Iron addition to soil specifically stabilized lignin

Steven J. Hall; Whendee L. Silver; Vitaliy I. Timokhin; Kenneth E. Hammel

doi:10.1016/j.soilbio.2016.04.010

Treesearch

Iron addition to soil specifically stabilized lignin

Formally Refereed

Authors:

Steven J. Hall, Whendee L. Silver, Vitaliy I. Timokhin, Kenneth E. Hammel

Year:

2016

Type:

Scientific Journal

Station:

Forest Products Laboratory

DOI:

https://doi.org/10.1016/j.soilbio.2016.04.010

Source:

Soil Biology and Biochemistry

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Abstract

The 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.

Keywords

Carbon stabilization, Iron, Lignin, Recalcitrance, Redox, Soil organic matter

Citation

Hall, 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.