PHOSPHOROUS CHARACTERIZATION IN A RESTORED AND MANAGED TALLGRASS PRAIRIE USING 31 P NMR

Tallgrass prairies at the Green Oaks Biological Field Station in Knox County, IL, were established beginning in 1955, making this the second-oldest area of restored prairie in the US. Regular prairie burns serve as the primary vegetative management strategy at the field station, creating an excellent location for investigating the specific influence of prescribed burning on phosphorous, which should be made more plant-available through the regular mineralization of plant-held forms. Preliminary analyses suggest that inorganic phosphate, organic orthophosphates and pyrophosphate are the dominant P forms found within the upper A horizons of these prairie Mollisols both before and after tri-annual burning events, indicating that phosphorous bioavailability is subject to limitation by P sorption and erosive losses instead of mineralization, and suggesting regular plant-availability of this soil nutrient. Comparison of soils in established prairie landscapes with those of remnant prairies and adjacent forested areas will aid in determining the specific influences of prescribed burning and sediment erosion on P maintenance within the soil nutrient pool.