The Passivation Effect on Cd of Mixing of Amaranthus chinense L. Straw and Phosphate Rock Powder in Cd Polluted Soil

Soil culture experiments were carried out to study the effects of the mixture of Amaranthus chinense L. straw and phosphate rock on soil pH, available phosphorus (AP), available potassium (AK) and DTPA-Cd content in Cd polluted soil. The results showed that: (1) 2% phosphate rock powder combined with 1%, 2%, 3% of Amaranthus chinense L. straw can significantly increase soil pH, AP and AK content. Compared with CK, pH was increased by 0.42~0.56, 0.53~0.70 and 0.47~0.73 units, respectively, and AP was increased by 19.03%~32.62%, 14.91%~43.63% and 18.88%~58.01%, respectively, and AK was increased by 201.46%~234.66%, 210.5%~266.56% and 184.07%~224.98%, respectively. (2) The DTPA-Cd content in soil decreased significantly after adding three different ratios of compound materials, which were 1.75%~9.01%, 2.86%~10.02% and 0.98%~8.7% lower than CK, respectively. In summary, the mixture of 1% Amaranthus chinense L. straw and 2% phosphate rock powder had the best passivation effect on Cd.