ABSTRACT
In spring 1996 the Finnish Forest Research Institute started a three-year study on the effects of sprinkling infiltration on forest soil, percolation water and vegetation. The aim of the research project was to determine the effects of sprinkling infiltration and surface runoff on soil nutrient concentrations, soil organic matter, the microbiological characteristics of the different soil layers, the nutrient status and growth of the tree stand and understorey vegetation, and the quality of percolation water. The results obtained during the first two years indicate changes in soil hydrology, an increase in the pH and base cation concentration of the soil, and changes in nitrogen cycling and the species abundance of the understorey vegetation. Nitrification increased strongly in the soil on the infiltration plots but, due to the large amount of infiltrated water, the nitrate concentrations in the groundwater were very low (mean value 0.2 mg/l).
