Uptake by Barley of Water Table‐ or Surface‐applied Cadmium

Abstract

AbstractSolutions of Cd were placed for 66 days at the bottom or top of columns (42‐cm long by 15‐cm diam) containing fine sandy loam soil, half of which were planted with barley (Hordeum vulgare L. ‘Liberty’) and half of which were bare, to determine rate of movement upward or downward of Cd. Three solutions with Cd, as CdSO4, were used: distilled water with 0.1 µg/ml Cd; distilled water with 10 µg/ml Cd; secondary effluent with 10 µg/ml Cd. An average of 200 ml/day was added to the top or bottom of columns with plants; there was no drainage water with top additions. An average of 100 or 50 ml/day was added to the top or bottom, respectively, of columns without plants. Drainage water, which collected at the bottom of columns without plants and watered from the top, was analyzed daily for Cd. Plants and soil were analyzed weekly for Cd concentration.In less than 7 days, Cd applied at the surface moved to the bottom and Cd applied at the bottom moved to the surface. At harvest, plants treated with Cd at the bottom contained up to three times more Cd than plants treated with Cd at the top because roots of plants with Cd at the bottom contained higher concentrations of Cd than roots of plants in columns with Cd at the top. Columns without roots had higher concentrations of extractable Cd than columns with roots. Concentrations of Cd in leachate from columns receiving 10 µg Cd/ml effluent were about two times higher than concentrations of Cd in leachate from columns receiving 10 µg Cd/ml water. About the same amounts of Cd were leached out of columns receiving 0.1 µg Cd/ml water or 10 µg Cd/ml water. The results showed that barley roots more readily absorbed Cd placed in a shallow water table than Cd placed in the soil surface.