Remediation of Lead Toxicity Using Phosphorus in Lead-Contaminated Agricultural Soils

Phosphorus (P) plays dual role in providing plant nutrition while suppressing lead (Pb) toxicity in soil-plant system. Remediation of lead toxicity with soluble P is a promising low-cost soil rehabilitation technology. An incubation experiment is conducted for assessing the bioavailability of Pb and P under simultaneous application in Pb-laden soils. The treatments consist of four Pb levels, 0, 5, 10 and 20 mg kg(-1) soil, and four P levels, 0, 10, 20 and 30 mg kg(-1) soil, with five periods of incubation (0, 7, 15, 30 and 60 days) arranged in a 4 x 4 x 5 factorial design. The important physical, physicochemical and chemical characteristics of soil samples are analyzed. Bioavailable P and Pb contents of the soil samples after incubation with Pb and/or P are determined. The results indicate that PbxP interactions significantly decrease bioavailable soil-Pb concentrations by 38.9-43.9%. Likewise, interactions of Pbxday and Pxday significantly reduce soil-Pb concentrations by 33.1-35.1 and 31.8-33.6% at different levels of Pb and P spiking, respectively. A ready reckoner is developed using the antagonism manifestation of Pb and P in soil, which suggests the administration of P doses with respect to Pb-loading and time elapsed to rejuvenate Pb-contaminated soils for healthy crop production.