Abstract: Corn was selected as the bioassay plant for the study of chlorsulfuron and metsulfuron methyl residue bioactivity in soils of typical agricultural areas of Jiangsu Province. The results of the study show that the inhibition rates of corn root growth is closely related to the application doses of the two herbicides. The ED 50 values reckoned from the dose response model show that ED 50 is negatively correlated with soil pH value and positively correlated with content of organic matter. The degradation and the residue levels of the two herbicides in soils with different conditions were studied and predicted.

Key words: chlorsulfuron, metsulfuron methyl, bioassay, soil, residue activity