Abstract: Three passivators （calcium and magnesium oxide （NL）, biochar （B） and carbonate rock （SRC） were used to pollute farmland soil with mild （S1） and moderate （S2） cadmium （Cd） in Daye city. Field experiments were carried out to discuss the effects of different passivators on available Cd contents in soil and Cd contents of rice grains. The results showed that all the three passivations significantly reduced the contents of Cd in rice grains. Compared with the control, the contents of Cd in rice grains in field test site S1 and S2 decreased by 42.88%~67.29% and 38.25%~52.59%, respectively, and the contents of Cd in rice grains in test site S2 even reached the national food safety standard （GB2762—2017 Cd≤0.2 mg/kg）. The above three passivator treatments reduced the contents of soil available Cd in different degrees. Compared with the control group, the contents of soil available Cd in S1 and S2 were decreased by 14.09% to 17.51%, 30.38% to 37.60% and 9.22% to 10.54%, respectively. Soil available Cd contents in S1 and S2 were a certain extent correlated positively with rice grains. Soil pH of S1 was significantly increased by three passivators, and soil pH was significantly negatively correlated with Cd content in rice grain, with a negative correlation coefficient （R²） of 0.727 8. There was no significant effect of the three passivating agent treatments on rice yield, and the requirements that the crop yield reduction not exceed 10% after the application of heavy metal passivating agents in the evaluation standard of NY/T3343—2018 was reached. The effect of in-situ remediation of the three passivating agents in the mild and moderate Cd polluted paddy soil was as follow： Biocharcoal>calcium and magnesium oxide>carbonate rock.

Key words: heavy metal, cadmium, soil remediation, passivator, rice