ABSTRACT
Physically uncomplexed organic matter is composed of particles of organic matter (OM) that
are not bound to soil mineral particles and can be isolated from soil by density (using heavy
liquids) or size (using sieving) fractionation. It is separated from soil on the premise that the
association of organic matter with primary soil (mineral) particles alters its function,
turnover, and dynamics in the soil environment. Uncomplexed organic matter has been
isolated to study the form and function of soil organic constituents and to assess the impacts
of land use, management, and vegetation type on carbon (C) and nitrogen (N) turnover and
storage (Gregorich and Janzen 1996; Gregorich et al. 2006, and references therein). It has
been separated and evaluated in studies pertaining to nutrient availability (Campbell et al.
2001), decomposition of plant residues (Magid and Kjærgaard 2001), physical protection of
soil organic matter (Beare et al. 1994), and aggregation processes (Golchin et al. 1994).
