Effect of soil inundation on its properties in the Region of Swiecko during summer flooding

The present experiments were earned out pn the soilrf of the Rybocice polder near Swiecko, which was purposefully flooded with waters of the Odra river during the summer flood of' 1977 that causet complete destruction of crops and meadow sward. The flooded areas remained under water for more than 30 days. The dominant soils found in this area are river alluvial soils (Fluvi- sols) of varying texture. Rceause of their location and poorly operating drainage system, the discussed soils are periodically too wet by nature or water-logged. In the spring (March/April) of 1998 the ground water table occurred at the depth of 30 cm on damaged grasslands and at 90 cm on some arable Holds. The content of organic carbon ranged from 0.7 to 3.2% in horizon A with depth of approximately 30 cm. Soil reaction was found to vary considerably - from pH (KCI) 4.2 to pH 7.6. Long purposeful inundation with flood waters was not found to have caused significant negative effects on chemical properties of the examined soils. No noticeable contamination with heavy metals (Pb„ Cu, Zn, Cd, Cr and Mn) or polieyclic aromatic hydrocarbons (PAH) was observed. Bulk density in this region, without any treatment from the period of flooding to the spring of 1998 was approximately 1.60 Mg/m3 as compared with 1.40 Mg/m3 on the field cultivated (ploughed) in spring and sown with spring cereal. The mean crop yield in 1998, when appropriate agro-techniques were applied, did not vary significantly from the long-term averages.