Soil phosphorus forms in hydrologically isolated wetlands and surrounding pasture uplands

Cheesman, Alexander W.;Dunne, Ed J.;Turner, Benjamin L.;Reddy, K. Ramesh

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 sods 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, I 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 (31)P nuclear magnetic resonance spectroscopy revealed that organic P was dominated by phosphomonoesters in boils wetland and pasture sods but that myo-inositol hexakisphosphate was not detected in any sample The tight coupling of total C and P in the sandy sods of the region suggests that the successful management of historically isolated wetlands for P sequestration depends on the long-terns accumulation and stabilization of sod organic matter.

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Journal of Environmental Quality

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1537-2537

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American Society of Agronomy

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DOI

10.2134/jeq2009.0398