Distribution of 14C-chlorsulfuron bound residues in soil organic matter

The reason why chlorsulfuron bound residues can still make an injury to rotational crops is still kept unknown. The experiment was conducted under laboratory conditions to determine the dynamics of extractable and non-extractable (bound) residues of chlorsulfuron in soil, and the distribution of chlorsulfuron bound residues in organic matter fractions. The results showed that extractable 14C-residues decreased to 25.12% of applied chlorsulfuron over an incubation period of 150 days; this in turn, the formation of bound residues increased to 47.07% of the applied. The proportions of 14C-bound residues in soil organic matter fractions increase in order of: humic acid (HA) < humin < fulvic acid (FA), most of bound residues existed in FA fraction, however, the amount of bound residues in humin fraction increase with incubation time. The fact that most of bound residues existed in water-soluble FA fraction is tentatively regarded as one of major reasons why 14C-chlorsulfuron bound residues can still make an injury to rotational crops