Fig. 1. Changes in (A) water-soluble P (WSP), (B) CaCl₂–P, and (C) modified Morgan-P (MMP) over time after amendment with KH₂PO₄ or manure (beef, dairy, poultry, or swine) applied at 100 mg total P kg^-1 soil. Data are corrected for extractable P in unamended soil, and data points are means of four observations; t is time (in days) after application of P sources.