NITROUS-OXIDE EMISSIONS AND DENITRIFICATION N-LOSSES FROM FOREST SOILS IN THE BORNHOVED-LAKE REGION (NORTHERN GERMANY)

In situ denitrification N-losses and nitrous oxide emissions were meas ured over 12 months from a beech and a drained black alder forest of N orthern Germany. Annual N-losses from the alder forest soil were appro ximately 15 times greater than from the beech forest soil (denitrifica tion: 7.0 vs 0.4 kg N ha(-1) y(-1); nitrous oxide: 4.9 vs 0.4 kg N ha( -1) y(-1), respectively). These results were attributed to the soil mo isture content, and contents of nitrate and water-soluble organic C co mpounds in the alder forest soil being significantly greater than in t he beech forest soil. The ratio denitrification N-losses-to-nitrous ox ide emissions revealed high denitrifier activity in the alder forest s oil while in the beech forest soil nitrification predominated. The tim e course of nitrous oxide emissions and denitrification N-losses on bo th sites were similar and underwent seasonal changes. The best predict or for the emissions of the alder forest soil was the soil temperature (r(2)=0.63 and 0.44 for nitrous oxide and denitrification, respective ly). (C) 1998 Published by Elsevier Science Ltd. All rights reserved.