Morphology and selected properties of alluvial soils in the Odra River valley, SW Poland

The aim of the research carried out in the middle Odra valley, SW Poland, was to demonstrate the diversification of the morphology and selected properties of alluvial soils used for agricultural purposes and to assess their changes in the conditions of river regulation. The research was carried out in the low valley of the Odra River in its middle course downstream from Wroclaw. Four soil profiles were exposed on the right bank of the Odra River on the Holocene floodplain terrace. Two profiles were located in the embanked zone used as grassland, and next two profiles were located outside the embankments in the areas used as arable lands. Soils were described, sampled and analyzed using the standard procedures in soil science. The studied soils differed in the morphological features of individual genetic horizons, the location of the groundwater table, the extent and intensity of redoximorphic features, as well as the depth and stratification of the alluvial parent material. This was reflected in the classification: Eutric Fluvic Gleysol (Pantoloamic), Eutric Gleyic Fluvic Cambisol (Ochric), Eutric Fluvic Stagnic Cambisol (Ochric), Eutric Stagnic Fluvisol (Katoarenic, Ochric, Brunic). In the area of this research, the effects of terrain micro-relief former meandering of the river are clearly visible, which is manifested by the heavier texture of the soils situated presently close to the river and lighter texture of soils located further away. The deep occurrence of the groundwater table in soils located in the slightly higher situated sites results in a lowering of vertical range of gleyic properties and their replacement with stagnic properties in the middle part of the soil profile. The change of the water regime contributed to the increase of biological activity, and thus the development of the cambic horizon. The transformation of alluvial soils used as permanent grassland into arable soils causes not only a decrease in the soil organic carbon content in the soil, but also a decrease in the unit sorption capacity of humus compounds.