The effect of sulphur addition and liming on soils in Norway spruce stands

Results are evaluated of the simulated input of sulphur in situ with the parallel application of dolomitic limestone. Soils of the experimental area are classified as acid Cambisols (developed on granodiorite) with an admixture of eolian materials, light-textured and with a low supply of fundamental nutrients. Saturation with basic cations is lower than 10%, pH value of soil (pH/H2O) in the surface humus ranges between 3.8 and 4.2, and in the upper mineral layer between 3.5 and 4.3. Surface humus amounts to about 50 t ha(-1). Sulphur doses were 0-300 kg ha(-1) year(-1) and doses of dolomitic limestone were 2500 or 5000 kg ha(-1). Soil pH increased significantly in the surface humus within the course of 5 years but was insignificant in the mineral soil. Liming resulted in the decrease of leaching of humic acids and improvement of soil saturation with basic cations. Soil solution showed lower acidity, higher conductivity and higher content of Ca and Mg. Leaf analyses showed a slight increase (but not significant) in the concentration of fundamental bioelements. Norway spruce aged 90-95 years exhibited a significantly higher increment of the assimilatory tissue biomass in the beginning. This trend, however, gradually decreased and, finally, ceased. At present, repeated liming is prepared with the aim to create better conditions for the regeneration of stands.