This part of the site was drained and levelled and used as an airfield during the First World War.
Some of the reclaimed marshes were later farmed for arable crops until 1989 when they were abandoned. Since the Trust began management of the Orford Ness marshes in 1993, natural regeneration of grassland (i.e. without the use of cultivation and re-seeding) has been allowed.
The river walls have stopped salt water from flooding the marshes on normal high tides. However, due to seepage and periodic flooding a residual salinity remains creating a sward composition in the pastures dominated by the rough grass sea couch (Elytrigia atherica) . Saltmarsh plants occur around the edges of the scrapes. Grazing and mowing aims to provide a variation in sward height that will encourage wading birds to breed within the open pasture areas.
Careful control of water levels combined now with alterations in the profile of the marshes to create wet scrapes and pools provides marginal feeding areas for breeding birds in the spring and summer, and in the autumn and winter larger flooded areas for passage and overwintering wildfowl.
The pasture and the scrub areas around the buildings provide habitat for passerines, some of which (with marsh harrier and other species) also make use of the reed marsh found within the airfield site.
On King's Marsh, although the bulk of the salt water has been prevented from flooding onto the marshes there is more seepage, some tidal exchange and also periodic inundations from the sea when the natural shingle sea bank is over-topped. As a result these marshes are more saline. These marshes are grazed but less intensively, and a more extensive approach is adopted to management of the wet pasture. The shape of the old saltmarsh creeks is still retained as part of the internal ditch system.
The elongated lagoons at the base of the wall are typical of 'borrow pits', where clay was 'borrowed' to create and then maintain the river walls. Specialised saline lagoon invertebrates such as starlet sea anemone can be found here.