GEOLOGIC NITROGEN IN PLEISTOCENE LOESS OF NEBRASKA

Research into the relationship between fertilizer use and water quality in Nebraska has resulted in the discovery of large quantities of geologic nitrate within the deep loess mantle of southwestern and central Nebraska. The NO//3** minus is first encountered at a depth of about 7 m and continues to an unknown depth in excess of 30 m. Nitrate-N values of 25 to 45 ppm characterize the N zone, but values to 87 ppm have been recorded. The NO//3** minus exists only under the leveler uplands of the region; however, it is on this plain that rapid development of irrigation is taking place and it has been shown that the NO//3** minus has been leached from beneath older irrigation sites on the plain.