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Greenhouse Gas Microbiology in Wet and Dry Straw Crust Covering Pig Slurry
Author(s) -
Hansen Rikke R.,
Nielsen Daniel Aa.,
Schramm Andreas,
Nielsen Lars P.,
Revsbech Niels P.,
Hansen Martin N.
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0336
Subject(s) - crust , methane , slurry , environmental chemistry , chemistry , nitrogen , ammonia , nitrous oxide , oxidizing agent , environmental science , environmental engineering , geology , geochemistry , organic chemistry
Liquid manure (slurry) storages are sources of gases such as ammonia (NH 3 ) and methane (CH 4 ). Danish slurry storages are required to be covered to reduce NH 3 emissions and often a floating crust of straw is applied. This study investigated whether physical properties of the crust or crust microbiology had an effect on the emission of the potent greenhouse gases CH 4 and nitrous oxide (N 2 O) when crust moisture was manipulated (“dry”, “moderate”, and “wet”). The dry crust had the deepest oxygen penetration (45 mm as compared to 20 mm in the wet treatment) as measured with microsensors, the highest amounts of nitrogen oxides (NO 2 − and NO 3 − ) (up to 36 μmol g −1 wet weight) and the highest emissions of N 2 O and CH 4 Fluorescent in situ hybridization and gene‐specific polymerase chain reaction (PCR) were used to detect occurrence of bacterial groups. Ammonia‐oxidizing bacteria (AOB) were abundant in all three crust types, whereas nitrite‐oxidizing bacteria (NOB) were undetectable and methane‐oxidizing bacteria (MOB) were only sparsely present in the wet treatment. A change to anoxia did not affect the CH 4 emission indicating the virtual absence of aerobic methane oxidation in the investigated 2‐mo old crusts. However, an increase in N 2 O emission was observed in all crusted treatments exposed to anoxia, and this was probably a result of denitrification based on NO x − that had accumulated in the crust during oxic conditions. To reduce overall greenhouse gas emissions, floating crust should be managed to optimize conditions for methanotrophs.