Iron oxyhydroxides in soils developed from Lower Palaeozoic sedimentary rocks in mid-Wales and implications for some pedogenetic processes

Lepidocrocite and goethite are pedogenetic crystalline Fe oxyhydroxides in the soils of mid-Wales. Lepidocrocite is more abundant and widespread, occurring in brown earths (Denbigh series) as well as morphological gleys. It is commonly dominant in horizons intermediate in depth. Goethite occurs in subsoils and was found to be dominant in the subsoil of surface water gleys (Cegin series). Apart from the Cegin series, a large proportion of the total free Fe occurs in non-crystalline forms. This amounted to 50–80% of the free Fe in organic and eluvial horizons of podzols. Despite lower proportions of non-crystalline Fe in Bs horizons, amounts were similar to those in eluvial horizons. Data on the distribution of crystalline and non-crystalline free Fe together with correlations observed between Fe and C extracted by pyrophosphate suggest that transformation and translocation of Fe in the podzols examined are governed by its association with organic fractions.