Accumulation of Selenium in Crops Grown on Sludge‐treated Soil

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Abstract
Uptake by barley (Hordeum vulgare L. var. Briggs), Swiss chard (Beta vulgaris L. var. Fordhook), and radish (Raphanus sativas L. var. Cherry Belle) of Se from composted Los Angeles County sewage sludge applied to land was studied in a long‐term field study. Sludge was applied at 0, 22.5, 45, 90, and 180 Mg/ha per year for 8 to 10 yr and the data reported here are for the last year of the study. Total surface (0–15 cm) soil Se increased with the highest rate of sludge addition from <0.1 mg/kg in the control soil to 1.2 mg/kg. Only 13 to 25% of the sludge‐applied Se could be accounted for in the 0‐ to 15‐cm depth of incorporation and there was no measurable Se (<0.1 mg/kg) in the subsoil to 150 cm. There was little or no measurable uptake of Se by barley leaf and grain at the level of detection (0.05 mg/kg) of this study, and there were also no significant increases in chard or radish Se concentrations with sludge addition. Selenium concentrations in chard (0.05–0.11 mg/kg) were severalfold lower than those in radish (0.17–0.26 mg/kg).