Bentonite Effects on Zinc Concentration in Plants Irrigated with Wastewater

Abstract

A greenhouse study was conducted to investigate the effect of bentonite on zinc concentrations in radish and corn irrigated with wastewater. The experimental units were plastic pots with a capacity of 5 kg and 14 kg for radish and corn, respectively. The soil was mixed with increasing doses of bentonite equivalent to 0, 30, 60 and 90 t·ha-1. The plants were irrigated with poor quality water with a concentration of 5 mg·L-1 Zn. On the occasion of the harvest of radish and corn, that is, at 30 and 60 days after the emergence, respectively, the plants were separated in aerial part and roots, dried in a forced circulation oven, weighed and ground for analysis of zinc in the plant tissues. After these analyzes, the translocation factor (TF), the translocation index (TI), the bioaccumulation in the plant (BFP) and in the root (BFR) were calculated. According to the conditions of this research, the incorporation of bentonite to the soil irrigated with water of inferior quality favored the development of radish and corn; allowed the retention of the Zn metal in the soil, reducing the concentrations of this metal in the root of the radish and in the aerial part of the corn; decreased the transfer of zinc from the soil to the plants under study.