Stabilization of Lead and Copper in a Contaminated Typic Torripsament Soil Using Humic Substances

Abstract

Potassium humate (KH) has been known as an effective metal stabilizer. Thus, contaminated soils amended with KH can be implied in horizontal expansion of forage maize to diminish the shortage in summer forage crops in Egypt. The implications of KH on the bioavailability, uptake and accumulation of lead (Pb) and copper (Cu) in maize plants grown on a contaminated soil are investigated. A pot experiment is conducted using a typic Torripsament soil naturally contaminated with Pb and Cu and treated with KH at rates of 0.0, 0.5, 1.0, and 2.0 g kg−1 soil. The KH applications decrease the diethylene triamine pentaacetic acid and water‐extractable Pb and Cu significantly and accordingly decrease their contents in maize shoots and roots compared with control treatment. The highest KH rate of 2.0 g kg−1 soil lower Pb concentration in maize shoots below the safe limit for animal feeding (5 mg kg−1). On the other hand, the KH applications could not achieve a significant reduction of bioavailable Cu and the contents in maize remained far away from the safe limit (4–15 mg kg−1). These findings prove the success of KH in restricting Pb transfer to food chain via maize uptake, while further work with higher application rates is recommended for Cu.