A method is provided that can amend treatment wetland soils and sediments in order to reduce pollutant export following the use of the wetland for contaminant removal. The method includes the steps of draining at least a portion of a water body and permitting the growth of vegetation on the sediments. Once grown, the resulting biomass is tilled into the soil, and the water body is permitted to re-hydrate. In some instances a portion of the vegetation can be harvested prior to tilling remaining crop residues into the soil. In another embodiment, the draining step occurs naturally.