Nitrogen that was held in the reeds and added organic matter could be entrapped by the sediment casing, making it available when subsequent planting takes place (as with ankara practiced in Cameroon). Nitrogen that is trapped in the sediment cover or char due to an increase of reactive sites on clay or biochar could be sequestered, avoiding the greenhouse gas release or eutrophication that would accompany simply dumping of the spoils on the shore. Inoculating seedling roots with mycorrhizal fungi would be a very helpful step. If native legumes or other nitrogen-fixing species can be found, planting their seedlings preceded by a dip in the proper bacterial inoculum could be all it takes to jump start the nitrogen cycle after charring. Plants that are easy to grow would be necessary in any case, since the soil would be otherwise devoid of microbes. The roots should be placed no deeper than the baked sediment layer, though the underlying baked sediment should be broken up to allow the roots to grow into the charred phragmites layer.
One currently followed method of phragmites eradication is described in this brochure and a more interesting slideshow. It may be less expensive than my method, but it is potentially more harmful to the environment (glyphosate) and takes two years to reach the point of replanting or initial restoration. My method can be performed in a matter of weeks and it sequesters carbon while recycling dredge spoils. Since applying glyphosate must be done in a way that avoids overspray and contacts all the targeted foliage, current methods may also be more labor intensive (adding expense) and pose a health hazard to the exterminators.
Another common method of eradicating phragmites involves burning in addition to herbicides. This video shows what a good tinder phragmites is. My covered method would be more controlled and hopefully much less smoky.
