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ABSTRACT
Annual row crop production on the naturally occurring claypan soils of the eastern Great Plains may require Held 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.
Abbreviations: ALL, all of plot compacted; LAI, leaf area index; NO, no intentional compaction; WT, wheel-track compaction; WTC, wheeltrack compaction followed by chisel plowing.
DURING recent decades as machinery size has increased to allow farming of larger areas with fewer passes, the weight of tractors and other machinery has also increased. The use of heavy-weight machinery potentially may contribute to compaction of soils and may affect crop growth and production. In the northern Corn Belt, Voorhees et al. (1978) found that wheel traffic increased soil bulk density and penetrometer resistance. High soil strength and bulk density can confine crop root growth (Laboski et al., 1998), alter root distribution (Kaspar et al., 1991), and result in a shallower root system (Oussible et al., 1992). When soil compaction suppresses total root...