Physical and Chemical Properties of Mixtures of Sludge and Saline Soil and Their Effects on Growth of Five Species of Wild Plants

Feasibility of the application of sludge to amelioration of coastal saline soil was studied through a pot experiment using 5 species of wild plants,Bidens pilosa,Echinochloa crusgalli,Schizonepeta tenuifolia,Kalimeris indica and Taraxacum mongolicm.Mixtures of sludge and coastal saline soil were prepared with the former accounting for 0,20%,40%,60%,80% and 100%,separately.In order to explore for the most suitable application ratio of the sludge to the soil and appraise the wild plant resources,physicochemical properties of the mixtures were determined and effects of the mixtures on survival rate,chlorophyll content and dry weight of the plants analyzed,and cumulative concentrations of heavy metals in the plants measured.Results show that it is feasible to use the sludge to ameliorate the coastal saline soil,when the concentration of sludge was between 20%-60%,the physicochemical properties of the mixtures satisfied "Planting Soil for Greening"(CJ/T 340—2011).The optimal sludge-soil ratio is 60%∶40%,and the survival rate of plants is 100%.Bidens pilosa,Echinochloa crusgalli,Schizonepeta tenuifolia,Kalimeris indica and Taraxacum mongolicm are excellent pioneer plant species in restore vegetation in the coastal area of Shanghai.