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Title: CHARACTERIZING LIGNIN CONTENT OF SOILS UNDER DIFFERENT MANAGEMENT BY USE OF ANALYTICAL PYROLYSIS

Author
item McCarty, Gregory
item Reeves Iii, James

Submitted to: USDA Symposium on Natural Resource Management to Offset Greenhouse Gas Emissions
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Lignin is an important procurer for stabilized soil C in ecosystems that are thought to have high potential for sequestering C which can decrease global warming by reducing atmospheric CO2. Some important soil carbon process models include plant residue lignin as a significant parameter in predicting C sequestration in soil. Assessing variations in the production and fate of lignin in ecosystems provides valuable information in determining differences in ecosystem ability to sequester and store C in soil. We studied the ability of pyrolysis/gas chromatography/mass spectroscopy to detect well characterized signature products from lignin pyrolysis. Analyses were performed on an equivalent C basis to provide direct assessment of the compositional differences in soil organic matter independent of differences in total C content. We found that pyrograms from certain ecosystems contain highly reproducible "fingerprints" for lignin that are highly reproducible and amenable for quantifying content. Soils under no-tillage management contained strong signatures for lignin which were absent in those under plow-tillage. Likewise, soils under long-term grass vegetation contained the strong lignin signals which were absent in paired sites under tillage. The literature suggests that soils under grass vegetation and no-tillage management have strong capacity to sequester C and that lignin is an important precursor for stabilized soil C. Our work indicates that soil lignin analysis is directly relevant to the capacity of ecosystems to sequester C. Analytical pyrolysis is also well suited for plant residue analysis and can provide important insight to the processes involved in humification and fate of lignin in agricultural ecosystems.