164-11 Assessing Native Phosphorus Availability in Riparian Soils of Northwestern Vermont.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: S11 General Soils & Environmental Quality: I
Monday, October 22, 2012: 11:00 AM
Duke Energy Convention Center, Room 251, Level 2
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Eric O. Young, Miner Institute, Chazy, NY, Donald S. Ross, Plant and Soil Science, University of Vermont, Burlington, VT, Barbara J. Cade-Menun, Semiarid Prairie Agricultural Research Center, Agriculture and Agri-Food Canada, Swift Current, SK, Canada, Caroline Alves, USDA-NRCS, Williston, VT and Thomas Villars, USDA-NRCS, White River Junction, VT
Factors affecting riparian soil phosphorus (P) availability can be important for nonpoint source P management in watersheds with extensive stream bank erosion.  We investigated P availability at multiple riparian sites in northwestern Vermont to characterize the relationship between soil type, P concentrations, and potential bioavailability.  A subset of samples was analyzed by solution nuclear magnetic resonance spectroscopy (31PNMR) and phosphatase enzymes to speciate P and evaluate potential bioavailability.  Both total and Modified Morgan extractable P were greater in the more imperfectly drained, finer-textured soils compared to coarser-textured soils.  This trend was confirmed in a set of soil profile samples from three different watersheds (n = 142).   For these samples, the ratio of oxalate extractable P to total P decreased linearly (R2 = 0.69) with increasing sand content.  The 31PNMR analysis revealed an array of soil organic P compounds, including the four known stereoisomers of inositol hexakisphosphate, which together comprised approximately 50% of the NaOH-EDTA extractable organic P.  For the same soils, about 70% of the total water-extractable P was unreactive, of which approximately 48% was hydrolyzed to orthophosphate by enzyme hydrolysis.  Results suggest a strong relationship between soil properties and native P concentrations and highlight the need for improved agri-environmental P indices in riparian zones that consider organic P.
See more from this Division: S11 Soils & Environmental Quality
See more from this Session: S11 General Soils & Environmental Quality: I