HR: 1340h
AN: B23D-1589    [Abstracts]
TI: Aliphatic and aromatic plant biopolymer dynamics in soil particles isolated from sequential density fractionation
AU: Caldwell, B
EM: bruce.caldwell@oregonstate.edu
AF: Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, United States
AU: * Filley, T
EM: filley@purdue.edu
AF: Purdue University, Department of Earth and Atmospheric Sciences, West Lafayette, IN 47907, United States
AU: Sollins, P
EM: phil.solins@oregonstate.edu
AF: Oregon State University, Department of Forest Sciences, Corvallis, OR 97331, United States
AU: Lajtha, K
EM: lajthak@science.oregonstate.edu
AF: Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, United States
AU: Swanston, C
EM: cswanston@fs.fed.us
AF: USDA Forest Service, Northern Research Station, Houghton, MI 49931, United States
AU: Kleber, M
EM: Markus.Kleber@oregonstate.edu
AF: Oregon State University, Dept. Crop and Soil Science, Corvallis, OR 97331, United States
AU: Kramer, M
EM: mkramer@es.ucsc.edu
AF: UC Santa Cruz, Earth and Planetary Sciences, Albany, CA 94710, United States
AB: A recent multi-layer-based soil organic matter-mineral interaction mechanistic model to describe the nature of soil organic matter-mineral surface mechanism for soil organic matter stabilization predicts that proteinaceous and aliphatic materials establish the core of strong binding-interactions upon which other organic matter is layered. A key methodology providing data underpinning this hypothesis is sequential density fractionation where soil is partitioned into particles of increasing density with the assumption that a partial control on organic matter distribution through density series is the thickness of its layering. Four soils of varying mineralogy and texture were investigated for their biopolymer, isotopic, and mineralogical properties. Light fractions (<1.8 g/cm3), although dominanted by organic detritus, did not always contain the highest concentration of lignin and substituted fatty acids from cutin and suberin while heavier fractions, 1.8-2.6 g/cm3, exhibited a progressive decrease in concentration in plant derived biopolymers with density. Extractable lignin phenols exhibited a progressive oxidation state with density. The concentration of biopolymers roughly mirrored the C:N ratio of soil particles which dropped consistently with increasing particle density. Although, in all soils, both lignin phenols and SFA concentration generally decreased with increasing density the ratio SFA/lignin varied with density and depending upon the soil. All soils, except the oxisol, exhibited an increase in SFA with respect to lignin suggesting a selective stabilization of those material with respect to lignin. In the oxisol, which showed little variation in its hematite dominated mineralogy across density, SFA/lignin remained constant, potentially indicating a greater capacity to stabilize lignin in that system. Interestingly, the lignin oxidation state increased with density in the oxisol. Given the variation in soil character, the consistency in these trends it suggests a general phenomenon of progressive decay in plant derived material with thinness of mineral coating but an overall relative increase in aliphatic character-all consistent with the multi-layer model.
DE: 0428 Carbon cycling (4806)
DE: 0429 Climate dynamics (1620)
DE: 0466 Modeling
SC: Biogeosciences [B]
MN: 2007 Fall Meeting