Agronomic and Economic Effect of Irrigation Rate in Corn Produced in Georgia

Abstract

Although the Southeast United States receives an average annual precipitation of 1300 mm, corn ( Zea mays L.) yield is often limited by erratic seasonal distributions. Irrigation studies were conducted from 2001 through 2008 on a Greenville fine sandy loam. Irrigation rates of 100, 66, 33%, and a non‐irrigated control were addressed with the 100% treatment following the recommendations of Irrigator Pro for Corn (model developed by USDA‐ARS). The objectives were to evaluate the effects of irrigation depth on grain yield, WUE, WUE i , and RWUE i of corn produced in the humid southeast region of the United States. The data were separated into 3 precipitation groups to address grain yield, water use efficiency (WUE), water use efficiency for irrigation (WUE i ), and net returns to WUE i (RWUE i ). Irrigation consistently increased grain yield regardless of precipitation amount. The highest grain yield resulted in the 100% treatment in the driest years. In the above average rainfall years, WUE responded inversely to irrigation amount. The highest WUE and WUE i occurred in the 100% irrigation amount during the below average rainfall years at 188.8 and 248.4 kg/ha/cm. The highest RWUE i occurred in the 100% rate in below average rainfall years at $17.62/ha/cm. Because of erratic rainfall distribution and crop stress, corn in the humid Southeast region should be produced with adequate irrigation.