Tuesday, November 6, 2007 - 10:15 AM
201-4

Corn Water Use Efficiency with Deficit Irrigation in High Yielding Settings.

Haishun Yang, Agronomy & Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68516-1690, Suat Irmak, Biological System Engineering, University of Nebraska - Lincoln, Lincoln, NE 68583, David Tarkalson, USDA-ARS, 3793 North 3600 East, Kimberly, ID 83341, D.T. Walters, Agronomy & Horticulture, University of Nebraska - Lincoln, Lincoln, NE 68583, and Kenneth Cassman, 279 Plant Sciences, PO Box 830724, University of Nebraska-Lincoln, University of Nebraska, Nebraska Center for Energy Sciences Research, Lincoln, NE 68583-0724.

Deficit irrigation is an irrigation method with water supply less than the amount of crop potential requirement. It saves irrigation water but requires better irrigation management in order to enhance crop water use efficiency and minimize the impact on crop growth and final yield. Using subsoil drip irrigation technology, we conducted a field experiment at two locations in Nebraska to study the impact of deficit irrigation on crop yield and water use efficiency of corn crop. Treatment includes full irrigation based on crop evapotranspiration water loss, 75% and 50% of full irrigation, and dryland (i.e., no irrigation). Irrigation timing was the same in all irrigated treatments during irrigation seasons and the crop was managed using the best management practices. The average yield of full irrigation treatment was 230 bu/acre. In comparison, the deficit irrigation with 75% and 50% of water supplies achieved 95– 99% and 81-91% of the yield of full irrigation, respectively. The higher the natural precipitation during the cropping seasons, the higher the yield. The overall crop water productivity was comparable between the treatments of 75% and 50% irrigation levels, being about 11 bu/inch water in 2005 and 13 bu/inch water in 2006. These values were higher than those of full irrigation and dryland treatments. Under the present high yielding management practices and deficit irrigation using subsoil drip irrigation technology, an average total water consumption of 19.2 inches produced an average corn yield of 226 bu/acre. In contrast, such a total water consumption would produce a corn yield of only 117 bu/acre in the same region two decades ago based on data of published studies. The enhanced crop water use efficiency is attributed to the combined settings of subsoil irrigation with deficit water supply, and improvement in other aspects of crop management and corn hybrids.

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