This report describes the establishment of a long-term, field-scale nitrogen tracing experiment for fertilizer-nitrogen at the Kearney Field Station, Parlier. The isotopic 14-nitrogen (obtained from Los Alamos through the cooperation of the U. S. Atomic Energy Commission) has been found to be an effective, practical fertilizer-nitrogen tracer—and is expected to be of particular value in future experiments toward understanding the cycling of nitrogen through the environment.