Fig. 4. Relationship of metal contents and total P contents in HCl fractions of soils. The four soil samples were mold-board plow in corn (CTCorn), Alabama pastoral Hartselle soils with 20-yr poultry litter applications (PLS20), Maine soil amended with dairy slurry at 150-d (MD150), and Oregon soil amended with dairy slurry at 150 d (OD150) (see Fig. 1 and 2) with the increasing order of P contents (m mol kg^–1 dry soil). Horizontal bars represent standard deviations of P contents. Vertical bars represent standard deviations of metal contents.