Evaluation of different amendments and foliar fertilizer for immobilization of heavy metals in contaminated soils

The aim of this study was to evaluate the effectiveness of soil amendments and foliar fertilizer on Cd and Pb immobilization in contaminated soils. A field experiment was conducted in contaminated soils, wherein four amendments (sepiolite (SE), single superphosphate (SSP), triple super phosphate (TSP), calcium magnesium phosphate (CMP)) in combination with one foliar fertilizer (ZnSO4) were investigated to reduce Cd and Pb bioavailability in calcareous soils. Total Cd and Pb concentrations in wheat, soil, and amendments were determined using inductively coupled plasma mass spectrometry. Available concentrations of Cd and Pb in soils were extracted using diethylenetriamine pentaacetic acid. The results indicated that application of these amendments and foliar fertilizer significantly decreased Cd availability in soils and Cd accumulation in wheat (P < 0.05); however, the soil amendments plus Zn fertilizer did not significantly decrease Cd and Pb concentrations in wheat. Compared with the control, application of soil amendments effectively reduced the available Cd and Pb in soils by 25.6954.13% and 9.8642.14%, respectively. Accordingly, the reduction of Cd and Pb concentrations in wheat grain by the soil amendments was 20.6841.38% and 23.6855.26%, respectively. Among all the treatments, the addition of SE + SSP and SE + CMP exhibited the most efficiency in reducing Cd and Pb availability, respectively, in the soil.