Aeration conditions, as measured by the platinum microelectrode technique, were less favorable in compacted soil layers than conditions known to limit root growth in noncompacted soil. However, reduced root penetration and top growth of tomatoes grown above these compacted layers could not be blamed upon either the high physical resistance to root penetration or poor aeration, individually, because both factors were simultaneously present in the compacted soil layers.

This research was supported by NSF grant GB-84.