ABSTRACT

Field experiments were established at the University of Arizona Marana and Maricopa Agricultural Centers as part of a cotton/small grain crop rotation conservation tillage project. In the 2002 cotton season, no-till planting of cotton into a dead barley cover or barley stubble, and elimination of cultivation for weed control greatly reduced the number of cultural operations required to grow a cotton crop. Adequate cotton weed control was achieved in reduced tillage systems using only postemergence herbicides, and a computerized weed-sensing, automatic spot spray technology reduced the amount of spray volume and herbicide used to control weeds. The reduction in herbicide spray volumes was more pronounced in cotton that had been planted into a thick layer of barley cover crop residues than in cotton that had been planted after a barley grain crop. Cotton yields in conservation tillage systems were similar to, or slightly lower than, yields in conventional tillage systems, and early cotton planting into barley cover crop residues tended to outyield cotton planted late following a barley grain crop. Solum barley was successfully planted on existing beds after shredding cotton stalks without tillage using a John Deere 1560 no-till grain drill, reducing costs associated with complying with pink bollworm control regulations.