Evaluation of four aluminum extraction methods using selected Brazilian soils

Thirty-two soil samples from different locations of the Rio de Janeiro Stat e, Brazil, were studied in order to evaluate the amount of aluminum (Al) ob tained by three extractants (1 M KC1, 1M NH4OAc, 0.5 M CUCl2) and by the ex traction of humic and fulvic acids (0.5 M NaOH, following purification). Th e results were discussed in relation to statistical correlations with soil organic matter content and soil PH (water). In general, the displacement of Al followed the order: CuCl2 > NH4OAc > KCL > humus extraction. The greate r amounts of Al extracted by CUCl2 were attributed mainly to Al from soil o rganic matter.