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Title: A wheat grazing model for simulating grain and beef production: model evaluation and validation

item Zhang, Xunchang
item TONY, L
item Phillips, William
item HORN, G
item EDWARD, J
item ZHANG, H

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2007
Publication Date: 11/4/2007
Citation: Zhang, X.J., Tony, L.A., Phillips, W.A., Horn, G.W., Edward, J., Zhang, H.L. 2007. A wheat grazing model for simulating grain and beef production: Model evaluation and validation [abstract]. ASA-CSSA-SSSA Annual Meeting, November 4-8, 2007, New Orleans, Louisiana. 2007 CDROM.

Interpretive Summary: Abstract Only.

Technical Abstract: One of the major livestock-cropping enterprises in the southern Great Palins is the grazing of winter wheat (Triticum aestivum L.) in the fall and winter and harvesting grain in June. For example, nearly one million hectares of winter wheat were grazed in 2000 in Oklahoma. Grazing winter wheat during the vegetative phase in addition to harvesting grain in early summer generally yielded greater economic returns compared to a grain-only system. Management of wheat for dual uses is complex because of the complicated interactions and tradeoffs between grain and beef production. In general, more cattle weight gains over longer grazing periods are obtained at the expenses of greater grain yield reduction. A wheat grazing model can be a useful tool for maximizing economic returns of the wheat and beef production systems. The wheat growth module in the Decision Support Systems for Agrotechnology Transfer (DSSAT) model was modified to include an energy-based cattle growth module to simulate dual-purpose winter wheat. The objective of this study is to evaluate and validate the modified model in simulating wheat re-growth and cattle weight gain. Wheat re-growth data from 1992 to 2002 collected at the Chickasha Research Station of the Oklahoma State University as well as cattle grazing data including forage availability and animal weight gain during winter and spring grazing were used to evaluate and validate the model. The preliminary results showed that the model satisfactorily simulated wheat re-growth following clippings. Predictions of cattle weight gain and wheat grain yield will be examined.