Effect of Atrazine, Fertilizer, and 2,4-D on Winter Grazing Preferences of Beef Cows on Northcentral Oklahoma Tallgrass Prairie

Abstract

A good condition, tallgrass prairie experimental area was treated with selected combinations of atrazine, 2,4-D, and NPK fertilizer in spring 1975 and 1976. Crude protein contents in November herbage ranged from 3.4% to 6.3% in treated samples. Untreated herbage contained 5.0% crude protein. Nonlactating beef cows were allowed to graze freely on the area during December, 1976. Utilization of herbage ranged from 43% to 87%. Utilization was greatest on NPK areas (82%), 3.4 kg atrazine + NP areas (85%), and 3.4 kg atrazine + NPK areas (87%). Decreaser species comprised a larger percentage of the total production on atrazine + NP, atrazine + NPK, and 2,4-D + NPK areas than on fertilizer-only areas. Tallgrass prairie treated with atrazine and fertilizer or 2,4-D and fertilizer was preferred by beef cows as winter forage over untreated herbage. There was a 15% increase in herbage utilization for every 1% increase in crude protein in the herbage in December.