The allophane content from two Chilean soils derived from recently deposited volcanic ash was investigated at the Soil Science Department of the Faculty of Agronomy (Chillán, Chile) by using a differential dilution method as proposed by Hashimoto and Jackson (1958).
The soil clay fraction, free from organic matter, divalent and monovalent cations, aluminum and iron free oxides, was treated by boiling with 0,5 N NaOH for 2.5 minutes.
The results show the allophane content (% mineral basis) ranges from 40,20% to 53% for the Arrayán soil and from 53,15% to 61.85% for the Santa Bárbara soil, which agfees with earlier research carried out in this area.
The SiO2/ Al2O3 mole ratio ranges from 0.99 to 1.40 for the Arrayán soils and from 0.79 to 1.09 for the Santa Bárbara soils.
More research is needed in arder to establish sorne definitive data about the characteristics presented by these soils.