Yield and Cadmium Accumulation of Forage Species in Relation to Cadmium Content of Sludge‐amended Soil

Abstract

Abstract Alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), sudangrass ( Sorghum halepense Pers var. Sudanense Hitche .), tall fescue ( Festuca elatior L.), and bermudagrass ( Cynodon dactylon Pers.) were grown in pot cultures under greenhouse conditions to study the effect of soil Cd levels on Cd uptake and yield. The substrate consisted of a soil (pH 7.5) pretreated with 1% municipal sewage sludge amended with variable amounts of CdSO 4 . Concentrations of Cd in soil varied from 0.09 (control) to 160 µ g Cd/g soil. Yields of dry matter (70C) were obtained by clipping off the shoots at early bloom stage. Samples of the clippings were analyzed for Cd and Zn. Soil was analyzed after the plant growth experiments were completed. Substrate Cd concentrations of 15, 30, 40, 95, and 145 µ g Cd/g were associated with a 25% yield depression for sudangrass, alfalfa, clover, fescue, and bermudagrass. Corresponding Cd concentrations of clippings were 9, 24, 17, 37, and 43 µ g Cd/g. The soil analysis revealed a close agreement between both DTPA‐Cd and saturation extract Cd and Cd uptake and crop yield data. Chemical analysis of saturation extracts showed an inverse effect of Cd on the solubility of Zn.