Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 1998
Publication Date: N/A
Technical Abstract: Winter wheat is used as a winter forage for stocker cattle throughout the Southern Great Plains. Planted in early September to mid October, winter wheat can provide forage from mid November until mid March, if the wheat is grown for grain, or until early May, if the wheat is grazed out. In either case the field is left fallow until replanted in the fall. Pigeonpea, an annual legume, has been suggested as a possible summer forage to be planted following winter wheat. This would provide a high quality forage to supplement summer grassland pastures. However there is a concern that sufficient soil water would be unavailable to successfully crop both winter wheat and pigeonpea. The EPIC model was used to determine the impact of winter wheat-pigeonpea rotation on soil water resources and chemical movement. Two 10-year periods were simulated using historical climate data. A dry (688 mm) and wet (935 mm) period were selected from a 40-year period with a mean annual precipitation of 800 mm. As expected there was an increase in runoff (96%) and soil loss (32%) between the dry and wet periods. During the wet periods percolation increase by 96% which increased the movement of agrochemical into the soil profile. However, simulations indicated that only 1% of the applied material was loss. Impact of the double cropping in dry periods on total crop production is still under evaluation.