The changes of the properties of physical-water post-bog soils on the drainage object meadow Upper Supraśl were analyzed in the work. Investigations were carried out in 1987–2013 on two meadow sites : the moist complex humid (PKWG-B) and the moist complex dry (PKWG-C). In the moist complex humid ground water moves in the range 30–98 cm of the surface and fed root soil layer. In the moist complex dry in the vegetation season the ground water was at a depth bellow 100 cm and its wasn’t available for meadow plants. Unfavorable water conditions in dry site (periodical and lasting longer lacks of the water soil) they caused increased of the bulk density and decrease of the full capacity of the water soil.