Fig. 1. Relationship between Mehlich 3– or Bray 1–extractable soil P and runoff filterable reactive phosphorus (FRP) for (a) the soil box studies of Fang et al. (2002), Kleinman and Sharpley (2003), Kleinman et al. (2002), Kleinman et al. (2004), McDowell and Sharpley (2001a), and Weld et al. (2001), and (b) the field-plot studies of Andraski and Bundy (2003), Andraski et al. (2003), Cox and Hendricks (2000), Daverede et al. (2003), Sharpley et al. (2001), and Turner et al. (2004) using tilled and no-till field plots.