EFFECTS OF WASTEWATER SLUDGE ON GROWTH OF PERENNIAL RYEGRASS (Lolium perenne L.)

The objectives of this study were to evaluate the effects of sun dried wastewater sludge (SDS) and peat amendments on perennial ryegrass (Lolium perenne L.) growth, as well as to identify the optimum rates of amendments and impact of irrigation frequencies for turfgrass production. The experiments were conducted over a 40-day period under greenhouse conditions in Bursa, Turkey in 2008 and 2009. The experimental design was a randomized split- split plot design with three replications. Irrigation frequencies served as main plots, amendments were subplots, and cover mixture rates were sub-subplots. Wastewater sludge samples were obtained from the Food Company, where the domestic and industrial wastewater was treated together. Results showed that the content of plant nutrient matter of SDS was high and its heavy metal contents were found below the critical levels according to the soil pollution control instructions. Based on these observations, we recommend amending soils with 50-75% SDS for optimum Lolium perenne L. growth. SDS amendment at these levels can greatly improve the soil nutrient supply without significantly affecting its heavy metal and soluble salt contents.