Study on the amendment of physicochemical properties of tidal flat soil by using sewage sludge

In this study, a field experiment was carried out at a new reclaimed tidal flat to investigate the effects of different rates (0, 75, 150, 300, 600 t/ha) of sewage sludge, which was derived from disposal of municipal sewage water, on soil physicochemical properties. The quality of the sewage sludge used in the study met the national standard of sewage sludge for agricultural use. Plots in the experiment were arranged as randomized block design with 3 replicates. The results show that the sewage sludge could significantly improve physicochemical properties of the tidal flat soil. With the increase of sewage sludge application, soil bulk density, specific weight and pH are decreased, while soil organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus and cation exchange capacity (CEC) are tended to increase, and the total potassium, available potassium are not changed significantly. The numbers of bacteria and actinomycete in the tidal flat soil treated with sewage sludge are significantly higher than those in the tidal flat soil which is naturally evolved.