Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2010
Publication Date: July 15, 2010
Citation: Garbrecht, J.D., Zhang, X.J., Schneider, J.M., Steiner, J.L. 2010. Utility of seasonal climate forecasts in management of winter-wheat grazing. Applied Engineering in Agriculture. 26(5):855-866. Interpretive Summary: In the US Southern Plains, winter wheat is grown as a dual purpose crop, producing a forage crop in fall and winter for grazing and beef production, and a grain crop in spring. In October producers prepare to purchase stockers for grazing, but their decision on how many stockers to purchase depends on anticipated, yet uncertain, levels of forage availability during the upcoming grazing season. Incorporating seasonal climate forecasts into the stocker purchase decision may improve estimates of fall-winter forage production, reveal potential grazing opportunities, reduce climate related risk, and increase profit margins. In this study, computer simulations were used to evaluate the utility of seasonal climate forecasts to influence the stocker purchase decisions. For central Oklahoma, relevant temperature forecasts were issued predominantly late in the grazing season and had limited decision value for selecting a stocking rate. Precipitation forecasts for the early wheat growing season produced useful decision information that could influence the stocker purchase. However, precipitation forecasts with sizable and relevant departure from average occurred, on average, only once every 3 years. It was concluded that current seasonal climate forecasts for central Oklahoma had limited utility for stocker purchase decisions.
Technical Abstract: Winter wheat in the southern Great Plains is a dual crop that produces livestock forage in the fall and winter and a grain crop in the spring. Forage production is highly dependent upon climatic variability, but stocking rate purchasing decisions must generally be made shortly after the fall planting season. Computer simulations were used to evaluate the utility of seasonal climate forecasts for estimating forage-biomass production and optimal stocking rate in central Oklahoma. Three seasonal precipitation and air temperature forecasts issued in August and September by the NOAA Climate Prediction Center for the period between 1997 and 2008 were selected for this investigation. Forecast selection criteria were timing, size and persistence of forecast departures from normal conditions. Relevant temperature forecasts for central Oklahoma were issued predominantly late in the grazing season and had limited decision value for selecting a stocking rate. Precipitation forecasts for the early wheat growing season produced useful decision information that could influence the stocking rate decision. However, precipitation forecasts with sizable and relevant departure from normal only occurred, on average, once every 3 years, and the uncertainties involved in the production and downscaling of these seasonal forecasts were large. It was concluded that current seasonal climate forecasts for central Oklahoma have limited utility for stocking rate decisions. Information on available soil water just prior to stocker purchase rate, and in combination with average seasonal climate expectations, appeared to present better opportunities for risk-based management of winter wheat grazing operations.