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Iron addition to soil specifically stabilized ligninAuthor(s): Steven J. Hall; Whendee L. Silver; Vitaliy I. Timokhin; Kenneth E. Hammel
Source: Soil Biology and Biochemistry
Publication Series: Scientific Journal (JRNL)
Station: Forest Products Laboratory
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DescriptionThe importance of lignin as a recalcitrant constituent of soil organic matter (SOM) remains contested. Associations with iron (Fe) oxides have been proposed to specifically protect lignin from decomposition, but impacts of Fe-lignin interactions on mineralization rates remain unclear. Oxygen (O2) fluctuations characteristic of humid tropical soils drive reductive Fe dissolution and precipitation, facilitating multiple types of Fe-lignin interactions that could variably decompose or protect lignin. We tested impacts of Fe addition on 13C methoxyl-labeled lignin mineralization in soils that were exposed to static or fluctuating O2. Iron addition suppressed lignin mineralization to 21% of controls, regardless of O2 availability. However, Fe addition had no effect on soil CO2 production, implying that Fe oxides specifically protected lignin methoxyls but not bulk SOM. Iron oxide-lignin interactions represent a specific mechanism for lignin stabilization, linking SOM biochemical composition to turnover via geochemistry.
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CitationHall, Steven J.; Silver, Whendee L.; Timokhin, Vitaliy I.; Hammel, Kenneth E. 2016. Iron addition to soil specifically stabilized lignin. Soil Biology and Biochemistry. 98: 95-98.
KeywordsCarbon stabilization, Iron, Lignin, Recalcitrance, Redox, Soil organic matter
- Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils
- Organo-mineral interactions and soil carbon mineralizability with variable saturation cycle frequency
- Enrichment of lignin-derived carbon in mineral-associated soil organic matter
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