Effect of gypsum application on heavy metal content in purple soil-rice system

A plot experiment was performed to investigate the effects of desulfurized gypsum on heavy metal(Cd, Pb, Zn, Cu) accumulation in soil, speciation, rice absorption and redistribution in purple paddy soil. The results showed that after desulfurated gypsum application, the total amount of Pb in soil increased significantly by 14.00%~68.77%(P-2 desulfurized gypsum application, the total amount of Cd in soil was not significantly different from that of control. With over 4 t·hm-2 application, the total amount of Cd increased significantly by 16.28%~19.94% compared with that of control(PP-2. The contents of Cd and Pb in paddy soils increased, while the contents of Zn and Cu showed no change. The form of Cd and Pb varied to stable state. Cd, Pb, Zn, Cu contents decreased to varying degrees.