Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2003
Publication Date: November 1, 2003
Citation: BUSSCHER, W.J., BAUER, P.J. SOIL STRENGTH, COTTON ROOT GROWTH AND LINT YIELD IN A SOUTHEASTERN USA COASTAL LOAMY SAND. SOIL AND TILLAGE RESEARCH. 2003. v. 74.p. 151-159. Interpretive Summary: For years, recommendations in the southeastern Coastal Plains have been to deep till annually to break up a subsoil hardpan that restricts root growth. In recent research, annual deep tillage, or even biannual deep tillage in the case of double crops, has been directly correlated to lower soil strengths and higher yields of corn, soybean, and wheat. The objective of this study was to see if the same relationships would hold true for cotton. Cotton was grown in wide, 0.96-m (38-in.) rows on a Norfolk loamy sand in four-row plots that were 15.5-m (50-ft) long. Plot treatments consisted of surface tillage with a disk or none, deep tillage with a forward-angled straight-shanked subsoiler or none, and rye winter cover crop or none. Treatment wheel tracks and row positions were maintained from year to year by centering tillage, planting, and harvesting equipment within plots. Root growth measured in early August was correlated to soil strength; it increased as mean or maximum soil strength decreased. Cotton lint yield was not related to either root growth or soil strength. Lack of correlation between yield and soil strength (tillage treatment) may have been the result of management practices that employed a small (3-m or 10-ft wide) disk in surface-tilled plots and maintained traffic lanes in all plots. These practices would help prevent re-compaction. These results indicate that deep tillage less than once a year might be a viable production practice for cotton grown in traditionally wide (0.96-m or 38-in.) rows on a Coastal Plain loamy sand soil. The blanket recommendation of annual subsoiling for growing cotton on Coastal Plain soils should be reconsidered by researchers and practitioners.
Technical Abstract: Inverse linear relationships between soil strength and yield in Coastal Plain soils that have subsurface genetic hard layers have been developed for corn (Zea mays L.), soybean (Glycine max L. Merr.), and wheat (Triticum aestivum L.) grown under management systems that include annual or biannual non-inversion deep tillage. In a field study, we tested this relationship for cotton (Gossypium hirsutum L.) grown in wide (0.96-m) rows hypothesizing that root growth and lint yield of cotton would increase with a decrease in soil strength associated with annual deep tillage or cover crop. Root growth and yield were evaluated for treatment combinations of surface tillage or none, deep tillage or none, and rye (Secale cereale L.) cover crop or none. Root growth increased (r**2 = 0.66 to 0.68) as mean or maximum soil strength decreased. Cotton lint yield was not significantly affected by the treatments. Lack of yield response to tillage treatment may have been the result of management practices that employed a small (3-m wide) disk in surface-tilled plots and maintained traffic lanes both of which help prevent re-compaction. These results indicate that less than annual frequency of subsoiling might be a viable production practice for cotton grown in traditionally wide (0.96-m) rows on a Coastal Plain soil (Typic Kandiudult). Annual subsoiling, a practice commonly recommended and used, should not be a blanket recommendation for growing cotton on Coastal Plain soils.