Greenhouse Gas Microbiology in Wet and Dry Straw Crust Covering Pig Slurry

Amer Soc Agronomy
Publication Type:
Journal Article
Journal of Environmental Quality, 2009, 38 (3), pp. 1311 - 1319
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Liquid manure (Slurry) storages are sources of gases Such 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 oil 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 mu mol 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, all increase in N(2)O emission was observed in all crusted treatments exposed to anoxia, and this was probably a result of denitrification based oil NO(x)(-) chat had accumulated in the crust during oxic conditions. To reduce overall greenhouse gas emissions, floating crust should be managed to optimize conditions for methanotrophs.
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