Since 1991, plots planted in a corn/soybean rotation were maintained under the following tillage treatments: (i) Conventional tillage (CT) employing fall moldboard plowing following corn, fall chisel plowing or disk ripping following soybean, with spring pre-plant cultivation prior to both corn and soybean, (ii) Conservation tillage (CsT) employing fall chisel plowing or disk ripping following corn, no fall plowing following soybean, with spring cultivation prior to soybean only, and (iii) No tillage (NT) employing no fall tillage or spring cultivation (Hansmeyer et al., 1997).  Plots measured 27.4-m (36 corn rows) wide by 61-m long.