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Title: Quantifying corn yield and water use efficiency in response to growth-stage based irrigation scheduling and seasonal water availability

Author
item FANG, Q - Qingdao Agricultural University
item Ma, Liwang
item Nielsen, David
item Trout, Thomas
item Ahuja, Lajpat

Submitted to: Advances in Agricultural Systems Modeling
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2014
Publication Date: 12/5/2014
Publication URL: http://handle.nal.usda.gov/10113/60869
Citation: Fang, Q.X., Ma, L., Nielsen, D.C., Trout, T.J., Ahuja, L.R. 2014. Quantifying corn yield and water use efficiency in response to growth-stage based irrigation scheduling and seasonal water availability. Advances in Agricultural Systems Modeling. doi: 10.2134/advagricsystmodel5.c1.

Interpretive Summary: Agricultural system model can help optimize limited irrigation water for higher crop yield and water use efficiency (WUE) across a wide range of climate conditions. In this study, the Root Zone Water Quality Model (RZWQM2) was calibrated for corn growth under a range of irrigation treatments from 2008 to 2011 in northeastern Colorado, USA. The calibrated model was then used to explore corn responses to various irrigation target levels (40%, 60%, 80%, and 100% potential crop evapotranspiration [PETc]) at vegetative and reproductive stages under unlimited, 50 cm, 40 cm and 30 cm seasonal irrigation water available. With unlimited or 50 cm irrigation water, high yield and WUE were obtained from the high irrigation targets for vegetative (100% PETc) and reproductive (80% to 100% PETc) stages. With 40 cm irrigation water, high yield and WUE were simulated at 80%-100% PETc irrigation targets between the vegetative and reproductive stages. With 30 cm irrigation water, however, meeting 100% PETc at the reproductive stage and 60% PETc at vegetative stage achieved highest yield and WUE. Long-term simulation showed that meeting the crop water requirement during the reproductive stage is more important than during the vegetative stage for high yield and WUE under these water limited conditions.

Technical Abstract: A calibrated agricultural system model can help optimize limited irrigation water for higher crop yield and water use efficiency (WUE) across a wide range of climate conditions. In this study, the Root Zone Water Quality Model (RZWQM2) was calibrated for corn growth under a range of irrigation treatments from 2008 to 2011 in northeastern Colorado, USA. Across the four years, the model simulated soil water, evapotranspiration (ET) and grain yield reasonably well with root mean square errors (RMSE) of 0.035 cm3/cm3, 5.65 cm and 354 kg/ha, respectively. Both simulated and measured grain yield and WUE showed similar responses to irrigation treatments. The model was then used to explore corn responses to various irrigation target levels (40%, 60%, 80%, and 100% potential crop evapotranspiration [PETc]) at vegetative and reproductive stages under unlimited, 50 cm, 40 cm and 30 cm seasonal irrigation water available. With unlimited or 50 cm irrigation water, high yield and WUE were obtained from the high irrigation targets for vegetative (100% PETc) and reproductive (80% to 100% PETc) stages. With 40 cm irrigation water, high yield and WUE were simulated at 80%-100% PETc irrigation targets between the vegetative and reproductive stages. With 30 cm irrigation water, however, meeting 100% PETc at the reproductive stage and 60% PETc at vegetative stage achieved highest yield and WUE. Long-term simulation showed that meeting the crop water requirement during the reproductive stage is more important than during the vegetative stage for high yield and WUE under these water limited conditions.