Influence of Irrigation and Conservation Tillage on Corn and Soybean Yields

Corn and soybean are sometimes grown in sequence in crop rotation systems for the purpose of maintaining higher yields as a result of reduced buildup of crop pests in comparison to monocropping systems. Corn consistently responds to ir rigation, even with short intervals of hot dry conditions be-tween rainfall events. Corn yield losses due to stress in ex cess of 2 bushels per acre per day of stress have been record ed (Rhoads, 1982). Conservation tillage has not been exten sively evaluated under irrigation. One advantage of conservation tillage is a lower fuel re quirement for tillage operations, although, yields may not be different from those obtained with conventional tillage (Forbes et al., 1984).Corn yield in Kentucky with conservationtillage was superior to conventional tillage when planting data was delayed (Herbeck et al., 1984). Soybean varieties responded differently to conservation tillage in Alabama (Granade and Akridge, 1984). Some soybean varieties yielded higher with conservation tillage than with conventional tillage, while others gave the opposite response, and still others did not res pond to tillage variables. Where soil compaction was a pro blem, subsoiling was necessary for soybeans to produce yields with conservation tillage equal to those with conventional tillage (Hovermale, 1984). Furthermore, subsoiling improv ed soybean yield in a conventional tillage system on a soil containing a traffic pan in North Florida (Rhoads, 1978). Objectives of this experiment were to determine corn and soybean yields with different tillage systems for both irrigated and unirrigated cropping systems