Chemical structure of soil organic matter and its role in aggregate formation in Haplic Chernozem under the contrasting land use variants

摘要

The different soil organic matter (SOM) pools were isolated from the surface horizons of Haplic Chernozem in contrast variants of land use: (a) free particulate OM, (b) occluded particulate OM, (c) clay-associated OM, and (d) OM of the fraction of the Residue (Res). The features of the chemical structure studied by solid-state C-13 NMR spectroscopy of these SOM pools in virgin Chernozem were used to demonstrate the changes that solid plant residues undergo during decomposition when they are incorporated into microaggregates. The extent of decomposition of organic materials in soils follows a continuum from fresh and partially decomposed organic materials in the discrete OM (Free and Occluded) to significantly/completely processed in the mineral-associated OM (Clay and Res).