Trace Element Relationships in Forest Soils

A systematic study initiated to gather information relating to trace elements status and related soil physical and chemical properties in four forest soilprofiles of the Belgian Ardennes brought forth the following information. The tendency for most of the elements io accumulate in coarser particle-size fractions is attributable to the stage of weathering the profiles underwent as revealed by the silt/clay ratios of the genetic horizons and the parent material. Owing to a very high degree of base-unsaturation, a similarity among titratable acidity and CEC is encountered in their relationship with trace elements (both total and extractable). On an average, 94.9% of the CEC is accounted for by ex. H and ex. Al of which 67.9% is made up by ex. H and 27 5% by ex. Al. Ex. H was found to be the most reliable predictor for all the elements investigated, exceptions being Mn (total) and Fe (extractable) where titratable acidity was the best. Extractable Pb, Zn, Cu and Ni are significantly related to total carbon contents. Pattern of extraction from Ao horizons indicated a more consistent trend of high Pb and Cu extraction (particularly Pb) than Zn and Ni, in terms of their total contents. This appears to be a significant deviation from the trend obtained in mineral soils, considering identical extractant, soil to extractant ratio and equilibration time in both cases.