DAYCENT is a biogeochemical model that simulates fluxes of C and N among the atmosphere, vegetation, and soil operating at daily time-steps. Key submodels include soil water content and temperature by layer, plant production and allocation of net primary production (NPP), decomposition of litter and soil organic matter, mineralization of nutrients, N gas emissions from nitrification and denitrification, and CH4 oxidation in non-saturated soils. Model outputs include: daily N-gas flux (N2O, NOx, N2), CO2 flux from heterotrophic soil respiration, soil organic C and N, NPP, H2O and NO3 leaching, and other ecosystem parameters.