21 soils meet the andic requirements according to the draft of the second edition of World Reference Base for Soil Resources (bulk density ≤ 0.9 kg dm-3, Alo + 0.5 Feo ≥ 20 g kg-1, phosphate retention ≥ 85 %) over at least some depth, 13 fulfil them over the required minimum thickness of an andic horizon and (the andic horizon starting within 25 cm from the soil surface) classify as Andosols. They are the first detected Andosols in South America outside the Andes. The other 6 soils fail the Alo + Feo criterion over the whole soil depth, 2 of them additionally the phosphate retention. Besides the 13 Andosols we have 12 Umbrisols and 4 Cambisols. 11 Umbrisols and the 4 Cambisols are higher weathered with high Fed and low Feo concentrations and may have developed from Andosols by crystallization of iron oxides.
15 soil profiles are under grassland and grassland-related vegetation, 12 under forest and shrubland. Forest and shrubland are more concentrated on steeper slopes and 7 soil profiles have a buried soil starting within 40 cm (buried soils were not found under grassland) and 4 others have a solum shallower than 60 cm. The upper horizons of all buried soils meet the andic requirements and, if present, form part of the andic horizon. According to pollen analyses, which indicate that the forest is not older than 3000 years, these buried soils probably developed under grassland. Generally, the upper topsoil horizons in the forest have clearly lower Feo and/or Alo concentrations, lower Feo / Fed ratios, and lower phosphate retentions than those of the grassland profiles. Contrary to 5 grassland topsoils none of them meets the andic requirements. Under forest, crystallization of iron oxides seems to be easier than under grassland.