Geels, C., Bak, J., Callesen, T., Frohn, L.M., Frydendall, J., Gyldenkærne, S., Hansen, A.G., Hutchings, N., Jacobsen, A.S., Pedersen, P., Schneekloth, M., Winther, S., Hertel, O. & Moseholm, L. 2006. NERI Technical report No. 568. 89 pp.

 

Summary

 

This report describes the technical status of the currently available tools applied for assessment of environmental impact in relation to ammonia emission from livestock farms and approvals according to national legislation regarding protection of the environment. These tools are the ammonia manual and a spreadsheet-tool developed for the Danish counties by a working group with the purpose of undertaking the calculations according to the ammonia manual. Furthermore a new and more user-friendly and robust method is suggested. The municipalities can benefit from using the suggested method in their future administration.

 

Implementation of an internet based operational tool instead of the excel spreadsheet available today, has several important advantages in relation to: user-friendliness, robustness, the possibility of applying more qualified calculation methods, and the possibility for continuous technical updating and quality control.

 

Future use of the present tool

The present tool has several errors and drawbacks, but the spreadsheet developed by the counties is working and is capable of describing the relation between livestock farms, the resulting emissions and the subsequent depositions of nitrogen to the surroundings. In the most simple form, the excel spreadsheet can, like today, be available on the internet with references to relevant databases and further documentation.

 

However, as a minimum a more detailed documentation of the different sheets and quality control of the calculations should be carried out. The included curves representing the atmospheric dispersion and deposition should also reflect results based on new and updated calculations with the OML-DEP model. Also the present instruction made by the counties should be updated.

 

Necessary update of the present tool

The existing tools are complicated and not easy to apply. Furthermore, application of the tools can in some cases require a number of subjective interpretations that might fall out differently depending on the expertise and experience of the administrative workers. In the future there is therefore an even higher risk of inconsistencies in the handling of the cases from municipality to municipality and maybe even from user to user.

 

The administrative workers in the municipalities have therefore sketched a list of what they would like to be included in a new tool.  The present tool does not fully fulfil these wishes.

 

Finally, there is a strong need for an update and validation of the tools based on the current knowledge. This is especially the case for the calculation of the emissions, including a seasonal variability, the curves representing dispersion and deposition on the local scale as well as a better estimation of the critical loads. Likewise, there is a need for continuous updating of the model calculated background deposition of nitrate.

 

Suggestion for a new model tool

A new and updated tool including three steps is suggested: 1) a simple screening of all livestock farms < 75 DE, 2) a standard method for all livestock farms > 75 DE based on standard curves and 3) a method based on detailed model calculations, in cases where the municipalities or the applicant might find it necessary due to special local conditions.

 

The new method will be based on a new set of standard curves reflecting uncertainties related to the model calculations and it will include a more appropriate adjustment of the background in the case of several sources in the area, Furthermore it will include effects of seasonal emission variations, changes in surface roughness etc.

 

The method can be set up to be available through the internet including references to relevant databases for e.g. emission, meteorology, maps of vegetation cover and background levels of nitrate based on information on the location of the individual agricultural buildings (stable and storages) and fields. Such an internet based system can be updated concurrently with the development of new knowledge without changing the user interface.

 

A new manual

During the project, the working group has not been able to formulate the text for a new manual. Before this can be done, several specific technical activities and selections need to be carried out, for example appointment of cut off criteria for depositions and critical distances to relevant nature.

 

Based on the present ammonia manual and the material written by the counties as well as new knowledge, a first version of the new manual can be prepared by December 1, 2006, assuming that the work is initiated early in 2006. The manual should then be further developed and updated in 2007.

 

Regardless of the decided degree of update of the methods, the development of a new internet based user interface will be appropriate in order to prevent the administrative workers from being introduced to two different tools within few years: first the present spreadsheet and thereafter a new and updated tool. A common user interface could in the first period (2007) be linked to the spreadsheet and later to the new tool without changing the interface.

 

The report includes several appendixes where the applied methods are documented and described.

 

Full report i pdf-format (1,501 kB).