SOLUBILITY OF IRON-OXIDES OF FOREST SOILS IN THE TAMM REAGENT

Dissolution of iron oxides and hydroxides of the forest zone soils by the Tamm reagent depends on many factors: crystallization, hydration, and aggregation of particles. The contact with phyllosilicates affects the solubility of iron minerals in different ways. The solubility of feroxyhyte is higher in concretions with a smaller amount of clay mine rals as compared to the whole soil. Different solubilities of goethite and hematite are: observed in the forest zone soils. The contribution of magnetite iron to Fe, (oxalate-soluble iron) ranges from 0 to 50%. In forest soils, the Fe-o value and the Fe-o/Fe-d ratio characterize particle dispersion and crystalline disorder, rather than the particle hydration and amorphism. This should be taken into account when apply ing the Fe-o/Fe-d ratio for classification purposes.