title: Soil phosphorus forms in hydrologically isolated wetlands and surrounding pasture uplands.
abstract: Newly created and restored wetlands play an important role in sequestering excess nutrients at the landscape scale. In evaluating the long-term efficacy of nutrient management strategies to increase wetland capacity for sequestering P, information is needed on the forms of P found across the upland-wetland transition. To assess this, we studied soils (0-10 cm) from four wetlands within cow-calf pastures north of Lake Okeechobee, FL. Wetlands contained significantly (P < 0.05) greater concentrations of organic matter (219 g C kg(-1)), total P (371 mg P kg(-1)), and metals (Al, Fe) relative to surrounding pasture. When calculated on an aerial basis, wetland surface soils contained significantly greater amounts of total P (236 kg ha(-1)) compared with upland soils (114 kg ha(-1)), which was linked to the concomitant increase in organic matter with increasing hydroperiod. The concentration of P forms, determined by extraction with anion exchange membranes, 1 mol L(-1) HCl, and an alkaline extract (0.25 mol L(-1) NaOH and 50 mmol L(-1) ethylenediaminetetraacetic acid [EDTA]) showed significant differences between uplands and wetlands but did not alter as a proportion of total P. Speciation of NaOH-EDTA extracts by solution 31P nuclear magnetic resonance spectroscopy revealed that organic P was dominated by phosphomonoesters in both wetland and pasture soils but that myo-inositol hexakisphosphate was not detected in any sample. The tight coupling of total C and P in the sandy soils of the region suggests that the successful management of historically isolated wetlands for P sequestration depends on the long-term accumulation and stabilization of soil organic matter.
authors.affiliation: Univ. of Florida/IFAS, Wetland Biogeochemistry Lab., Soil and Water Science Dep., 106 Newell Hall, Gainesville, FL 32611, USA. cheesman@ufl.edu
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Cheesman
authors.forename: Ed J
authors.initials: EJ
authors.lastname: Dunne
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Turner
authors.forename: K Ramesh
authors.initials: KR
authors.lastname: Reddy
mesh_terms: D000383:Agriculture; D009682:Magnetic Resonance Spectroscopy; D010758:Phosphorus / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D014867:Water / Q000737:chemistry; D053833:Wetlands
chemical_list: D012987:Soil; D014867:Water; D010758:Phosphorus