Uptake of Cadmium and Zinc from Sludge by Barley Grown Under Four Different Sludge Irrigation Regimes1
- M. B. Kirkham2
Barley (Hordeum vulgare L. ‘Liberty’) was irrigated at four different rates with liquid sewage sludge containing three concentrations of Cd to determine an optimum irrigation frequency that would minimize Cd and Zn movement from the sludge crust into the soil profile. Concentrations of 65, 79, and 205 µg/g Cd in anaerobically digested sludge were used, attained by adding 14 or 140 µg Cd as CdSO4 to sludge containing 65 µg/g Cd. Zinc was 4,350 µg/g in all sludges. Barley was grown in 40 cm by 15 cm columns of soil under greenhouse conditions for 69 days. Beginning 28 to 39 days after planting, sludge was applied periodically to each column, but at four different frequencies: 50 ml daily, 200 ml every 4 days, 400 ml every 8 days, and 600 ml every 12 days. Concentrations of Cd and Zn in the roots, leaves, grain, soil, and sludge crusts were measured. Cadmium concentration in leaves was < 3 ppm and, in grain, Cd was < 0.25 ppm. The Cd concentration in the roots varied (3.3 to 16.2 ppm) with Cd concentration the sludge and increased with decreasing frequency of irrigation. Cadmium and Zn concentrations of the sludge crusts increased with increasing frequency of irrigation. Soil columns irrigated daily were continuously wet at the surface, whereas soil columns irrigated every 4, 8, or 12 days dried between irrigations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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