Sources Degrees of freedom F values Main effect   CaCO3 rate (Ca) 2 37.42*** Linear   38.81*** Quadratic   33.29*** Source of P (P) 2 33.33*** P rate (R) 2 06.85*** Linear   09.36** Quadratic   NS Interactions Ca x P 4 9.90*** Ca x R 4 NS P x R 4 NS Ca x P x R 8 NS

Table 2: Analysis of variance on the influence of calcium carbonate (CaCO3), P source and P rate on dry matter yield of the above ground portion of corn grown on a sulfide tailing under greenhouse conditions **, ***: significant at P<0.01 and P<0.001, respectively; NS, non-significant at P<0.05