Effects of the Application of Composted Sewage Sludge on Soil Fertility and Plant Growth
The land use is expected to be the main disposal way of municipal sludge.The field experiment was set with different appli-cation amounts of aerobic compost of municipal sewage including 0％,30％,50％,70％,100％(the volume ratio of composted sew-age sludge to soil)to explore the effects of composted sewage sludge application on soil fertility,plant growth and soil heavy metals contents.The results showed that the application of composted sewage sludge did not cause soil acidification,and the level of soil fertil-ity was improved from tertiary level to the secondary one.The contents of main nutrient components in soil increased significantly with the increase in sewage sludge compost application.When the addition proportion of composted sewage sludge was 50％,1.9 times of organic matter,3.0 times of alkali-hydrolyzed nitrogen,9.5 times of available phosphorus and 3.7 times of available potassium were observed compared with the control.The growth rate of Argyranthemum frutescens(Linn.)Sch.-Bip was the highest when the addition proportion of composted sewage sludge was 50％,and that of Salvia japonica Thunb.and Festuca elata Keng ex E.Alexeev & Lolium perenne Linn.were 30％with best growth.However,there was no significant difference of the growth of Cerasus subhirtella(Miq.)Sok.with different addition proportion.Although the application of composted sewage sludge would lead to a slight increase in soil heavy metals content,it was far below than the pollutant index and limit value stipulated in"Disposal of sludge from municipal wastewater treatment plant-Quality of sludge used in forestland"(CJ/T362-2011),and did not cause soil heavy metals pollution.This study will provide a theoretical basis and data support for the land utilization of composted sewage sludge.
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