The fate and effects of sewage sludge constituents in a soil-plant system are influenced by factors such as climate, management and composition of the sewage sludge. In addition, soil properties affect the chemical reactions and processes which occur after application of sewage sludge to a soil. Soil properties that affect the reactions and resultant plant uptake of sewage sludge constituents include pH, organic matter, cation exchange capacity (CEC), iron and aluminum oxides, texture, aeration, specific sorption sites and water availability. The trace element content of crops is a function of the plant available level in the soil and the modifying influences of soil chemical and physical properties. Soil organic matter and the resultant impact on pH buffering can influence the effect of liming on trace element uptake. In terms of phytotoxicity, research data available indicates that the maximum metal loadings allowed in the CEC-metal limit approach are conservative.