Soil-forming processes and properties of soils developed from fluvic materials in the headwater river valleys of Middle Pomerania, north Poland: A case study of the Kamienna stream

This study was aimed at characterizing the soil-forming processes and certain properties of soils that have developed from alluvial sediments in the valley of the Kamienna stream, which represents a headwater stream valley deeply incised into the glacial and fl uvioglacial deposits of Middle Pomerania, north Poland. Seven soil pro fi les distributed, along the stream, were described, sam-pled, and analyzed using standard procedures. The parent materials of the soils showed strati fi cation and were characterized by a sandy texture with considerable admixtures of gravel in some horizons. A textural measures indicated their accumulation in a highly dynamic fl uvial environment. The soils showed broad spatial heterogeneity, highlighting the importance of local-scale factors in their formation. The accumulation of soil organic matter (SOM) and gleying from groundwater were identi fi ed as major soil-forming processes, which was re fl ected in soil reference groups dis-tinguished – Eutric Gleyic Fluvisols, Fluvic Gleyic Mollic Umbrisols, Fluvic Gleyic Phaeozems, and Fluvic Phaeozems. The soils were characterized by deep A horizons and high SOM contents. The strati fi cation of these horizons can indicate the partially allochthonous origin of this component, with the headwater bogs in the upper and middle courses of the stream potentially its source. Additionally, the soils were rich in nitrogen, but poor in total P, K, Ca, Mg, Fe, and Al. The generally low contribution of free Fe oxides to the soils indicated poorly advanced weathering, whereas the predominance of amorphous forms of Fe over crystalline could be the effect of high moisture and the SOM content. The soils were also characterized by a low cation exchange capacity, that varied depending on the SOM and clay contents. The soils were generally acidic, with pH values fl uctuating around 5.0–7.0, in most cases, although the predominance of acidic over basic ions was not appar-ent in the sorption complex.