The mesocosm study was implemented next to and using soil from a field experiment established in 2002 to study the effects of OR additions and N fertilizer on SOM and aggregate dynamics. In the field experiment, OR treatments consisted of a no-input control and three ORs of differing quality, with or without 120 kg fertilizer-N ha 1 season1 added. Thus, three annual OR additions of 4 Mg C ha1 yr1 had been applied to the field treatments prior to mesocosm construction. The field experiment had a split plot design with OR as the main plot while the addition of N fertilizer was the subplot. For further details of the field experiment see