Effects of Incubation and Liming on Yield and Heavy Metal Uptake by Rye from Sewage‐Sludged Soil

Abstract

Abstract Rye ( Secale cereale L., var. Balboa) was grown under controlled conditions on Evesboro sandy loam amended with digested secondary sewage sludge. Our purpose was to measure plant yield and uptake of Cd, Cu, Pb, and Zn as functions of sludge application rate (0 to 10%, dry weight basis), sludge origin (Baltimore, Md., and Washington, D. C.), pH of soil‐sludge mixture (two levels), incubation time between mixing and planting (0 to 7 weeks), and plant age (three clippings). Plant yields from successive clippings decreased as sludge application rates increased. Uptake of the four metals increased with sludge additions and with plant age, in the order Zn > Cd > Pb ≃ Cu. Metal uptake decreased in the order Zn > Cd > Pb > Cu with addition of lime. Incubation considerably diminished Cu and Pb uptake. All observations point to organic matter complex formation in the order Cu > Pb > Zn > Cd. The relative uptake of HCl‐extractable Cd from soil was greater than that of Zn, especially upon liming, while the total uptake of these metals then decreased.