Ammonia losses from the storage and application of raw and chemo-mechanically separated slurry

The effect of combined chemical–mechanical pig slurry separation on ammonia (NH3) emissions was investigated in a field scale study. We determined the amount of volatized ammonia emitted from the solid and liquid fractions of raw pig slurry during its storage and after its broadcast to an alfalfa (Medicago sativa L.) meadow under summer and winter conditions. The solid fraction accounted for the largest NH3 losses during both storage and land application. Chemical–mechanical separation of raw pig slurry under winter conditions caused a slight (−2%) reduction in NH3 emissions during manure management (storage + broadcast application), as opposed to an emission increase of as much as 17% for separation under summer conditions. Evidence from this study suggests that environmental benefits are possible if solid and liquid fractions are managed using state-of-the-art NH3 mitigation options, such as covered manure storage and band spread slurry application.