Effects of different soil amendments on dredged sediment improvement and impact assessment on reed planting.

Large amounts of dredged sediment have been produced from dredging projects worldwide, and utilizing it as a resource has become particularly important. This work improved the dredged sediment using biochar (BC), humic acid (HA), and desulfurized gypsum (DG) to restore wetland substrate. The effects of different amendments, applied alone or in combination, on the physicochemical properties and nutrient contents of the dredged sediment were analyzed. The improvement effects were evaluated through reed planting experiments for three months. The results indicated that BC significantly improved the plant nutrient indicator of the dredged sediment. HA reduced the BD and pH of the dredged sediment and increased its contents of various nutrients. DG enhanced the physical indicators of the dredged sediment and could be considered for dredged sediment with high nutrient contents. The two-way ANOVA results indicated that the H3 (BC-6% + HA-6% + DG-10%) combined amendment treatment group showed the optimal improvement effect on the dredged sediment. In the reed planting experiments, the average plant height and average growth rate in the H9 (BC-6% + HA-4% + DG-20%) combined amendment treatment group were the maximum, reaching 45.18 cm and 0.486 cm/d, respectively. This work is expected to raise awareness of the need to utilize marine dredged sediments as resources. [Display omitted] • BC decreases 27.00% BD and increases 23.99-fold OM, 3.08-fold AP and 7.24-fold AK. • DG decreases 1.72 units pH and performs 2.76-fold increase in electrical conductivity. • HA increases 4.98-fold cation exchange capacity and 1.68-fold hydrolyzable nitrogen. • A-5 group germination number and C-4 group total biomass both reach maximum. • H9 group, A-5 group and H3 group show maximum average plant height at high, medium and low water levels, respectively. [ABSTRACT FROM AUTHOR]