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Soil Organic Matter in Its Native State: Unravelling the Most Complex Biomaterial on Earth
journal contribution
posted on 2016-01-19, 00:00 authored by Hussain Masoom, Denis Courtier-Murias, Hashim Farooq, Ronald Soong, Brian P. Kelleher, Chao Zhang, Werner E. Maas, Michael Fey, Rajeev Kumar, Martine Monette, Henry J. Stronks, Myrna J. Simpson, André J. SimpsonSince
the isolation of soil organic matter in 1786, tens of thousands
of publications have searched for its structure. Nuclear magnetic
resonance (NMR) spectroscopy has played a critical role in defining
soil organic matter but traditional approaches remove key information
such as the distribution of components at the soil–water interface
and conformational information. Here a novel form of NMR with capabilities
to study all physical phases termed Comprehensive Multiphase NMR,
is applied to analyze soil in its natural swollen-state. The key structural
components in soil organic matter are identified to be largely composed
of macromolecular inputs from degrading biomass. Polar lipid heads
and carbohydrates dominate the soil–water interface while lignin
and microbes are arranged in a more hydrophobic interior. Lignin domains
cannot be penetrated by aqueous solvents even at extreme pH indicating
they are the most hydrophobic environment in soil and are ideal for
sequestering hydrophobic contaminants. Here, for the first time, a
complete range of physical states of a whole soil can be studied.
This provides a more detailed understanding of soil organic matter
at the molecular level itself key to develop the most efficient soil
remediation and agricultural techniques, and better predict carbon
sequestration and climate change.