Optimizing No-Till Cropping Systems Under Limited Irrigation.

Research was conducted for 8 years under sprinkler irrigation at Tribune, Kansas to evaluate limited irrigation in several no-till crop rotations on grain yield, water use, and profitability.  Crop rotations were 1) continuous corn, 2) corn-winter wheat, 3) corn-wheat-grain sorghum, and 4) corn-wheat-grain sorghum-soybean.  Irrigation was limited to 10 inches annually with 5 inches applied to wheat, 15 inches to corn (when in rotation with wheat), and 10 inches to grain sorghum, soybean, and continuous corn.  Crop water productivity and yield of corn was greater when grown in rotation than with continuous corn.  The length of the rotation did not affect grain yield or crop water productivity of grain sorghum or winter wheat.  Continuous corn was generally the most profitable cropping system.  However, changes in prices or yields could result in multi-crop rotations being more profitable, indicating the potential for alternative crop rotations to reduce risk under limited irrigation.