ABSTRACT
Dissolved organic matter (DOM) represents a relatively small fraction of the total organic
matter in soil (0.04%–0.2%; Zsolnay 1996). However, because of its mobility and presumed
labile nature, DOM is often perceived as the most active fraction of soil organic matter.
Research in the past 20 years has shown that DOM can play an important role in a number of
key soil processes including the transport of nutrients (Murphy et al. 2000; Michalzik et al.
2001), organic contaminants and metals in the soil profile (Herbert and Bertsch 1995;
Zsolnay 1996), replenishment of C at depth (Michalzik et al. 2001; Guggenberger and Kaiser
2003), and as a substrate for microbial activity (Burford and Bremner 1975; McGill et al.
1986; Chantigny et al. 1999; Marschner and Kalbitz 2003).
