The relative effectiveness of Mehlich I (.025N H2SO4+ .05N HCl) and Mehlich III (0.2N CH3COOH + 0.25N NH4NO3+.015N NH4F + .013N HNO3+ .001M EDTA) extractants as predictors of Mn, Cu and Zn uptake was assessed in a greenhouse experiment with four Delaware soils. The soils were adjusted to eight pH levels by addition of Ca(OH)2or elemental S, and received comparable amounts of Mn, Cu and Zn as either (1) MnSO4+ CuSO4+ ZnSO4or (2) Poultry Manure. Mehlich 1 and III extractable Mn and Zn, but not Cu, were well correlated in most instances. Excellent correlations were obtained between Mn uptake and Mehlich I and Mehlich III extractable Mn, for all soils and sources. In general, however, neither Zn nor Cu was found to correlate well with plant uptake. Based on this study, conversion to Mehlich III, as a routine soil test extractant for micronutrients, would not result in a significant improvement over the currently used Mehlich I extractant.