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Fig. 1. The 0- to 20-cm mean (n = 4) soil (A) oxalate-extractable Al, (B) oxalate-extractable Fe, (C) oxalate-extractable P, and (D) oxalate-extractable–based phosphorus saturation index (PSIox) from biosolids plots amended with 0, 6.7, 13, 27, or 40 Mg ha–1 biosolids. The 0, 6.7, 13, and 27 Mg ha–1 biosolids rates were applied in 1982, 1984, 1986, 1988, 1990, 1992, 1994, 1996, 2000, and 2002. The 40 Mg ha–1 biosolids rate was applied at 6.7 Mg ha–1 in 1982 and at 40 Mg ha–1 in 1984, 1986, 1988, and 1990. Above the bars, same letters are not significantly different at 
= 0.05, determined by Fisher's Protected LSD. Error bars represent 1 SE of the mean.
