Acidification of slurry in barns, stores and during application: review of Danish research, trials and experience
Acidification is recognised as a method for reduction of ammonia volatilisation of manure. During the last two to three years acidification of slurry has become common in Denmark. In 2012 it has been estimated that about 11 % of all applied slurry in Denmark was acidified, and in 2013 it is expected that up to 20 % will be acidified. In all cases sulphuric acid is used for acidification, because sulphuric acid is a very strong acid, it is relatively cheap and it contributes significantly to the content of sulphur in the slurry. Acidification can take place in the barn, in the slurry tank or during application of the slurry in the field. Recent Danish research and trials have shown a significant reduction of ammonia volatilisation after application of the slurry in the field (typically a 50 % reduction compared to untreated slurry) and a subsequent increase of yield due to a higher amount of nitrogen available to the crop.