Emission of greenhouse gases from manure Sven G. Sommer Dept. of Agricultural Engineering Danish Institute of Agricultural Sciences

Change in temperature

GHG emission inventories

Livestock manure is a source of greenhouse gases Nitrous oxide (N 2 O) produced during nitrification and denitrification of nitrogen in manure Methane (CH 4 ) produced during anaerobic break down of organic matter in manure

Global warming potential of N 2 O and CH 4 N 2 O:310 times higher climate warming potential than that of carbon dioxide CH 4: 21 times higher potential than that of carbon dioxide

Methane production Biomasse: Animal manure Organic waste Hydrolysis Dissolved substrate Acidogenesis H 2 +CO 2 Acetognesis VFA>C2 CH 4 +H 2 O+ CO 2 CH 3 -COOH Methanogenesis Hydrolysis is process rate controlling VFA transformation reduced due to: High NH 3 Sudden changes in environment Feedback: High VFA conc. reduces hydrolysis

Transformation of N in animal manure

Methane emission

Slurry - methane Sommer et al. 2005;P. Kai, P.J. Dahl & H.D. Poulsen, 2005.

Nitrous oxide

Housing Deep litter cattle - little N 2 O emission (Henriksen et al. 2000)

Temperature gradients in manure heaps High temperatures near heap surface Low temperatures in the centre of the heap Anaerobic part: CH 4 Intermediate zone Aerobic zone: N 2 O

Covering a heap of manure, oxygen UncoveredCovered Centre Ambient 10 cm below surface

Solid manure store – methane (Hansen MN et al. 2005) Uncovered Covered Un-covered heap Covered heap 10 cm below surface Centre

Solid manure store – nitrous oxide (Hansen MN et al. 2005) Uncovered Covered 10 cm below surface Centre Un-covered heap Covered heap

Stored slurry nitrous oxide LECA Straw Surface crust

Conclusion Inhouse manure stores: –Methane production, –No nitrous oxide emission (except from pig deep litter ?) Outside stores: –Methane from slurry and solid manure, –Nitrous oxide from solid manure and traces from crust on slurry