Predicting Winter Wheat Grain Yield under Grazed and Non-Grazed Production Systems Jason Lawles

Objectives To evaluate the effects of grazing winter wheat on our ability to predict yield.

Importance of Winter Wheat Grazing in Oklahoma Oklahoma farms are diversified Cow-calf, and wheat production 2003 crop year 6.4 million acres of wheat planted 2002 crop year 6 million acres planted that 60% was grazed, 0ver 3.6million acres 2002 crop year 3.5 million acres harvested

Materials and Methods Experimental Sites: Experimental Design: Hydro, Marshall Grazing Research Station Experimental Design: Split-block with 4 replications 2174, Ok101 wheat variety Pre-plant N rates of 0,56,112, 168 kg ha-1 applied as 34-0-0 Pre-plant P flat rate of 58 kg ha-1 applied as 0-46-0 at Hydro sites

Materials and Methods Experimental Design (cont.): Forage + Grain production system Grain-only production system

Initial soil test data from grazing sites Location NH4-N NO3-N P K pH Hydro Home place 10 19 37 372 5.10 Hydro Barn 9 20 28 300 6.51 Marshall Grazing 20 84 74 409 4.45 Research Station

Field Activities Location Planting date Field size Stocking rate Days grazed lbs removed Ave. daily gain Hydro 9/28/03 143 acres 210lb/ac 115 days 276 lb/ac 2.4lb/day Barn Hydro 9/23/03 154 acres 220 lb/ac 128 days 345 lb/ac 2.7lb/day Home place Marshall 9/3/03 25 acres

Conclusion Harvest data will be collected It will take three weeks to identify variability Grazing should not effect our ability to predict yield mid-season