Effect of Copper Supplied in the Form of Different Cu-Saturated Sludge samples and Copper Salts on the Cu-Concentration and Dry Matter yield of Corn Grown in Sand

Abstract

A growth chamber experiment (sand culture) was conducted in order to investigate the effect of degree of copper saturation of a sludge sample on the dry matter yield of corn and on copper concentration. Various application levels of copper in the range of 2.5 to 40.8 μg Cu/g sand were also tested.

The results have clearly shown that the increasing degree of copper saturation of the sludge sample, from 9.8 to 98.3%, caused an increasing toxic effect on the corn growth and on the enhancement of copper concentration. This observation is true for all the application levels, however, the effects are more pronounced at higher levels, i.e. 20.4 and 40.8 μg Cu/g sand. Sludge which was 3.4% copper saturated (containing 2 077 μg Cu/g dry sludge) did not affect, at all the application levels, either growth or copper concentration. The limiting value of copper in sludge, in Switzerland and many other countries, is 1000 μg Cu/g dry sludge.