Free oxide distribution in poorly and well drained soils developed on calcareous alluvial deposits

摘要

A study on the distribution of free iron and manganese oxides was conducted in soils developed on calcareous alluvial deposits under subhumid climatic conditions, in Western Greece. Soil samples from two well drained soils and from two poorly drained soils, classified as Alfisols, were collected and used in this study. After certification of soil homogeneity the acid ammonium oxalate and dithionite-citrate-bicarbonate methods were used to extract free iron and manganese oxides from the samples. Iron oxides extracted by the dithionite-citrate-bicarbonate method (Fe_d) were significantly higher than the iron oxides extracted by the ammonium oxalate method (Fe_o), indicating that a considerable fraction is present in crystalline forms, independent ofdrainage status. A confirmation of free iron oxides and fine clay was detected. The ratios Fe_o/Fe_d and (Fe_d-Fe_o)/total Fe (Fe_t) could not be used to distinguish the well drained soils from the poorly drained soils. Manganese movement in a soluble form is independent of the fine clay.