Since ammonia gas has been highly satisfactory as a nitrogenous fertilizer it is surprising that there is no record of any experimental work on its analogue phosphine as a source of plant phosphorus. Phosphine has many obvious disadvantages; but the fact that it is more than ten times as concentrated as superphosphate, our standard arable phosphatic fertilizer, surely merits some consideration. Commercial handling may not present any more serious problems than did some of the modern phosphorus insecticides.