Effect of nitrification inhibitor on nutrient composition of winter wheat forage 1

Winter wheat (Triticum aestivum L.) is an important source of forage for cattle in the southern Plains. While high in quality, wheat pasture is prone to cause thousands of cattle deaths annually from nitrate poisoning, bloat, and wheat pasture poisoning, a syndrome of unknown cause. A large portion of the stocker cattle deaths on nitrogen fertilized pastures occur from unknown causes that appear to be related to forage composition. The objectives of this study were to determine seasonal trends in nutrient composition and to determine the effect of nitrapyrin, a nitrification inhibitor, on the change in nutrient composition of wheat forage over winter. The wheat was planted the last week of August on a Pullman clay loam soil (fine, mixed, thermic Torrertic Paleustol). Clip samples were collected periodically and analyzed for nutrient composition. Nitrogen, phosphorus, and potassium concentrations of the wheat forage varied during the season. Levels tended to be highest with the onset of growth and to decline as growth was decreased by cold weather. Nitrapyrin did not affect the concentration of any of the nutrients examined in the wheat forage. Concentration of nutrients, other than potassium, tended to be highly correlated with each other in both years of the study.