ABSTRACT
Sanitary landfills, created for the disposal of solid waste, usually are developed into parks after they are closed. However, soil amelioration with organic matter is usually needed to restore fertility and promote revegetation. Sewage sludge creates a massive waste disposal problem. The use of composted sewage sludge [biosolid] as a soil conditioner might restore the soil fertility at landfill sites and simultaneously alleviate the need for sewage sludge disposal. We applied biosolid to waste landfill soil and evaluated its effects on soil properties and tree growth in a field experiment. Biosolid improved soil characteristics including moisture, organic matter, and nitrogen content and also increased tree height and diameter at breast height. Physiological measures, such as chlorophyll content and photosynthetic rate, showed positive responses in trees grown in biosolid treatments. Heavy metal concentrations in soil and tree leaves after applying compost did not differ from concentrations measured at control sites. Therefore, we conclude that the use of biosolid in waste landfills would be an efficient, environmentally beneficial, and cost-effective method to restore the conditions of landfill soil for plants