Limited Irrigation Response of No-till Cropping Systems for the High Plains

Declining ground water is not a new dilemma in Nebraska, however, the drought across the high plains and inter-mountain west the last eight years has magnified the problem in the High Plains Aquifer. Under limited irrigation, less water is applied than is required to meet full evapotranspiration demand and the crop will be stressed. The goal is to manage cultural practices, crop residues, soil moisture and irrigation timing so resulting water stress has less impact on yield. Our objective was to determine the yield potential of winter wheat, corn, dry edible beans and canola that receives water allocations of 4, 8 or 12 inches of irrigation. No-till rotations were initiated in 2005 with each crop present each year. Irrigation scheduling was based on past research and by tracking crop phenology. Yearly precipitation for 2005 to 2007 was 19.46, 12.13 and 9.36 inches (30-year average is 15.5 inches) which represent above average moisture to extreme drought conditions. Relative yields for the three irrigation levels were: 61, 79 and 95% for wheat, 66, 83, and 96% for corn, 64, 82, and 94% for dry bean and 83, 93 and 995 for canola. Data show that even low water allocations (4 to 8 inches per crop) can produce from 60%to 85% of fully irrigated yields. Production functions can help producers decide how to allocate water on the basis of crop productivity and potential economic return.