The accumulation of zinc in oat grown in soils treated by incubated sewage sludge with peat and straw

The effect of addition of treated sewage sludge on the accumulation of Zn in plants was tested in pot experiment. The additions of eight months preincubated sewage sludge at temperature of 20°C under aerobic and anaerobic conditions with addition of peat and straw were tested. Two different combinations were designed: first consisted of 50% sludge + 35% peat and 15% straw, and second was made of 50% sludge + 5% peat and 45% straw (expressed as dry matter). Three different soils Chernozems, Luvisols, and Fluvisols and three sludges were tested in the experiment. Oat (cv. Pan) was planted as experimental crop. All treatments were fertilized by NPK. Green biomass of oat was harvested and analyzed. At treatments with addition of both composted sludges pH dropped down causing higher mobility of Zn in sewage sludge. Oat grown in these treatments contained higher amount of Zn compared to untreated soils. The application of anaerobically treated sludge led to increased Zn content in biomass compared to aerobically incubated one. Predominant effect on Zn accumulation in plants was determined by tested soil. The highest content was determined in plants grown on Fluvisols. The biomass yield was more affected by source of sewage sludge than by the soil type used. Treatments amended by anaerobically incubated sludge showed tendency to higher biomass production due to their higher content of nitrogen and carbon.