The sources, uptake, and assimilation of nitrogen by plants has a history that dates from the time of the ancient Greeks, and the elucidation of the interlocking questions occupied some of the finest philosophical and scientific minds of Europe for considerably longer than two millenia. Current acidic precipitation, containing a significant amount of nitrogen, has again focused attention on the role of precipitation nitrogen in plant nutrition. THAT CONTEMPORARY precipitation in industrial nations is 10 to 20 times more acidic than prior to 1940 and that a significant fraction of the hydrogen ions are derived from nitric acid (Likens et al., 1975; Galloway and Likens, 1981) have occasioned renewed interest in the role of precipitation as a source of assimilable nitrogen. The topic is far from new; ancient agriculturists knew that soils lost fertility over time in cultivation and that they were restored by annual inundations of the flood plains along the Nile, Tigrus, Indus, and