Monitoring trace gas fluxes (N₂O, CH₄) from different soils under the same climatic conditions and the same agricultural management

In order to determine the effects of soil type on flux rates of N₂O and CH₄ a 43-months field experiment with undisturbed soil monoliths (2 m height, 1 m² surface) was carried out. Four replicates of three sites in southern Germany were installed in a lysimeter station near Munich. All sites formerly were used as arable fields. The soil types varied in texture, gravel, pH and C and N content. The most important factor in this investigation was to expose the different soil types to the same climatic conditions and to the same agricultural management. Despite of the same conditions differences in both N₂O and CH₄ flux rates were found. Annual N₂O emissions ranged from 0.3 to 2 kg N₂O-N ha^-1a^-1 and CH₄ uptakes ranged from -1.13 to -0.59 kg CH₄-C ha^-1a^-1. N₂O emissions from 'Hohenwart' were 7 times higher than the emissions measured from 'Kelheim'. Furthermore, the CH₄ uptakes from 'Kelheim' were 4.5 times higher than the 'Hohenwart' measurements. Calculating the global warming potential (GWP) as CO₂-equivalents from N₂O and CH₄ fluxes of the investigated soils the atmospherical load from 'Kelheim' was 75±91, from 'Scheyern' it was 468±119 and from 'Hohenwart' it was 611±192 kg CO₂ ha^-1a^-1.