Cotton Responses to Tillage and Rotation during the Turn of the Century Drought

Longer rain-free periods are predicted to occur more often in the southeastern United States as a result of global climate change. This nonirrigated field study was conducted from 1997 through 2002, which coincided with the 1998-2002 drought that affected most of the United States. The objective was to determine the effect of rotation and tillage on cotton (Gossypium hirsutum L.) productivity. Treatments in the study were rotation [cotton rotated with corn (Zea mays L.), cotton planted after a rye (Secale cereale L.) winter cover crop, and continuous cotton with no cover crop] and tillage system (conventional tillage and conservation tillage). Two levels of aldicarb [2-methyl-2-(methylthio)propanal O-{(methylamino)carbonyl}oxime] (0 and 1.18 kg a.i. ha(-1)) were also included because of known soil management effects on thrips (Frankliniella sp.) and root-knot nematodes (Meloidigyne incognita). The predominant soil types were Bonneau loamy sand (loamy, siliceous, subactive, thermic Arenic Paleudult) and Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudult). Rotation did not affect cotton yield in any year. Tillage did not affect cotton yield in 1997. Conservation tillage resulted in an average 25% yield increase in cotton lint yield over conventional tillage during the 5-yr drought. Tillage and aldicarb affected both thrips and root-knot nematodes, but lack of interaction among these factors for lint yield suggested that management of these pests was not the predominant cause for the cotton yield increase with conservation tillage. Conservation tillage for cotton production could be an important method to help mitigate the effects of climate change in the region if change occurs as predicted.