Fig. 3. The relative content of Feo, Fed, Alo and Ald in the YPF and OPF soils after water,
oxalate, DCB, or H2O2 treatments. The original contents of Feo, Fed, Alo and Ald in the two
untreated soils were set as 100%. Different letters on the column indicate a significant
difference between treatments at p b 0.05.
Different letters after each value indicate a significant difference among the intensity
treatments at p b 0.05 level.