N.sub.2O, NO, N.sub.2 and CO.sub.2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N.sub.2 O), nitric oxide (NO) and dinitrogen (N.sub.2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N.sub.2 O, NO and carbon dioxide (CO.sub.2). Furthermore, the release of N.sub.2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N.sub.2 O emissions were very low (