Initial = data collected from conventionally tilled (CT) continuous corn (CC) plots in 2002, CT2007 = data collected from conventionally tilled plots in 2007, NT2007 = data collected from continuous no-till plots in 2007, ft = total porosity, AS = aggregate stability, POM = sand free particulate organic matter, SPQ = soil physical quality, ΔSPQ = rate of change in soil physical quality and ns = non-significant