A whole-farm assessment of the efficacy of slurry acidification in reducing ammonia emissions

Publication Type:

Journal Article


European Journal of Agronomy, Volume 28, p.148-154 (2007)




Livestock slurry in animal houses, in manure stores and applied on fields is in Denmark the most important source of ammonia (NH3) in the atmosphere. The emitted NH3 is a source of NH3 and ammonium (NH4 +) deposition, which causes eutrophication of N-deficient ecosystems and may form NH4 +-based particles in the air, which are a risk to health. This study examines the reductions in NH3 emissions from pig houses, manure stores and manure applied in the field achieved by acidifying the slurry in-house. Sulphuric acid was used to acidify pig slurry to pH < 6 and the system was constructed is such a way as to prevent foaming in the animal house as well as during storage. Acidification of the pig slurry reduced the NH3 emission from pig houses by 70% compared with standard techniques. Acidification reduced NH3 emission from stored slurry to less than 10% of the emission from untreated slurry, and the NH3 emission from applied slurry was reduced by 67%. The mineral fertilizer equivalent (MFE) of acidified slurry was 43% higher compared with the MFE of untreated slurry when applied to the soil. The odour emission from the slurry was not affected significantly by the treatment. The slurry acidification system is approved Best Available Technology (BAT) in Denmark.