Soil Ecology, Research and Technology Centre, West Coast, University of Kiel, Germany.
1Present address: Department of Soil, Water and Environment, University of Dhaka, Dhaka-1000, Bangladesh, E-mail: h.r.khan@bdcom.com.
Nitrous oxide, nitrate and ammonium were analyzed from three sites in the Northwest coastal saltmarsh soils of Germany in order to find out the reason for irregular emissions of nitrous oxide from the soils. Emission rates of N2O within the consequent (1994–95) years were about 0.3 kg ha−1 yr−1 (mean of 110 samples over 2 years, SD = 39) for the Haplic Sulfaquent and about 1.0 kg ha−1 yr−1 for the Typic Sulfaquent, which reflected a low concentration of this gas throughout the soil profiles. But the concentrations in every section of 10 cm towards the depths of 100 cm were almost double than that of the atmospheric concentration (0.30 ppmv); even in a few pockets, the concentrations detected were more than 1.5 ppmv. The maximum mean concentration of N2O throughout the year was measured during June followed by May for Typic Sulfaquent, while the highest concentrations were obtained from both the profiles of Haplic Sulfaquents during May followed by September. The minimum concentrations of N2O in all the profiles were detected during August. A significant positive (r = 0.23*) correlation was obtained (except winter) between the emissions of N2O and their corresponding temperatures. But no correlation was found between the concentrations of N2O (with mean values round the year) at different depths and their corresponding redox potentials, organic matter contents and the concentrations of NH4+-N in soil solution. The low emissions and high concentrations of N2O might be due to the influence of trappings of the N2O in soil pockets, which also resulted in the high concentrations of NO3-N and NH4-N in the soils.
Coastal saltmarsh soils, N2O, NO3-N, NH4-N, redox potential
