In the Piedmont and Mountain physiographic regions of North Carolina, regionalization of dairy and poultry confined animal feeding operations have concentrated animal waste applications to clayey soils. Application of more phosphorus (P) in manure than is removed by crops can lead to a buildup in soil Mehlich-3 P (M3P). In some cases, M3P concentrations of these soils are above agronomic thresholds for optimal crop yield raising a concern over P movement to surface waters, including via subsurface pathways. Currently, the NC Phosphorus Loss Assessment Tool (PLAT) is used to estimate P losses in leaching and runoff from many agricultural soils. The PLAT assesses P loss from soils grouped into soil management groups (SMG) sorted by an array of factors, i.e., landscape position, parent material, particle size class, and dominant soil properties. Our objectives were 1) to determine the extent of P leaching in soils of the Piedmont and Mountain regions of NC following animal waste applications; 2) to assess whether Piedmont and Mountain SMGs are useful in predicting sites for potential P leaching; and 3) to evaluate the relationship between M3P and water-soluble P (WSP) in benchmark soils of the regions, determine the dominant soil factors affecting WSP concentrations, and reevaluate SMGs based on these relationships. This research will help validate the identification of sites at risk of P leaching by PLAT and with quantifying these losses.