Experiments Concerning Diffusion of Nitrogenous Compounds from Healthy Legume Nodules or Roots

Introduction It has long been common knowledge that the cultivation of legumes fol]owed by their addition to the soil increases soil nitrogen. Occasionally also it has been claimed that the soil can be enriched in nitrogen before the death of the legumes and even while they are young and growing vigorously. Most of the recorded experiments on this point have been inconclusive, although sometimes very favorable to the idea. Recently, however, VIRTANEN and his associates (II, Iz, I3, I4, I6, I7, I8, I9, 20, 2I, 22), of Helsingfors, Finland, have carried out a series of rigidly controlled experiments in which they found, not only that nitrogenous compounds are given off into nitrogen-free sand in this way but that enough of such compounds are given off to permit normal development of non-legumes growing in the same sand. This whole subject has recently been reviewed in detail by NICOL (7). The present work is along the same line and represents chiefly an attempt to duplicate their results, mostly with other crop plants and under somewhat different conditions. A preliminary statement was presented at the New York meeting of the Society of American Bacteriologists in December, I935, and an abstract has been published in connection with that meeting. (6).