Review produced evidence on environmental benefits of wetlands

Wetlands are effective in removing nitrogen and phosphorus from the water passing through them, but both planning and a smart design are needed to achieve optimum results. According to a Mistra EviEM review of existing research, a reasonably low flow of water is required.

‘One finding was that, to restore a natural wetland after the land has been used for farming, you have to remove the topsoil. If you don’t, the phosphorus that accumulated there during the time the area was in agricultural use may be released. The same problem doesn’t seem to arise with wetlands that are newly established on arable land. This may be because, to create them, you generally have to remove a large quantity of soil to start with,’ said Magnus Land at Mistra EviEM.