Fig. 6. Average air permeability in and out of wheel tracks in no chisel and chisel plow treatments during 1987 through 1989. Treatments are: WT-IN (in wheel tracks—no chisel plow), WT-OUT (out of wheel tracks—no chisel plow), WTC-IN (in wheel tracks—chisel plowed), and WTC-OUT (out of wheel tracks—chisel plowed). Bars with the same letter are not statistically different at P < 0.10 according to the LSD test.