EN
The research was conducted in a young Scots pine (Pinus sylvestris) plantation located in a dune area of the Toruń Basin (N Poland). The aim of the study was to investigate differences in dynamics of soil water conditions followed different method used for site preparation. The three plots were investigated in the study: belt of soil prepared by a mill, north−facing slope of a dune (FR−N), belt of soil prepared with a mill, south−facing slope of a dune (FR−S) and soil prepared with a plough (furrows) on the ridge of a small aeolian mound (LPZ). On each plot soil samples were taken and soil moisture was regularly measured from April to December of 2013 (the TDR method). The measurements of soil moisture were taken at four depths (3, 10, 25 and 50 cm) at intervals of ca. 2 weeks. Additionally, soil moisture was also measured on 25.08.2015. It was done to determine soil water conditions for a deep summer drought (the measurements were taken twice this day – just before and after rain which turned to be the first since ca. a month). Reserves of soil moisture and shares of water unavailable to plants were calculated for every measure day for each study plot. As a result of higher organic carbon content, values of soil actual moisture as well as reserves of soil moisture were almost regularly higher for belts mixed with a mill than for furrows prepared with a plough (fig. 1, 3). Opposite relation was found, however for the summer drought (tab. 2). This was explained by the higher repellence of rich in organic mater, dried material occurring in belts. On 25.08.2015 much lower improvement of water conditions after rain was also stated for this material than for topsoil in LPZ. Unfavoured soil water conditions for plants occurring in belts in dry periods could explain relatively low dynamics of pine growth revealed for the variant of soil preparation in a previous study. However, it was concluded that a forest mill should be recommended for forestry, because the device much less disturbs topsoil than a plough. Besides, differences in growth parameters of pines followed different methods of soil preparation used before planting decline in next years of a stand growth.