Evaluation of denitrification and decomposition from three biogeochemical models using laboratory measurements of N2, N2O and CO2

For the calculation of miss- ratio between relative treatment differences of measured and ing soil physical parameters (e.g the soil gas diffusion coef- modeled values is 1, if the measured and the modeled values ficients) the respective pedotransfer functions were applied changed with the same magnitude in the same direction. [...] the ratio is bigger than 1, the direction of measured and mod- eled values is the same, but the magnitude of the response is 2.2.3 DNDC bigger in the model than was seen in the measured values. [...] If the value is between 0 and 1, the direction is the same, but the The DeNitrification–DeComposition model (DNDC) is a magnitude of the response is smaller in the model than was complex, widely used process-based model of C and N bio- seen in the measured values. [...] Similarly, in the ryegrass-treated sand, the pat- quite low, and the fluctuation of the values does not always tern and the magnitude of measured and modeled fluxes were follow the changes in the measured values. [...] The slow increase in the denitrifier portance of better simulating microbial dynamics to better biomass that Coup modeled in the silt-loam soil could be the account for the drivers of decomposition, because these ulti- reason that the modeled ansvf is orders of magnitude smaller mately influence the denitrification flux estimations (Philip- than the ansvf measured in another silt-loam soil of simi.