Multielement soil extractant solutions are used by several soil testing laboratories to determine the plant availability of several nutrients by the same extractant, to decrease costs and labor. The Mehlich-1 (M1) and Mehlich-3 (M3) solutions are often used for this purpose. In this study, they were used to evaluate soil P availability using 360 soil samples of the State of Rio Grande do Sul (Southern Brazil). The correlation coefficients between the P concentrations extracted by these solutions were strongly associated and highly significant. The P concentrations extracted by the M3 solution were on average 50 % higher than those extracted by M1. The soil clay content affected the P extraction capacity of the M3 solution, requiring an adjustment table for the interpretation of the P value by this method, as proposed here.
soil test; Mehlich-1; Mehlich-3
