Persistence of dissolved organic matter explained by molecular changes during its passage through soil

Vanessa Nina Roth, Markus Lange*, Carsten Simon, Norbert Hertkorn, Sebastian Bucher, Timothy Goodall, Robert I. Griffiths, Perla G. Mellado-Vázquez, Liesje Mommer, Natalie J. Oram, Alexandra Weigelt, Thorsten Dittmar, Gerd Gleixner

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Citations (Scopus)

Abstract

Dissolved organic matter affects fundamental biogeochemical processes in the soil such as nutrient cycling and organic matter storage. The current paradigm is that processing of dissolved organic matter converges to recalcitrant molecules (those that resist degradation) of low molecular mass and high molecular diversity through biotic and abiotic processes. Here we demonstrate that the molecular composition and properties of dissolved organic matter continuously change during soil passage and propose that this reflects a continual shifting of its sources. Using ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, we studied the molecular changes of dissolved organic matter from the soil surface to 60 cm depth in 20 temperate grassland communities in soil type Eutric Fluvisol. Applying a semi-quantitative approach, we observed that plant-derived molecules were first broken down into molecules containing a large proportion of low-molecular-mass compounds. These low-molecular-mass compounds became less abundant during soil passage, whereas larger molecules, depleted in plant-related ligno-cellulosic structures, became more abundant. These findings indicate that the small plant-derived molecules were preferentially consumed by microorganisms and transformed into larger microbial-derived molecules. This suggests that dissolved organic matter is not intrinsically recalcitrant but instead persists in soil as a result of simultaneous consumption, transformation and formation.

Original languageEnglish
Pages (from-to)755-761
JournalNature Geoscience
Volume12
DOIs
Publication statusPublished - 5 Aug 2019

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    Roth, V. N., Lange, M., Simon, C., Hertkorn, N., Bucher, S., Goodall, T., Griffiths, R. I., Mellado-Vázquez, P. G., Mommer, L., Oram, N. J., Weigelt, A., Dittmar, T., & Gleixner, G. (2019). Persistence of dissolved organic matter explained by molecular changes during its passage through soil. Nature Geoscience, 12, 755-761. https://doi.org/10.1038/s41561-019-0417-4