Location: Water Management and Systems ResearchTitle: Modeling evapotranspiration and crop growth of irrigated and non-irrigated corn in the Texas high plains using RZWQM
|Malone, Robert - Rob|
|Evett, Steven - Steve|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2018
Publication Date: 10/1/2018
Citation: Zhang, H., Malone, R.W., Ma, L., Ahuja, L.R., Anapalli, S.S., Marek, G.W., Gowda, P.H., Evett, S.R., Howell, T.A. 2018. Modeling evapotranspiration and crop growth of irrigated and non-irrigated corn in the Texas high plains using RZWQM. Transactions of the ASABE. 61(5):1653-1666. https://doi.org/10.13031/trans.12838.
Interpretive Summary: Accurate quantification and management of crop evapotranspiration (ET) are critical to optimizing crop water productivity for both dryland and irrigated agriculture, especially in the semiarid regions of the world. State-of-the-science agricultural system models have been widely accepted for developing water management information to increase water productivity in agriculture. However simulation models response to non-irrigated dryland management has not been thoroughly evaluated with weighing lysimeter measurements. ARS scientists compared simulated maize production and crop ET using two water stress factors in RZWQM2 against daily ET measurements from irrigated and non-irrigated weighing lysimeters in Bushland Texas. The results suggest both methods in the RZWQM2 model are promising for simulating crop production and ET under dryland and irrigated conditions.
Technical Abstract: Accurate quantification and management of crop evapotranspiration (ET) are critical to optimizing crop water productivity for both dryland and irrigated agriculture, especially in the semiarid regions of the world. In this study, four weighing lysimeters in Bushland TX, were planted to maize in 1994 with two fully irrigated and two non-irrigated for measuring crop ET. The Root Zone Water Quality Model (RZWQM2) was used to evaluate soil water balance and crop production with potential evapotranspiration (PET) estimated from either the Shuttleworth and Wallace method (PTSW) or the ASCE Standardized alfalfa Reference ET multiplied by crop coefficients (PTASCE). As a result, two water stress factors were defined from actual transpiration (AT) and were tested in the model against the lysimeter data, i.e., AT/ PTSW and AT/PTASCE. For both water stress factors, the simulated daily ET values were reasonably close to the measured values, with underestimated ET during mid-growing stage in both non-irrigated lysimeters. Root Mean Squared Deviations (RMSDs) and relative RMSDs (RMSD/observed mean) values for leaf area index, biomass, soil water content, and daily ET were within simulation errors reported earlier in the literature. For example, the RMSDs of simulated daily ET were less than 1.52 mm for all irrigated and non-irrigated lysimeters. Overall ET was simulated within 3% of the measured data for both fully irrigated lysimeters; under-simulated by less than 11% using both stress factors for non-irrigated lysimeters. Our results suggest both methods are promising for simulating crop production and ET under dryland and irrigated conditions.