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Dossier

Emissions – more than just an unpleasant odour

Von Jochen Hahne und Marcus Clauß | 22.06.2022


AT Institute of Agricultural Technology

When incorrectly operated stables or improperly expelled manure literally “stink to high heaven”, residents are often alarmed. But odour nuisance is just one part of the problem.

Animal husbandry is the most important source of ammonia emissions in Germany. Ammonia (NH3) is a gas that is formed from urea, which is excreted via the urine and feces of animals. The emissions occur along the entire manure chain: from the stables, the slurry and manure storage areas as well as in fields and meadows where manure is applied.

Animal husbandry is also the largest emitter of the greenhouse gas methane (CH4) in Germany. The emissions are primarily due to the digestion of ruminants. Storage of animal excrement under oxygen-free conditions, for example in a slurry pit, promotes methane emissions. By deploying slurry and manure in biogas plants, the methane can be used, specifically in terms of climate protection, for power generation.

A topic that is of increasing interest in public discussions is the emission of bioaerosols. In particular, airborne microorganisms such as bacteria or moulds from stables are suspected to negatively affect human health. Here science is called for, because the potential risk for humans has been insufficiently researched so far.

Figures & Facts

Emissions of ammonia from agriculture

Emissions of ammonia lead, via input of nitrogen, to eutrophication of close-to-nature ecosystems. Through further transformation processes they contribute to soil acidification, groundwater contamination and indirect emission of nitrous oxide. Moreover, the emission of ammonia causes the generation of particulate matter and thus jeopardises human health.

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Emissions of ammonia from agriculture

Greenhouse gas emissions from agriculture

In 2020, German agriculture was responsible for the emission of about 56.1 million tons of carbon dioxide equivalents. This corresponds to 7.7 % of the overall emissions in Germany. Main sources are emissions of methane from animal husbandry and nitrous oxide from agricultural soils.

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Greenhouse gas emissions from agriculture

Expertise

Bioaerosols : Tiny particles, big effect

In addition to gaseous emissions livestock also releases airborne microorganisms such as bacteria or molds. These bioaerosols are suspected to affect the health of residents in the immediate vicinity of stables. The evidence is still insufficient, but many questions remain unanswered.

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Bioaerosols : Tiny particles, big effect

The situation in pig keeping

Odorants and particulate matter can be removed efficiently by bio filters. Problematic, however, is the separation of ammonia. In the meantime, many pig farmers have invested in exhaust air treatment systems.

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The situation in pig keeping

The situation in poultry keeping

Exhaust air treatment in poultry keeping is characterized by high air volume flows and high particulate matter loads. Particulate matter results in problems in air scrubbing Which is why a selective upstream dust removal is pursued. Due to the high costs, only very few poultry farms have exhaust air purification systems.

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The situation in poultry keeping

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