Technical Abstract: The root-restricting layers present in most Southeastern soils prevent adequate root growth into the soil profile. Reduced root elongation contributes to temporal drought stress which annually limits yield potential in this region. Many farmers combat this layer of soil by annually subsoiling, usually to a depth of 25-40 cm. However, the depth of this root-restricting layer varies greatly from field to field and also within the field. Knowledge about the variation of the depth of this layer will help to determine if application of a uniform tillage depth is the most effective method of soil compaction amelioration. A tractor-mounted multiple-probe soil cone penetrometer was used to determine the depth of the root-impeding layer in several fields in Alabama and Mississippi. The root-restricting layer was found to vary greatly in most fields. For one field in northern Mississippi, measurements of hardpan depth were found to vary mainly due to traffic effects, but were also found to be sensitive to soil moisture. The depth of hardpan was also found to be somewhat spatially dependent, and the semivariogram was fitted reasonably well by a spherical model. This spatial dependence in the depth of hardpan in this Southeastern field potentially indicates that applying tillage to a uniform depth to an entire field in this region could result in excessive expenditures of tillage energy.