Ammonium, nitrate, and total nitrogen in the soil water of feedlot and field soil profiles

A level feedlot, located in an area consisting of Wann silt loam changing with depth to sand, appears to contribute no more NO₃^- nitrogen, NH₄⁺ nitrogen, and total nitrogen to the shallow water table beneath it than an adjacent cropped field. Soil water samples collected at 46, 76, and 107 cm beneath the feedlot surface generally showed NO₃^- nitrogen concentrations of less than 1 μg/ml. During the summer months, soil water NO₃^- nitrogen increased at the 15-cm depth, indicating that nitrification took place at the feedlot surface. However, the low soil water NO₃^- nitrogen values below 15 cm indicate that denitrification takes place beneath the surface.