Specjacja fosforu w leśnych glebach glejobielicowych terasy nadzalewowej Słupi

The studies focused on phosphorus speciation in Gleyic Podzols of the supra−flood terrace of the Słupia River, south from Słupsk (N Poland). The content and within profile distribution of phosphorus were considered in the context of parent material origin and the influence of podsolization, high groundwater level, forest vegetation and vicinity of the town. Four soil profiles representing Gleyic Albic Ortsteinic Podzols and Umbric Gleyic Albic Ortsteinic Podzols developed from aeolian sand were described. Samples were taken from distinguished horizons and physical and chemical properties were analyzed using standard procedures. Sequential extraction of phosphorus was performed by the method of Hedley et al. [1982]. The soils were characterized by strong acidic reaction, high abundance of organic matter and low degree of mineral substrates weathering. Profile distribution of free iron oxides was typical for Podzols. The content of total phosphorus in parent materials varied from 142.2 to 365.0 mg/kg, whereas in solum from 103.0 to 1035.6 mg/kg, reaching the highest values in B horizons and the lowest in E horizons. The noted concentration was high as compared to the soils of the same type within the area of Poland. Increased phosphorus concentration can be caused by the influence of high groundwater level and vicinity of the town, as a source of biogenic substances. The predominance of residual fraction in solum evidences young age of the studied soils, which is confirmed also by the results of thermoluminescence dating. Profile distribution patterns of total phosphorus and its fractions reflects the influence of groundwater, vegetation and soil−forming processes in turnover of this element. The results confirm also strong linkage between iron and phosphorus in the soils.