In order to investigate the effects of biochar on the adsorption and desorption characteristics of cadmium (Cd) elements

the adsorption kinetics

isothermal adsorption and desorption of Cd

2+

in red soil paddy soils amended with biochar were studied by a primary equilibrium method. The results showed that after applying biochar of CK (0 t/hm

2

)

A10 (10 t/hm

2

)

A20 (20 t/hm

2

)

A30 (30 t/hm

2

) and A40 (40 t/hm

2

)

the adsorption of Cd

2+

in red paddy

soil was dominated by chemical adsorption and heterogeneous multi-surface adsorption. The maximum contents of adsorption and desorption of each treatment were between 2 933~3 346 mg/kg and 171~192 mg/kg

respectively. The biochar enhanced the adsorption and fixation capacity for Cd

2+

in red paddy soil and improved the buffer capacity for Cd

2+

. The improvement of adsorption and desorption capacity in red paddy soil amended with biochar was shown as follows:A30

>

A40

>

A20

>

A10. High addition of biochar could saturate the soil adsorption point. Therefore

the adsorption capacity of biochar was relatively low. In conclusion

addition of 30 t/hm

2

biochar was the most reasonable measure.