The copper in the saturation extract of dried Davis sewage sludge was mainly in a complexed form. A Cu2+ specific ion electrode was used to determine the extent of complexation. Absorption experiments showed that the Kd value of 90 cc g-1. Paper electrophoresis was used to define the complexes according to their mobility in an electric field. Six fractions of positive, negative and neutral charge were isolated. The fraction of Cu in the sludge which was water soluble was found to increase significantly upon drying. The low Kd values on soil and the large percentage of complexed Cu suggested that sewage sludge may be a potential source of contamination of water and plant systems.

A 3-year study of the accumulation of soluble salts and boron in a soil profile following trickle irrigation with well water is completed. Irrigation treatments consisted of three levels of water applications based on estimated evapotranspiration (ET)requirements of grape vines. Estimates of ET were obtained from soil data using a neutron (CPN) meter. Soil water potentials obtained by tensiometers at different soil depths provided information about soil water movement. Analysis of soil samples taken in late 1981 showed slow but continued salt and boron accumulation during irrigation periods. Plant samples showed boron accumulation in the grape leaves during the irrigation season. Leaves from the lowest irrigation level (2/3 ET) showed higher boron contents than did the 3/3 ET level which was higher than the 4/3 ET irrigation treatment. Chloride accumulation in the plant leaves increased similar to that of boron, however, sodium did not, although it did accumulate in leaf petioles during the irrigation season in all treatments. In general, plant tissues reflected the sodium, chloride, and boron concentrations found in the soil. Grape yields in 1982 responded to the higher irrigation levels and yields were considerably larger than the local area average.