Irrigated Corn Yield Response to Water

ABSTRACT IRRIGATED corn yield response to water deficits, water-yield functions, and potential for limited irriga-tion were evaluated during a 3-yr level border field study at Bushland, TX (Southern High Plains). Seasonal evapotranspiration (ET) by treatments irrigated for high yields was 66.7 to 78.9 cm, seasonal irrigation water re-quirements were 40 cm, grain yields were 9,520 to 10,850 kg/ha, and seasonal water-use efficiencies were 125 to 146 kg/ha-cm. Water deficits reduced average grain yields by 172 to 287 kg/ha-cm and average seasonal water-use efficiencies by 67 to 94 percent below the ade-quate water-high yield treatment. The threshold seasonal ET for beginning of grain yield was about one-half of seasonal ET for high yields. The relationship of ET and grain yield was compared with results from other studies. Because of sensitivity of corn to plant-water stress in the climate of relatively high evaporative demand in the Southern High Plains, we concluded that limited irriga-tion of corn should not be practiced.