The humus state of initial soils under forest canopy on tailings of oilshale quarries

摘要

The humus composition of newly formed soils (Rendzinas and Calcareous Regosols) on stony tailings of oil shale quarries in the northeastern part of Estonia has been studied for thirty years. These soils develop under the canopies of pine, alder, larch, and birch forests. They are characterized by the moder type of forest litter and the humus profile (A-AC) with a thickness of 20-25 cm. The fulvate-humate type of humus contains a considerable portion of insoluble residue, including humus-containing fragments of the Kukruze oil shale (kukersite). The organic matter of plant origin has a relatively high solubility and consists of humus complexes with sesquioxides, calcium fulvates, and some other organic compounds firmly bound with the mineral matter of tailings.