparent electrical conductivity in this context of HMZ definition.
“New research should make use of current sensor systems, which can gather data at sufficiently high density to characterize small-scale variations now known to be present in majority of fields [2].”
“Several studies have shown the practical interest and the potential of ECa monitoring for designing and establishing HMZ, implementing smart sampling, and elaborating prescription fertilizer maps [11]. This potential is due to the fact that this parameter integrates the main properties affecting crop productivity [2], namely, texture, soil moisture, organic matter content, and soil cationic exchange capacity [12,15].”
- The electrical conductivity had to be measured in the soil samples. The electrical conductivity of the saturation paste extract should be measured or at least the 1: 5 conductivity.
R- Laboratory measurement of electrical conductivity in soil samples was not included in the standard package of analyzes supported by the projects that finance this research work. We register and acknowledge the reviewer suggestion for future field work related to the calibration/validation of ECa measurement tools.
- In the captions of Figures 6-11 the units of apparent electrical conductivity had to be given. Only then can one assess the level of salinity.
R- The suggestion was accepted: the units of apparent electrical conductivity were included in captions of Figures -11. Thank you very much.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The paper significantly improved with revisions made by the Authors and consequently I suggest to accept the manuscript in present form
