Recycling organic wastes from agricultural sources by composting
is widely applied in China. Particular attention must be paid to the
changes that the material undergoes during composting to obtain
high quality compost. Various parameters, such as C/N ratios, waterextractable
organic matter (WEOM), electrical conductivity, and cation
exchange capacity, have been applied to monitor organic matter
transformation and evaluate the stability of composted materials
[1–3]. Composting is the biochemical transformation of waste organic
matter by microorganisms, whose metabolism occurs in the watersoluble
phase. Thus, a change in WEOM is a good indication of organic
transformation and compost stability [4]. In addition, WEOM can interact
with a number of inorganic and organic pollutants because of
the presence of oxygen-containing and aromatic functional groups
in its constituents, which play significant biochemical and geochemical
roles in land systems [5]. Therefore, the structural characterization
of WEOM extracted from composted materials is essential for the successful
application of composting.
To date, WEOM analysis has mainly focused on conventional parameters,
such as dissolved organic carbon (DOC) concentration and