Under ideal conditions, subsoiling should be 75 to 80 percent successful in breaking up compacted layers. In some cases, two passes at an angle to each other may be required to completely fracture compacted soil.

The ground should be lifted slightly and remain relatively even behind the subsoiler, without major disruption of surface residues and plants. No more than a little subsoil and a few rocks should be pulled to the surface. If large furrows form behind the subsoiler, the shanks may not be deep enough, the angle on winged tips may be too aggressive, or the travel speed may be too high.

Tests showing that a subsoiling project has been successful include:

• The force required to push a soil penetrometer into the ground, known as the soil index reading, should drop.
• A sharpened steel rod with a handle should be easier to push vertically into the ground.
• Soil bulk density (the weight of a soil sample divided by its volume) should drop after subsoiling.