Controls On Phosphorus Retention in Native, Disturbed and Hydrologically Restored Agricultural Wetlands.

Restoration of wetland function represents a priority emphasis of watershed programs aimed at improving water quality. The efficiency of newly created or restored wetlands to assimilate phosphorus (P) has been tied to the properties and maturation of wetland soils. Newly created wetland sediments that have low initial P concentrations relative to their P sorption capacity will rapidly sorb P until reaching an equilibrium that resembles concentrations in natural systems containing similar sediments. Those that have high initial P values relative to their P sorption capacity will tend to release P. Understanding this dynamic is key to assessing wetland ecosystem services regarding P retention in efforts involving wetland restoration. We sought to assess differences in the P chemistry of wetland soils of the Mid-Atlantic Coastal Plain across an alteration gradient of use, from native to drained and in agricultural production to restored. Soils from 48 wetlands were sampled and analyzed for an array of P properties. Preliminary results point to significant differences in soil P by wetland category within certain geographic areas. Total P was lowest in restored wetland soils, but not significantly different in currently farmed wetland or native wetland soils. Despite the similarity in total P, oxalate extractions revealed that agricultural soils were significantly more saturated with respect to iron and aluminum than either of the other two soil types, while the native wetlands soils were the least saturated.