Effect of inorganic and organic amendments on maize biomass, heavy metals uptake and their availability in calcareous and acidic washed soil

Soil washing with chelators followed by addition of amendments has been used for remediating heavy metals contaminated soil. This study investigated the effects of amendments (Ca(OH)2, biochar and chicken manure) on maize (Zea mays L.) biomass, heavy metals uptake and heavy metals availability in mixed chelator (MC)-washed soils. The results showed that the stem–leaf and root biomass of maize increased by 102.94% and 52.34% in the acidic MC-washed soil with Ca(OH)2 and chicken manure, respectively, compared with the acidic MC-washed soil without amendments. Compared with the calcareous MC-washed soil, the addition of amendments in acidic MC-washed soil that had a significant effect on reducing metal concentration in stem–leaf of maize. Among the amendments, Ca(OH)2+Chicken manure most effectively decreased the uptakes of Cd, Pb, Cu, and Zn in stem–leaf of maize planted in the acidic MC-washed soil by 89.7%, 52.8%, 57.7%, and 60.2%, respectively, compared with the acidic MC-washed soil without amendments. The reason for this finding is that the amendments significantly decreased the transfer factor of heavy metals in maize. Therefore, the combination of Ca(OH)2 and chicken manure has the potential feasibility for the restoration of MC-washed soil, especially for the acidic MC-washed soil.