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Fig. 2. The effect of lime and S treatments on Al3+ activity [(Al3+)] in a 30-cm soil profile. Because there was a significant treatment x depth interaction, all treatment comparisons were made within depth increments. Within depths, data points followed by the same letter(s) are not significantly different using Tukey's pairwise comparisons (P 
0.05). A log (Al3+) of approximately –6 corresponds to the level where Al phytotoxicity has been expressed by many crops (dotted line).
