A three-depth soil mechanical impedance sensor was developed and tested within a laboratory soil bin. Soil mechanical impedance measurements were made on a continuous basis at three simultaneous depths of 178, 279, and 381 mm from one end of the soil bin to the other using three prismatic tips and three Omega LCF500 load cells. This article discusses how the sensor can be used for measuring the soil mechanical impedances that plant roots encounter during normal growth. The soil sensor also offers excellent opportunities to study the forces acting on soil-engaging implements and subsequent control of tillage tools. Compaction created from past tillage machinery operation and trafficking by heavy equipment sometimes forms “plowpans” in crop fields. These layers, as well as other naturally occurring dense soil layers that impede water infiltration and root penetration, can be located using the three-depth soil mechanical impedance sensor. The laboratory experiment for testing and verifying the device’s performance showed that the three-depth sensor can measure differences in soil mechanical impedance with depth and location and that these impedances correlate well with corresponding cone penetrometer measurements.