The Dose-Effect Relevance between the Proportional Mixed Soil with Sewage Sludge Compost and Growth Response of the Horticultural Plant

In order to gain a better understanding of land application of sewage sludge, we studied the effects of sewage sludge compost on the tall fescue and the marigold compared with the control group (Shanghai tidal bank soil) in greenhouse experiment. The mixed proportion of the sludge compost in the Shanghai tidal bank soil was controlled respectively in 0%, 5%, 10% and 20%. The plants grown on the compost-amended soil showed a different growth dynamic, such as delay in germinating and flowering and a smaller root system. It was demonstrated that there was significant dose-effect relevance between the compost-amended soil and the growth response of plants. Due to barren tidal bank soil the plants could not grow well. With 5-10% sludge compost added, the burgeon rate of the seeds increased and the growth of target plants were better than those in tidal bank soil. The biomass and seed yield have been increased. However, when the mixed proportion of sludge compost increased over 10%, the burgeon rate of seeds decreased obviously, or even no germination as a result of some inhibitive effect from mixed soil. 20% was recommended to be the maximum limit of mixed proportion of the sludge compost in tidal bank soils for the horticultural plants, and the suitable proportion of the sludge compost added was controlled between 5-10%.