Fig. 5. Increase of soluble P_i by 3-phytase hydrolysis. Reaction mixtures contain 0.322 mM P and none (control) or 3.22 mM Fe or Al ions. Pi, KH₂PO₄; IP6, phytate; EHa, Elliott soil standard humic acid; EFa, Elliott soil standard fulvic acid; WHa, Waskish peat reference humic acid; WFa, Waskish peat reference fulvic acid. Values are averages ± standard deviations (n = 6).