Effects of soil structure destruction on methane production andcarbon partitioning between methanogenic pathways in tropical rain forestsoils
Controls on methanogenesis are often determined fromlaboratory incubations of soils converted to slurries. Destruction ofsoil structure during slurry conversion may disrupt syntrophicassociations, kill methanogens, and/or alter the microsite distributionof methanogenic activity, suppressing CH4 production. The effects ofslurry conversion on methanogenesis were investigated to determine ifdisruption of aggregate structure impacted methanogenesis, substrateutilization, and C partitioning between methanogenic pathways. Soils werecollected from the tropical rain forest life zone of the LuquilloExperimental Forest, Puerto Rico, and exposed to different physicaldisturbances, including flooding and physical homogenization. Slurryconversion negatively impacted methanogenesis. Rates of CH4 productiondeclined by a factor of 17 after well-aggregated soils were converted toslurries. Significantly more 13C-acetate was recovered in CO2 compared toCH4 after slurry conversion, suggesting that methanogens consumed lessacetate after slurry conversion and may have competed less effectivelywith other anaerobes for acetate. Isotopic data indicate that therelative partitioning of C between aceticlastic and hydrogenotrophicpathways wasunchanged after slurry conversion. These data suggest thatexperiments which destroy soil structure may significantly underestimatemethanogenesis and overestimate the potential for other microorganisms tocompete with methanogens for organic substrates. Current knowledge of thefactors that regulate methanogenesis in soil may be biased by thefindings of slurry-based experiments, that do not accurately representthe complex, spatially heterogeneous conditions found in well-aggregatedsoils.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Basic EnergySciences. Chemical Sciences Geochemical and Biological Sciences Division; National Aeronautics and Space Administration Fellowship NGT5-50331,National Science Foundation Grant DEB-2026547 and LTER Program; AW MellonFoundation, California Agricultural Experiment Station
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 901044
- Report Number(s):
- LBNL-60694; JGREA2; R&D Project: 468202; BnR: KC0303020; TRN: US200711%%771
- Journal Information:
- Journal of Geophysical Research, Vol. 111, Issue 1-8; Related Information: Journal Publication Date: 2006; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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