Cotton Production Systems for Soil and Energy Conservation in Coastal Plain Soils

Cotton growers in the southern USA are facing new production problems that are reducing farm profits and sustainability: 1) herbicide-resistant weeds are spreading throughout the Southeast, 2) thrips are consistently ranked as an important insect pest group Beltwide, 3) the most effective tool for managing nematodes and thrips (aldicarb) currently is only available in the southeastern USA in limited amounts, and 4) fuel costs have increased significantly over the last ten years. An interseeding system was developed at Clemson University that allows planting of cotton into standing wheat, about 2 - 3 weeks before wheat harvest. This system, which combines benefits of crop residue and minimum tillage operations, has the potential to alleviate many of the production problems cited above, while enhancing farm profits and soil properties. Crop residue associated with the interseeding production system reduced weed populations and required significantly less herbicide inputs compared with the conventional system. Columbia lance nematodes populations were reduced in the interseeding system by 83% without an application of nematicide. Populations of thrips were reduced by 74% in the interseeding production system. No differences were observed between the yields from interseeded and the conventional full-season cotton. However, revenues from the interseeding system were higher due to harvest of the wheat crop. In addition, the interseeding system consumed 35% less fuel than the conventional production systems.

Effects of Tillage and Planting Methods on Narrow and Wide Row Cotton Production

Cotton (Gossypium hirsutum L.) is an economically important crop for the Southern United States. The southern US also has a long growing season suitable for double cropping a second crop after small grains;however, the harvest date for the small grains typically occurs after the optimum planting window for cotton which reduces yield potential. A relay intercropping system was developed at Clemson University that allows interseeding of cotton into standing wheat 2 to 3 weeks before harvest with interseeded cotton yields similar to the conventional mono-cropped cotton. Therefore, the objectives of this study were 1) to determine the optimum tillage and planting methods for narrow row (76-cm) and wide row (97-cm) cotton, and 2) to compare narrow and wide row systems for conventional tillage cotton, cotton interseeded into standing wheat, and cotton planted into a terminated wheat cover crop on coastal plain soil. Two replicated tests were conducted to accomplish these objectives. In Study 1, conventional narrow row cotton combined with a deep tillage operation using Paratill yielded 23% more than conventional wide row cotton which had a deep tillage operation with a subsoiler just before planting. There were no differences between the conventional (97-cm row spacing) mono-crop and interseeded cotton yields. In Study 2, there was no significant difference in yield between narrow-row and wide-row cotton for each cropping system during the two years study. Both wide and narrow-row full season cotton had significantly higher yields than interseeded and cover crop planting systems in year two of the study. The two conservation cropping practices, wheat used as a cover crop and interseeding, showed considerable promise for reducing energy requirements, soil erosion, and wind-borne cotton damage associated with bare soil in conventional tillage. This research demonstrates the benefits of interseeding and narrow row spacing for sustainable cotton production in coastal plain soils of the Southern United States.