NITROGEN MINERALIZATION AND H-SYLVESTRIS L) FOREST SOIL AS AFFECTED BY LIMING( TRANSFERS IN A SCOTS PINE (PINUS)

H+ production due to N uptake in a mature Scots pine stand subjected t o high NHS deposition was previously estimated to amount to approx. 2. 2 kmol ha(-1) y(-1). The question whether H+ transfers related to N mi neralization (ammonification and nitrification) offset or corroborate this proton production is investigated in the present research. To det ermine N mineralization, soil cores were used of which both ends were closed with layers of ion exchange resin (IER) to prevent influx and e fflux of ions. The effect of liming on N mineralization and the result ing H+ production was investigated in 7 incubation periods of each ca. 8 wk. Because of its high mobility NO3 accumulated in both IER layers at the expense of that in the incubated forest floor and mineral soil . Net N mineralization in the soil cores as a whole amounted to 40 and 77 kg N ha(-1) in 384 d in the control and limed plots, respectively. In both treatments ca. 65% of mineralized N was nitrified. H+ product ion due to N mineralization amounted to approx. 1.2 kmol ha(-1) y(-1) in the control and limed plots. Liming reduced the amount of C in the forest floor, but not forest floor mass, because of an increased mixin g with mineral particles.