ABSTRACT
Summary Several field experiments showed in average only weak effect of applied sewage sludge on the content of Pb, Cd, Fe, Ni and Cu in the yield.
Increasing amount of sludge increased the Zn content in plants markedly and regular. In a field experiment, 28 different crops were grown in 0, 10 (incorporated) and 40 cm decomposed sludge. The heavy metal content varied greatly from crop to crop. Different parts of the plant contained different amounts of the various elements. Increasing amount of sludge affected the average content in plants in this order: Zn > Mn > Ni>Cu>Pb, Cr. In a pot experiment increasing temperatures resulted in higher content of Mn, Fe, Zn and Cd, while the content of Ni, Cu and Mo were little influenced.
