Monday, November 5, 2007 - 12:30 PM
33-11

Using EPIC Simulation Model to Manage Irrigated Crops.

Jonghan Ko1, Giovanni Piccinni2, Evelyn Steglich3, Thomas Gerik3, Thomas Marek4, Terry Howell5, and Armen Kemanian3. (1) Texas AgriLife Research, Texas A&M University, 1619 Garner Field Road, Uvalde, TX 78801-6205, (2) Texas A&M University - Soil & Crop Sciences, Texas A&M University TAES, 1619 Garner Field Road, Uvalde, TX 78801-6205, (3) Texas A&M University TAES, 720 East Blackland Road, Temple, TX 79502, (4) Texas A & M University, Texas Agricultural Station, 6500 Amarillo Blvd. West, Amarillo, TX 79106, (5) USDA-ARS, USDA/ARS ., PO Drawer 10 2300 Exper. St. Rd, Bushland, TX 79012-0010

Simulation models are becoming of interest as a decision support system for management of crop water use and assessment of production. EPIC was used to compare measured crop evapotranspiration (ETc) with two methods of estimating ETc and to evaluate the possibility of using it as a decision support tool for irrigation management of crops. We measured actual ETc using a weighing lysimeter, soil water with a neutron probe, and crop yields by field sampling. The measured variables were compared with simulated variables using EPIC (erosion productivity impact calculator). Simulated ETc agreed with the lysimeter, in general, but some simulated ETc was biased compared with measured ETc. Simulated soil water, generally, matched with the measured soil water. Furthermore, EPIC was used to simulate yield differences at various irrigation regimes and management strategies. The effectiveness of using EPIC for irrigation scheduling will be discussed in comparison with using reference ET with growth stage specific crop coefficients. The feasibility of using the EPIC model as a decision support tool for real-time management of irrigated crops will be discussed.