Methane Oxidation in Slurry Storage Surface Crusts
- Søren O. Petersen *a,
- Barbara Amonb and
- Andreas Gattingerc
- a Danish Institute of Agricultural Sciences, P.O. Box 50, DK-8830 Tjele, Denmark
b Institute of Agricultural, Environmental and Energy Engineering, University of Agricultural Sciences, A-1180 Vienna, Austria
c GSF-Research Center for Environment and Health GmbH, Institute of Soil Ecology, D-85764 Neuherberg, Germany
Livestock manure is a significant source of atmospheric methane (CH4), especially during liquid storage. In liquid manure (slurry) storages a surface crust may form naturally, or an artificial surface crust can be established. We investigated whether there is a potential for CH4 oxidation in this environment. Surface crust materials were sampled from experimental storages with cattle slurry (with natural crust) or anaerobically digested cattle slurry (with straw layer) that had been stored with or without a wooden cover. Extracts of surface crust material were incubated with 5.6% CH4 in the headspace, and methanotrophic activity was demonstrated in all four treatments following a 4- to 10-d lag phase. Subsequent incubation of field-moist surface crust material with 350 μL L−1 CH4 also showed CH4 oxidation, indicating a potential for CH4 removal under practical storage conditions. There was no CH4 oxidation activity during incubation of autoclaved samples. Methane oxidation rates were 0.1 to 0.5 mg kg−1 organic matter (OM) h−1, which is comparable with the activity in wetlands and rice paddies. Partial drying increased CH4 oxidation to 0.2 to 1.4 mg kg−1 OM h−1, probably as a result of improved diffusivity within the surface crust. Rewetting reversed the stimulation of methanotrophic activity in some treatments, but not in others, possibly due to a decline in CH4 production in anaerobic volumes, or to growth of methanotrophs during incubation. This study presents direct evidence for methanotrophic activity in slurry storages. Measures to ensure crust formation with or without a solid cover appear to be a cost-effective greenhouse gas mitigation option.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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