EFFECTS OF DIFFERENT DOSES OF SEWAGE-SLUD GE ON SOIL AND PLANTS OF A CULTIVATED AND A GRASSLAND SITE IN THE LOWER VALLEY OF THE RIVER MURZ

A two years' experiment in Murzhofen and St. Lorenzen in Styria was ca rried out for measuring the effects of sewage sludge application on so il and plants. In the course, small plots with an area of 20 square me ters each were treated with different intensities of application. In t he highest intensity 7.5 tons of dry substance per ha and year was app lied on the cultivated sites, 3.75 tons per ha and year on the grassla nd. An enrichment of heavy metals such as zinc, copper, lead and cadmi um was noticed on the cultivated soil. Higher contents of lead and mer cury could be found in the grassland soil. The plants of the grassland (first reaping) showed a clear increase of zinc and nickel. An increa se of zinc and lead was also found in silage-maize. Yet neither the cu ltivated nor the grassland site showed a more intensive growth of weed s compared to the untreated plots. A better growth of silage-maize as well as grass (first reaping) was quite obvious because of sewage slud ge application. The results of this two years' experiment show no sign ificative negative effects on soils and plants according to the presen t laws and regulations in Styria.