ARS | Publication request: Improving evapotranspiration simulations under water stress with the CERES-Maize crop model

Submitted to: Environmental and Water Resources Institute World Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2012
Publication Date: May 23, 2012
Citation: Dejonge, K.C. 2012. Improving evapotranspiration simulations under water stress with the CERES-Maize crop model. Agricultural Water Management. May 20-24, 2012

Technical Abstract: Limitations on fresh water resources in Colorado, USA, have caused farmers to consider limited irrigation as an alternative to full irrigation practices, where the crop is intentionally stressed during specific growth stages in an effort to maximize yield per unit water consumed, or evapotranspiration (ET). Recent studies have shown the CERES-Maize crop growth model to perform well under full irrigation, but will overestimate ET of corn under limited irrigation management. Local sensitivity of model inputs affecting ET was evaluated, prompting a change to the coefficient that partitions potential ET into plant transpiration and soil evaporation, and more significantly the model code was adjusted to create a dynamic crop coefficient (Kc) as a function of the crop leaf area index. The new model more accurately represents expected ET under full and limited irrigation, for example reducing late-season ET potential from a plant with reduced canopy and closely representing FAO-56 crop coefficient curves under full irrigation. The new model was tested using experimental data, and under limited irrigation showed significant improvement in model error for ET and water use efficiency. reducing late-season ET potential from a plant with reduced canopy and closely representing FAO-56 crop coefficient curves under full irrigation. The new model was tested using experimental data, and under limited irrigation showed significant improvement in model error for ET and water use efficiency.