REVIEW AND ANALYSIS OF THE VARIABLES INFLUENCING AMMONIA EMISSIONS FROM LIVESTOCK

Abstract

Ammonia is an atmospheric pollutant that leads to the acidification and eutrophication of soil and water and contributes to the formation of secondary atmospheric particulate matter. According to the current estimates from national and local emission inventories, livestocks and soil fertilization are the main sources of this pollutant. Legislation aimed at reducing and controlling ammonia emissions intervenes on several fronts: setting limits and emission reduction targets at the national level and defining technological reference standards for certain types of livestock.

In this study, the national average emission factors for ammonia, referred to the latest update of the national inventory of emissions into the atmosphere (IIR 2023), were compared with the results obtained from the decision support and authorization software at the farm level: BAT-tool Plus, which is widely used in the context of integrated environmental authorizations. BAT-tool Plus was used to process two emission scenarios, corresponding to a maximum (HE = high emissions) and a minimum emission (LE = low emissions) scenario. The HE scenario was obtained by always inserting high emission and low efficiency techniques, while the LE scenario was processed considering some of the best available techniques.

The compatibility of national estimates with what can be obtained at the level of the single farm was here verified. Therefore, using data obtained from global scale measurements and collected in the DATAMAN database, it was possible to investigate the consistency and alignment of national emission factors and livestock simulations, in a much wider geographical context.

The statistical analyses on measured data carried out in this study confirm the influence that various factors, such as variables related to the level of technological implementation, the chemical and physical characteristics of manure and some meteorological parameters, have on ammonia emissions from the livestock.

Regarding the housing stage, the variables that mostly affect ammonia emissions are linked to the amount of nitrogen (N) excreted by the animal and to other characteristics of the animal shelters, such as the flooring type and the ventilation system.

In reference to the storage, the presence of a cover on the slurry and the type of the cover itself are the variables that mostly affect ammonia emission rates.

Finally, broadcast is the most emissive spreading method; the action of the wind may affect ammonia emissions when the land distribution is not followed by any incorporation of manure into the soil. It would be useful in the future to investigate the concomitance and associated influence of other factors, such as the time of incorporation of manure into the soil and some chemical-physical parameters of soil.