Field Crop Production 45 th Croatian & 5 th International Symposium on Agriculture Effect of sewage sludge treatment on mobility and soil-plant transfer of Cu, Mn, Ni and Zn

Abstract A pot experiment was set up for examining the effect of sewage sludge loads on soils and barley plants (Ni, Mn, Cu and Zn status). Four soils were tested as follows: acid and calcareous sandy soils as well as heavier acid and calcareous loamy soils with different basic soil properties. The examined soil nutrient fractions were: ammonium-acetate + EDTA extractable and pseudo total (cc. HNO 3 + H 2 O 2 digestion). The applied sewage sludge loads were: 0, 2.5, 5, 10 and 20 g sludge dry matter / kg air-dry soil. Number of treatments was 80 (4 soil types x 5 sludge load levels x 4 replicates). The transfer values (BCF: ratio of plant /soil element content) for both barley straw and grain were the highest on acidic sand for all investigated elements. The BCF values were decreasing in function of sludge loads in most cases. The transfer of Mn to the straw was 12 times higher than to the grain. This value for Ni and Zn was 1.5 and 1.3 respectively. The Cu transfer to the straw was only 0.78 % of the transfer to the grain. The most mobile (mobility: ratio of soil pseudo total concentration/soil NH 4 -acetate + EDTA extractable fraction) element among the investigated elements was Cu. Ni was the most fixed in the soils. The investigated elements were the most mobile on acidic sand