The production of artificial snow has increasecl considerably in the last years to meet unstable snow conclitions cluring the ski season. Commonly, ice nucleation active (INA) bacteria are added to the snow to enhance ice crystal formation. Furthermore, salts like ammoniurn nitrate (NH₄NO₃) are appliecl on surfaces of racing pistes to harden the snow. In this stucly, we investigated the influences of these snow additives on soil nitrogen dynamics in alpine soils carrying out snowmelt experiments in a climate chamber.
The soil was sampled in Davos (CH) (46°47'N; 9°49'E), at an elevation of about 1530 m a.s.l. The vegetation cover was represented by a permanent meadow (Trisetetum flavescentis). Plastic columns with a permeable septum at the bottom were fìlled with 100 g of fresh top soil and three types of snow made of (l) deionised water, (2) deionised water with INA bacteria and (3) deionised water with NH₄NO₃. The snow was melted in the climate chamber simulating spring melting rate (3 mm hour^-1). Ammonium and nitrate concentrations were determined before and after the melt treatments in the soil and, after the treatments, in the meltwater and in the soil leachates.
The melting of the snow without additivies and with INA determined a decrease of N-NH₄⁺ and N-NO₃^- soil concentration, while the melting of the snow containing NH₄NO₃ caused an increase. Nevertheless all the meltwaters determined the inorganic N leaching from the soil. The inorganic N concentration in the leachates ranged between 11.1 mgL^-1 and 71.7 mgL^-1 after the melting respectively of snow with INA and NH₄NO₃.
These results suggest that the meltwater of snow with NH₄NO₃ may act as a fertilization. The use of INA seemed not to affect the soil inorganic nitrogen dynamics. All the meltwaters determined the inorganic N leaching from the soil, revealing the importance of spring snowmelting in the soil nutrient dynamics of alpine soils.