Review Reports - Optimisation of the Resource of Land-Based Livestock Systems to Advance Sustainable Agriculture: A Farm-Level Analysis

Round 1

Reviewer 1 Report

The authors proposed a methodology in a farm level to analyze a farm system from the pasture growth data from each Land Management Unit to maximize income. The author also provided a livestock reconciliation budget resulting in an optimal solution for a farm operation and reported on animal purchase and sale dates and supplementary feed details. The work is interesting and courageous, and the problem which the authors intend to solve is important and interesting.

In order to point out the technical contribution of the paper, please summarize the technical achievements of this work in the Introduction section. Also, the contributions should be highlighted and given at the end of Introduction section.

For better readability and comprehensibility, please highlight the key research problem of this work clearly.

A table that compares the related work and the proposed mechanisms is suggested to be summarized at the end of Related Work Section.

The most references are out of date. Author would add more recently works and discuss the recently development. I suggest that this manuscript should be to cite more references in recent years, especially in 2017-2019.

The readability of the paper should be improved and insights from the provided figures should be provided. Otherwise, it is difficult to follow the paper.

Author Response

Comments and Suggestions for Authors

Our responses are in italics

In order to point out the technical contribution of the paper, please summarize the technical achievements of this work in the Introduction section. Also, the contributions should be highlighted and given at the end of Introduction section.

Good comment by the referee. We have clarified the technical contribution of the work by adding additional text to the last paragraph in the introduction

Line 99-101 “In this paper, we describe a model framework that tackles the inability of most farm system models to incorporate spatial biophysical variation as an integral part of the analysis”

Line 107-110 “Critically the model framework maintains the link between available pasture and livestock requirements for each LMU throughout all calculations, to enable the livestock type and number carried and the pasture mass required on each LMU throughout the year to achieve the required animal performance levels, to be included as model outputs”.

For better readability and comprehensibility, please highlight the key research problem of this work clearly.

We have added the following in addition to the comments to the previous comment by the referee.

Line 17-19 abstract “While advances in the application of geospatial information systems and remote sensing technologies offer much to agriculture, capturing and using that rich spatial biophysical information is not a feature available in most farm existing farm systems models. In this paper we tackle this gap describing”

Line 70-73 Introduction “Currently they are not a feature available in most farm systems model. Where they are found they are largely limited to exploring the influence a change in practice on one part of the farm has on the whole”

A table that compares the related work and the proposed mechanisms is suggested to be summarized at the end of Related Work Section.

Not clear what the referee was asking

The most references are out of date. Author would add more recently works and discuss the recently development. I suggest that this manuscript should be to cite more references in recent years, especially in 2017-2019.

Research attempting to capturing and use spatial biophysical information in farm systems models dates back prior to research prior to 2000. While linear programming continues to be used it is limited to optimising the farm as a single land unit. To make that point references through to 2019 are included. That said a reference is never too old if it contains data and findings relevant to the discussion.

The readability of the paper should be improved and insights from the provided figures should be provided. Otherwise, it is difficult to follow the paper.

We have made changes to the structure of the paper (e.g. shifted testing of the model to the result section) and split Table 3, with the OVERSEER data in a new table (Table 5). That helps with the flow of the paper

Reviewer 2 Report

This paper describes in detail the framework of the model / computerprogram AgInform. It divides the land area in 7 land management units. Grazing of animals is part of it. Modelling of grazing is quite a challenge. Therefore this model was quite a challenge to construct, I suppose. That is a positive asset to this paper.

Some questions/remarks:

The framework of the model is extensively described in the M&M section. The result section is much more compact. In this context, is the article balanced?

Testing farm and case study farm and base and fecund farm are used in different parts of paper without clear introduction, I believe. This is confusing to me.

Many equations are listed in the M&M section. I think that comprising of equations is possible. Take for instance "Animal income" on page 5. Is it not possible to replace all 10 animal species, which are now listed separately, by just using the word "animal 1-10" or "species 1-10" to express all together?!

Steady state needs to be ensured (page 4, lines 148-149) and page 3, lines 140-142). The consequences from this condition have in my opinion not clearly be explained, for instance in the discussion section.

Also: How to imagine that the "standing herbage mass at the end of year must equal that at the start of the year............."? (lines 140-142).

The outputs from AgInform are the "steady state livestock policies" (page 16, line 513) ........... I am not sure I understand.

Supplementary costs are the costs associated with "making and feeding out supplementary feed...". I am not sure what is meant with feeding out. Supplementary feed transferred to other land units seems to be a different action.

Testing of the model function takes place on pages 16 and 17. This is part of M&M. In the results section is a case study presented. I was expecting the testing to be with a different farm than the calculations with the case study farm. However, on line 544 is mentioned that Table 1 is used for the key data of the tested farm. Table 1 characterizes the case farm. Thus you obviously talk about the same farm. Why to present this testing part in M&M and the further work with this farm in the Results section?

