2002 ARCSS All-Hands Workshop

Bioavailability and Chemical Characteristics of Soil: Organic Matter in Arctic Soils

Xiaoyan Dai¹, Chien-Lu Ping², Gary J Michaelson^3
1Soil Science, University of Wisconsin-Madison, 1525 Observatory Drive, Madison, WI, 53706, USA, Phone (608)262-8295, Fax (608)265-2595, xiaoyandai@facstaff.wisc.edu
²Agriculture and Forestry Experiment Station, University of Alaska Fairbanks, 533E Fireweed Rd., Palmer, AK, 99645, USA, Phone (608)746-9462, Fax (608)746-2677, pfclp@uaa.alaska.edu
³Agriculture and Forestry Experiment Station, University of Alaska Fairbanks, 533 E Fireweed Rd., Palmer, AK, 99645, USA, Phone (907)746-9482, Fax (907)745-6268, pngjm@uaa.alaska.edu

The purpose of this study was to evaluate bioavailability and chemical characteristics of soil organic matter (SOM) in Arctic tundra soils. Laboratory incubation technique was used to determine CO₂ respired from the samples during the incubation period which was used as an index of bioavailability of the SOM. Cross polarization magic angle spinning (CPMAS) ¹³C NMR and liquid-state ¹³C NMR, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques were applied to evaluate the chemical characteristics of the SOM. Amino sugar contents in these soils were measured to indicate the microbial contribution to SOM.

The study of the bioavailability and chemical composition of SOM in soils of Arctic tundra suggests that, with global warming, these soils may have a greater potential to contribute to greenhouse gas emissions than soils from other regions, since the decomposition processes of organic matter in Arctic tundra soils respond to temperature increase more than those in other region soils; the major components in these tundra soils contributing to CO₂ evolution are polysaccharides and low-molecular-weight compounds such as neutrals and organic acids; the accumulation of organic matter in these soils is believed to be due to selective preservation although some inert humic substances are formed by condensation processes.

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