[en] Dynamics of bound residues of ¹⁴C-chlorotoluron, distribution of the bound residues in the components of humus, and their absorption by step-crop (rice) were investigated in paddy soil and black soil under simulated aerobic and anaerobic conditions respectively. The results show that: (1) The bound residues of ¹⁴C-chlorotoluron in soil were very considerable and increasing with the incubation time. The organic substance and humidity contained in the soil affected the bound residues remarkably. The bound residues in black soil with more organic substance and clay particles were higher than those in paddy soil, and under anaerobic conditions were higher than under aerobic conditions. (2) Bound residues of ¹⁴C-chlorotoluron mainly bound with the components of soil humus, the distribution of which was in the order of humin>humic acid>fulvic acid. (3) Bound residues of ¹⁴C-chlorotoluron in soils could be absorbed by step-crop (rice) and moved to the upper part, that would cause chemical injury, chlorosis and necrosis for the leaf tip