Above does not make sense to me. Actually it would be good to do model testing with a variety of farms. Please, explain the rational behind this choice.

Figure 2: utilization; please explain what utilization means in this graphic.

Figure 3 needs more explanation in my opinion.

Fecund appears in the title of figure 3. I have the impression that Fecund farm system (line 588 on next page) was not introduced earlier in the paper. But I may have missed it. Anyway it requires some explanation.

The outputs of the model were tested within the OVERSEER model (page 21, line 609). This concerns the environmental impact. OVERSEER is already mentioned in table 3, line 536 without explanation, I believe. This is rather confusing.

The integral application of AgInform and OVERSEER does not lead to optimization of environmental impact, right? Just explain in the paper. Also: What is the purpose of the sentence on lines 628-629? You mean this is work still to be done?

Author Response

Comments and Suggestions for Authors

Our responses are in italics

This paper describes in detail the framework of the model / computer program AgInform. It divides the land area in 7 land management units. Grazing of animals is part of it. Modelling of grazing is quite a challenge. Therefore this model was quite a challenge to construct, I suppose. That is a positive asset to this paper.

Some questions/remarks:

The framework of the model is extensively described in the M&M section. The result section is much more compact. In this context, is the article balanced?

After giving the suggestion by the reviewer serious thought we have decided to leave the model description in the M&M section, but in doing so have taken up the suggestion of the reviewer below and have grouped animal types, using subscripts. This has shortened the M&M section and provides the balance the reviewer is asking for.

Testing farm and case study farm and base and fecund farm are used in different parts of paper without clear introduction, I believe. This is confusing to me.

We have gone through the manuscript and hopefully brought more clarity by limiting descriptions to farm level case (Base Farm) and Fecund farm

The grouping of animal types, using subscripts is a very good suggestion by the reviewer which we have taken on board and have changed the manuscript accordingly. We have left the description of the model in the M&M section

Equal numbers of adult breeding stock at the start and end of year are also required to ensure steady state. The steady state is also a proxy for the farm system that maximizes profit within defined boundaries, where forage availability is not eroded, or animal numbers and liveweights compromised.

Also: How to imagine that the "standing herbage mass at the end of year must equal that at the start of the year............."? (lines 140-142).

Have added the following to the text to clarify. Line 155. "The amount of feed on hand at the 31^st Decembers must equal the amount of standing feed available on the 1^st of January"

The outputs from AgInform are the "steady state livestock policies" (page 16, line 513) ........... I am not sure I understand.

To clarify have addressed by changing the text Now line 447 reads “The outputs from AgInform® are the livestock types, classes and numbers that”

Supplementary costs are the costs associated with "making and feeding out supplementary hay and silage feed...". I am not sure what is meant with feeding out

We have removed the word “out” it is very much a local terminology that is not required

Supplementary feed transferred to other land units seems to be a different action.

Yes it is another action and so the cost of making and feeding out the hay or silage is assigned to that LMU See equation 6

AgInform®. The pasture can either contribute to the existing feed pool or can be added to the supplementary feed pool as either hay or silage line 129 if it is feasible to harvest supplementary feed on that LMU.

The model can then choose to use that supplementary feed when required. The feed pool supports livestock (sheep, cattle, or deer).

We have moved the testing of the farm level case (Base farm) from the M&M section to results. This will help with the flow.

We have also added a paragraph at the start of the results section to help with the flow of the paper

Table 1 is now limited to a list of inputs required by the model to align with Table 2 which lists the model outputs.

The data for the farm level case (Base farm) has been moved to Appendix B.

Above does not make sense to me. Actually it would be good to do model testing with a variety of farms. Please, explain the rational behind this choice.

Hopefully we have clarified the confusion by the paragraph added at the start of the results section

Figure 2: utilization; please explain what utilization means in this graphic.

There is a definition in the paper now line 350 (utilisation of the feed (i.e. the proportion of DM that disappears which is consumed by the animals). Have added that to the figure description,

Figure 3 needs more explanation in my opinion.

We have added to the description

We have clarified this by describing in the first paragraph of the results section.

We have shifted the Overseer data in Table 3 (line 444) to a new Table 5 (Line 560)

The integral application of AgInform and OVERSEER does not lead to optimization of environmental impact, right?

Agreed and have changed the text accordingly

Just explain in the paper.

Also: What is the purpose of the sentence on lines 628-629? You mean this is work still to be done?

We have clarified in the text

Round 2

Reviewer 2 Report

I think the authors have carefully responded to the comments. I see improvement, especially by (a bit of) reorganizing of the paper.

The added paragraph at the beginning of the results section was a must, in my opinion.