Application of sewage sludge to soils with different level of lime as a soil amendment for bermudagrass (Cynodon dactylon (L.) pers.) and Perennial ryegrass (Lolium perenne (L.)) growth and bioaccumulation of heavy metals

Dried and stabilized sewage sludge taken from Antalya Hurma waste water treatment plant was applied in 0 (Aç0), 0.5 (AÇ0.5), 1 (AÇ1), 2 (Aç2), 4 (AÇ4), 8 (AÇ8) ton da-1 doses to two soils containing different levels of CaCO3, 8% (T1) and 19.4% (T2) respectively, and bermudagrass (Cynodon dactylon L. Pers.) and perennial ryegrass (Lolium perenne L.) were grown on those soils. While there wasn't any significant change at pH of the growing medias (soil and sewage sludge mixture), the level of EC and organic matter. Sewage sludge applications to growing media also increased total N, P, K, Ca, Mg and Na concentrations of the growing media. Due to the applications of sewage sludge, the total concentrations of Fe, Zn, Mn increased in both media at which bermudagrass and perennial ryegrass plants grown. But while Cu concentration of media with bermudagrass increased, it decreased in perennial ryegrass growing media. After a general evaluation of soils concerning in less of the level of limestone, levels of total Fe, Zn, Mn and Cu concentrations in T1 soil was determined to be higher than T2 soil. Sewage sludge treatment to growing media of Bermuda increased to total Ni and Cr concentrations, as for the total Cd concentration a slight but not significant decrease has been determined. Sewage sludge treatment to growing media of perennial ryegrass increased the total concentration of Ni and caused a slight decrease in total concentrations of Cr and Cd. Total concentrations of Ni, Cr and Cd in growing media were determined to be higher in T1 soil than T2 soil. With the increased level of sewage sludge application; seedling emergence and turfgrass establishment rate of bermudagrass and perennial ryegrass were decreased; plant height, turfgrass colour rated, chlorophyll content measured under field conditions with the device Minolta-SPAD 502 Plus, total chlorophyll values as an obtained result of analysis in laboratory conditions, dry weight yield, N, P, K, Ca, Mg and Na concentrations of plants were increased. Fe and Zn concentrations of bermudagrass increased depending on the sewage sludge application rates; while Mn and Cu concentrations decreased. The effects of sewage sludge application on Ni, Cr, Pb and Cd concentrations were not significant on the bermudagrass. Sewage sludge application decreased Fe, Mn, Cr and Cd concentrations of perennial ryegrass, however it increased Zn and Cu concentrations. On the other hand, Ni concentration of perennial ryegrass decreased with the increasing rate from AÇ0.5 to AÇ1, and then started to increase after this rate. Calculated bioaccumulation values (BAFFe, BAFZn, BAFMn, BAFCu, BAFNi, BAFCr and BAFCd) for the shoots of grown grasses were found to be lower than BAF critical limit value of 1, proving those plants are not hyperaccumulators. In conclusion, sewage sludge treatments did not create any risk in experiment soils and turfgrasses in terms of heavy metal concentration, moreover, sewage sludge treatments have positive effects on turfgrasses growth due to the fact that sewage sludge increase organic matter, macro and micro nutrient concentrations in soils. Since there is no significant difference between 4 ton da-1 (AÇ4) and 8 ton da-1 (AÇ8) doses in terms of investigated criteria, 4 ton da-1 doses is considered to be sufficient.