Assessment of Odour and Ammonia Impacts for a Novel Fattening Piggery Tailored for Animal Welfare and Low Emission Rates

Round 1

Reviewer 1 Report

General
The topic is very relevant. The presented low emission pig housing system is really a promising approach and should be described in more detail.
A scientific article should integrate a scientific structure with aim(s), method, results (supplemented with descriptive parameters) and statistics (variation between days, panellists, sampling points). Results and discussion should be separated.
The aim of the paper was not stated (neither in the abstract nor in the introduction).

The VERA Test Protocol has to be considered for Livestock Housing and Management Systems if emission factors shall be derived https://www.vera-verification.eu/app/uploads/sites/9/2019/05/VERA_Testprotocol_Housing_v3_2018.pdf

Then, a detailed test design, sampling and measurement strategy should be integrated, e.g. fixed case-control approach, case-control in time or a multi-farm approach.

The comparison with the emission factors of VDI 3894-1 or the Styria standard factor as a reference goes too far from the measured conditions and results (without modelling).

 I suggest splitting the article into several articles, for example:
a) Development and description of the emission-reducing husbandry system, taking into account animal welfare,
b) Method and results of ammonia concentration,
c) Method and results of odour recognition by the panellists.
(A comment to dispersion modelling: This is questionable for odour, due to unknown changes between source and impact.)

Details:

 

Chapter 1: No literature with regard to odour is integrated.

Chapter 2: The description of the fattening piggery should give more information about the layout, the housing elements, surface per animal and zone, total number of animals, live weight on the investigated days, feed intake, amount of straw, frequency of scraping and so on. Additionally the equipment for the different emission reduction measures should be presented with the principles and execution details.

Chapter 3: Some relevant aspects are missing:
a) method of sampling ammonia,
b) method of odour investigation, training of panellists.

Line 159 and 172: Has the sonic anemometer been affected by the building or by the forest? What are the consequences of this?

Figure 3: The observed wind direction and wind speed is shown during the whole period from Jan to July 2022. An additional Figure would be necessary to show the wind direction and wind speed exactly during the field inspections.

Chapter 4.1:
The results of odour–hour frequencies could be depicted by panellist, by distance to the pig house, by wind velocity, by the prevailing plume, by colder/warmer season to obtain more detailed information.

Line 216: Reference to chapter 2 not consistent.

Line 230-236: Within this research, the combined odour emission rate cannot be traced back to individual quantitative factors, because the test design does not allow this. 

Table 2: The comparison with emission factors in literature does not seem appropriate.

Chapter 4.2:
A Figure with wind direction and wind speed during the period from Jan to Nov 2021 is missing.

Table 3: The comparison with emission factors in literature does not seem appropriate.

Chapter 5:
A reduction of ammonia emissions can be stated (without a precise percentage), but not from odour, because of changes between odour source and impact, the modelling is not firm.

See also the comment with the information of VERA and the missing reference (General).

The natural ventilation and the perpendicular to the pig house dominating wind direction may be relevant for odour perception in the field (but this is only one situation of the approaching flow). A reduction of odour at the source may not be corresponding with odour impact, because there are many aspects combined.

So, I propose to make a major revision. The article or the articles should be significantly improved to demonstrate this relevant topic.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The ms describes the measurement of odour and ammonia emissions from a new barn type using Lagrangian modelling. This is relevant as there is a lack of good emission data and new low-emission barn types are needed.

The ms focuses far too much on the existing emission factors and not enough on the description of the methods used, in particular on measurement of ammonia. Only one barn has been measured. However, the location and surrounding of that barn is fine.The feed and manure is not described. Even though ammonia is reported in very concentrations (ppbv), there is no description of the sampling and analytical method. What are the LoD, the recovery, calibration etc.

For the modelling part, I miss information on the number sampled, the filtering et cetera for ammonia.

It is fine with comparison with the current emission factors, but this dominate the whole ms.

I suggest that the authors concentrate on describing the barn, feed, manure, analytical methodology and then only do a comparison in the discussion section.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

General comment.
I have found the paper very interesting and well designed. The problem is well indroduced and the general structure is clear and well defined.
Also conclusion are also well described and coherent with the content of the paper. There are however some specific technical aspects which are to be better explained and sometimes appears not so evident to the reader,
in this respect some modification are requested/suggested, as explained in the following comments.

Specific comments and minor corrections along the text.

Page 2, Lines 49-52:
The statement should probably be rephares after the parenthesis

Page 3, line 99:
It is unclear how the odour hours are simulated. It seems clear that the model enits odour units, but what is the limit, for the model to define
if an hour is an "odour hour" or not? Is there any limit for this? The authors should better explain this point.

Page 4, comment on Fig. 2:
Have the spatial distribution of the monitoring sites something to do with the local wind distribution? If yes, it shound be written in the text

Page 5, there is a detailed description of the meteorological data collected by a local sonic anemometer. Are these data used as an input to the meteolological model? If yes, the author should spend some words on
how this is done, for example is the "prognostic model" really used in a prognostic way? Which boundary conditions are used?

Page 8, Ammonia emissions, lines 240-248
Which averaging time is considered for the concentrations cited in the text? I imagine they are monthly means but it is probably better to write it.

Page 8, Ammonia emission, line 253
The authors should better clarify how Equation 2 is used to estimate the montly background. Is that formula used to estimate the source srenght
or is it used only to calculate the background? And in this case in which way?

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The MS has been revised and improved. It was added that ammonia was measured by passive samplers. The description of the results should be more detailed.

The description of the simulation of ammonia emission is still insufficient. Criteria as necessary turbulence (wind speed), corrected for changing wind direction are not described. The ammonia emission is a crucial part of the MS and that part should be described in details.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The author answered to all the requests. Some critical aspects present in the first version have been clarified, making the paper clearer for the reader. The corrected version of the paper is therefore substantially improved and, in my opinion, ready to be published.

Author Response

Please see the attachment.

Author Response File: Author Response.docx