The water-physical properties of drained top peat-moorsh soil layers (0–30 cm) were investigated. The measurements were performed on Biebrza 29 site (Kuwasy peatlands, middle basin of Biebrza river valley). The soil moisture content (using TDR and gravimetric methods), pressure head, bulk density and groundwater depth were measured. The relationships between groundwater depth and moisture content (a) and pressure head (b) were proposed. The influence of bulk density on volumetric moisture content of top layers was shown. Based on measured data (pressure head and moisture content) in the field and laboratory conditions the comparison between retention characteristics were presented. The pF curves are very similar in the range observed in the natural conditions. The histeresis (differences between pF curves during sorption and desorption of water ) was observed for the top layer 0–10 cm.

83-92