Submitted to: Biological Systems Simulation Group Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 17, 2007
Publication Date: April 17, 2007
Citation: Baumhardt, R.L., Staggenborg, S., Gowda, P., Colaizzi, P.D. 2007. Modeling to evaluate irrigation management strategies to maximize cotton yield and water use efficiency. In: Biological Systems Simulation Group Proceedings, April 11-13, 2007, Beltsville, Maryland. p. 41-42. Technical Abstract: Cotton [Gossypium hirsutum (L.)] grows well under semiarid water stress conditions and is a principal crop on the Southern Great Plains for both dryland and irrigated regimes. Increasing irrigation costs due to high fuel prices and decreasing well capacity of the declining Ogallala Aquifer, compel Southern High Plains agricultural producers to maximize yield while minimizing irrigation input. Our objective was to compare irrigation frequency, amount, and duration effects on simulated cotton yield for two initial soil water contents and identify irrigation strategies for optimum yield. Using GOSSYM and long-term (1958-2000) weather records, we simulated cotton lint yields on a Pullman soil (fine, mixed, superactive, thermic Torrertic Paleustoll) with initial plant available water content of 50 or 100% at planting. Cotton simulations were dryland (rain) and with supplemental deficit irrigation (2.5, 3.75, and 5.0 mm/d) applied using 4, 7, and 10 d intervals for 4, 6, 8, and 10 weeks beginning 37 d after emergence. Cotton yield, evapotranspiration (ET), and water use efficiency (WUE) generally increased with treatments that raised cumulative irrigation such as increasing irrigation rate and duration. For example, yield increased steadily from 222 kg/ha for dryland up to 701 kg/ha for the high 5.0 mm/d irrigation rate with initial soil profile water content of 50%. Because rain plus soil water from the 100% profile water content met much of the cotton water needs, irrigation treatment effects on yields, ET and WUE were diminished. Simulated cotton lint yields increased overall approximately 20% when irrigation frequency decreased from 4 to 10 d intervals due, in part, to decreased soil water evaporation. A spatially weighted mean yield was calculated for irrigation strategies ranging from uniform applications at 2.5 mm/d and variable applications distributed 66% at 3.75 mm/d plus 33% dryland or 50% at 5.0 mm/d plus 50% dryland. For 50% plant available soil water content at planting, simulated cotton lint yields for variable irrigation were approximately 5% greater than the corresponding uniform irrigation strategy.