NITROGEN ACCUMULATION IN SURFACE HORIZONS OF MOORLAND PODZOLS - EVIDENCE FROM A SCOTTISH SURVEY

Composite samples of L/F/H horizons from Calluna moorland peaty podzol profiles, derived from granites or granitic tills, have been collecte d from all over Scotland on a 20-km grid basis. The sites were all in the altitude range 200-500 m with a slope from 5-45 degrees. At low to moderate total N and NH4+ deposition (i.e. less than or equal to 9 an d less than or equal to 4 kg ha(-1) year(-1), respectively), total soi l N and soil C:N ratio increased almost linearly with atmospheric N de position. The N accumulation appears to be related to N deposition and to the effect of acidification upon organic matter accumulation rate, with C accumulating relatively much faster than N, to increase the C: N ratio at sites with low to moderate N deposition. At total N or NH4 deposition values >9 and 4.0 kg ha(-1) year(-1), respectively, the C: N ratio declined with increasing N deposition.