Evaluation of composted sewage sludge (CSS) as a soil amendment for Bermudagrass growth

In order to evaluate the growth of Bermudagrass (Cynodon dactylon L.) in soils amended with 5-100% composted sewage sludge (CSS) and the impacts of CSS amendment on soil physical and chemical properties an experiment was conducted. Soils amended with < or = 20% CSS did not significantly affect the seedling emergence, while the contents of chlorophyll, nitrogen, phosphorous and potassium of Bermudagrass grown in such soils were greatly improved. Bulk density, water retention and nutrient contents of the soil were also improved with the amendment of CSS, but high CSS contents introduced excessive amounts of heavy metals and soluble salts. Results show that Cu, Zn and Pb accumulated slightly (up to approximately 2.3 times) in clippings of Bermudagrass grown in CSS-amended soils compared to those grown in the base and reference soils, while no significant Cd absorption in shoots of Bermudagrass occurred. The detrimental effects on seedling emergence and turfgrass growth observed on substrates with high (> or = 40%) CSS contents were mainly attributed to the presence of high soluble salt concentrations. The findings suggest that addition of CSS at 10-20% levels can greatly improve the soil nutrient supply for turfgrass growth without significantly affecting heavy metal and soluble salt contents of the soil.