Thursday, November 16, 2006 - 11:15 AM
324-5

Distribution of Soil Phosphorus Fractions in Acid Soils of Forested Watersheds.

Michael San Clements1, Ivan Fernandez1, Stephen A. Norton1, Aria Amirbahman1, and Lindsey Rustad2. (1) Univ of Maine, Orono, ME 04469, (2) USDA Forest Service, 35 Crystal Ln, Cumberland, ME 04021-9538

Long-term acidification of forested watersheds through increased atmospheric deposition of nitrogen (N), and sulfur (S) may result in the depletion of soil base cation pools, increased soil acidity, mobilization of aluminum (Al) and possibly phosphorous (P).  Research is currently underway to quantify P dynamics in soils across a range of watersheds with varying climates, parent materials, vegetation, and acid inputs.  Soil samples were collected in the study watersheds along transects running perpendicular to first order streams.  Soil exchangeable cations and pH were measured on all samples.  Fractionation techniques were used to partition soil P into: labile P, Fe-P, Al-P, Ca-P, and refractory P.  Differences in soil P pools indicate the varying influence of metal chemistry and acidity on P retention and release in these soils.  Spatial patterns in soil chemistry by depth and position relative to the stream provide insights into linkages between soil and stream chemistry.

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