SIMULATING SOYBEAN WATER STRESS EFFECTS WITH RZWQM AND CROPGRO MODELS

Authors: Nielsen, David; Ma, Liwang; Ahuja, Lajpat; HOOGENBOOM, G - UNIVERSITY OF GEORGIA

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2002
Publication Date: 11/1/2002
Citation: NIELSEN, D.C., MA, L., AHUJA, L.R., HOOGENBOOM, G. SIMULATING SOYBEAN WATER STRESS EFFECTS WITH RZWQM AND CROPGRO MODELS. AGRONOMY JOURNAL. 2002. v. 94. p. 1234-1243.

Interpretive Summary: Dryland farmers in the central Great Plains would like to diversify their production systems with a legume. They would like to know the potential productivity of soybean under the variable precipitation conditions in this region. Crop models exist that could be used with existing long-term weather records to determine the yield variability of dryland soybean production. But these models require calibration and validation prior to using for prediction purposes. We calibrated and evaluated two models, the generic plant model from the Root Zone Water Quality Model and CROPGRO- Soybean from DSSAT. After calibration, both models predicted leaf area development, plant height, above-ground biomass, phenology, soil water extraction, crop water use, and seed yield well enough to be used for prediction purposes.

Technical Abstract: Dryland agricultural production in the central Great Plains is diversifying and intensifying from the traditional wheat-fallow system. Currently there is interest among producers to determine whether soybean (Glycine max (L.) Merrill) would be a successful alternative crop to add to rotations. The Root Zone Water Quality Model (RZWQM) and CROPGRO-Soybean have the potential to simulate soybean growth, development, and yield. The models require calibration for soybean grown in the specific environmental conditions of the central Great Plains before any long-term assessments of soybean yield potential under the highly variable precipitation patterns of this area can be made. The objective of this study was to calibrate and test RZWQM and CROPGRO-Soybean for soybean growth, yield, and water use under a range of water stress conditions normally encountered by dryland production systems in the central Great Plains. Data from five experiments, each with four levels of water availability (20 data sets), were used to evaluate the leaf area, plant height, above ground biomass, evapotranspiration, soil water extraction, and yield of soybean. Data from one water level of one experiment was used to calibrate the models, and the other 19 data sets were used as evaluation data sets. A yield susceptibility function was added to RZWQM to account for differences in crop responses to water stress during different growth stages. The models generally estimated the yield to within 10-15% of measured values. The models should be useful tools in evaluating the potential for soybean as an alternative crop in dryland rotations in the central Great Plains.