Slurry additives reduce ammonia by 75%

Chemical additives can reduce ammonia emissions from livestock housing by over 75%, a study by researchers at the Agri Food and Biosciences Institute (AFBI) has found.

Ammonia from slurry on concrete surfaces in farm buildings is estimated to be responsible for one-third of total ammonia emissions in UK agriculture.

The AFBI study involved applying a mixture of dairy cow faeces and urine to 1m2 concrete surfaces at a depth of 2mm to replicate the thin layer of slurry that is left after a floor has been scraped.

Researchers tested 10 different chemical products by applying them to the slurry-coated concrete surfaces and measuring subsequent ammonia emissions in an airtight chamber.

The study, published in Biosystems Engineering, found that four of the additives resulted in a significant difference in ammonia emissions when compared to a control test that received no chemical treatment.

Reductions

An acidifier with the product name Alum recorded the sharpest decline, with emissions down 76%. Two other acidifiers saw reductions of 69% and 41%, while a disinfectant product led to a 59% drop in ammonia emissions.

“Experimental data suggests that targeting a slurry pH of 6 at the housing floor stage can significantly reduce NH3 (ammonia) emissions from fresh excreta,” the scientific paper reads.

The AFBI researchers state that acidified slurry should pose no health risk to cattle or farm staff, although they acknowledge that acidifiers could affect soil pH when treated slurry is applied to land.

The scientists recommend that future research is conducted in actual livestock housing where the depth of slurry on concrete, as well as temperature and wind speed, will vary significantly.

Research

The paper states that further research is also needed on ammonia emissions from chemically treated slurry at both the storage and land spreading stages.

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