Herbicide residues in composts: pH and salinity affect the growth of bioassay plants.

Herbicide residues have raised new concern since 1999 when damage to plants appeared to result from composted turf clippings (Bary et al. 2001; Rynk 2000). Other case reports of some incidents suggested that other unknown sources of phytotoxicity were present in composts used in gardens (Nielson 2003). Several plant bioassays have been reported to test composts for herbicide residues (SPU 2002; WERL 2003; Fauci 2003; Fauci et al. 2002; KCSW 2002) and in Washington one standardized procedure has been developed (WA-DOE 2003).