Nitrogen losses during the storage of liquid livestock manures

Nitrogen losses during the storage of liquid livestock manures were measured in short- and long-term model experiments (35–68/191–200 days) with cattle and pig slurries. The true nitrogen losses were strongly correlated with the storage time. They were also often higher than they were previously thought to be, even without aeration. Calculated on the ash content they ranged between 1·4 and 20·5% of the total nitrogen content after 35 days, and between 17·1 and 53·6% after 180 days. The differences did not depend on the species of animal, but on the origin of the slurries. Furthermore, they seemed to depend on the pH-value. Other alternating effects between the N-losses (ammonia volatilization) and any other parameter (e.g. mineralization rate) could not be derived from this investigation.