Abstract: The invention relates to a method of reducing emission of ammonia from animal manure and a plant for the method and a used of such a plant. The method comprises adding to the manure of both an acid compound such as sulphuric acid, H2S04, and of oxygen, O2. The acid compound results in the pH value dropping to below 7.0 whereby the emission of ammonia is substantially limited. The oxygen results in a very high activity of bacteria transforming organic nitrogen compounds to in-organic compounds that are possible for plants to assimilate when manure is spread in fields. Surprisingly, it has also should to be the case that the oxygen added, and thus the enhancing of the activity of the bacteria. results in a reduction of the amount of acid compound needed to he added and results in reducing, almost eliminating, the risk of hydrogen sulphide, H2S, being formed.