INFLUENCE OF TREATED SEWAGE SLUDGE APPLICATIONS ON TOTAL AND AVAILABLE HEAVY METAL CONCENTRATION OF SANDY LOAM SOIL

The objective of this study is to determine influence of treated sewage sludge (TSS) rates on total and available heavy metal concentrations in a sandy loam soil. The experiment was conducted in the experimental fields of Ege Agricultural Research Institute during 2011-2012 in Menemen-Izmir. Study area is in the Western Anatolia region of Turkey (38 degrees 56'87.96"-38 degrees 56'91.02"N; 27 degrees 03'57.52"-27 degrees 03'58.61"E). The field study was conducted in 20 plots in a randomized-block design with four replications and five different applications including control, mineral fertilizer, treated sewage sludge 12.5 Mg.ha(-1); 25.0 Mg.ha(-1); 37.5 Mg.ha(-1) as dry matter. The plots dimensions were 3 m width and 3 m length. Corn (Zea mays) was planted as the first crop. On the other hand, wheat (Triticum vulgare) was planted as the second crop. During the experiment, soil samples were taken five times in two years. Increasing TSS applications to this soil resulted in significantly increased concentrations of total Zn in soil as average of 5 sampling periods. However, concentrations of total Cu, Cd, Cr, Ni and Pb in soil did not significantly change. Total heavy metal concentrations in soil were found under threshold values for all sampling periods in this study. Increasing treated sewage sludge aplications were significiantly increased available (diethylenetriaminepentaacetate-DTPA-extractable) Cu, Ni and Zn concentrations in soil as average of 5 sampling periods when compared with control. However, available Cd, Cr and Pb concentrations in soil did not change significantly.