A study of some brigalow soils based on trace-element profiles

Abstract

Evidence indicative of layering in the original parent material of a soil can be obtained from trace-element profiles. Some of the layers detected by this means in the parent materials of the brigalow soils examined were not apparent in the field. Trace element profiles also provided confirmatory evidence for the occurrence of a buried soil. The present alkaline-acid boundary of brigalow soils with acid substrata frequently did not coincide with a layer interface, and two distinct levels of concentration of pH-sensitive trace elements were found in the alkaline layer of some of these soils. These observations are compatible with movement of the alkaline-acid boundary during pedogenesis. Of the elements boron, cobalt, copper, gallium, manganese, molybdenum, nickel, lead, vanadium, and zirconium, all but cobalt, manganese, and nickel, which were pH-sensitive, had profiles that were typical of grey and brown soils of heavy texture. In addition, the average silt-plus-clay profile of the brigalow soils examined was almost identical with that of typical soils of this taxonomic group. These results support the conclusion from field observations that, apart from reaction, brigalow soils are mostly typical grey or brown soils of heavy texture.