Ammonia, dust and odour emissions

Pigs on a meadowClick to enlarge
Pig farming - a source of ammonia emissions
Source: Yü Lan /

Intensive livestock farming is a key agricultural sector in Germany, but one that unfortunately generates ammonia emissions, odours and dust that are hazardous to the environment and a nuisance to persons living in close proximity to livestock farms.

Agricultural emissions

Some 95 per cent of Germany’s ammonia emissions are attributable to farming. According to the Emissionsberichterstattung 2013 (2013 emissions report), agricultural ammonia emissions break down as follows: cattle farming, 52 per cent; pig farming, 20 per cent; poultry farming, 9 per cent; chemical-fertilizers, 15 per cent. Most pig-farming ammonia emissions occur in pigsties, whereas most livestock farming ammonia emissions are attributable to fertilizer storage and use. Ammonia emissions are released into the atmosphere, where they can react with other atmospheric components and subsequently accumulate in ecosystems. Ammonia itself and ammonium (which originates from ammonia) cause considerable terrestrial and water ecosystem pollution secondary to acidification and eutrophication (nutrient input). Soil acidification and eutrophication of natural and quasi-natural ecosystems (e.g. fens, mires, heathland and waterbodies) can bring about changes in biodiversity. Ammonia emissions can be particularly high in the environs of large livestock farms and can cause direct damage to vegetation. Ammonia and ammonium are also key precursor substances for the formation of particulate matter, which is a health hazard.

Apart from ammonia, livestock farming also causes odour and dust emissions (which can also contain organic components such as microbes) that can be hazardous to persons living near such point sources. Waste-air cleaning systems, which reduce pigsty and cattle barn emissions, are used by more than 1,000 German farms (mainly pig farms). Waste air cleaning systems combined with subfloor suction systems are currently being tested in pigsties, as this solution uses less energy and is suitable for open-air pigsties. On the other hand, further R&D is needed for poultry production.

Legal framework and reduction objectives

Under the NEC Directive (which is currently being revised) and the UN/ECE CLRTAP Gothenburg Protocol, since 2010 Germany is limited to 550,000 tons of ammonia emissions annually. This limit is currently being exceeded or is not being reliably met. Hence additional measures are needed, because an agreement on further reductions in international emissions has been concluded in the guise of the UN/ECE CLRTAP Gothenburg Protocol.

Construction or renovation of intensive livestock farming facilities exceeding a certain size is subject to a Federal Immissions Control Act (Bundesimmissionsschutzgesetz) approval procedure, for which input from the general public must also be elicited, depending on the type of livestock and number of animal places involved, as stipulated by the Vierte Verordnung zur Durchführung des Bundesimmissionsschutzgesetzes (4. BImSchV). Such facilities must be constructed and operated in accordance with the state of the art. These regulations transpose into German law the Industrial Emissions Directive (IED) 2010/75/EC, among other EU legislation.

Under the IED, it is currently being determined whether EU cattle farms should be included in the extensive immissions control approval procedure. This change is long overdue from an environmental protection standpoint, in view of the fact that cattle account for around 50 per cent of ammonia emissions and 92 per cent of methane emissions resulting from digestion fermentation. Under current German law, cattle farms with more than 600 animal places are merely subject to a simplified immission control approval procedure (pursuant to column 2 of the 4. BimSchV regulation), without input from the general public.

In addition, poultry and pig farms that fall within the scope of the Industrial Emissions Directive (IED) and that exceed a defined emission limit value such as 10,000 kg/year for ammonia, are required to register with the Pollutant Release and Transfer Register (PRTR), which is run and published by the UBA. It also transposes into German law the UN ECE Convention on Long-Range Transboundary Air Pollution. The EU has also ratified this protocol and plans to establish a European PRTR that will also contain German data.

Abatement measures

Nitrogen emission abatement measures need to be implemented at ammonia emission point sources. The following such measures are available for all production phases and processes and classes of animals:

  • Measures in cow-sheds and pigsties, and for storage: waste air cleaning; low-emission loose-housing systems for pigs and cattle; covering storage facilities; hygienic measures.
  • Low-emission livestock manure and fertilizer spreading methods (particularly for urea) ( direct livestock-manure application; low emission techniques for fertilizer and livestock manure).
  • Appropriate feeding strategies (low protein multi-phase feeding)
  • Livestock manure separation (improving transportability by separating solid and liquid components; reducing pollution by building biogas facilities in regions with a high density of livestock farms).

Moreover, good agricultural practices should be implemented, i.e. extremely low emission processes for all production phases. Optimized nitrogen emission management should take into account ecological parameters (low NH3 emissions) as well as economic and social parameters.

Further efforts should be made to optimize chemical-fertilizer nitrogen efficiency (higher plant nitrogen absorption per fertilizer application) and to minimize nitrogen surpluses (nitrogen input minus plant nitrogen uptake).