Abstract:

The Cd²⁺ adsorption-desorption in soil and the content of Cd²⁺ in roots and fruits were studied by treatment with the earthworm and effective microorganisms (EM), using the orchard brown soils and potted three-year-old apple trees (Malus domestica Borkh) as materials. The results showed that the adsorption ratio of the Cd²⁺ in the soils reduced and the desorption ratio of Cd²⁺ enhanced as the soil Cd²⁺ concentration increasing. According to the Langmuir equation, the adsorption strength and the Maximum Buffering Capacity (MBC) of the soil to Cd²⁺ decreased after the soil was treated with the earthworm and EM. The earthworm and EM reduced the adsorption ratio of the soil for Cd²⁺ and increased Cd²⁺ desorption ratio in the soil of higher Cd²⁺ concentration. And the EM had more obvious effect compared with earthworm. In the root and fruit, Cd content increased with Cd²⁺concentration increasing in the soil. The earthworm and EM significantly promoted the uptakes of Cd²⁺ in the root and the accumulation of Cd²⁺ in the fruit, and the effect was more remarkable when the Cd²⁺ concentration was higher in the soil.

Key words: apple, earthworms, microorganisms, cadmium, adsorption, desorption