THE ASSOCIATION OF VANADIUM AND MOLYBDENUM WITH IRON OXIDES IN SOILS

High concentrations of V and Mo in ironstone gravels have previously been reported. Examination of soils in which ironstone concretions have formed during pedogenesis indicates that Mo/Fe ratios are in fact higher in the finer fractions than in these gravels, whereas the V/Fe ratios tend to be independent of particle size. In the lateritic podzolic soils examined, the observed association between V and Fe in the iron oxides of the fine earth fraction (< 2 mm) is maintained during any solution of this fraction and any subsequent transportation and precipitation involved in the development of the gravels. Differences in the degree of association with Fe shown by Mo and V are considered to be due to different modes of transport of these elements through the soil. It is suggested that V moves as a vanadyl cation whereas Mo is transported as a complex anion.