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Simulating Corn, Soybean, and Wheat Yield
and Development
Under Varying Water, Nitrogen, and Planting Date Conditions
with RZWQM and DSSAT
Models
D.C. Nielsen, L. Ma, S.A. Saseendran, L.R. Ahuja
PROBLEM: Dryland agricultural production in the central Great Plains is
diversifying and intensifying from the traditional wheat-fallow system. Corn has
already been added to many rotations, and soybean has been proposed as a
possible alternative crop. Computer models exist which could be used to simulate
growth, development, and yield of both of these crops and others. But these
models have not been adequately calibrated and tested under the limited and
variable water conditions of the central Great Plains in which water stress
frequently affects plant development and yield.
APPROACH: The Root Zone Water Quality Model (RZWQM), and CERES-Maize,
CERES-Wheat, and CROPGRO-Soybean as used in the Decisions Support System for
Agrotechnology Transfer (DSSAT) were calibrated and evaluated using corn,
soybean, and wheat data collected from line-source, gradient-irrigation
experiments and dryland nitrogen fertility experiments conducted at Akron, CO
during several growing seasons. Plant height, leaf area, phenological
development, soil water extraction, water use, dry matter development, and grain
yield were measured and compared with computer model simulation results.
RESULTS: RZWQM simulated corn, soybean, and wheat yield acceptably under
all water availability conditions, and provided somewhat better simulation of
soil water content than the DSSAT models.
FUTURE PLANS: The results of the corn and soybean comparisons made under
varying water availability conditions have been published. The results of the
wheat comparisons made under varying nitrogen variability have been submitted
for publication. The comparisons of the fully irrigated corn made under varying
planting dates are partially completed. Future plans call for region-wide
evaluations of soybean as an alternative crop using the calibrated models, as
well as simulations of various crop rotations and identification of best adapted
crop sequences. The author may be reached via e-mail at:
D.C. Nielsen
or phone: 970-345-2259. |