Abstract: Experimental results showed that the degradation rate of chlopyrifos was very slow in sterilized soils (S soil), and very quick in soils, which were previously treated with chlopyrifos (D soil). However, the degradation rate was between the rates mentioned above, in unsteritized and untreated soils (CK soil) after 30 days treated with chlopyrifos. This phenomenon indicated that microorganisms played an important role in chlopyrifos degradation, and using chlopyrifos could induce chlopyrifos degrading microorganisms. In the soils which were treated with chlopyrifos for 60 days later, the degradation rates of 50 mg穔g^-1 chlopyrifos in different soils were the same as that in the soils treated with chlopyrifos 30 days later. The degradation rate of chlopyrifos in the D soil was still more rapid than that in the CK soil and s soil, but the distinction was reduced 90 days after treated. The degradation rate of chlopyrifos in the D soil was almost the same as that in the CK soil 120 days after treated. After 30 days treated with chlopyrifos, adding 0.1%, 1%, 10% D soil to the S soil, the degradation rates of chlopyrifos increased to varying degrees compared with the s soil.

Key words: Spectral indices method, Water content, Soil-adjusted water index