renewed acidification after soil liming (reacidification) related to ammonium nitrate (AN) and calcium nitrate (CN) fertilisation in three long-term grassland experiments (started in 1981) have been performed. The experiments were set up in randomised blocks in 4 repetitions in 1981, and were localised in the Mazowieckie voivodeship. The soils under the experiments differed in their physical and chemical properties. Lime (CaCO₃) was used once directly on the sward, at the beginning of the experiments in doses related to hydrolytic acidity levels I Hh and 2 Hh. Two doses of nitrogen (N₁ – 120, N₂ – 240 kg/ha) in the AN form, and since spring 1992 in CN form were used. Phosphorus and potassium were applied at constant doses. The pH_KCl level of each 5 cm soil layer down to 25 cm depth from each fertilising treatment was measured. The recognition of specific dynamic of acidification and reacidification in the separate 5 cm layers, on the background of different soil properties, doses and forms of nitrogen fertilisers can be helpful in characterising the N transformation processes as well as nutrient consumption by the herbage, the roots mass of which is contained mostly in 0-15 cm upper soil layer.