Annual row crop production on the naturally occurring claypan soils of the eastern Great Plains may require field operations during somewhat wet conditions and this potentially results in soil compaction by the commonly-used, heavy-weight tractors and equipment. The objectives of this experiment were (i) to determine if compaction reduced yield and growth of soybean [ Glycine max (L.) Merr.] and grain sorghum [ Sorghum bicolor (L.) Moench] grown on a claypan soil (fine, mixed, thermic Mollic Albaqualf) and (ii) to determine the effect of wheel tracks on selected soil properties and whether chisel plow tillage could reduce wheel-track compaction. Compaction treatments were (i) ALL - all of the plot compacted, (ii) WT - wheel-track compaction, (iii) WTC - wheel-track compaction followed by a chisel tillage operation, and (iv) NO - no intentional compaction. In general, it took until the third year of annually repeated compaction in the ALL treatment to reduce crop growth and yields compared with the NO compaction treatment. Even though nearly half of the area was compacted each year in the WT treatment, few measured crop parameters decreased. In wheel tracks, soil penetrometer resistance and bulk density increased and air permeability decreased compared with out of tracks. However, chisel tillage appeared to eliminate the compaction by reducing penetration resistance and bulk density and increasing air permeability to values similar to out of tracks. Thus, compaction of claypan soils may not often be a problem for producers in this area, especially if occasional chisel tillage is included to remove possible compacted zones.
