As global soil models begin to consider the dynamics of carbon below the surface layers, it is crucial to assess the realism of these models. We focus on the vertical profiles of soil C predicted across multiple biomes form the Community Land Model (CLM4.5), using different values for a parameter that controls the rate of decomposition at depth versus at the surface, and compare these to observationally-derived diagnostics derived from the International Soil Carbon Database (ISCN) to assess the realism of model predictions of carbon depthattenuation, and the ability of observations to provide a constraint on rates of decomposition at depth.